POM injection molding is used for acetal gears, bushings, rollers, clips, sliding blocks and precision mechanical parts. It offers low friction, good wear resistance and dimensional stability, but it has relatively high shrinkage and must be processed within a safe temperature window to avoid degradation.
POM can be an excellent production material when a plastic part needs smooth motion, stiffness and repeatable dimensions. The same properties that make it useful also demand careful mold design, venting, gate location and shrinkage allowance.
Why Use POM for Injection Molded Parts
Acetal is selected when friction, wear, fatigue and dimensional consistency are more important than a low raw material price.
| POM advantage | Useful part type | Design note |
|---|---|---|
| 低摩擦 | Gears, sliders and bushings | Check mating material and lubrication. |
| Good fatigue behavior | Clips, springs and moving features | Avoid sharp notches and over-stress. |
| 寸法安定性 | 精密機械部品 | Plan shrinkage and moisture conditions. |
| Wear resistance | Rollers and guide parts | Review load, speed and temperature. |
| 耐薬品性 | Fuel or cleaning exposure in some cases | Confirm exact fluid compatibility. |
POM DFM Checklist
- Allow for typical acetal shrinkage during mold design.
- Use uniform wall thickness where practical.
- Avoid trapped gas and poor venting because POM degradation can be serious.
- Review gate location for precision dimensions and appearance.
- Confirm whether homopolymer or copolymer POM is better for the application.
POM vs Other Engineering Plastics
POM is not always better than nylon, PC or PBT. It is strongest when sliding behavior, wear and precision are central requirements.
| 素材 | Choose it when | Tradeoff |
|---|---|---|
| POM / acetal | Low friction and precision are required | Higher shrinkage and strict processing control. |
| ナイロン | Higher toughness or structural strength is needed | Moisture affects dimensions. |
| PC | Impact and transparency are important | More stress and drying sensitivity. |
| PBT | Electrical and dimensional stability are needed | Different impact and flow behavior. |
| 覗き見 | Very high heat and chemical performance are needed | Much higher cost. |
Internal Links for POM Part Decisions
A POM part should be evaluated against part tolerance, load, wear pair, mold cost and annual volume.
- Plastic injection molding materials guide
- Plastic gear design material selection guide
- CNC machining vs injection molding decision guide
よくある質問
What is POM injection molding used for?
POM injection molding is used for gears, bushings, rollers, sliding blocks, clips and precision mechanical parts that need low friction and wear resistance.
Does POM have high shrinkage?
Yes. POM is a crystalline plastic with relatively high shrinkage, so mold dimensions, wall thickness and gate location must be planned carefully.
Is POM better than nylon?
POM is often better for low-friction precision parts, while nylon can be better for toughness and structural applications. The best choice depends on load, moisture, wear and temperature.
What is the main processing risk with POM?
POM must not be overheated or held too long at high temperature because degradation can create gas and safety risks. Processing control and venting are important.
