PENGARUH UKURAN PASIR TERHADAP POROSITAS DAN DENSITAS PADA PENGECORAN ALUMINIUM SILIKON (95% Al- 5% Si) DENGAN METODE PENGECORAN EVAPORATIF
Oleh Dosen Pembimbing
: Arip Sanjaya : Dr.Ir. I Ketut Gede Sugita, MT : Dr.Ir. I Gusti Ngurah Priambadi, MT ABSTRAK
Pengecoran Lost Foam (Evaporative Casting) adalah salah satu metode pengecoran logam dengan menggunakan pola polystyrene foam. Material yang banyak digunakan untuk pengecoran Lost Foam (Evaporative Casting) adalah aluminium. Aluminium memiliki sifat yang unggul dibandingkan dengan material lainnya, namun harus ditambahkan paduan dan heat treatment agar kekuatan dan kekerasanya meningkat. Pengecoran ini menggunakan pasir silika sebagai media cetakan cor. Proses pengecoran seringkali ditemukan cacat, salah satunya adalah porositas dan cacat penyusutan (shrinkage). Penelitian ini dilakukan pengecoran dengan menggunakan cetakan ukuran mesh pasir silika 0,180 mm, 0,250 mm, dan 0,315 mm. Hasil dari cor dengan memvariasikan cetakan ukuran mesh pasir didapati nilai porositas dan densitas. Cetakan ukuran 0,180 mm didapati nilai porositasnya 691,08434 atau 6,91% dan nilai densitas 2.578,01418 gram/cm3. Cetakan ukuran 0,250 mm didapat nilai porositas 690,41213 atau 6,90% dan nilai densitas 2.575,51020 gram/cm3. Cetakan 0,315 mm didapat nilai porositas 693,82827 atau 6,93% dan nilai densitas 2.588,23529 gram/cm3. Data hasil penelitian bertujuan untuk mencari nilai porositas seminimal mungkin, dimana dengan memvariasikan ukuran butiran pasir diharapkan cacat yang terjadi minim. Hasil data penelitian di atas didapati hasil cor cetakan ukuran mesh pasir 0,250 mm memiliki nilai porositas yang minim, yaitu 690,41213 atau 6,90 %. Kata kunci : Evaporative casting , mesh pasir, porositas.
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EFFECT OF SIZE OF SAND AND DENSITY ON POROSITY CASTING ALUMINUM SILICON (95% Al-5% Si) WITH CASTING EVAPORATIVE Author Guidance
: Arip Sanjaya : Dr.Ir. I Ketut Gede Sugita, MT : Dr.Ir. I Gusti Ngurah Priambadi, MT ABSTRACT
Lost Foam Casting (Evaporative Casting) is a metal casting method using polystyrene foam patterns. The material used for casting Lost Foam (Evaporative Casting) is aluminum. Aluminium has superior properties compared to other materials, but must be added to the alloy and heat treatment in order to increase the strength and hardness. This casting using silica sand as a medium mold castings. The casting process is often found defective, one of which is the porosity and shrinkage defects (shrinkage). This research was carried out by using a mold casting silica sand mesh size of 0.180 mm, 0.250 mm, and 0.315 mm. Results from the mold cast by varying the size of the mesh sand porosity and density values were found. 0.180 mm size mold was found 691.08434 value or 6.91% porosity and density values 2578.01418 g / cm3. Mould size of 0.250 mm obtained value 690.41213 or 6,90% porosity and density values 2575.51020 g / cm3. Moulds 0.315 mm 693.82827 obtained value or 6.93% porosity and density values 2588.23529 g / cm3. Data from the study aims to find a minimum porosity value, wherein by varying the grain size of the expected defect that occurs is minimal. Results of research data on the results found sand cast molds 0.250 mm mesh size has a porosity value is minimal, ie 690.41213 or 6.90%. Keywords : Evaporative casting, mesh sand, porosity.
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KATA PENGANTAR Puji syukur penulis panjatkan kepada Tuhan Yang Maha Esa, karena atas berkat rahmat-Nya penulis dapat menyelesaikan skripsi yang berjudul “Pengaruh Ukuran Pasir Terhadap Porositas Dan Densitas Pada Pengecoran Aluminium Silikon (95% Al-5% Si) Dengan Metode Pengecoran Evaporatif’’. Penulisan skripsi ini merupakan salah satu syarat mahasiswa untuk memperoleh gelar Sarjana Teknik di jurusan Teknik Mesin. Dalam penyusuna skripsi ini, penulis mendapat banyak bantuan, saran serta bimbingan dari berbagai pihak. Untuk itu penulis mengucapakan banyak terima kasih yang sebesarbesarnya kepada : 1. Bapak Dr.Ir. I Ketut Gede Sugita, MT selaku Ketua Jurusan Teknik Mesin Fakultas Teknik Universitas Udayana. 2. Bapak Dr.Ir. I Ketut Gede Sugita, MT Selaku Dosen Pembimbing I. 3. Bapak Dr.Ir. I Gusti Ngurah Priambadi, MT Selaku Dosen Pembimbing II. 4. Bapak Dewa Ngakan Ketut Putra Negara, ST. MSc Selaku Dosen Pembimbing Akademik. 5. Bapak/ Ibu dosen serta staf pegawai Jurusan Teknik Mesin Fakultas Teknik Universitas Udayana. 6. Keluarga yang selalu mendukung dan membantu dalam perkuliahan hingga penyusunan skripsi. 7. Seluruh sahabat dan kawan-kawan Jurusan Teknik Mesin yang telah membantu dalam penyelesaian skripsi. Penulis menyadari bahwa skripsi ini tentu jauh dari kesempurnaan, oleh karena itu kritik dan saran yang sifatnya membangun sangat penulis harapkan dari berbagai pihak. Sekali lagi penulis mengucapkan banyak terima kasih dan penulis mohon maaf apabila ada kekurangan atau kesalahan dalam penulisan skripsi ini.
Bukit Jimbaran,
Penulis
v
Juni 2016
DAFTAR ISI Halaman LEMBAR PENGESAHAN ................................................................................... LEMBAR PERSETUJUAN .................................................................................. ABSTRAK ............................................................................................................. ABSTRACT ........................................................................................................... KATA PENGANTAR............................................................................................ DAFTAR ISI .......................................................................................................... DAFTAR GAMBAR.............................................................................................. DAFTAR TABEL .................................................................................................. DAFTAR RUMUS .................................................................................................
i ii iii iv v vi viii x xi
BAB I PENDAHULUAN...................................................................................... 1.1 Latar Belakang .................................................................................... 1.2 Rumusan Masalah............................................................................... 1.3 Tujuan Penelitian ................................................................................ 1.4 Batasan Masalah ................................................................................. 1.5 Manfaat Penelitian ..............................................................................
1 2 2 3 3 3
BAB II DASAR TEORI ....................................................................................... 2.1 Teori Pengecoran ............................................................................... 2.2 Metode Pengecoran ........................................................................... 2.3 Pengecoran Lost Foam ( Evaporative Casting ) ................................. 2.4 Alumunium ........................................................................................ 2.4.1 Sifat Fisik Alumunium ........................................................... 2.4.2 Sifat Mekanik Alumunium ...................................................... 2.5 Silikon ................................................................................................ 2.5.1 Sifat Fisik Silikon ................................................................... 2.5.2 Diagram Fase Paduan Alumunium Silikon ............................ 2.6 Macam-Macam Cacat ......................................................................... 2.6.1 Jenis-Jenis Cacat Pengecoran .................................................. 1. Porositas ............................................................................. 2. Hot Tear and Crack ........................................................... 3. Inclusion ............................................................................ 4. Misruns .............................................................................. 5. Cold Shuts ......................................................................... 6. Shrinkage .......................................................................... 2.7 Pengujian Porositas............................................................................. 2.7.1 Sinyal-Sinyal Pada Alat Uji SEM ...........................................
4 4 4 5 8 9 9 10 10 10 11 11 12 14 14 15 15 16 16 18
BAB III METODE PENELITIAN ...................................................................... 3.1 Diagram Alir Penelitian ...................................................................... 3.2 Bahan Dan Alat Penelitian .................................................................
19 19 20
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3.2.1 Bahan Penelitian ....................................................................... 3.2.2 Alat Penelitian ......................................................................... 1. Alat Pengecoran Spesimen ............................................... 2. Alat Uji Spesimen Hasil Pengecoran ................................ 3.3 Pelaksanaan Penelitian ....................................................................... 3.3.1 Proses Pembuatan Spesimen ( Proses Pengecoran ) ................ 1. Persiapkan Alat dan Bahan ................................................ 2. Pembuatan Cetakan ........................................................... 3. Peleburan Logam ............................................................... 4. Penuangan Kecetakan ........................................................ 5. Pendinginan ....................................................................... 6. Pembongkaran Cetakan ..................................................... 7. Pemeriksaan Hasil Coran ................................................... 3.3.2 Proses Pengujian Spesimen .................................................... 1. Proses Pembuatan Spesimen Untuk Pengujian .................. 2. Uji Densitas ....................................................................... 3.4 Waktu Dan Tempat Penelitian ........................................................... 3.4.1 Tempat Penelitian ....................................................................
20 22 22 25 28 29 29 29 29 30 30 30 30 30 30 32 32 32
BAB IV HASIL DAN PEMBAHASAN .............................................................. 4.1 Data Hasil Penelitian ......................................................................... 4.1.1 Data Hasil Pengujian Porositas .............................................. 4.1.2 Data Hasil Pengujian SEM ..................................................... 4.1.2 Hasil Data Uji Imagej ............................................................. 4.1 Pembahasan .......................................................................................
33 33 33 37 41 43
BAB V PENUTUP ................................................................................................ 5.1 Kesimpulan ........................................................................................ 5.2 Saran ..................................................................................................
44 44 44
DAFTAR PUSTAKA ............................................................................................
45
LAMPIRAN ..........................................................................................................
47
LEMBAR PERNYATAAN ...................................................................................
58
LEMBAR ASISTENSI .........................................................................................
59
SK SKRIPSI/PEMBIMBING ..............................................................................
63
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DAFTAR GAMBAR Halaman Gambar 2.1 Tahap Proses Pengecoran Lost Foam ............................................... Gambar 2.2 Grafik Diagram Fasa Al-Si ............................................................... Gambar 2.3 Porositas gas....................................................................................... Gambar 2.4 Porositas shrinkage ............................................................................ Gambar 2.5 Hot tear and Crack ............................................................................. Gambar 2.6 Inclusion .............................................................................................. Gambar 2.7 Misruns ............................................................................................... Gambar 2.8 Cold shut ............................................................................................. Gambar 2.9 Pengukuran densitas............................................................................ Gambar 3.1 Diagram Alir Penelitian ...................................................................... Gambar 3.2 Aluminium .......................................................................................... Gambar 3.3 Pasir Silika ........................................................................................ Gambar 3.4 Dapur Peleburan ................................................................................ Gambar 3.5 Blower ............................................................................................... Gambar 3.6 Kowi .................................................................................................... Gambar 3.7 Timbangan Digital .............................................................................. Gambar 3.8 Cetakan Pasir ..................................................................................... Gambar 3.9 Sterofoam .......................................................................................... Gambar 3.10 Alat Pemotong Sterofoam ............................................................... Gambar 3.11 Alat Uji SEM (Secanning Electron Microscopy) ............................ Gambar 3.12 Varnier Caliper ................................................................................. Gambar 3.13 Gregaji Tangan .................................................................................. Gambar 3.14 Amplas .............................................................................................. Gambar 3.15 Aoutosol ............................................................................................ Gambar 3.16 Kain Beludru ..................................................................................... Gambar 3.17 Bagian Dalam Cetakan ..................................................................... Gambar 3.18 Spesimen Uji ..................................................................................... Gambar 4.1 Hasil Cor Menggunakan Cetakan Mesh Pasir 0,180 mm ................. Gambar 4.2 Spesimen Uji Densitas Dan Porositas ............................................... Gambar 4.3 Grafik Densitas Sampel .................................................................... Gambar 4.4 Grafik Porositas ................................................................................ Gambar 4.5 Sepesimen Uji SEM ........................................................................... Gambar 4.6 Hasil Uji SEM Material Cor Spesimen I Mesh Pasir 0,180 mm ................................................................................................................................. Gambar 4.7 Hasil Uji SEM Material Cor Spesimen III Mesh Pasir 0,250 mm ................................................................................................................................. Gambar 4.8 Hasil Uji SEM Material Cor Spesimen II Mesh Pasir 0,315 mm viii
6 11 13 13 14 14 15 15 17 19 21 22 23 23 23 24 24 24 25 25 25 26 26 26 27 29 31 33 34 35 37 37 38 39
................................................................................................................................. Gambar 4.9 Imagej Spesimen I Mesh Pasir Ukuran 0,180 mm ............................ Gambar 4.10 Imagej Spesimen III Mesh Pasir Ukuran 0,250 mm ......................... Gambar 4.11 Imagej Spesimen II Mesh Pasir Ukuran 0,315 mm .......................... Gambar 4.12 Grafik Batang Nilai Porositas Hasil Uji Imagej ...............................
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40 41 41 42 42
DAFTAR TABEL Halaman Tabel 2.1 Macam-Macam Temperatur Penuangan Logam Cair ke dalam Cetakan ................................................................................................... Tabel 2.2 Sifat Fisik Aluminium ............................................................................ Tabel 2.3 Sifat Mekanik Aluminium ...................................................................... Tabel 2.4 Sinyal Pada Alat Uji SEM ...................................................................... Tabel 3.1 Alat Penelitian ........................................................................................ Tabel 4.1 Hasil Pengujian Densitas Sampel ........................................................... Tabel 4.2 Hasil Pengujian Porositas ....................................................................... Tabel 4.3 Hasil Penelitian .......................................................................................
x
7 9 10 18 27 35 36 43
DAFTAR RUMUS Halaman Rumus 2.1 Densitas sample ................................................................................... 16 Rumus 2.2 Densitas teoritis Alumunium Silikon .................................................. 16 Rumus 2.3 Perhitungan Porositas ........................................................................... 17
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