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Acetal
Plastic
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Acetal plastic (polyoxymethylene) is a strong and rigid plastic. It
has a relatively low coefficient friction against metals, acetals,
and other plastics. Two types of acetal plastic exists, which are
homopolymer (Delrin) and copolymer (Celcon or Ultraform).
- Acetal plastic is
great for parts where dimensional stability is important, due to
acetal being creep resistant.
- Acetal has a high
tensile strength, stiffness, resilience, and fatigue endurance.
- Acetal has moderate
toughness, while a having excellent dimensional stability and
outstanding abrasion resistance among other plastics.
- Some acetal products
include automotive applications, such as gears, clips, lugs,
door handles, seat-belt components, and window-support brackets,
plumbing products, valves, pumps, shower heads, toys, garden
sprayers, zippers, watch gear, mechanical pen/pencil parts, milk
pumps, and food conveyors.
Specifications:
| Property |
Copolymer Acetal |
Homopolymer Acetal |
|
PHYSICAL PROPERTIES |
| Specific gravity |
1.41 |
1.42 |
| Specific volume (in^3/lb) |
19.7 |
19.5 |
| Water absorption, 24h, (%) |
0.22 |
0.25 |
| MECHANICAL
PROPERTIES |
| Tensile strength (psi) AT 73 F |
8,800 |
10,000 |
| Tensile strength (psi) AT 160 F |
5,000 |
6,900 |
| Elongation |
55 |
40 |
| Tensile modulus (10^5 psi) |
4.1 |
5.2 |
| Flexural strength (psi) |
13,000 |
14,100 |
| Flexural modulus
(10^5 psi) AT 73 F |
3.75 |
4.10 |
| Flexural modulus (10^5 psi)
AT 160 F |
1.8 |
2.30 |
| Impact strength, Izod
(ft-lb/in) |
|
|
Notched |
1.3 |
1.4 |
|
Unnotched |
20 |
24 |
| Fatigue endurance limit, 10^7
circles (psi) |
3,300 |
4,300 |
| Hardness, Rockwell M |
80 |
94 |
| FRICTIONAL
PROPERTIES |
| Coefficient of friction |
|
|
Self |
0.35 |
0.30 |
|
Against Steel |
0.15 |
0.15 |
| THERMAL
PROPERTIES |
| Thermal conductivity |
|
|
(10^-4 cal-cm/sec-cm^2-C) |
5.5 |
8.9 |
|
(Btu-in/hr-ft^2-F) |
1.6 |
2.6 |
| Coefficient of thermal
expansion -40 to +185 C |
8.5 |
10.0 |
| Deflection temperature (F)
AT 264 psi |
205 |
277 |
| Deflection temperature (F)
AT 66 psi |
316 |
300 |
| Flammability rating |
HB |
HB |
| ELECTRICAL
PROPERTIES |
| Dielectric strength (V/mil) |
|
|
5 mils |
2,100 |
3,000 |
|
20 mils |
- |
2,000 |
|
90 mils |
500 |
500 |
| Dielectric constant |
|
|
At 1 kHz |
3.7 |
3.7 |
|
At 1 MHz |
0.006 |
0.005 |
| Volume resistivity (ohm-cm)
At 73 F 50% RH |
10^14 |
10^15 |
| Arc resistance (s), 120 mils |
240 (burns) |
220 (burns, no tracking) |
*Information provided by IAPD
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