Studi Pengecoran Aluminium Dengan Metode Gravity Investment Casting Dan Centrifugal Investment Casting Terhadap Density, Porositas, Struktur Mikro Dan Kekerasan

This study aims to determine the comparison of gravity investment casting and centrifugal investment casting methods on density, porosity, microstructure and hardness values with aluminum raw materials from used pistons. In this study, two casting methods were used, namely gravity investment casting and centrifugal investment casting with a casting temperature of 750°C. Chemical composition testing using Emission Spectrometry (ASTM E-1251). Observation of porosity was carried out by macro photography using a digital microscope and comparing the results of each variation of the mold temperature. Hardness test using Rockwell hardness tester (ASTM E-384). Testing the microstructure of the castings using a metallographic microscope (ASTM E3-11). The results of the chemical composition test show that this material contains (Al) 71.05%, (Si) 13.65%, (Cu) 7.178%, (Fe) 3.4508%, (Zn) 1.7870% and the elements others up to 100%, according to the ASTM standard B-85 is classified into Aluminum Al-Si (Aluminum – Silicon) A413.0. The results of the calculation of the density of the test object from the gravity investment casting are 2.6764 gr/cm3 and the centrifugal investment casting is 2.6978 gr/cm3. The results of porosity observations that the amount of porosity affects the density value. The results of the observation of the microstructure consist of the phase (Al) and the phase (Si). The beta phase granules (Si) in gravity investment casting appear to be larger and less numerous. In centrifugal investment casting, the beta phase granules are seen to be smaller and more numerous. The size, number and distribution of beta granules affect the hardness value. The results of hardness testing with gravity investment casting have a hardness value of 86.84 HVN, centrifugal investment casting has a hardness value of 98.50 HVN