Abstract:
This research aimed to study factors of Milling affecting to surface roughness and hardness of tool
steel SKD61. Material used in the experiment was tool steel ns SKD 61 which had hardened
between 700 plus or minus 40 HV (60 plus or minus 2 HRC) and the carbide coaled with poly crystalline deposition tool is
used for cutting tool. The experiment was done by three factors that consist of depth of cut, cutting
speed and feed rates and was run on three levels. The 54 specimens were used to milling and results
were collected by surface roughness tester and hardness testing machine. The results showed that to
study factors that affect the surface roughness was the depth of cut and feed rate which had
statistically significant at level of .01 and cutting speed affect on the smooth surface are statistically
significant at .05. Moreover, the interaction between cutting speed and depth of cut was influenced
on the surface roughness with statistically significant at the level of .05. That means roughness of
the surface depends on the depth of cut and feed rates. That is, increase the depth of cut and feed
rates, resulting in a surface quality was increase. Also, the main factors affecting the hardness of the
surface was depth of cut that increasing of depth of cut affect to the hardness of the surface was
reduce with statistical significance level of 0.01. The experiment results was show that the depth of
cut at 0.1, 0.3 and 0.5 mm, the average hardness after the milling were reduce 38.04 HV 47.21 HV
and 57.17 HV respectively.