Tolerances will vary from part to part, depending on the materials, size, shape, number of cutouts and other configuration possibilities.

However, as a general rule of thumb, the following tolerances should apply.

Formed Dimensions:
±.020″ for the 1st 12″
±.002″ for each additional inch

Hand Trimmed Dimensions:

CNC Dimensions:

CNC and hole to hole tolerances sometimes must be increased due to the coefficient of thermal expansion. Our CNC and other computerized trimming machinery are capable of cutting to within ±.0005, however, plastic does move due to temperature changes. The formula is as follows:

Length (inches) x temperature difference (F°) x .00005″
Example” 20″ at 90°F will move to 19.98″ @ 70°F
20″ x 20°F x .00005 – .020″

Please keep this in mind when designing any plastic part. Slots and over-sized holes work well.

Further discussions are welcome to help you overcome any possible design problems.

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