POM (Polyoxymethylene)
Polyoxymethylene (POM), also known as acetal or Delrin (a widely recognised brand name from DuPont), is an engineering plastic renowned for its excellent mechanical properties, including high strength, stiffness, and dimensional stability. Below is a detailed summary of POM’s properties, benefits, and applications.
Properties of POM
Mechanical Properties
- Strength: POM exhibits high tensile and compressive strength, making it ideal for applications requiring resistance to significant forces.
- Stiffness: The material is highly rigid and resists deformation under load.
- Wear Resistance: POM’s low coefficient of friction and exceptional wear resistance make it suitable for moving parts and bearings.
Thermal Properties
- Glass Transition Temperature (Tg): Approximately -60°C, ensuring excellent performance at low temperatures.
- Melting Point: Ranges between 175°C and 180°C.
- Heat Resistance: POM can withstand temperatures of up to 100°C to 120°C without significant deformation.
Chemical Properties
- Chemical Resistance: POM is resistant to many solvents, acids, and bases. However, it has limited resistance to strong oxidising agents and certain esters and ketones.
- Moisture Absorption: Low moisture absorption ensures POM retains its mechanical properties in humid environments.
Physical Properties
- Density: Approximately 1.41 g/cm³, making it moderately dense compared to other engineering plastics.
- Surface Finish: POM provides a smooth and attractive finish, making it suitable for aesthetic applications.
Electrical Properties
- Electrical Insulation: POM offers excellent electrical insulating properties, which makes it a reliable choice for electrical and electronic components.
Benefits of POM
- High Strength and Stiffness: POM combines strength and rigidity, making it ideal for structural and mechanical applications.
- Low Friction Coefficient: Its low friction reduces wear, making it perfect for components with moving parts.
- Dimensional Stability: POM maintains its dimensions well under varying temperatures, ensuring reliable performance in precision applications.
- Durability: A combination of strength and wear resistance makes POM a long-lasting material for demanding uses.
Applications of POM
Industrial
- Precision Components: Widely used for gears, bearings, sliding blocks, and valves due to its strength and wear resistance.
Automotive - Vehicle Components: Found in control mechanisms, switches, fuel systems, and engine parts due to its durability and dimensional stability.
Electronics
- Enclosures and Components: POM’s excellent electrical insulation properties make it suitable for electronic housings and parts.
Consumer Products
- Everyday Items: Used in tools, household goods, and sporting equipment thanks to its strength and aesthetic qualities.
Medical Equipment - Precision Devices: Employed in some medical devices for its strength, accuracy, and resistance to chemicals.
Processing and Fabrication
Processing Techniques
- Injection Moulding: Used for creating complex shapes with high precision.
- Extrusion: Ideal for producing long, continuous shapes like rods and profiles.
- Machining: POM is highly machinable, allowing for the creation of precise parts.
Tooling and Equipment
- Sharp Tools: It is essential to use sharp, well-maintained tools when machining POM to achieve optimal surface finishes and dimensional accuracy.
Conclusion
Polyoxymethylene (POM) is a versatile engineering plastic with exceptional mechanical, thermal, and chemical properties. It is particularly well-suited for applications requiring high strength, wear resistance, and precision. This combination of properties makes POM a popular choice across a wide range of industrial and consumer applications.
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