STUDI PEMBUATAN GRINDING BALL UNTUK MENGGANTIKAN
GRINDING BALL IMPOR PADA INDUSTRI SEMEN
Suharno1), Yuyun Estriyanto1)
1) Staf Pengajar Jurusan Pendidikan Teknik Mesin FKIP UNS e-mail myharno@yahoo.com
ABSTRACT
The increasement in cement production cost due to the increasment of electricity and fuel cost must be anticipated by reducing imported components dependencies, especially grinding ball. This study aims to determine the characteristics of imported grinding ball used by Indonesian main cement factory. The material used in this study is different two imported grinding ball Brand A ( 40 mm) and Brand B ( 60 mm) which used by PT. Semen Holcim Tbk. The characterization of the grinding balls are conducted by visual observation, chemical composition test, hardness test, and metallographyc test. Visual observation shows that the imported grinding ball appear to have a rough surfaces, both sleced are whitish and there are small cracks on all specimens. Chemical composition test shows that that the imported ball mill ( 40 mm) contain 2,08% C and 11,608% Cr, while the ( 60 mm) one contain 2,08% C, 16,58% Cr. Both specimen are martensitic white cast iron ASTM A532 Class II Type A and B. Hardnes test shows that the outer part of the grinding ball have higher hardness then the inner one with the value of 781,9 kg/mm2 ( 40 mm)
and 975,4 kg/mm2 ( 60 mm). The lowest hardness value are 542 kg/mm2 ( 40 mm) and 561
kg/mm2 ( 60 mm). Moreover, the metallographyc test shows that both materials have perlite,
cementite and martensite sructure. In the second year of research is focused on providing treatment of the grinding ball engineered by providing a hardening heat treatment by varying the temperature, holding time, and quench media. In the second year of research is focused on providing treatment of the grinding ball engineered by providing a hardening heat treatment by varying the temperature, holding time, and quench media. The result can be concluded that the chemical composition of the third test As Cast grinding ball indicates that the heat treatment tests showed that the grinding ball printouts can be hardened as a whole. The test results showed that the microstructure of grinding ball As Cast Cr 12, Cr 17, Cr 21 has a structure of martensite, pearlite structure, and structure of Cr carbide. From this data is expected to be forwarded for further research to test the concentration of local use of grinding ball on the cement industry obviously to find out the effectiveness of local pemngujian grinding ball.
