February 2021 Volume 3

EQUIPMENT & TECHNOLOGY

About GPMI GPMI, Gemini Group’s forge tooling facility, is a preferred partner for the design and development of world-class hot, cold, and warm forge tooling systems, proudly made in the USA. From bolsters and cassettes to dies and punches, GPMI has the experience and capabilities to handle all of your forge tooling needs. This article is an excerpt from our eBook, Reducing the Cost of Your Forging Process, which is a free resource available for download on our website. The full eBook will provide additional considerations when it comes to tool design, material selection, heat treatment, coatings, and tolerances on how they can impact the efficiency of your forging operation. Visit geminigroup.net/e-book to download your copy. ■ Author: Terry McInerney Email: TMcInerney@geminigroup.net

example, stainless steels and nickel alloys are more difficult to forge than carbon steel at the same temperature and will impact tool life accordingly. • Contact time – the greater the length of time the heated billet is in contact with the die surface the faster the die will wear, and the greater likelihood of heat checking. If the tool is in contact with the billet for a prolonged period, it is possible that the tool will transform to austenite, and then reharden during the cooling process, which may lead to cracking. • Type of forging operation – hammer dies tend to fail more often by cracking than dies utilized in press forging operations. This makes sense when considering the higher impact loads experienced in hammer forging. In processes involving longer contact times, thermal fatigue (heat checking) is the more common mode of failure. • Type of lubricant – there are pros and cons to the various lubricants used in forging. Oil-based lubricants will burn between the billet and the die cavity causing excess wear or erosion, while water-based lubricants have a greater cooling effect, which increases the risk of cracking due to thermal fatigue.

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