ACETAL (CO-POLYMER)

ACETAL (CO-POLYMER)

Material Information

Acetals are thermoplastics with the chemical name “PolyOxyMethylene” (POM). Overall, acetal provides high strength and stiffness, enhanced dimensional stability, low moisture absorption, a low coefficient of friction, good wear and abrasion properties, good chemical resistance, and is easy to machine. Moisture, lubricants, and solvents including gasoline have little effect on acetal, making them ideal for parts incorporating self-threading screws or interference fits. Acetals are available in a copolymer grade, a homopolymer grade (Delrin®), and a variety of filled Delrin® grades.

The acetal copolymer (unfilled) offers excellent performance at a slightly lower cost than the acetal homopolymer Delrin®. Acetal copolymer is more resistant to hot water and hot air than the homopolymer. Although acetal copolymer is usually porosity free, it may exhibit center line porosity. However, certain grades such as Acetron® GP guarantee the material is porosity free while providing the same performance and machinability. The low stress levels and high strength assure flatness and dimensional stability up to a continuous service temperature of 180º F. Acetal is available in standard white (natural) and black in the form of rod, plate, and strip. Colors are available as a custom run. However, only the natural (white) grades of acetal are FDA, USDA, NSF, Canada AG, and 3-A Dairy compliant at a premium price and possibly a custom run.

Application

  • Gears
  • Washers
  • Bushings
  • Clips
  • Lugs
  • Door handles
  • Cranks
  • Handles
  • Housings
  • Fuel systems
  • Window-support brackets
  • Plumbing products
  • Consumer items such as toys and zippers
  • Mechanical components that require dimensional stability

Properties

  • Low moisture absorption
  • High strength, stiffness
  • Good dimensional stability
  • Porosity free
  • Easy to machine
  • Good combination of mechanical properties
  • Chemical resistance to fuels and solvents
  • Good wear and abrasion properties
  • FDA, USDA, NSF, Canada AG, and 3-A Diary compliant

Physical

Astm Test Method

Acetal (Co-Polymer)

Density (lb/in^3) D792 0.051
Specific Gravity D792 1.41
Water Absorption @ 24 hours (%) D570 0.2

Mechanical

Tensile Strength (PSI) D638 9,500
Tensile Modulus (PSI) D638 400,000
Tensile Elongation at Break (%) D638 30
Flexural Strength (PSI) D790 12,000
Flexural Modulus (PSI) D790 400,000
Compressive Strength (PSI) D695 15,000
Compressive Modulus (PSI) D695 400,000
Izod Impact (Notched), ft-lb/in D256 1
Rockwell Hardness D785 M88, R120

Thermal

Coefficient of Thermal Expansion,
10^-5/°F
D696 5.4
Heat Deflection Temperature 264 psi, ºF D648 220
Melting Point, °F D3418 335
Continous Service Temp (Operating), °F - 180
Thermal Conductivity, BTU-in/hr-ft² °F F433 1.6
Flammability Rating UL94 HB

Electrical

Dielectric Strength, Short Term,
(Volts/Mil) @ .125″ Thick
D149 420
Volume Resistivity (ohm/square) D257 10^15
Dielectric Constant at 1 MHz D150 3.8
Dissipation Factor at 1 MHz D150 0.005

NOTE:

The information contained herein are typical values intended for reference and comparison purposes only. They should NOT be used as a basis for design specifications or quality control. Contact us for manufacturers' complete material property datasheets. All values at 73°F (23°C) unless otherwise noted.