Investigation on friction coefficient under high pressure such as cold forging was carried out by press-in punch test. Work specimen was made of chromium-molybdenum steel SCM415, and punch specimens were made of four kinds of tool steels, and cemented carbide as a die material. Punches were finished by no.240, no.800 emery papers or lapping. Four kinds of oils and a lubricant were examined for frictional characteristics. Press-in force versus press-in depth was measured by press-in punch test. It was tried to calculate friction coefficient by numerical calculus of press-in force. PVD treatments had good effect of low seizure properties. Especially, DLC treatment was free from siezure.
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