Pengaruh kecepatan putar terhadap sifat fisis dan mekanis pada centrifugal casting aluminium alloy velg sepeda motor

BAMBANG, Undiana, Dr.Eng. Priyo Tri ISwanto, S.T.,M.Eng

2010 | Tesis | S2 Teknik Mesin

Salah satu kendala untuk industri kecil pengecoran velg adalah kualitas produknya masih lebih rendah dari produk pabrikan besar. Hasil penelitian terdahulu menyimpulkan bahwa kualitas produk industri kecil dipengaruhi oleh metoda pengecoran yang digunakan yaitu metoda gravity casting. Untuk meningkatkan kualitas sifat fisis dan mekanis, maka metoda pengecoran dapat diubah menjadi metoda sentrifugal. Penelitian ini bertujuan untuk mengetahui pengaruh kecepatan putar terhadap sifat fisis dan mekanis pada proses pengecoran sentrifugal serta menentukan kecepatan putar yang dapat menghasilkan velg yang mempunyai sifat fisis dan mekanis yang paling optimum. Penelitian ini dilaksanakan dengan metoda ekperimental untuk itu telah dibuat satu cetakan dari logam beserta alat pemutar yang mampu berputar dengan kecepatan yang dapat diatur hingga 700 rpm. Dengan melaksanakan pengecoran pada variasi putaran antara 400 hingga 700 rpm serta pengujian pada hasil pengecoran maka akan terlihat perubahan sifat sifat fisis dan mekanis akibat variasi putaran tersebut. Pengujian yang dilakukan meliputi uji tarik, uji kekerasan, uji impact, uji densitas serta struktur mikro. Pengamatan terhadap hasil penelitian ini menunjukkan bahwa telah terjadi peningkatan sifat fisis dan mekanis yaitu kekuatan tarik naik dari 142,46 N/mm2 menjadi 176,89 N/mm2, uji kekerasan menunjukan kenaikan dari 27,72 kg/mm2 menjadi 42,50 kg/mm2, uji impack menunjukkan peningkatan dari 0,036 J/mm2 menjadi 0,063 J/mm2. Penelitian ini menunjukan bahwa pengecoran sentrifugal mampu menaikan kualitas sifat fisis dan sifat mekanis pada produksi velg sepeda motor

One of the constraints for a small velg casting industry is that the lower quality of its products than that of large manufacturers. The results of earlier research concluded that the quality of small industry’s products was influenced by the casting method applied, that is, gravity casting method. To enhance the quality of physical and mechanical properties, the casting method can be changed to be centrifugal method. The purpose of this research was to find out the influence of revolution speed on physical and mechanical properties in centrifugal casting process and to determine a revolution speed that can produce velgs with most optimum physical and mechanical properties. This research was conducted by an experimental method. Accordingly, a mold and a revolving instrument that can revolves at a speed adjustable up to 700 rpm has been made. By conducting casting at a revolution varying from 400 rpm to 700 rpm and testing of the results of casting, it could be seen the changes in physical and mechanical properties resulting from the varying revolutions. The testing conducted included tensile test, hardness test, impact test, density test, and microstructure. The observation on the results of research showed that there were increases in physical and mechanical properties, that is, tensile strength increased from 142.46 M/mm2 to 176.89 N/mm2, hardening test from 27.72 kg/mm2 to 42.50 kg/mm2, and impact test from 0.036 J/mm2 to 0.063 J/mm2. This research showed that centrifugal casting was capable of enhancing the quality of physical and mechanical properties in motorcycle velg production.One of the constraints for a small velg casting industry is that the lower quality of its products than that of large manufacturers. The results of earlier research concluded that the quality of small industry’s products was influenced by the casting method applied, that is, gravity casting method. To enhance the quality of physical and mechanical properties, the casting method can be changed to be centrifugal method. The purpose of this research was to find out the influence of revolution speed on physical and mechanical properties in centrifugal casting process and to determine a revolution speed that can produce velgs with most optimum physical and mechanical properties. This research was conducted by an experimental method. Accordingly, a mold and a revolving instrument that can revolves at a speed adjustable up to 700 rpm has been made. By conducting casting at a revolution varying from 400 rpm to 700 rpm and testing of the results of casting, it could be seen the changes in physical and mechanical properties resulting from the varying revolutions. The testing conducted included tensile test, hardness test, impact test, density test, and microstructure. The observation on the results of research showed that there were increases in physical and mechanical properties, that is, tensile strength increased from 142.46 M/mm2 to 176.89 N/mm2, hardening test from 27.72 kg/mm2 to 42.50 kg/mm2, and impact test from 0.036 J/mm2 to 0.063 J/mm2. This research showed that centrifugal casting was capable of enhancing the quality of physical and mechanical properties in motorcycle velg production.

Kata Kunci : Pengecoran sentrifugal,Porositas,Sifat fisis dan mekanis