Wear Behavior of a DLC-Coated Blanking and Deep Drawing Tool Combination

In macro forming a DLC-coating can increase durability and decrease wear of a deep drawing tool. Due to size effects, the behavior in micro range can differ from the behavior in macro range. To investigate durability and wear in micro deep drawing a blanking and deep drawing tool combination was developed, capable of maximum stroke rate of 200 parts per minute. Experiments with copper foil (E-Cu58) of 0.05 mm thickness were performed to produce cylindrical micro cups with a diameter of 1 mm using the lubricant Lubrimax Edel C. The tool material is stainless steel (German standard 1.2379). The punch has a diameter of 0.9 mm and the die diameter is 1.06 mm. To increase durability and decrease wear in micro deep drawing a DLC-coated tool is used. DLC-coated and uncoated tools are compared in long term test regarding wear behavior. Furthermore, the die radii of the tools are measured optically and cross-sections of the tools are made to analyze the microstructure. Experiments show, that the DLC-coating starts to delaminate during the first 5000 strokes. By analyzing the cross section it can be recognized a high density of scattered carbides and pores with different sizes up to 35 μm in the tool material are visible, causing delamination. Furthermore, higher load and stress in micro forming provides delamination. Thus a high influence on the durability of the DLC-coatings base material can be reported in micro range.