Polyoxymethylene (POM), also known as acetal, polyacetal and polyformaldehyde is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability. As many other synthetic polymers, it is produced by different chemical firms with slightly different formulas and is therefore sold under many commercial names like Delrin, Celcon, Hostaform, etc.

POM is characterized by its high strength, hardness and stiffness to ~40ºC. POM is intrinsically opaque white, but it is available in all colors. POM has a density of 1.410-1.420 g/cm³.

POM homopolymer is a semi-crystalline polymer (75-85% crystalline) with a melting point of 175ºCelsius. The POM copolymer has a slightly lower melting point of 162-173ºCelsius.

POM is a tough material with a very low coefficient of friction.
Unit of Measure


N/A 7/62 in2 67/77 mm


N/A White

Material Resin

N/A Delrin

Tolerance (±)

N/A 0.002 in

Bead Finish

N/A Polished


N/A 1.42 g/cm³

Max Operating Temperature

N/A Heat Deflection 121 ºCMelting Point 178 ºC

Tensile Strength

N/A 11000 psi

Durometer/Hardness Rating

N/A 120R


N/A No

Acetal Resistance

  • Excellent to Formaldehyde, Oils and Alcohols
  • Good resistance to Methylethylketones
  • Limited resistance to Solvents
  • Poor resistance Acids

Acetal Quick Facts

  • Maximum Temperature: 180ºF 80ºC
  • Minimum Temperature: -40ºF -40ºC
  • Autoclavable: No
  • Melting Point: 320ºF 160ºC
  • Tensile Strength: 8,800 psi
  • Hardness: R107
  • UV Resistance: Poor
  • Opaque
  • Rigid
  • Specific Gravity: 1.41

Acetal Fabrication

  • Highly machinable
  • Excellent for mechanical parts
  • Pulleys, sheaves, bearing surfaces
  • Gears, bushings, shafts
  • Wear resistant surfaces
  • Excellent stiffness

Additional Information

N/A Uses

Mechanical gears, sliding and guiding elements, housing parts, springs, chains, screws, nuts, fan wheels, pump parts, valve bodies.

  • Sports: Paintball accessories. Used for machined parts of paintball markers that does not need the strength of aluminum, such as handles and reciprocating bolts. POM is also used in air soft guns, in order to decrease the noise of the piston.

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