Tribological effects of punch with micro-dimples in blanking under high hydrostatic pressure

A blanking apparatus has been devised to estimate the tribological behaviour between a punch and a blank under high hydrostatic pressure. Severe tribological conditions such as thin oil film, high pressure, and small amount of oil supply are induced between the punch and blank. To increase an amount of supplied oil between the punch and the blank, a punch with micro-dimples is applied. Appropriate conditions of the punch with these micro-dimples improve the tribological conditions. The necessary conditions of the micro-dimples such as arrangement, coverage, and depth are experimentally shown to extend the tool life in precision blanking.