PENGARUH PENGGUNAAN CHIL DAN LUBANG PENDINGIN PADA CETAKAN TROMOL REM TERHADAP STRUKTUR MIKRO BESI COR KELABU

Abstract

According to the increase of the vehicle engine amount in Indonesia as means of transportation has been impacted to the increase of vehicle component needs. One of this vehicle component was bus/truck drum brake. The early result of the research showed the low of drum brake material quality UKM local product, especially in microstructure that not suitable with ASTM standard which cause this product lose compete with import product. The microstructure of import products are pearlite and graphite flake distribution A, whereas the matrix of local product are ferrite, pearlite, and semenite, and have graphite flake distribution A, B, and D. This microstructure caused the local product of drum brake easy to crack. This research concerned to fix the microstructure of drum brake UKM local product. The research has done with the foundry method sand casting with- modified mold by added the variation chil and hole cooler variation, and without variation. The foundry material such as gray cast iron and the pouring temperature maintained with temperature 1275 C – 1350 C. Each specimen of the foundry result has done with micrographic testing with the enlargement 100 X, etsa nital 2.5 % and hardness testing by using Rockwell method which converts to Brinell. From the drum brake micrographic, either using chil variation, hole cooler or without variation in the matrix, has seen graphite length which formed have a measurement 3-5, whereas for the formed phase, ferite and semenite contents average from chil variation, hole cooler, and without variation in the matrix with the totality under 5 %. In the hardness testing, drum brake without matrix variation has the highest hardness value 190 HB and the lowest 182,8 HB, whereas drum brake with chil variation, the highest hardness value 174,3 HB and the lowest 167,6 HB; and for drum brake hole cooler variation, the highest hardness value 217,3 HB and the lowest 214,9 HB.