Design Consideration For Forging Dies
Forging die-design aspects:
- Die design is more empirical and requires experience. Design of die depends on the processing steps, nature of work piece material, its flow stress, temperature of working, frictional condition at interface etc.
- Volume of billet is to be accurately calculated so that there is neither under filling nor excess filling.
- Proper selection of parting line – the line where the two dies meet is very important. Parting line is so chosen that the flow of material is uniformly divided between the two dies – as far as possible.
- Maximum of 3% of the forging thickness is allowed for flash thickness. Flash gutter is to be provided in order to reduce forging loads.
- Draft angles between 3 degree and 10 degree are normally provided for easy ejection of forging.
- Corner radii are to be larger as far as possible to facilitate smooth flow of material.
- Forging temperature decides the type of die material for forging.
- Commonly, for ferrous alloys, a forging temperature of 900 to 1200 degree C is used. For aluminium alloys, it is from 400 to 450 degree C. For copper alloys, it is 625 to 950 degree C.
- Die materials commonly used are tool steels, high carbon high chromium die steels, high carbon, high chromium, molybdenum die steels etc.
- Lubrication also plays a role in the accuracy and surface finish of forging. Commonly, for hot forging, glass, graphite, molybdenum disulfide are used as lubricants. For cold forging, mineral oils are used.
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