2. Flashless Forging
• "true" closed die forging in which metal deformed in a
die cavity permits virtually no excess metal to escape.
• Carried out in an elevated temperature which in
between cold and hot forging.
• Warmed work piece is compressed between a punch
and a die having the shape of the compressor scroll or
balance plate until deformation occurs.
3. flashless forging imposes requirements on
process control that are more demanding
than impression die forging . most important
is that the work volume must equal the space
in the die cavity within. Very close tolerance
if the starting blank is too large excessive
pressures may cause damage to the die or
press. if the blank is too small, the cavity will
not be filled because of the special demands
by flashless forging . the process lends itself
best to part geometrics that are usually
simple and symmetrical and to work materials
such as a precision forging process.
5. • . The process is used to produce a near-net or net
shape forging. The dies make no provision for
flash because the process does not depend on
the formation of flash to achieve complete filling.
Actually, a thin fin or ring of flash may form in the
clearance between the upper punch and die, but
it is easily removed by blasting or tumbling
operations, and does not require a trim die. The
process is therefore called "flashless forging", and
is sometimes called "enclosed die forging".
7. Advantages of flashless forging
• Part produced is more ductile.
• Higher strength.
• Higher production rate.
• Little or no material is wasted.
• Produced part are in net shape.
10. figure 19.17
flashless forging (1)just before initial contact with work piece, (2)partial
compression, and (3)final punch and die closure. Symbols v and f
indicate motion(v=velocity) and applied force respectively
• coining is of course in the minting of coins shown in Figure 19.18. The process is also
used to provide good surface finish and dimensional accuracy on workparts made by
other operation.
