China Yunnan Yuntianhua POM YUNCON®M90  Acetal copolymer resin in stock

Introduction to POM (Polyoxymethylene)

Basic Definition POM, short for Polyoxymethylene, is commonly known as acetal plastic. It ranks among the five major general engineering plastics. It is a highly crystalline linear thermoplastic resin with repeating unit -CH₂-O- in its molecular chain, featuring a crystallinity of 70%~85%. Virgin POM pellets are milky white or light yellow and opaque.

There are two main types based on synthesis processes:

• Homopolymer POM (POM-H):Produced by polymerization of pure formaldehyde. It has higher crystallinity, superior tensile strength, rigidity and wear resistance. Drawbacks include poor thermal stability, easy thermal decomposition and weak resistance to acids and alkalis. 

• Copolymer POM (POM-C):Copolymerized with a small amount of epoxy monomer, containing a few C-C bonds in molecular chains. It delivers outstanding thermal stability, hydrolysis resistance, acid & alkali resistance and easier processability. 

POM  Key Advantages Mechanical Properties (Core Strength, comparable to lightweight metals)

• High rigidity, hardness and tensile strength (60~70 MPa), with specific strength close to steel.

• Low friction coefficient & self-lubricating property: excellent wear resistance, works stably under oil-free sliding conditions.
  

• Excellent fatigue resistance and creep resistance: resistant to deformation and fracture under repeated alternating loads, ideal for gears, fasteners and transmission components.

• Good toughness, retains impact resistance at -40 °C with great resilience.

POM Dimensional & Environmental Stability

• Stable electrical insulation performance, barely affected by temperature and humidity changes.

• Resistant to oil, weak acids, weak alkalis and most organic solvents (alcohols, esters, lubricants). 

• Extremely low water absorption (far lower than PA nylon), maintaining tight dimensional tolerance for precision parts in humid environments.

• Continuous service temperature range: -40 °C ~ 100 °C; short-term peak temperature up to 120 °C.

Processing Performance:Good melt flowability, suitable for injection molding, extrusion and CNC machining; high surface gloss and uniform colorability.

Limitations & Disadvantages

1. Relatively high molding shrinkage; mold shrinkage compensation is required for precision molds.

2. Poor flame retardancy: highly flammable with low oxygen index, no self-extinguishing ability; formaldehyde gas will be released when decomposed at high temperatures.

3. Poor weather resistance: prone to chalking, cracking and embrittlement under long-term UV exposure; UV stabilizer modification is mandatory for outdoor applications.

4. Not resistant to strong acids, concentrated alkalis, phenols and halogenated hydrocarbons, which cause cracking and corrosion.

 POM Main Application Fields

• Sanitary & Fluid Control: Valve spools, water pump impellers, pipe joints (copolymer POM is preferred for hydrolysis resistance).
  

• Hardware & Daily Consumer Goods: Faucet valve cores, zipper teeth, door locks, stationery gears, toy transmission structures, food-contact wear-resistant fittings.

• Mechanical Transmission (Largest Application): Gears, bearings, sliders, pulleys, cams, sprockets, precision fixtures; substitutes copper and zinc alloys.

• Electrical & Electronic Appliances: Internal transmission parts of switches, connectors, reels, precision structural components for home appliances.

• Automotive Industry: Fuel pump housings, pipe connectors, window lifter gears, door lock mechanisms, wiper linkages, plastic fasteners.

POM Simple Grade Selection Guide

• Low friction & silent operation → POM filled with silicone oil or PTFE

• Flame retardant requirement → Special flame-retardant modified POM

• Stable injection molding, hydrolysis/chemical resistance, humid & high-temperature environments → Copolymer POM (universal first choice) 

• Outdoor exposure → UV-stabilized modified POM

• High strength & wear resistance, dry indoor working conditions → Homopolymer POM.