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Plastic injection moulding is the process of melting plastic pellets (thermosetting/thermoplastic polymers) that once malleable enough, are injected at pressure into a mould cavity, which fills and solidifies to produce the final product.


The radius should always be with regards to the part thickness thereby eliminating the prospects of high-stress concentration and resulting in the breakage of the plastic part.

General guideline suggest that the thickness at the corner should be in the range of 0.9 times the nominal thickness to 1.2 times the nominal thickness of the part.

Sharp corners spell stress thereby affecting the manufacturability of parts.

Wall Thickness

Given the different nature of the composition of plastics, plastic parts should always have walls with uniform thickness.

General guidelines suggest that wall thicknesses for reinforced plastic materials should be between the range of 0.75 mm to 3 mm and those for unfilled materials should be 0.5 mm to 5 mm.

Swerving away from the recommended would give rise to unfavorable results such as shrinkage and warpage.

Ninad Kashid

Aug 10, 2022


Design Guidelines for Plastic Injection Moulding

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