Tolerances for Plastic Machined Parts

 “What tolerance can you hold?”

The answer to that depends on several factors including material choice, part configuration and the type of machining operation and technique. Generally speaking, plastics are not as stable as metals but with the right approach, accurate parts can be produced.

Vanderveer Industrial Plastics is continuously seeking growth, and always interested in pushing the limits of plastic machined parts. If your product demands close tolerances, just let us know. We are up for the challenge and can often meet the goal with a little time and patience.

  • The larger the part, the greater the required tolerance.  Most plastic machined parts do not often have dimensions larger than 12?. We operate in an envelope mostly below 12?, if you have parts larger than 12? consider it big. Materials with a high Coefficient of Thermal Expansion (UHMW, HDPE) require more latitude on tolerance. Consider +/-.010? if possible. Additional tolerances are not out of the question, but keep in mind that thermal affects will need to be monitored more closely.
  • It is easier to hold size with round parts than flat parts. Material manufacturing processes and the efficiency of material removal in turning play a vital role here. Some of the closest tolerance machined plastic parts are round. +/-.0001 is achievable, given the right material and configuration.
  • Flat parts are notoriously difficult to keep flat. Flat parts require careful consideration of geometry, material, and approach. Few rules of thumb exist that can guide us through the plastic fabrication of flat parts. The thicker the part, the greater the chance at maintaining a target flatness. If machining is required, expect to see a bow without special handling. If the component calls for flatness better than .005, please contact Vanderveer Industrial Plastics to discuss your requirements.

In summary, tolerances are all about the specific plastic machined parts. As tolerance demands are always moving toward more accurate, we are committed to staying ahead and will work hard to meet the design expectations.

If you are interested in receiving more information on the materials mentioned, have questions about product, or would like to receive a quote please contact us at, call 1-(714)-579-7700 or visit our website at We look forward to hearing from you!




Click here to submit a Request for Quote
Or call us today at 714.579.7700