Application of DLC Coating to Ironing Die

The possibilities of application of DLC-Si coating to the die in dry ironing process have been investigated by strip-ironing type tribometer. Alloy tool steel and high speed steel were used as substrate material for ironing dies. Two types of substrate surface texture were prepared by lapping and grinding. And two types of die edge angle were prepared. High tensile strength steel and brass were tested as workpieces. The surface appearance of die, friction coefficient during ironing and surface roughness of ironed workpiece were measured. The friction coefficient of DLC-Si coated die in the dry ironing process is relatively low. Galling does not occur on the die surface. In case of high tensile strength steel, the damage grows with the number of tests. The surface roughness of a brass workpiece does not increase with repeat ironing. The DLC-Si coating could be applied to the dry ironing process in this investigated condition.