Problems of wear in forging dies

The wear of the die profile governs the useful life of the forging die. The various factors influencing the wear include excessive pressure, excessive temperature, abrasive action, and thermal and mechanical fatigue. The thermal fatigue, was found to be more disastrous than mechanical fatigue in shortening the working life of the die, mainly due to high temperature structural transformations. The paper discusses, critically, the various factors that may be controlled to minimize thermal and Mechanical fatigue. The other factors have also been briefly dealt with. Mention has been made of the various lubricants that are commonly used for both hot and cold die forging with emphasis to their specific applications. Selection of a proper die material and design of the flash land of the die are also the critical features in reducing die stresses. Some of the design considerations for die life are discussed briefly. Some guidelines in designing performing dies are also discussed, since proper design of preforming dies minimizes metal losses into flash and achieves complete die filling. (Dr. R. Sharan, Shri N.P. Saksena and Shri R.Prasad, National Institute of Foundry & Forge Technology, Ranchi)