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Parts should be tested in the worst case environment.
MOULDING PRODUCT DESIGN TIPS &
GENERAL GUIDELINES

When you design parts for plastic injection
molding, follow the basic points outlined here.

Injection Molded Parts
Varying Uniform
wall thickness wall thickness
Wall Thickness: Use an approximately
uniform wall thickness throughout your
design. Incorrect Correct

Keep walls thin - typically between 1/32" and
1/10". This allows for proper cooling and
Think wall Thin wall
reduced cost by minimizing use of material.
Thin walls also reduce problems with material
shrinkage, warpage, residual stresses and
improve mould fill and cycle times. Although
Incorrect Correct some unevenness will occur due to shrinkage,
walls as thick as 1/5" can be used.

Think Thick wall
wall with Rib
Ribs : To strengthen parts, instead of using
thicker walls, use additional structures such as
ribs.
When using a rib make it about half the main
Incorrect Correct
wall thickness. Thickness of ribs should be 50-
60% of the walls to which they are attached, Height of ribs should be less than three
times the wall thickness, Round the corners at
the point of attachment, Apply a draft angle of at
Think Rib Thick Rib least 0.25°.

Round corners and edges wherever possible,
provide radius. Avoid sharp corners.
Incorrect Correct

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