What are the primary physical and mechanical properties of POM resin?

Polyoxymethylene (POM) resin, also known as acetal, is a high-performance engineering thermoplastic known for its excellent balance of physical and mechanical properties. Here are its primary characteristics:

High Stiffness and Strength:

Tensile Strength: POM resin has high tensile strength, typically around 60-70 MPa for copolymers and 70-90 MPa for homopolymers, making it suitable for load-bearing applications.
Modulus of Elasticity: It has a high modulus, typically ranging from 2.5 to 3.0 GPa, providing stiffness and rigidity.

Low Friction and Wear Resistance:
POM exhibits excellent low friction and is highly resistant to wear, making it ideal for moving parts like gears, bearings, and sliding components.
It has a low coefficient of friction (0.1 to 0.3), which helps minimize energy losses in mechanical systems.

Dimensional Stability:
Due to its crystalline structure, POM maintains good dimensional stability even under varying thermal and mechanical loads, reducing the risk of warping or distortion.
Its low water absorption (typically <0.25%) contributes to this stability, especially in humid environments.

Good Fatigue and Creep Resistance:
POM resists fatigue well in cyclic loading applications and has good creep resistance, meaning it can withstand prolonged stress without permanent deformation.

High Impact Resistance:
POM has good impact strength, especially at lower temperatures, making it tough and durable in demanding applications. The notched impact strength is often around 5-10 kJ/m².

Thermal Properties:
Melting Temperature: POM has a melting point of approximately 165-175°C (329-347°F), depending on the type (homopolymer vs. copolymer).
Continuous Use Temperature: POM can be used in temperatures ranging from -40°C to 100°C (in some cases up to 120°C) without significant degradation.
Thermal Expansion: It has a relatively low coefficient of thermal expansion, contributing to its dimensional stability across temperature variations.

Chemical Resistance:
POM is resistant to many solvents, fuels, and chemicals, including alcohols, hydrocarbons, and alkalines.
However, it is vulnerable to strong acids and oxidizing agents, which can degrade its structure.

Electrical Insulation Properties:
POM is a good electrical insulator with high dielectric strength, making it suitable for electrical and electronic components.

Density:
The density of POM resin is typically around 1.41–1.43 g/cm³, which is relatively low compared to metals but typical for engineering plastics.
These properties make POM resin a preferred material for high-performance applications, especially in mechanical, automotive, electrical, and consumer products.