MODUL PRAKTIKUM PROSES MANUFAKTUR II LABORATORIUM PENGECORAN LOGAM

MODUL PRAKTIKUM PROSES MANUFAKTUR II

LABORATORIUM PENGECORAN LOGAM

KEMENTRIAN RISET TEKNOLOGI DAN PENDIDIKAN TINGGI UNIVERSITAS BRAWIJAYA FAKULTAS TEKNIK JURUSAN TEKNIK MESIN MALANG 2017

PL I PENGUJIAN KOMPOSISI PASIR CETAK

1.1

Tujuan Pengujian Kadar Air

1. Praktikan mengetahui dan memahami persentase kadar air pasir cetak 2. Praktikan mengetahui penguapan rata-rata pasir cetak 3. Praktikan mengetahui laju penguapan pasir cetak

1.2

Pelaksanaan Pengujian Kadar Air

1.2.1 Alat dan Bahan yang Digunakan A. Alat yang Digunakan 1. Moisture Analyzer Alat ini digunakan untuk mengukur kandungan kadar air pasir cetak. Spesifikasi alat : Merk

: Saitorius

Voltase

: 115-230V (AC)

Model

: MA 30

Frekuensi

: 50-60 Hz

Arus

: 3,3 A / 1,6 A

Sample Disk

: Ø 90 mm

Housing Dimensions (WxDxH)

: 217x283x165 (mm)

Net weight

: approx. 5.5 (kg)

Sample weight

: max. 30 g, typical 5–10

Temperature increments

: 5 °C

Measuring Heating Method

: by infrared rays, determination of weight loss

Readability (moisture content)

: 0.01%

Temperature range

: +40 – +160 °C

Laboratorium Pengecoran Logam Jurusan Mesin Universitas Brawijaya

Gambar 1.1 Moisture Analyzer Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 2. Timbangan Elektrik Alat ini digunakan untuk menimbang berat pasir cetak sebelum dan sesudah diukur kandungan kadar airnya. Spesifikasi alat : Merk

: Melter

Frekuensi

: 50-60 Hz

Type

: PJ 3000

Voltase

: 100-120V 80mA /200-240V 45mA

Beban maksimal

: 2100 gram

Dimensi (PxLxT)

: 31x29x6 (cm)

Gambar 1.2 Timbangan Elektrik Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya


3. Cawan Alat ini digunakan untuk wadah spesimen yang akan di masukan pada moisture analyzer. Spesifikasi : Tipe Produk

: Weighing dish

Diameter

: 90 mm

Kapasitas

: 80 ml

Gambar 1.3 Cawan Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya B. Bahan yang Digunakan Bahan yang digunakan adalah pasir cetak sebanyak ....... gr, dengan komposisi : - pasir silika

: ........... %

- pengikat

: ........... %

- air

: ........... %

1.2.2 Urutan Kerja Pengujian Urutan kerja dalam pengujian ini adalah : 1. Ambil pasir cetak kemudian timbanglah seberat 25 gram sebanyak 3 buah sebagai spesimen. 2. Nyalakan Moisture Analyzer dengan menekan tombol ON/OFF sampai terdengar bunyi alarm. 3. Masukkan cawan pertama ke dalam alat penentu kelembapan kemudian panaskan pada suhu 110 oC selama 10 menit. 4. Mengatur temperatur dengan menekan tombol F1 dan tekan F1 kembali untuk menaikkan suhu sampai 110 oC kemudian tekan ENTER 5. Mengatur waktu pemanasan dengan menekan tombol F2 dan tekan tombol F1 untuk mengatur waktu sampai 10 menit kemudian tekan ENTER 6. Tekan ENTER untuk menghilangkan TAR lalu letakkan spesimen di dalam cawan.


7.

Tutup penutup Moisture Analyzer lalu tekan ENTER untuk mengeksekusi.

8.

Catat kandungan kadar air yang terbaca pada alat pengukur tiap menitnya.

9.

Setelah terdengar bunyi alarm, ukurlah berat akhir pasir cetak setelah dikeringkan dengan menekan tombol CF.

10. Ulangi langkah 3 – 9 untuk cawan berikutnya.


DIAGRAM ALIR PENGUJIAN KADAR AIR PASIR CETAK

Gambar 1.4 Diagram Alir Pengujian Kadar Air Pasir Cetak


1.3

Pengolahan Data

1.3.1 Data Hasil Pengujian

Tabel 1.1 Data Hasil Pengujian Kadar Air Berat Spesimen Awal No. ( gram )

Berat Spesimen Akhir ( gram )

Kadar Air ( % )

1. 2. 3. 4. 5. Sumber :

Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya

Tabel 1.2 Hasil Perhitungan Berat Awal No. ( gram )

Berat Akhir ( gram )

Kadar Air (%) ( X )

( X

-X )

( X - X )2

1 2 3 4 5 Σ Sumber :


1.3.2 Perhitungan Data Hasil Pengujian Perhitungan Statistika : - Kadar air rata – rata ( x ) X=

x .............................................................................................................1-1 n


- Simpangan baku (  ) =

 ( x  x)

2

n 1

................................................................................................1-2 

- Simpangan baku rata – rata (  ) 

 =

 n

...............................................................................................................1-3

- Kesalahan relatif (Kr) Kr =

 .................................................................................................................1-4 x

  Kr  100% ....................................................................................................1-5

- Derajat kebebasan (db) = n – 1 .........................................................................................................1-6 t.(  /2;db) ...........................................................................................................1-7 - Interval penduga kesalahan permeabilitas pasir cetak

1.3.2 Perhitungan Data Hasil Pengujian Perhitungan Statistika ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


1.4

Tujuan Pengujian Kadar Pengikat

1. Praktikan mengetahui persentase kadar pengikat dalam pasir cetak 2. Praktikan mengetahui dan mampu menganalisis pengujian kadar pengikat

1.4.1 Pelaksanaan Pengujian Kadar Pengikat 1.4.2 Alat dan Bahan yang Digunakan A. Alat – alat yang digunakan. 1.

Kompor listrik Alat ini digunakan untuk mengeringkan spesimen Merk

: Maspion (tipe 1)

Daya

: 300-600 W

Berat

: 3 Kg

Dimensi (PxLxT)

: 24x22x4 (cm)

Sistem pemanasan dengan elemen koil Bodi plat besi

Gambar 1.5 Kompor listrik Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 2. Timbangan Elektrik Alat ini digunakan untuk menimbang spesimen sebelum dan sesudah dikeringkan. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 1.2 dan penjelasannya).


3.

Panci Digunakan sebagai wadah pasir cetak untuk menghilangkan pengikat dan mengeringkan pasir pada kompor listrik Dengan spesifikasi : Bahan

: Aluminium

Berat

: 400 g

Diameter

: 25 cm

Tinggi

: 14 cm

Tebal

: 1 mm

Gambar 1.6 Panci Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 4.

Gelas Ukur Alat ini digunakan untuk mengukur volume larutan yang dipakai. Dengan spesifikasi : Kapasitas

: 250 ml

Tinggi

: 32 cm

Diameter

: 4 cm

Tebal

: 1,5 mm

Bahan

: Glass


Gambar 1.7 Gelas ukur Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya B. Bahan - bahan yang digunakan. Bahan yang digunakan untuk pengujian kadar pengikat antara lain : - Pasir cetak seberat 100 gr - Larutan NaOH 2,5 % sebanyak 50 ml - Air sebanyak 950 ml

1.4.3 Urutan Kerja Pengujian Urutan kerja pengujian kadar pengikat pada pasir cetak adalah : 1.

Timbang pasir cetak seberat 100 gr sebagai spesimen

2.

Larutkan pasir di dalam 950 ml air pada panci

3.

Tambahkan NaOH 2,5 % sebanyak 50 ml atau sekitar 2,5 gr

4.

Aduk campuran tersebut dan biarkan pasir mengendap selama 5 menit

5.

Buang airnya sebanyak 5/6 dari tinggi permukaan air. Ingat : Jangan Sampai Pasir Ikut Terbuang.

6.

Tambahkan airnya hingga seperti semula dan ulangi langkah kerja 4, 5, 6 dan diamkan selama 5 menit hingga airnya jernih

7.

Panaskan pasir cetak dalam panci dengan kompor listrik pada daya 600 watt.

8.

Aduk pasir hingga kering

9.

Timbang pasir cetak kering tersebut dan catat hasilnya

10. Hitung kadar lempung dengan rumus di bawah ini : Kadar pengikat =

Berat Awal - Berat Akhir x100 % - Kadar Air Rata-Rata ...................1-8 Berat Awal


1.5

Pengolahan Data

1.5.1 Data Hasil Pengujian Tabel 1.3 Data Hasil Pengujian Pengikat Berat Spesimen Awal No (gr)

Berat Spesimen Akhir (gr)

Kadar Pengikat (%)

1 2 3 4 5 Sumber :


Tabel 1.4 Data Hasil Perhitungan Berat Awal Berat Akhir No (gr) (gr)

% Kadar Pengikat (X )

(X -X )

( X - X )2

1 2 3 4 5 Σ Sumber :


1.5.2 Perhitungan Data Hasil Pengujian Perhitungan Statistika : - Persentase kadar pengikat pada spesimen : Kadar pengikat =

Berat Awal - Berat Akhir x100 % - Kadar Air Rata-Rata ................1-9 Berat Awal

- Kadar lempung rata – rata ( X ) X=

.

X ........................................................................................................................1-10 n


- Simpangan baku (  ) 

=

( X  X ) 2 .......................................................................................................1-11 n 1 

- Simpangan baku rata –rata (  ) 

 =

 ....................................................................................................................1-12 n

- Kesalahan relatif (KR) 

 KR = ....................................................................................................................1-13 X   Kr  100% ...........................................................................................................1-14

- Derajat kebebasan (db) = n – 1.................................................................................................................1-15 t(α/2;db) .....................................................................................................................1-16 - Interval penduga kesalahan prosentase kadar lempung pasir cetak x  {t .( 2; db ). }  x  x  {t .( 2 ; db ). } ..............................................................1-17


1.5.3 Perhitungan Data Hasil Pengujian Perhitungan Statistika ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


1.6

Tujuan Pengujian Distribusi Besar Butir Pasir Cetak

1 Praktikan Mengetahui besar butir pasir melalui nomor kehalusan 2 Praktikan mampu menganalisis dan melakukan pengujian distribusi besar butir pasir cetak

1.6.1 Pelaksanaan Pengujian Kadar Air 1.6.2 Alat dan Bahan yang Digunakan A. Alat – alat yang digunakan. 1. Mesin Pengguncang Rotap Alat ini berfungsi untuk menyaring pasir Spesifikasi alat : - Jenis

: Rotap

- Tipe

: VS 1

- Merk

: Retsch

- Voltase

: 220 V

- Daya

: 430 Watt

- Buatan

: Jerman Barat

- Artikel

: 30 40 0010

- No. Serie

: 01849038

- Frekuensi

: 50 Hz


Gambar 1.8 Mesin Pengguncang Rotap Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 2. Timbangan Pasir Elektrik Alat ini digunakan untuk menimbang pasir yang akan diuji. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 1.2 dan penjelasannya). 3. Cawan Alat ini digunakan untuk menampung pasir silika. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 1.3 dan penjelasannya).

1.6.3 Urutan kerja pengujian Urutan kerja pengujian distribusi pasir cetak adalah : 1. Ambil pasir silika seberat 50 gr sebanyak 3 sampel. 2. Susun ayakan dari bawah ke atas dengan tingkat mesh semakin ke atas semakin besar meshnya, kemudian letakkan pada mesin pengguncang Rotap. 3. Letakkan spesimen pasir silika pada ayakan paling atas lalu tutup. 4. Hidupkan mesin pangguncang Rotap selama 15 menit dengan frekuensi getar 50 Hz. 5. Setelah selesai, timbang berat pasir yang berada pada masing-masing mesh. 6. Cari harga Sn dari tiap-tiap mesh yang ada dari tabel-tabel yang terlampir. 7. Hitung besar nomor kehalusan pasir cetak dalam skala FN maupun standar AFS.


DIAGRAM ALIR PENGUJIAN DISTRIBUSI BESAR BUTIR PASIR CETAK

T

Y

Gambar 1.9 Diagram Alir Pengujian Distribusi Besar Butir Pasir Cetak


1.7

Pengolahan Data

1.7.1 Data hasil pengujian

Tabel 1.5 Data Hasil Pengujian Ukuran Mesh No (m)

Berat 1 (gr)

Berat 2 (gr)

Berat 3 (gr)

1 2 3 4 5 6 7 8 9 Sumber :


Rumus yang digunakan untuk mencari nomor kehalusan pasir cetak adalah: AFS Number 

 (Wi . Mi ) ......................................................................1-18  Wi

Dimana : AFS Number = Nomor kehalusan butir pasir standar AFS W

= Berat pasir pada ayakan ke – i

M

= Faktor pelipat untuk ukuran butir ayakan ke – i


Tabel 1.9 Data Perhitungan Spesimen 1 Ukuran Mesh No Us (m)

M

Wn1

(Wn1 . Sn)

1 2 3 4 5 6 7 8 9 Sumber :


Contoh Perhitungan 1 : ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................



M

Wn2

(Wn2 . Sn)

1 2 3 4 5 6 7 8 9 Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya Contoh Perhitungan 2 : ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................



M

Wn3

(Wn3 . Sn)

1 2 3 4 5 6 7 8 9 Sumber :


Contoh Perhitungan 3 : ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


1.7.2 Perhitungan Data Hasil Pengujian Perhitungan Statistika ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


1.8

Pembahasan

................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


PL II PENGUJIAN KARAKTERISTIK PASIR CETAK

2.1

Tujuan Pengujian

1. Agar praktikan mengetahui macam-macam karakteristik pasir cetak. 2. Agar praktikan mengetahui faktor-faktor yang mempengaruhi karakteristik pasir cetak. 3. Agar praktikan mengetahui cara menguji karakteristik pasir cetak.. 4. Agar praktikan mampu menganalisis karakteristik pasir cetak.

2.2.1 Pelaksanaan Pengujian Permeabilitas 2.2.2 Alat dan Bahan yang Digunakan Alat-alat yang digunakan dalam pengujian ini adalah : 1.

Stop Watch Alat ini digunakan untuk mengukur waktu sampai 2000 cc udara.

Gambar 2.1 Stopwatch Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 2.

Sand Rammer Alat ini digunakan untuk menumbuk pasir cetak menjadi bentuk spesimen yang dikehendaki yaitu panjang 5 cm dan diameter 5 cm (luas penampang = 19,625 cm2). Spesifikasi alat : - Tipe

: POU

- Merk

: George Fisher

- Fabr

: 2054

- Buatan

: Jerman Barat


Gambar 2.2 Sand Rammer Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 3. Permeabilitas Meter Alat ini digunakan untuk mengetahui seberapa besar angka permeabilitas dari pasir cetak yang diuji. Spesifikasi alat : - Tipe

: POU

- Buatan

: Jerman Barat

- Fabr

: 1725


Gambar 2.3 Permeabilitas Meter Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 4.

Timbangan Elektrik Alat ini digunakan untuk menimbang bahan dan berat spesimen yang akan digunakan dalam pengujian. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 1.2 dan penjelasannya).

2.2.3 Urutan Kerja Pengujian 1.

Panaskan pasir cetak selama 60 menit dengan temperatur 110 °C

2.

Siapkan 150 gr pasir cetak untuk pengujian ini dengan menggunakan sand rammer,

3.

Buka pelindung orifice dan pilihlah salah satu posisi penunjuk skala yang akan digunakan. -

Tanda biru untuk skala p (Permeabilitas) = 0-50 cm3/menit

-

Tanda merah untuk skala p (Permeabilitas) = 0-500 cm3/menit



Skala p (Permeabilitas) dibaca dari skala merah bagian luar dari pengukuran tekanan




Skala paling dalam menunjukkan tekanan dinamis antara orifice dan spesimen dalam mm kolom air (mm Wh).

4. Memutar keran pada posisi B dan angkat tabung udara ke atas secara perlahan-lahan hingga angka Nol terlihat tepat pada batas tabung bawah lalu kunci pada posisi E, 5. Letakkan tabung spesimen berikut spesimen di dalamnya pada orifice, 6. Putar keran pada posisi A bersamaan mulai menghitung waktu dengan stop watch saat udara dialirkan ke spesimen pasir cetak. Hal ini ditandai dengan tabung udara mulai turun ke bawah, 7. Catat besar p (Permeabilitas) spesimen pasir cetak dengan tekanan yang terbaca pada skala permeabilitas meter saat 1000 cc udara yang sudah terlewatkan, 8. Catat waktu yang dibutuhkan untuk mengalirkan udara sebanyak 2000 cc melalui tabung spesimen pasir cetak yang diuji. 9. Ulangi langkah 1-8 sampai spesimen 3 serta catat data P (tekanan).


DIAGRAM ALIR PEMBUATAN SPESIMEN UJI PERMEABILITAS

Gambar 2.4 Diagram Alir Pengujian Kadar Air Pasir Cetak


DIAGRAM ALIR UJI PERMEABILITAS

T

Y

T

Y

T

Y


T

Y

Gambar 2.5 Diagram Alir Pengujian Permeabilitas


2.3 Pengolahan Data 2.3.1 Data hasil pengujian

Tabel 2.1 Tabel Hasil Pengujian Tekanan (p) No ( mm ka )

Waktu (t)

Panjang (l)

Permeabilitas

( menit )

( mm )

( ml/menit )

1 2 3 4 5 Sumber :


Tabel 2.2 Tabel Perhitungan Permeabilitas No

P ( ml/menit )

( P - P )2

(P-P)

1 2 3 4 5 Sumber :


2.3.2 Perhitungan Data Hasil Pengujian Perhitungan Permeabilitas P

V .H .....................................................................................................2-1 p . A.t

di mana : P

= Permeabilitas ( cm3/menit = ml/menit )

V = Volume udara yang dialirkan ( 1 ml = cm3 ) H = Tinggi spesimen ( cm ) p = Tekanan fluida yang mengalir ( 10 gr/cm² = 10 cmKa )


A = Luas penampang spesimen ( cm2 ) T

= Waktu yang diperlukan untuk mengalirkan 1 liter udara (menit)

Perhitungan Statistika - Permeabilitas Rata-rata ( P ) : P=

ΣP ............................................................................................................2-2 n

- Simpangan Baku ( δ ) :

( P  P ) 2 ..............................................................................................2-3 n 1



- Simpangan Baku Rata-rata ( δ ) : δ=

δ ................................................................................................................2-4 n

- Kesalahan Relatif ( Kr ) : Kr 

 .............................................................................................................2-5 P

  Kr  100 % .................................................................................................2-6

- Interval Penduga Kesalahan : P - { t ( α/2 ; db ) . δ } < P < P + { t ( α/2 ; db ) . δ } ..........................................2-7

2.3.3 Perhitungan Data Hasil Pengujian  Perhitungan Permeabilitas ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ...................................................................................................................................




Perhitungan Statistika ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................


2.4 Pembahasan ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


2.5

Pelaksanaan Pengujian Kekuatan

2.5.1 Alat dan Bahan yang Digunakan A. Alat yang Digunakan 1.

Universal Strength Machine Alat ini digunakan untuk menguji kekuatan pasir cetak. Spesifikasi alat : -

Merk : Georg Fischer

-

Buatan : Jerman Barat

Gambar 2.6 Alat Penguji Kekuatan Pasir Cetak Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya Keterangan gambar : 01. Main Piston 02. Low Pressure Gauge 03. Pressure Piston Hydraulic Press Hand Operated 04. Handwheel 05. Throttle Reflux Valve 06. Plug In Coupling 07. Compression Insert


2. Locking Plug Kepala penekan untuk uji kekuatan tekan 3. Kepala penekan untuk uji kekuatan geser

Gambar 2.7 (a) Kepala penekan untuk uji kekuatan tekan, (b) Kepala penekan untuk uji kekuatan geser Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 4. Kepala penekan untuk uji kekuatan tarik

Gambar 2.8 Kepala penekan untuk uji kekuatan tarik Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya 5. Sand rammer Alat ini digunakan untuk memadatkan pasir cetak dalam tabung spesimen. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 2.2 dan penjelasannya). 6. Timbangan elektrik Alat ini digunakan untuk menimbang pasir cetak sebelum dibuat spesimen. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 1.2 dan penjelasannya).


7. Cetakan spesimen uji kekuatan geser

Gambar 2.9 Skala alat uji kekuatan pasir cetak Sumber : Laboratorium Pengecoran Logam Jurusan Mesin Fakultas Teknik Universitas Brawijaya B. Bahan yang Digunakan Bahan yang digunakan adalah pasir cetak sebanyak ....... gr, dengan komposisi : - pasir silika : ........... % - pengikat

: ........... %

- air

: ........... %

2.5.2 Urutan Kerja Pengujian A. Urutan Kerja Pengujian Kekuatan Tekan a. Langkah-langkah pengujian tanpa perlakuan panas 1. Ambil campuran pasir cetak seberat 150 gr, lalu buat spesimen uji tekan dengan menggunakan sand rammer (spesimen sebanyak 5 buah). 2. Pasang kepala uji tekan pasir cetak pada alat uji kekuatan pasir cetak. 3. Letakkan spesimen pada kepala uji tekan pasir cetak secara hati-hati jangan sampai rusak. 4. Putar handwheel secara terus menerus dengan putaran konstan dan perlahanlahan hingga spesimen hancur. 5. Baca dan catat besar kekuatan tekan pasir cetak tersebut (lengkap dengan satuannya) pada skala paling luar yang terdapat pada alat uji tekan pasir cetak. 6. Lakukan langkah 1–5 untuk spesimen berikutnya.


b. Langkah-langkah pengujian dengan perlakuan panas Langkah pengujian sama dengan tanpa perlakuan, hanya setelah pasir cetak dibentuk spesimen uji tekan lakukan pemanasan dalam dapur pemanas dengan suhu 110C selama 1 jam. B. Urutan Kerja Pengujian Kekuatan Geser a. Langkah-langkah pengujian tanpa perlakuan panas 1. Ambil campuran pasir cetak seberat 150 gr, kemudian buat spesimen uji geser dengan menggunakan sand rammer (spesimen sebanyak 5 buah). 2. Pasang kepala uji geser pasir cetak pada alat uji kekuatan geser pasir cetak. 3. Letakkan spesimen pada kepala uji geser secara hati-hati jangan sampai spesimen rusak. 4. Putar handwheel secara terus menerus dengan putaran konstan dan perlahan-lahan hingga spesimen hancur. 5. Baca dan catat besar kekuatan tekan pasir cetak tersebut pada skala yang di tengah pada alat uji geser tersebut. b. Langkah pengujian dengan perlakuan panas Langkah pengujian sama dengan tanpa perlakuan, hanya setelah pasir cetak dibentuk spesimen uji geser lakukan pemanasan dalam dapur pemanas dengan suhu 110C selama 1 jam. C. Urutan Kerja Pengujian Kekuatan Tarik a. Langkah-langkah pengujian tanpa perlakuan panas 1. Ambil campuran pasir cetak seberat 125 gr, kemudian buat spesimen uji tarik dengan menggunakan sand rammer (spesimen sebanyak 5 buah). 2. Pasang kepala uji tarik pasir cetak pada alat uji kekuatan pasir cetak. 3. Letakkan spesimen pada kepala uji tarik pasir cetak secara hati-hati jangan sampai rusak. 4. Putar handwheel secara terus menerus dengan putaran konstan dan perlahan-lahan hingga spesimen hancur. 5. Baca dan catat besar kekuatan tarik pasir cetak tersebut (lengkap dengan satuannya) pada skala paling dalam yang terdapat pada alat uji tarik pasir cetak. 6. Lakukan langkah 1–5 untuk spesimen berikutnya.


b. Langkah-langkah pengujian dengan perlakuan panas Langkah pengujian sama dengan tanpa perlakuan, hanya setelah pasir cetak dibentuk spesimen uji tarik lakukan pemanasan dalam dapur pemanas dengan suhu 110C selama 1 jam.


DIAGRAM ALIR PEMBUATAN SPESIMEN UJI TEKAN DAN GESER

T

Y

Gambar 2.10 Diagram Alir Pembuatan Spesimen Uji Tekan dan Geser


DIAGRAM ALIR PEMBUATAN SPESIMEN UJI TARIK

T

Y

Gambar 2.11 Diagram Alir Pembuatan Spesimen Uji Tarik


DIAGRAM ALIR PENGUJIAN KEKUATAN TEKAN

Gambar 2.12 Diagram Alir Pengujian Kekuatan Tekan


DIAGRAM ALIR PENGUJIAN KEKUATAN GESER

Gambar 2.13 Diagram Alir Pengujian Kekuatan Geser


DIAGRAM ALIR PENGUJIAN KEKUATAN TARIK

Gambar 2.14 Diagram Alir Pengujian Kekuatan Tarik


2.6

Pengolahan Data

2.6.1 Data hasil pengujian A. Data Hasil Pengujian Kekuatan Tekan

Tabel 2.3 Data pengujian tanpa perlakuan Kekuatan Tekan No (N/cm2)

_ (X-X)

_ (X-X)2

1 2 3 4 5  Sumber :


Tabel 2.4 Data hasil pengujian dengan perlakuan panas Kekuatan Tekan _ No 2 (X-X) (N/cm )

_ (X-X)2

1 2 3 4 5  Sumber :



B. Data Hasil Pengujian Kekuatan Geser Tabel 2.5 Data pengujian tanpa perlakuan Kekuatan Geser No (N/cm2)

_ (X-X)

_ (X-X)2

1 2 3 4 5  Sumber :


Tabel 2.6 Data pengujian dengan perlakuan panas Kekuatan Geser _ No (X-X) (N/cm2)

_ (X-X)2

1 2 3 4 5  Sumber :



C. Data Hasil Pengujian Kekuatan Tarik

Tabel 2.7 Data pengujian tanpa perlakuan panas Kekuatan Tarik _ No (X-X) (N/cm2)

_ (X-X)2

1 2 3 4 5  Sumber :


Tabel 2.8 Data pengujian dengan perlakuan panas Kekuatan Tarik _ No (X-X) (N/cm2)

_ (X-X)2

1 2 3 4 5  Sumber :


2.6.2 Perhitungan Data Hasil Pengujian A. Perhitungan pengujian kekuatan tekan Perhitungan statistika 

- Perhitungan kekuatan rata-rata ( X ) 

X=

X n

............................................................................................................2-8


- Simpangan baku (  ) 

=

( X  X ) 2 ................................................................................................2-9 n 1 

- Simpangan baku rata –rata (  ) 

 =

 ..............................................................................................................2-10 n

- Kesalahan relatif (KR) 

 KR = .............................................................................................................2-11 X   Kr  100% ....................................................................................................2-12

- Derajat kebebasan (db) = n – 1 .........................................................................................................2-13 t(  /2;db).............................................................................................................2-14 - Interval penduga kesalahan prosentase kadar lempung pasir cetak x  {t .( 2; db ). }  x  x  {t .( 2 ; db ). } .......................................................2-15

Uji T - Tingkat kesalahan

( )

- Derajat bebas

(db)

- Dari tabel t di dapat, t((  /2;db) - Hipotesa : 1. Daerah terima, H0: μ1 = μ2 2. Daerah tolak,

H1 : μ 1 ≠ μ 2 

3. t hitung =



( X1  X 2 ) {( n1  1)12  (n2  1) 22 }(1 / n1  1 / n2 ) n1  n2  2

........................................2-16


2.6.2 Perhitungan Data Hasil Pengujian A. Perhitungan pengujian kekuatan tekan Perhitungan statistika .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. ..............................................................................................................................


B. Perhitungan Pengujian Kekuatan Geser Perhitungan statistika ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. .................................................................................................................................


C. Perhitungan Pengujian Kekuatan Tarik Perhitungan statistika .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. ..............................................................................................................................


2.7 Pembahasan ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


PL III PERENCANAAN PENGECORAN

3.1

Tujuan Pengujian

1. Agar praktikan mampu memahami dan mempersiapkan apa saja yang dibutuhkan dalam perencanaan pengecoran 2. Agar praktikan dapat merencanakan dan membuat cetakan pasir, sistem saluran dan pola. 3. Agar praktikan mampu memecahkan masalah-masalah dalam perencanaan pengecoran

3.2

Pelaksanaan Pembuatan Cetakan Pasir

3.2.1 Alat dan bahan yang digunakan Alat-alat yang digunakan dalam pengujian ini adalah : 1.

Rangka Cetak (Cope dan Drag) Alat ini digunakan sebagai tempat untuk membuat cetakan pasir.

2.

Saluran Masuk dan Saluran Penambah Alat ini digunakan sebagai tempat mengalirnya logam cair dalam cetakan.

3.

Pola Alat ini digunakan untuk membuat bentuk/rongga cetakan benda cor.

4.

Papan Datar Alat ini digunakan sebagai tempat landasan dalam membuat cetakan.

5.

Kamera Digunakan sebagai alat dokumentasi.

Bahan yang digunakan adalah pasir cetak dengan komposisi pasir silica, bentonit, dan air serta : 1. Pasir silika halus 2.

Grafit


3.2.2 Urutan Kerja Pembuatan Cetakan Pasir Langkah-langkah dalam pembuatan cetakan adalah : 1. Aduk pasir cetak dengan komposisi tertentu dengan tangan agar campurannya merata. 2. Letakkan pola cetakan pada papan datar berikut drag, kemudian masukkan pasir cetak dan padatkan hingga rata dan padat memenuhi drag. Ratakan permukaan pasir cetak bagian atas dengan papan kayu. 3. Balik drag, kemudian taburi pola dengan grafit. Sedangkan untuk pasir cetak taburi dengan pasir silika halus agar pola dan pasir cetak tidak lengket, kemudian ratakan dengan kuas secara hati-hati. 4. Letakkan cope di atas drag, kemudian letakkan saluran turun dan saluran penambah. 5. Isi cope dengan pasir cetak, padatkan dan selama pemadatan jangan sampai saluran turun maupun saluran penambah berubah posisinya. 6. Ambil saluran turun, saluran penambah dengan hati-hati jangan sampai pasir ikut terangkat. 7. Angkat cope dari drag secara hati-hati, kemudian ambil polanya. Apabila masih terjadi kerusakan, maka tempatkan kembali pola ke posisi semula dan isi bagianbagian yang rusak tersebut dengan pasir cetak. 8. Taburi rongga bekas pola tersebut dengan grafit, kemudian ratakan dengan kuas secara hati-hati. 9. Letakkan kembali kup di atas drag, kemudian cetakan yang sudah jadi tersebut letakkan di tempat yang aman dan datar, di atas cetakan beri pemberat.

 PERHATIAN !!!!!! 1. Sekali cavity rusak akan sulit untuk diperbaiki dan pembuatan cetakan pasir harus diulang kembali. Oleh karena itu berhati-hatilah ketika menggerakkan rangka cetak. 2. Urutan kerja praktikum di atas dapat berubah sesuai dengan bentuk benda yang akan dicor.


Gambar 3.1 Rangka Cetak Sumber : Tata Surdia (1996: 95)

Gambar 3.2 Prosedur Pembuatan Cetakan Pasir Sumber : (Tata Surdia 1996 : 94)


Contoh Pola : 1. Pola Plat Pasangan

Gambar 3.3 Pola Plat Pasangan Sumber : Mechanical Inventions (2017) 2. Pola Cetakan Sapuan

Gambar 3.3 Pola Cetakan Sapuan Sumber : Iron Foundry (2010) 3. Pola Cope dan Drag

Gambar 3.4 Pola Cope dan Drag Sumber : Mechanical Inventions (2017)


3.3 Rancangan Cetakan Pasir dan Pola 3.3.1

Sistem saluran

................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


3.3.2 Gambar Cetakan Pasir dan Pola (Terlampir)

3.4 Studi Kasus dan Pemecahannya 3.4.1 Kasus pada cetakan pasir yang dibuat ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


3.4.2 Pemecahan masalah ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


PL IV PENUANGAN LOGAM DAN INSPEKSI

4.1

Tujuan Praktikum

1.

Praktikan dapat mengetahui dan memahami definisi beserta macam pengecoran logam

2.

Praktikan dapat mengetahui macam cacat coran beserta penyebab dan pencegahannya.

3.

Praktikan mampu menganalisis hasil coran beserta solusi pada cacat coran

4.2

Pelaksanaan Penuangan

4.2.1 Alat dan Bahan yang Digunakan Alat yang digunakan dalam praktikum ini adalah : 1. Stopwatch Digunakan untuk menghitung waktu penuangan. (Untuk spesifikasi dan gambar dapat dilihat pada gambar 2.1 dan penjelasannya). 2. Kamera Digunakan sebagai alat dokumentasi.

4.2.2 Urutan Kerja Penuangan Logam Praktikum ini dilakukan dengan urutan kerja sebagai berikut : 1. Panaskan dan cairkan aluminium di dalam dapur listrik di atas titik cairnya ( 900C). 2. Pakai pelindung tubuh, sarung tangan dan kaca mata sebelum mengambil logam cair dari dalam dapur. 3. Siapkan cetakan pasir dan dekatkan pada dapur. 4. Sebelum mengambil logam cairnya, maka bersihkan dulu terak-terak di atasnya dengan alat pengambil terak. 5. Setelah bersih dari terak, ambil logam cair dengan ladel secara hati-hati, kemudian tuangkan logam cair kedalam cetakan pasir melalui saluran masuk. 6. Selama penuangan, jaga kecepatan tuangnya jangan sampai terlalu cepat atau terlalu lambat. Gunakan stopwatch untuk mencacat waktu penuangan dan hentikan stopwatch ketika logam cair sudah muncul dari saluran keluar. 7. Hentikan penuangan jika logam cair sudah muncul dari saluran keluar. 8. Kembalikan logam cair sisa ke dalam dapur. 9. Bongkar cetakan pasir jika logam sudah dingin. INGAT!!!! Pembongkaran jangan


sampai merusak coran. 10. Amati hasil coran dan analisa permasalahan yang timbul pada hasil coran. Jangan lupa mendokumentasikan hasil coran dengan kamera.


DIAGRAM ALIR UJI PIKNOMETRI

Gambar 4.1 Diagram Alir Pengujian Piknometri


4.3

Hasil Coran

A. Benda Cor I

Gambar 4.2______________________________________ Sumber : Dokumentasi Pribadi B. Benda Cor II

Gambar 4.3______________________________________ Sumber : Dokumentasi Pribadi


4.4

Pembahasan

................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. .................................................................................................................................................


MODUL PRAKTIKUM PROSES MANUFAKTUR II LABORATORIUM PENGECORAN LOGAM

Recommend Documents