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GENERAL PROPERTIES Acetal is the common name for a family of thermoplastics with the chemical name "PolyOxy-Methylene". Acetal is available in a general purpose copolymer grade, a homopolymer version (Delrin ®), and several filled Delrin ® grades. Acetal provides high strength and stiffness, enhanced dimensional stability, and is easy to machine. As a semi-crystalline material, acetal is characterized by a low coefficient of friction and good wear properties.
FEATURES
• High strength, stiffness, dimensional stability • Very low moisture absorption • Good wear and abrasion resistance • Wide range chemical resistance (including many solvents)
ACETAL GRADES ACETAL COPOLYMER (unfilled)
The copolymer grade offers excellent performance at a slightly lower cost than Delrin ®. Acetal copolymer may exhibit center line porosity, but porosity-free material is available. Certain grades are FDA, USDA, NSF, Canada AG and 3-A Dairy compliant. Low stress levels and high strength assure flatness and dimensional stability up to a maximum continuous service temperature of 180°F (80°C). Acetal copolymers are available in a wide variety of colors (including Red, Orange, Yellow, Green, Blue, Violet, Black, White & Natural.)
DELRIN ® (unfilled)
Delrin ® acetal homopolymer offers slightly higher mechanical properties than acetal copolymer, but may contain a low density center (also known as "center line porosity") especially in large cross-sections. The homopolymer also gives slightly less chemical resistance than copolymer acetal. For example, Delrin ® is ideal for small diameter, thin-walled bushings that benefit from the additional strength and rigidity of homopolymer acetal. Delrin ® is available in natural and black colors.
DELRIN ® AF (PTFE-filled)
This material is manufactured from Delrin ® homopolymer resin which has been uniformly filled with a dispersion of PTFE (Teflon ®) fibers. Delrin ® AF is a unique thermoplastic material for use in moving parts in which low friction and long wear life are important. It retains 90% of the mechanical strength of unfilled acetal homopolymer, while offering very low friction and almost no "slip-stick" behavior. Delrin ® AF is dark brown in color.
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TYPICAL PROPERTIES of ACETALS | ||||
| ASTM or UL test | Property | Acetal Copolymer |
Delrin ® Homopolymer |
Delrin ® AF PTFE-filled |
| PHYSICAL | ||||
| D792 | Density (lb/in³) (g/cm³) |
0.051 1.41 |
0.051 1.41 |
0.054 1.50 |
| D570 | Water Absorption, 24 hrs (%) | 0.2 | 0.2 | 0.2 |
| MECHANICAL | ||||
| D638 | Tensile Strength (psi) | 9,500 | 11,000 | 8,000 |
| D638 | Tensile Modulus (psi) | 400,000 | 450,000 | 435,000 |
| D638 | Tensile Elongation at Break (%) | 30 | 30 | 15 |
| D790 | Flexural Strength (psi) | 12,000 | 13,000 | 12,000 |
| D790 | Flexural Modulus (psi) | 400,000 | 450,000 | 435,000 |
| D695 | Compressive Strength (psi) | 15,000 | 16,000 | 16,000 |
| D695 | Compressive Modulus (psi) | 400,000 | 450,000 | 350,000 |
| D785 | Hardness, Rockwell | M88 / R120 | M89 / R122 | M85 / R115 |
| D256 | IZOD Impact Notched (ft-lb/in) | 1.0 | 1.0 | 0.7 |
| THERMAL | ||||
| D696 | Coefficient of Linear Thermal Expansion (x 10-5 in./in./°F) |
5.40 | 4.70 | 5.00 |
| D648 | Heat Deflection Temp (°F / °C) at 264 psi |
220 / 104 |
250 / 121 |
244 / 118 |
| D3418 | Melting Point Temp (°F / °C) | 335 / 168 | 347 / 175 | 347 / 175 |
| - | Max Operating Temp (°F / °C) | 180 / 82 | 180 / 82 | 180 / 82 |
| C177 | Thermal Conductivity (BTU-in/ft²-hr-°F) (x 10-4 cal/cm-sec-°C) |
1.6 5.5 |
2.5 8.6 |
- |
| UL94 | Flammability Rating | HB | HB | HB |
| ELECTRICAL | ||||
| D149 | Dielectric Strength (V/mil) short time, 1/8" thick | 420 | 450 | 400 |
| D150 | Dielectric Constant at 1 MHz | 3.8 | 3.7 | 3.1 |
| D150 | Dissipation Factor at 1 MHz | 0.005 | 0.005 | 0.010 |
| D257 | Volume Resistivity (ohm-cm) at 50% RH | 1015 | 1015 | 3.0 x 1016 |
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.DELRIN and TEFLON are registered trademarks of DuPont
All values at 73°F (23°C) unless otherwise noted.