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Injection Molding: Wall Thickness

This post is part of our Injection Molding Design Guide series.

Wall thickness is one of the primary design concerns when it comes to plastic injection molding. Improperly designed walls can lead to many costly problems and production setbacks. In this article, we’ll discuss how your material influences your wall thickness, why making walls too thick or too thin is problematic, and the importance of uniform wall thickness.

Material Matters

The most important factor when determining your part’s wall thickness is what material you are using. Material choice should be one of the first decisions you make when designing your part for injection molding because your wall thickness will depend on how sturdy and flexible your material is. Materials have different compositions and characteristics, which makes some better suited for thinner walls and others for thicker walls. Depending on a material’s mechanical properties, it may be hard for it to flow into a tight area. This is especially true of fibre-reinforced materials, which demand you design your walls toward the thicker end of your material’s suggested thickness range.

For quick reference, we’ve provided a chart of the recommended thickness ranges for some of the most common injection molding materials.

MaterialInches (in)Millimeters (mm)
ABS0.045 - 0.1401.143 - 3.556
Acetal0.030 - 0.1200.762 - 3.048
Acrylic0.025 - 0.1500.635 - 3.81
Liquid crystal polymer0.030 - 0.1200.762 - 3.048
Long-fiber reinforced plastics0.075 - 1.0001.905 - 25.4
Nylon0.030 - 0.1150.762 - 2.921
Polycarbonate0.040 - 0.1501.016 - 3.81
Polyester0.025 - 0.125