Holes: Minimum hole diameter should
be equal to or greater than 1.2 times the material
thickness.
Edge
to Holes: The distance between hole and edge
should be a minimum of two stock thicknesses.
Hole
to Form: Spacing is normally 2.5 times the
material thickness plus the bend radius.
Slot
to Form: Spacing for long slots should be
at least four times the material thickness plus
the bend radius.
Notches & Tabs: Should
not be narrower than 1.5 times the material thickness.
Form to Hole: Spacing should
be
great enough so that hole distortion does not occur. |
L-Shaped
Parts: Should include a
bend relief notch to avoid cracking or fracture.
Grain
Direction: Constraints are particularly
important in harder stock. The line of sharp V-bend
should not be parallel with the grain direction,
otherwise cracking or fracture is likely to occur.
Burrs: Burrs are a Result of the normal stamping
process. Burrs on the outside of a bend may create
fractures. Burr height will range up to 10% of
material thickness. Burrs can be removed utilizing
a number of different processes.
Shapes: Round is the easiest to draw, followed
by square with adequate corner radii. Irregular
shapes and those that combine two basic shapes
into one are much more difficult and costly to
produce. |
Corners: Should be as generous as possible to facilitate
manufacturing. Normally, the punch and die radius
should be a minimum of four times the material
thickness.
Squareness: Normal variation on formed 90-degree
bends is usually within plus or minus 1 degree.
Feature
Distortion: Distortion is more likely
to occur when various design features like holes
or slots are too close to an edge, form, or each
other. This is more apparent in drawn parts, which
undergo much more deformation than formed parts.
Flatness: Should not be over-specified. Requiring
flatness of less than .003in./in. may require a
secondary operation at added expense. |
