Forging

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Typical forging defects Cracking at the flash Cold shut or fold Internal cracking • Flash line crack, after trimming-occurs more often in thin workpieces. Therefore should increase the thickness of the flash. • Cold shut or fold , due to flash or fin from prior forging steps is forced into the workpiece. • Internal cracking, due to secondary tensile stress. Suranaree University of Technology Tapany Udomphol Jan-Mar 2007
Summary • Mainly hot forging – Blacksmith, now using water power, steam, electricity, hydraulic machines. • Heavy forging - Hydraulic press = slow, high force squeeze. - Pieces up to 200 tonnes with forces up to 25,000 tonnes. - Simple tools squeeze metal into shape (open-die forging). - Sufficient deformation must be given to break up the ‘as cast’ structure. - Reheating is often needed to maintain sufficient temperature for hot working. - <strong>Forging</strong> is costly but eliminates some as-cast defects - Continuous ‘grain flow’ in the direction of metal flow is revealed by etching. - Impurities (inclusions and segregation) have become elongated and (unlike casting) gives superior properties in the direction of elongation. Suranaree University of Technology Tapany Udomphol Jan-Mar 2007
Page 1 and 2:
Chapter 2 Forging Subjects of inter
Page 3 and 4:
Introduction • Forging is the wor
Page 5 and 6: Forging operations Fullering is use
Page 7 and 8: Classification of forging processes
Page 9 and 10: Hammer and press forging processes
Page 11 and 12: Forging hammer or drop hammer Belt
Page 13 and 14: Power hammer • Power hammer provi
Page 15 and 16: Example: Hydraulic Press forging
Page 17 and 18: Typical values of velocity for diff
Page 19 and 20: Open-die forging • Open-die forgi
Page 21 and 22: Closed-die forging operation billet
Page 23 and 24: Example: Die set and forging steps
Page 25 and 26: Shape classification •The degree
Page 27 and 28: Preform design is the most difficul
Page 29 and 30: General considerations for preform
Page 31 and 32: www.nitrex.com Die materials Requir
Page 33 and 34: Die materials Die life can be incre
Page 35 and 36: Calculation of forging loads The to
Page 37 and 38: D o h o h D We have engineering str
Page 39 and 40: • Consider the force acting on a
Page 41 and 42: As the frictional force µσ y is u
Page 43 and 44: The total forging load, P, is given
Page 45 and 46: Example: The flash has high deforma
Page 47 and 48: In the case of sticky friction, if
Page 49 and 50: The mean forging load (in the stick
Page 51 and 52: Forming textures Redistribution of
Page 53 and 54: Residual stresses in forging • Th
Page 55: Typical forging defects www.mece.ua
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Forging

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