In the latest Tooling by Design column, titled “Punch Chipping and Wear,” which I conducted for MetalForming Magazine, die makers and tooling engineers shared their most pressing challenges in the press shop. One recurring issue in focus this month is tool chipping and wear.
The use of higher-strength sheet materials in automotive applications, such as medium- and high-carbon steels, stainless steels, and advanced high-strength steels, while advantageous for their properties, can lead to reduced tool life and premature failures. These materials bring about tool-failure mechanisms like chipping, cracking, and abrasive wear during cutting operations, with galling being more common during forming processes.
Chipping and cracking, particularly, pose significant challenges. To address these issues, it becomes crucial to maintain optimal cutting clearances between punch and die components when working with high-strength materials. Tight clearances increase the risk of chipping and wear due to heightened stripping and frictional forces between the work materials and the tooling surfaces.
Chipping is the most prevalent failure mode during cutting, punching, and blanking of high-strength materials. It occurs when process stresses reach levels that cause fatigue in the tooling material, often signaling a lack of toughness. This can result from various factors, including improper material selection, heat treatment, EDM fabrication, or operating conditions like alignment and feed rates.
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Photo and article with all rights reserved, courtesy of metalformingmagazine.com