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Read morePOM (Acetal) Rods & Sheets — Complete Guide
07 October, 2026 | Admin
POM, also known as acetal or polyoxymethylene, is one of the most widely machined engineering plastics. POM acetal rods and sheets are chosen for precision parts that need stiffness, low friction, dimensional stability and a smooth finish, such as gears, bushes, rollers, valve parts and food-machinery components. This guide explains grades, properties, applications and limits so you can specify POM with confidence.
Homopolymer vs Copolymer
POM comes in two main types:
- POM-H (homopolymer): slightly higher stiffness, strength and hardness. Well suited to highly loaded precision parts.
- POM-C (copolymer): better resistance to hot water, alkalis and long-term thermal ageing, with lower centreline porosity in thick stock. It is the most common stock-shape grade for general machining.
For most machined components, POM-C is the default. POM-H is chosen where maximum stiffness or creep resistance is needed.
Key Properties
- High stiffness and strength for a plastic, with good fatigue resistance
- Low friction and good wear resistance, often run without lubrication
- Low moisture absorption, so dimensions stay stable, unlike nylon
- Excellent machinability with tight tolerances and a smooth surface finish
- Typical continuous service temperature around 100°C, depending on grade
- Good resistance to fuels, solvents and many neutral chemicals
Limits to Be Aware Of
- POM is attacked by strong acids, such as hydrochloric and sulphuric acid, and by oxidising agents.
- It has limited UV resistance outdoors unless stabilised or black grades are used.
- It burns readily and is not suitable where flame resistance is required.
- It cannot be solvent-bonded easily.
Typical Applications
- Gears, sprockets, cams and pulleys
- Bushes, bearings and wear strips
- Rollers and conveyor components
- Valve bodies and pump components for neutral fluids
- Food-processing machine parts, using food-contact grades where required
- Insulators and electrical housings
- Jigs, fixtures and precision spacers
Forms and Colours
POM is commonly supplied as round rods, sheets and plates in natural (white) and black. Black grades offer better UV stability. Stock sizes vary by supplier, so contact us with the diameter or thickness you need.
Machining Tips
- Use sharp tools with positive rake; POM produces clean chips.
- Avoid excessive heat build-up; use coolant or air for deep cuts.
- For thick plates or large-diameter rods, POM-C reduces the risk of porosity in the centre.
- Stress-relieve before final machining of high-precision parts if distortion is a concern.
POM vs Nylon vs Other Plastics
POM and nylon often compete for the same parts. POM holds tolerance better in humid conditions because it absorbs far less water, while nylon is tougher under impact and better at absorbing shock. For a wider comparison, read our POM vs Nylon vs UHMWPE vs PTFE guide.
Related products: POM Acetal Sheets & Rods and Engineering Plastics. Every order from Diode is supplied with a Material Test Certificate.
How to Specify POM for a New Part
Start with the operating environment. Confirm the maximum temperature, any contact with acids, chlorinated water or oxidisers, and whether the part runs dry or lubricated. Next, define the load: static, sliding, rotating or impact. Finally, set the tolerances you need and the quantity. With those details, our team can confirm whether POM-C, POM-H or an alternative such as nylon or PTFE suits the job, and quote stock or machined parts.
Frequently Asked Questions
What is the difference between POM-C and POM-H?
POM-H is slightly stiffer and stronger; POM-C has better hot-water and alkali resistance and less centre porosity in thick stock.
Is POM acetal food safe?
Food-contact grades are available. Specify the requirement when ordering so the correct grade is supplied.
Can POM handle acids?
No. POM is attacked by strong acids and oxidisers. Consider PP, PVDF or PTFE for acidic environments.
Why choose POM instead of nylon?
POM absorbs far less moisture, so it keeps tighter tolerances in humid environments.
Request a Quotation
Send the sizes, grade (POM-C or POM-H), colour and quantities you need to our Al Khobar team for a quotation on POM acetal rods and sheets.
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