Lou KrenStamping High-Strength Stainless? Coating is a Tool Lifesaver
July 29, 2020Comments
With parts customers of Penn United Technologies, Inc. trying to do more with less, and designing components that depend more and more on smaller cross-sections while needing to support higher loads, higher-strength part materials often get the call. As a result, reports Jim Marraccini, engineering team leader at metal-parts/components supplier and die builder Penn United Technologies, high-strength stainless steels often are the part material of choice.
“In turn, our forming and drawing punches and dies experience more contact forces than in the past,” Marraccini says. “Also, using higher-strength materials eliminates the need for secondary operations such as heat treating. Some parts in the past were made from annealed materials and heat treated in a secondary operation. To reduce costs involved in a secondary heat treating process, these materials have been switched to higher-strength grades.”
Bottom line: Increased use of higher-strength materials stresses tooling components. To combat such challenges, Penn United opts to coat selective die components and tooling faces to increase tool life and better prevent issues such as galling.
With manufacturing operations based in Pennsylvania, chiefly out of the company headquarters in Cabot, Penn United and its 740-plus employees churns out parts around the clock, six days/week. The company produces its own tooling, primarily progressive dies but also including transfer and single-hit dies, destined for mechanical presses in capacities from 25 to 300 tons, as well as servomechanical presses from 150 to 200 metric tons. The presses churn out connectors, brackets, bearing races and many other part types, with some deep-draw applications, at speeds from 25 to 1000 strokes/min. for a diverse customer base across automotive, medical, telecommunications, energy and other markets.
The effectiveness of coatings in extending tool life and mitigating part-quality issues became apparent to Penn United years ago, and has led to a long-term relationship with Phygen Coatings Inc., a Minneapolis, MN, coatings provider. Back then, in the mid-2000s, Penn United experienced galling on draws of Type 301 stainless steel. The company, aware of and following developments with various tool coatings, selected one particular coating, which was able to extend carbide-tool (most tooling in use at Penn United is carbide) life to 15,000 hits between recoating—an improvement, but Penn United was looking for more. So, the Penn United team tried Phygen’s FortiPhy chromium nitride physical-vapor-deposition (PVD) coating technology. To say that the company experienced improved results is an understatement, as Marraccini reports that after the switch “we instantly were able to run several million hits before tool failure and the need to have the components reworked and recoated.”
With its inhouse tooling expertise, Penn United is quite well-versed in determining, during design, the potential trouble spots in tooling where coating proves advantageous, or in identifying areas on current-production tooling that can benefit.
