Acetal resin

Acetal resin is a semi-crystalline copolymer with high mechanical strength, stiffness, flowability, wear resistance and good processability.

Water absorption is almost zero, and it maintains dimensional and stability characteristics. Its physical properties remain unchanged in different types of environments. Adding glass fibre can improve mechanical strength, stiffness and dimensional stability. Thanks to its characteristics, it is suitable for contact with foodstuffs.

Main characteristics of acetal resin

• High mechanical strength, high rigidity, and high hardness, low coefficient of friction.
• Good impact strength even at low temperatures.
• Low moisture absorption (at 0.8% saturation), excellent machinability. It is very close to the characteristics of non-ferrous materials for which it can be substituted with excellent results. It is used expressly for automatic machines.
• Lower tendency to deform over time compared to polyamides.
• High dimensional stability and hydrolysis resistance (at +140°F).

There is a distinction between homopolymers (POM-H) and copolymers (POM-C). Due to their higher crystallinity, POM-H offers a slightly higher density, hardness and mechanical strength. However, POM-C provides higher impact resistance, better abrasion resistance and higher thermal and chemical resistance. In addition, POM-C is generally less expensive.

Sectors of use

• Mechanical: one of the most widely used engineering plastics for precision mechanical parts.
• Food: it is approved according to current regulations (e.g. FDA, EU FCS). It can be used in contact with foodstuffs.
• Chemical: it is resistant to weak acids, alkaline solutions, organic solvents, benzene, petroleum and alcohol.
• Thermal: it is suitable for components that have to work constantly at temperatures between 60 and 80°C.
• Electrical: not hygroscopic, it is commonly used for electrical purposes as an insulator.

Disadvantages of acetal resin

It has low abrasion resistance, especially in dirty and dusty environments. It is not self-extinguishing and is not very resistant to strong acids (e.g. sulphuric acid). It is not resistant to UV radiation. The effect of UV radiation combined with atmospheric oxygen oxidises the surface and leads to alteration of the initial colour over time.

Applications

Guide and slide elements, pump component clamps, fan impellers, bearing housings, gear wheels, hinges, dimensionally stable precision parts, electrical insulators and sliding components.