Increase in ironing limit of stainless steel cups with lubricants containing ceramic particles

The seizure resistance in the ironing process of stainless steel cups was improved with lubricants containing Al₂O₃ particles, and the ironing limit of the cups was increased. The effects of suspending different concentrations of Al₂O₃ particles in paraffin based oils on increasing the ironing limit of SUS430 cylindrical cups before seizure were investigated using a lapped tungsten carbide die. By containing c = 2vol% of Al₂O₃ particles having nominal diameter d between 0.02 to 4 micrometres in an oil with a kinematic viscosity of 500 mm²/s, the ironing limit of the cup was 8% under a punch speed of 100 mm²/s. The limit was similar to the limit using a commercial low-viscosity oil with chlorine additive. The kinematic viscosity of the base oil was reduced. In d = 0.2 μm and c = 0.5vol%, the limit of the oil more than kinematic viscosity of 180 mm²/s was similar to the limit by the commercial oil. In d = 4 μm and c = 1vol%, the limit of the oil having more than kinematic viscosity of 100 mm²/s was effective. It was found that the seizure resistance in the ironing process was improved by the proper ironing conditions with lubricants containing particles.