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Designing Products for Steel Rule Die
Cutting
When
designing your parts, it is always important to keep in mind the
impact your design has on the manufacturing process. Key points to
consider are highlighted below:
Allow a radius on all
corners:
A radius of 1 mm or less
creates a
corner in the steel rule die which is stronger than a square corner.
Sharp corners require tooling to be joined at the corner, creating a
weak point in the tool, which can cause deflection in the tool as a
part with localized deformation.
Avoid holes too close to
the edge of
a part:
Replace holes close to edge
with
U-slots or notches. When holes are attempted close to the edge
of a part, localized distortion may be present, or the hole
may tear out.
Design with materials and
processes
in mind:
Leaving the default
tolerances of +/-
0.005” on your drawing can be an expensive habit. Die cut
parts cannot hold the same tolerances as machined parts. The
design should reflect not only the tolerances of the
tool, but include the cutting tolerances and the dimensional
stability of the material.
Material Stability:
Many materials require
cutting
tolerances much greater than the tolerance of the tool. For example,
Nomex® aramid paper Is hygroscopic and can expand up to 2%
in the direction of the grain, due to changes in humidity.
Therefore, a 10” part could expand up to 0.2”. Also, soft and dense
foams and rubbers can have distorted edges when die cut. This
distortion usually
does not affect the fit of the part, but when measured, is shown to be
out of
tolerances. Tolerances should be designed with the material and
application in mind.
Please contact one of our technical representatives to determine the
most suitable
tolerance for your application. This will help us produce parts that
perform as you expect, in the most
economical fashion.
Graphics courtesy of ITW
Formex Design
Guide www.itwformex.com
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