Overview
POM (Polyoxymethylene), also known as Acetal, Polyacetal, or Delrin® (a common homopolymer trade name), is a high-performance engineering thermoplastic renowned for its exceptional dimensional stability, low friction, wear resistance, stiffness, and machinability.
POM is often considered one of the best engineering plastics for precision mechanical components because it combines metal-like rigidity with lightweight performance. Its low moisture absorption and excellent creep resistance make it ideal for precision parts operating in demanding industrial environments.
POM is widely used in:
- Precision Gears
- Bearings and Bushings
- Rollers and Conveyor Components
- Automotive Components
- Electrical Insulators
- Medical Device Components
- Pumps and Valve Parts
- Industrial Machinery Components
Due to its excellent balance of mechanical performance and processability, POM is one of the most popular engineering plastics for precision applications.
Material Specification
| Property | Value |
|---|---|
| Material Designation | POM |
| Full Name | Polyoxymethylene |
| Common Names | Acetal, Polyacetal |
| Material Family | Engineering Thermoplastic |
| Density | 1.41–1.43 g/cm³ |
| Appearance | Natural (White), Black, Colored |
| Typical Manufacturing Methods | CNC Machining, Injection Molding, Extrusion |
| Standard Forms | Rod, Sheet, Tube, Pellets |
Chemical Composition
POM is a semi-crystalline thermoplastic composed of repeating formaldehyde units.
| Component | Function |
|---|---|
| Polyoxymethylene Polymer | Structural Matrix |
| Stabilizers | Thermal Stability |
| Lubricants (Optional) | Friction Reduction |
| Reinforcements (Optional) | Enhanced Strength |
Common variants include:
- POM Homopolymer (Delrin®)
- POM Copolymer
- Glass Filled POM
- PTFE Filled POM
- Conductive POM
Mechanical Properties
Typical Values
| Property | Value |
|---|---|
| Tensile Strength | 60–75 MPa |
| Yield Strength | 60–70 MPa |
| Elongation at Break | 20–40% |
| Flexural Strength | 85–110 MPa |
| Flexural Modulus | 2.5–3.5 GPa |
| Hardness | Rockwell M85–95 |
| Compressive Strength | 90–120 MPa |
Typical Mechanical Performance
| Property | Performance |
|---|---|
| Stiffness | Excellent |
| Wear Resistance | Excellent |
| Fatigue Resistance | Excellent |
| Creep Resistance | Excellent |
POM offers one of the best combinations of stiffness and wear resistance among engineering plastics.
Physical Properties
| Property | Value |
|---|---|
| Density | 1.41–1.43 g/cm³ |
| Water Absorption (24h) | 0.2–0.5% |
| Saturated Water Absorption | 0.8–1.0% |
| Thermal Conductivity | 0.30–0.35 W/m·K |
| Electrical Resistivity | >10¹⁴ Ω·cm |
| Specific Heat Capacity | 1500 J/kg·K |
POM exhibits extremely low moisture absorption compared with nylon materials.
Thermal Properties
| Property | Value |
|---|---|
| Melting Point | 165–175°C |
| Glass Transition Temperature | -60°C |
| Heat Deflection Temperature | 100–120°C |
| Continuous Service Temperature | -40°C to 100°C |
| Short-Term Service Temperature | Up to 140°C |
POM maintains excellent dimensional stability across a wide operating temperature range.
Strength-to-Weight Ratio
| Material | Density (g/cm³) | Tensile Strength |
|---|---|---|
| POM | 1.42 | 70 MPa |
| PA66 | 1.14 | 90 MPa |
| ABS | 1.05 | 45 MPa |
| Aluminum 6061 | 2.70 | 310 MPa |
POM offers high strength while remaining lightweight and easy to machine.
Wear Resistance
| Property | Performance |
|---|---|
| Abrasion Resistance | Excellent |
| Sliding Wear Resistance | Excellent |
| Surface Durability | Excellent |
| Bearing Performance | Outstanding |
POM is widely used for gears, bearings, and sliding components.
Friction Properties
| Property | Value |
|---|---|
| Coefficient of Friction | 0.20–0.35 |
| Self-Lubricating | Yes |
| Dry Running Capability | Excellent |
| Noise Reduction | Excellent |
Its naturally low friction reduces the need for external lubrication.
Dimensional Stability
| Property | Performance |
|---|---|
| Moisture Resistance | Excellent |
| Thermal Stability | Excellent |
| Shrinkage Control | Excellent |
| Precision Machining Capability | Outstanding |
POM is one of the most dimensionally stable engineering plastics available.
Chemical Resistance
| Chemical Environment | Performance |
|---|---|
| Oils & Greases | Excellent |
| Fuels | Excellent |
| Solvents | Good |
| Alcohols | Excellent |
| Hydrocarbons | Excellent |
| Weak Alkalis | Good |
| Strong Acids | Poor |
POM performs exceptionally well in automotive and industrial fluid environments.
Electrical Properties
| Property | Value |
|---|---|
| Volume Resistivity | >10¹⁴ Ω·cm |
| Surface Resistivity | >10¹³ Ω |
| Dielectric Strength | 18–25 kV/mm |
| Dielectric Constant | 3.7–4.0 |
POM is commonly used in electrical and electronic precision components.
Machinability
| Process | Rating |
|---|---|
| CNC Milling | Outstanding |
| CNC Turning | Outstanding |
| Drilling | Outstanding |
| Tapping | Outstanding |
| Routing | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| POM | Outstanding |
| Nylon | Excellent |
| ABS | Excellent |
| Polycarbonate | Good |
POM is widely considered one of the easiest engineering plastics to machine.
Injection Molding Characteristics
| Property | Rating |
|---|---|
| Moldability | Excellent |
| Flow Characteristics | Excellent |
| Production Efficiency | Excellent |
| Surface Finish | Excellent |
| Dimensional Accuracy | Outstanding |
POM is widely used for precision injection molded parts.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ISO | POM |
| ASTM | Acetal Resin |
| DIN | POM |
| JIS | Polyacetal |
| GB/T (China) | 聚甲醛（POM） |
| UL | Acetal Thermoplastic |
Available Forms
| Product Type | Availability |
|---|---|
| Rod | Yes |
| Sheet | Yes |
| Tube | Yes |
| Pellets | Yes |
| Injection Molded Parts | Yes |
| Machined Components | Yes |
Typical Applications
Industrial Machinery
- Precision Gears
- Bearings
- Bushings
- Rollers
- Guide Rails
Automotive Industry
- Fuel System Components
- Door Mechanisms
- Window Regulators
- Gear Assemblies
Electrical Industry
- Switch Components
- Connectors
- Insulators
- Precision Electrical Parts
Medical Industry
- Surgical Device Components
- Instrument Mechanisms
- Equipment Parts
Consumer Products
- Mechanical Assemblies
- Sporting Equipment
- Appliance Components
Packaging Industry
- Conveyor Components
- Wear Strips
- Guide Systems
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| CNC Machining | Outstanding |
| Injection Molding | Outstanding |
| Extrusion | Excellent |
| Secondary Assembly | Excellent |
Advantages
Outstanding Machinability
One of the easiest engineering plastics to machine precisely.
Excellent Wear Resistance
Ideal for gears, bearings, and moving components.
Low Friction
Provides self-lubricating performance.
Excellent Dimensional Stability
Low moisture absorption ensures tight tolerances.
High Fatigue Resistance
Performs well under repeated loading.
Good Chemical Resistance
Suitable for industrial and automotive environments.
Limitations
Limited UV Resistance
Outdoor applications may require UV-stabilized grades.
Lower Impact Resistance Than Nylon
Less tough under severe impact conditions.
Acid Sensitivity
Strong acids can degrade the material.
Moderate Heat Resistance
Not suitable for extreme high-temperature environments.
Comparison with Common Engineering Plastics
| Property | POM | PA66 | ABS | PC |
|---|---|---|---|---|
| Wear Resistance | Outstanding | Excellent | Moderate | Good |
| Dimensional Stability | Outstanding | Good | Good | Excellent |
| Moisture Resistance | Excellent | Moderate | Good | Good |
| Machinability | Outstanding | Excellent | Excellent | Good |
| Impact Resistance | Good | Excellent | Good | Excellent |
Comparison with Nylon
| Property | POM | PA66 |
|---|---|---|
| Moisture Absorption | Much Lower | Higher |
| Dimensional Stability | Better | Good |
| Wear Resistance | Better | Excellent |
| Impact Resistance | Lower | Higher |
| Machinability | Better | Excellent |
Available Surface Finishes
Standard Finishes
- Natural Finish
- Black Finish
- Molded Finish
Functional Finishes
- CNC Machined Finish
- Precision Ground Finish
- Polished Finish
Specialty Grades
- PTFE Filled POM
- Glass Filled POM
- Conductive POM
- Food Grade POM
Frequently Asked Questions (FAQ)
What is POM?
POM (Polyoxymethylene) is an engineering plastic known for excellent dimensional stability, wear resistance, and low friction.
What is POM used for?
Typical applications include:
- Gears
- Bearings
- Bushings
- Rollers
- Precision Mechanical Components
Is POM better than Nylon?
For precision parts requiring dimensional stability and low moisture absorption, POM is often preferred. Nylon generally offers higher impact resistance.
Is POM self-lubricating?
Yes. POM naturally exhibits low friction and excellent wear characteristics.
Can POM be machined?
Yes. POM is one of the best engineering plastics for CNC machining.
Why choose POM?
Because it combines:
- Outstanding Machinability
- Excellent Wear Resistance
- Low Friction
- High Dimensional Stability
- Long Service Life
What is the difference between Delrin and POM?
Delrin® is a trade name for POM homopolymer. POM also includes copolymer grades from various manufacturers.
Does GCNOV provide POM manufacturing services?
Yes. GCNOV provides:
- POM CNC Machining
- POM Injection Molding
- Custom Plastic Fabrication
- Prototype Development
- Surface Finishing
- Low-Volume Production
- Mass Production
- Precision Mechanical Component Manufacturing