acetal c
acetal c
POLYOXYMETHYLENE COPOLYMER (pom-c)
POLYOXYMETHYLENE COPOLYMER (pom-c)
Acetal C, also known as Polyoxymethylene Copolymer (POM-C), is a high-performance engineering thermoplastic widely used in precision engineering and manufacturing. It is characterised by its "tough and slippery" nature and favoured for its exceptional balance of physical, mechanical, and chemical properties, making it a reliable substitute for metal in many industrial applications.
Unlike its counterpart, Acetal H (Homopolymer), Acetal C is produced by polymerising two different monomers. This structure results in a material with superior chemical resistance, better long-term thermal stability, and a significantly reduced risk of "centreline porosity" (voids or bubbles in the core of the material), making it more suitable for high-precision machining and food-contact environments.
Key Properties
Mechanical & Physical
- High Dimensional Stability
Extremely low moisture absorption (typically around 0.8% at saturation) ensures parts hold their shape and tolerances even in wet or humid conditions. - Low Coefficient of Friction
Naturally self-lubricating with excellent sliding properties, reducing wear on moving parts. - High Strength & Stiffness
Offers a high modulus of elasticity and tensile strength, capable of withstanding significant mechanical loads. - Excellent Machinability
One of the easiest plastics to machine; it produces small, clean chips and does not "gum up" cutting tools.
Chemical & Thermal
- Chemical Resistance
Highly resistant to many solvents, oils, fuels, and strong alkalis (pH 4–13). - Steam/Hydrolysis Resistance
Superior to Acetal H in hot water and steam environments (up to roughly 85°C for continuous exposure). - Operating Temperature
Suitable for continuous use in air at temperatures up to 100°C (212°F). - Impact Resistance
Maintains toughness even at low temperatures (down to -40°C or -50°C). - Regulatory Compliance
Most grades are FDA, USDA, and EU compliant for direct contact with food.
COMMON APPLICATIONS
Technical Details
| TEST METHOD | VALUE | VALUE (IMPERIAL) | |
|---|---|---|---|
| PHYSICAL PROPERTIES | |||
| Density | ISO 1183 | 1.41 g/cm³ | 0.051 lb/in³ |
| Water Absorption (24h) | ISO 62 | 0.20% | 0.20% |
| Water Absorption (Saturation) | ISO 62 | 0.80% | 0.80% |
| MECHANICAL PROPERTIES (at 23°C) | |||
| Tensile Strength at Yield | ISO 527 | 66–67 MPa | 9,500–9,700 psi |
| Tensile Modulus of Elasticity | ISO 527 | 2,800–3,000 MPa | 400–435 ksi |
| Elongation at Yield | ISO 527 | 15% | 15% |
| Elongation at Break | ISO 527 | 30–40% | 30–40% |
| Flexural Strength | ISO 178 | 91 MPa | 13,200 psi |
| Flexural Modulus | ISO 178 | 2,600 MPa | 377 ksi |
| Charpy Impact (Notched) | ISO 179 | 6–8 kJ/m² | 2.8–3.8 ft-lb/in² |
| Rockwell Hardness | ISO 2039-2 | M 84 | M 84 |
| THERMAL PROPERTIES | |||
| Melting Temperature | ISO 11357 | 165–168°C | 329–335°F |
| Heat Deflection Temp (1.8 MPa) | ISO 75 | 100–105°C | 212–221°F |
| Max. Service Temp (Long Term) | 100°C | 212°F | |
| Min. Service Temp | -50°C | -58°F | |
| Thermal expansion (CLTE) | ISO 11359 | 110 x 10⁻⁶/K | 6.1 x 10⁻⁵/°F |
| Thermal Conductivity | 0.31 W/(K·m) | 2.15 BTU·in/(hr·ft²·°F) | |
| Flammability Rating | UL 94 | HB | HB |
| ELECTRICAL PROPERTIES | |||
| Dielectric Strength | IEC 60243 | 20–40 kV/mm | |
| Volume Resistivity | IEC 60093 | > 10¹³ – 10¹⁴ Ω·cm | |
| Surface Resistivity | IEC 60093 | > 10¹³ Ω | |
| Dielectric Constant (1 MHz) | IEC 60250 | 3.8 | |
| Dissipation Factor (1 MHz) | IEC 60250 | 0.005 – 0.008 |
These values are typical averages and should be used for material selection and design guidance only.
Technical Details
| TEST METHOD | VALUE | |
|---|---|---|
| PHYSICAL PROPERTIES | ||
| Density | ISO 1183 | 1.41 g/cm³ |
| Water Absorption (24h) | ISO 62 | 0.20% |
| Water Absorption (Saturation) | ISO 62 | 0.80% |
| MECHANICAL PROPERTIES | ||
| Tensile Strength at Yield | ISO 527 | 66–67 MPa |
| Tensile Modulus of Elasticity | ISO 527 | 2,800–3,000 MPa |
| Elongation at Yield | ISO 527 | 15% |
| Elongation at Break | ISO 527 | 30–40% |
| Flexural Strength | ISO 178 | 91 MPa |
| Flexural Modulus | ISO 178 | 2,600 MPa |
| Charpy Impact (Notched) | ISO 179 | 6–8 kJ/m² |
| Rockwell Hardness | ISO 2039-2 | M 84 |
| THERMAL PROPERTIES | ||
| Melting Temperature | ISO 11357 | 165–168°C |
| Heat Deflection Temp (1.8 MPa) | ISO 75 | 100–105°C |
| Max. Service Temp (Long Term) | 100°C | |
| Min. Service Temp | -50°C | |
| Thermal expansion (CLTE) | ISO 11359 | 110 x 10⁻⁶/K |
| Thermal Conductivity | 0.31 W/(K·m) | |
| Flammability Rating | UL 94 | HB |
| ELECTRICAL PROPERTIES | ||
| Dielectric Strength | IEC 60243 | 20–40 kV/mm |
| Volume Resistivity | IEC 60093 | > 10¹³ – 10¹⁴ Ω·cm |
| Surface Resistivity | IEC 60093 | > 10¹³ Ω |
| Dielectric Constant (1 MHz) | IEC 60250 | 3.8 |
| Dissipation Factor (1 MHz) | IEC 60250 | 0.005 – 0.008 |
These values are typical averages and should be used for material selection and design guidance only.
CHEMICAL RESISTANCE
| CATEGORY | REPRESENTATIVE SUBSTANCE | RATING | NOTES |
|---|---|---|---|
| Acids (Weak) | Acetic Acid (10%) | B | Limited resistance; long-term exposure causes etching |
| Acids (Strong) | Sulfuric or Hydrochloric Acid | C | Do not use. Rapidly decomposes the polymer |
| Alcohols | Ethanol, Isopropanol | A | Excellent resistance |
| Alkalis (Bases) | Sodium Hydroxide | A | POM-C is much better than POM-H (Delrin) here |
| Aromatic Hydrocarbons | Benzene, Toluene | A | Very stable |
| Chlorinated Solvents | Methylene Chloride | B | Can cause swelling over time |
| Fuels | Petrol, Diesel, Kerosene | A | Ideal for automotive fuel system components |
| Ketones | Acetone, Methyl Ethyl Ketone (MEK) | A | Generally very resistant |
| Oxidizing Agents | Bleach (Sodium Hypochlorite) | C | Causes brittleness and surface chalking |
| Water / Steam | Hot Water ($>80$°C) | B | Susceptible to hydrolysis over very long periods |
RATING SCALE:
A (Excellent): Little to no effect.
B (Good/Fair): Minor swelling or slight changes in properties; acceptable for short-term exposure.
C (Poor): Severe degradation or stress cracking. Not recommended.
CHEMICAL RESISTANCE
| CATEGORY | EXAMPLE | RATING |
|---|---|---|
| Acids (Weak) | Acetic Acid (10%) | B |
| Acids (Strong) | Sulfuric or Hydrochloric Acid | C |
| Alcohols | Ethanol, Isopropanol | A |
| Alkalis (Bases) | Sodium Hydroxide | A |
| Aromatic Hydrocarbons | Benzene, Toluene | A |
| Chlorinated Solvents | Methylene Chloride | B |
| Fuels | Petrol, Diesel, Kerosene | A |
| Ketones | Acetone, Methyl Ethyl Ketone (MEK) | A |
| Oxidizing Agents | Bleach (Sodium Hypochlorite) | C |
| Water / Steam | Hot Water (>80°C) | B |
RATING SCALE:
A (Excellent): Little to no effect.
B (Good/Fair): Minor swelling or slight changes in properties; acceptable for short-term exposure.
C (Poor): Severe degradation or stress cracking. Not recommended.
FAQ
SERVICES
Plastock has extensive experience in all cutting, laser and manufacturing techniques across a huge range of industries and materials using the latest technologies. With expert engineering knowledge and world class equipment, we can help with the design, development, fabrication and installation or your project. No job is too big or too small.
SERVICES
Plastock has extensive experience in all cutting, laser and manufacturing techniques across a huge range of industries and materials using the latest technologies. With expert engineering knowledge and world class equipment, we can help with the design, development, fabrication and installation or your project. No job is too big or too small.
BONDING
CNC
Design & Development
Fabrication
Installation
Laser Cutting
Polishing
Specialist
Speak to a member of the team today on 01494 449975, or click the button below...