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| Deep Drawing Round Shells: A
round blank of sheet metal is centered over a die and
a pressure pad applies force to one side of the blank.
Next, a punch under extreme pressure forces the material
into the die. As this happens, different forces cause
the material to actually flow into the final shape,
which is similar to that of the punch. Multiple successive
operations may be required to obtain the desired final
length and diameter. |
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| Deep Drawing Rectangular
Shells: Drawing a rectangular shell involves
varying degrees of flow severity. Corners require
the same cold working pressures as round shells,
while sides and ends require simple bending. One
determining factor in setting maximum draw depth
is size of corner radii. The distance between centers
of corner radii should be no less than six times
the corner radius, and the bottom radius should be
equal to or larger than the corner radius. |
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| Beading: Creating
a double layer of material to add strength or a feature,
by actually doubling back the material on to itself. |
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| Blanking: A round
or shaped piece of sheet metal is cut from a larger
coil in preparation for further deep drawing operations. |
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| Bulging: Material
is displaced or stretched to create a larger diameter
ring beyond the original body diameter. Typically,
the largest ring has two to three times the original
material thickness per side. |
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| Coining: Material
is displaced to form specific shapes in the part. Coining
typically should not exceed a depth of 30 percent of
the material thickness. Requiring more force than normal
deep draw, this operation also requires strong, durable
tooling. |
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| Coning: A portion
of the part’s diameter is decreased in comparison
to the diameter of the surrounding geometry. |
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| Cupping: A flat
disk or shaped blank is formed into a shell. This operation
is typically the 2nd station in a tool, coming after
the blank. |
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| Drawing: A cupped
part is drawn into successively smaller diameters
and usually longer lengths. |
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| Extruding: After
a smaller pilot hole is pierced, a larger diameter
punch is pushed through, causing the hole to enlarge
and the edge of the material to stretch in length. |
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| Ironing/Wall Thinning: Material
is reduced in the wall of the part. Generally, ironing
should not exceed a depth of 30 percent of the material
thickness. |
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| Leak Testing: Finished
parts can be tested for leakage using a pressure decay
system. This can be accomplished either in press or
as a post-process secondary. |
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| Necking: A portion
of the part is reduced in diameter to less than the
major diameter. While similar to coning, there is a
significant transition from one diameter to the other. |
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| Notching: A round,
square, or shaped notch is cut in the edge on the open
end of the part. |
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| Piercing (Bottom): A
round or shaped portion of material is cut from the
drawn part. The scrap material is called a “slug.” |
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| Piercing (Side): Multiple
holes are pierced in the side wall of the part. These
holes may be round or shaped. Size of pierce is critical
due to slug removal issues. |
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| Restriking: Used
to set the radii of the finished part as well as setting
lengths and shapes. |
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| Stamping/Marking: Part
identification can be coined onto the finished part. |
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| Threading (Rolled): Threads
are formed onto the part using a form wheel and arbor. |
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| Trimming (Pinch): Excess
material is trimmed away from the finished part without
leaving a flange. The inside edge will have a rounded
appearance. |
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