Molding tolerance is a specified allowance on the deviation in parameters such as dimensions, weights, shapes, or angles, etc. To maximise control in setting tolerances there is usually a minimum and maximum limit on thickness, based on the process used. Injection molding typically is capable of tolerances equivalent to an IT Grade of about 9–14. The possible tolerance of a thermoplastic or a thermoset is ±0.008 to ±0.002 inches. In specialised applications tolerances as low as ±5 µm on both diameters and linear features are achieved in mass production. Surface finishes of 0.0500 to 0.1000 µm or better can be obtained. Rough or pebbled surfaces are also possible.
All plastic material will expand and contract under the influence of heat and moisture. Our tolerance guide will give more general information on the characteristics of most common resin types for typical part features.
We will work closely with you to optimize your designs for manufacturing. We will indicate any areas where poor design may produce thermal stress, shrinkage, warping, etc. Consult our design guide for more information on common defects and how to avoid them.