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.