13-2 Forgings
• Forging consists of plastically deforming,
either by a squeezing pressure or sharp blows,
a cast or sintered ingot, a wrought bar or
billet, or a powder-metal shape, to produce a
desired shape with good mechanical
properties. Practically all ductile materials can
be forged
Closed-Die Forging
• Made by hammering or pressing metal until it conforms closely to
the shape of the enclosing dies
• “closed-die forging” is the term applied to all forging operations
involving 3-D control
• Impression die
– Workpiece placed on bottom half die
– Top-half die closed and workpiece undergoes elastic compression until its
enlarged sides touch the side walls of the die impression
– Excess material-flash
• 3 main classes
– Single-impression
– Double-impression
– interlocking
MANUFACTURING MATERIAL
FORGING DIES
General design rules
• Corner & fillet radii- should be sufficient to facilitate the flow
of metal
– Cold shuts: a lap where 2 surfaces have folded against eachother
forming a weak spot that may open into a crack
– Cold shuts occur where there are sharp fillets or deep sections
• Draft angle- the slope given to the side walls of the die in
order to facilitate removal of the forging (usually 7°exterior
contours and 10° interior contours)
• Parting Line- line of meeting of the dies
Drafting Practices particular to forging
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Draft angles and parting lines
Corner and fillet radii
Forging tolerances
Heat treatment
Locations of trademark, part number, and vendor specs
Dimensioning
• Depth of the die impression
• Only one dimension from the parting line.
This surface is then used to establish other
dimensions (figure 13-30)
• Allowances for machining
• Composite drawings- generally the forged part
is shown on one drawing with the forging
outline shown in phantom lines
MANUFACTURING MATERIAL
FORGING DRAWING
MANUFACTURING MATERIAL
MACHINING DRAWING