Tolerance and dimensional control of products

The successful use of plastics requires an appreciation of the dimensional accuracy that can be achieved at reasonable cost. Although metal parts only rarely change after shaping or machining, plastics parts may be subject to relatively large dimensional changes associated with the following  

The dimensional instability of plastics might be regarded as intolerable by an engineer experienced only in metals behaviour, but the inherent flexibility and resilience of most plastics materials can be adapted by such design features as force- or clip-fits. 

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