Posted November 1, 2016

Working with Acetal

Plethora now offers acetal, also known as Delrin® 150 or acetal homopolymer, as a material option for our milling service. This page covers tips for designing acetal parts and some properties of acetal as a material.


When your design calls for a plastic part, acetal has relatively low moisture absorption compared to other plastics, high crystallinity, and high machinability. It also boasts a high fatigue endurance, superior impact and creep resistance, chemical resistance to fuels and solvents, and good wear and abrasion properties.

Like all materials, acetal has some limitations. It has poor resistance to acids, is subject to UV degradation, is flammable, and difficult to bond. It is also hard to keep flat over large areas and has centerline porosity as a result of its multiple layers being bonded together, so it is not suitable for all projects.


Acetal is often used in precision parts requiring high stiffness, low friction, and excellent dimensional stability. It is ideal for creating hard, lightweight parts. Acetal resins are often used in the production of:

  • gears,
  • guide rails,
  • electrical connector housings,
  • electronics enclosures,
  • knife handles,
  • non-marring clamps and fixtures,
  • and a wide variety of other parts, as well.

Working with Acetal

Acetal is prone to chipping and stringy burrs but you can mitigate this risk:

  • Add large chamfers or fillets to the tops of features
  • Avoid sharp corners on your part profile
  • A small radius fillet is always better than a sharp corner or edge

Acetal expands and contracts with variance in temperature and moisture, so allow for generous interference tolerances - make holes large, and make slots oversized so your parts will fit together. Acetal also has a low tear-out strength, so if your part has threads, make them deep.

Material Properties

Working with acetal Plethora

We’re excited to be offering this new material and will be continuing to expand our selection in the coming months. If you have any questions, please feel free to get in touch at

Topics: materials, Manufacturing, DFM