1. What is POM? The Engineering Thermoplastic Revolution
POM (Polyoxymethylene), known as acetal or Delrin, delivers exceptional mechanical properties:
- Near-zero moisture absorption
- 70 MPa tensile strength
- 0.2-0.3% shrinkage rate
- Self-lubricating (μ=0.1-0.3 vs. steel)
Used in 78% of high-precision mechanisms requiring dimensional stability.
2. POM vs. Competing Engineering Plastics
| Property | POM | Nylon 66 | ABS | PEEK |
| Tensile Strength | 70 MPa | 85 MPa | 40 MPa | 100 MPa |
| Moisture Absorb. | 0.2% | 2.8% | 1.5% | 0.1% |
| Max Temp | 100°C | 120°C | 80°C | 250°C |
| Cost/kg | $3-5 | $5-8 | $2-4 | $150-200 |
POM dominates in cost-sensitive precision applications, such as gears and bearings.
3. Injection Molding Processing Guide
Optimal Parameters for POM
| Parameter | Standard POM | Glass-Filled POM |
| Melt Temp | 190-210°C | 200-220°C |
| Mold Temp | 80-105°C | 90-120°C |
| Injection Pressure | 80-130 MPa | 100-150 MPa |
| Drying (Time/Temp) | 3h/110°C | 4h/120°C |
Critical Tip: Maintain <0.1% moisture to prevent formaldehyde gassing.
4. Solving Common POM Material Defects
| Defect | Cause | BFY Mold’s Solution |
| Warping | Uneven cooling | Conformal cooling channels |
| Sink Marks | Inadequate packing | 95% gate sealing pressure |
| Cracks | Over-crystallization | Post-mold annealing |
| Gas Burns | Trapped air | Vacuum venting system |
5. Industry Applications & Case Studies
Automotive
- Fuel system components: POM 30% GF withstands ethanol blends
- Gears: 1 million+ cycles at 1500 RPM (tested per ISO 6336)
Medical
- Inhaler mechanisms: USP Class VI compliant POM grades
- Surgical tools: Autoclavable at 134°C
Consumer Electronics
- Keyboard switches: 10M actuation lifespan
- Connector housings: UL 94 HB flame rating
6. Material Selection Guide
| POM Type | Key Features | Ideal Application |
| Homopolymer | Higher stiffness | Precision gears |
| Copolymer | Better chemical resist. | Fuel contact parts |
| 30% GF | 2x creep resistance | Load-bearing brackets |
| PTFE Blended | 50% lower friction | Self-lubricating bearings |
7. BFY Mold’s POM Expertise
- Specialized Equipment:
- Low-shear screws (L/D=22:1)
- Dehumidifying dryers (less than -40°C dew point)
- Quality Assurance:
- ISO 9001-certified production
- CMM inspection (±0.01mm)
- 48-hour material certification
8. About 10 Essential POM Material FAQs
1. What’s the difference between POM and Delrin?
Delrin is DuPont’s homopolymer POM; generic POM includes copolymers with better chemical resistance.
2. How to prevent POM warping?
Maintain mold temp at 90±2°C and use uniform wall thickness (1.5-3mm).
3. Can POM be bonded or welded?
Yes: Epoxy bonding (shear strength 15-20MPa) or hot-plate welding (for hermetic seals).
4. Is POM food-safe?
FDA-compliant grades exist, but they should be avoided for acidic or lipid-rich foods due to the potential release of formaldehyde.
5. What causes POM part shrinkage?
Excessive crystallinity. Solution: Increase injection speed and packing pressure.
6. Maximum continuous use temperature?
90-100°C for standard grades; 120°C for glass-filled versions.
7. How does UV affect POM?
Causes surface chalking. Use carbon-black filled grades or protective coatings.
8. Typical tolerance capabilities?
±0.05% for dimensions less than 50mm; ±0.1% for larger parts.
9. Cost comparison to metal parts?
60-80% lower cost than machined brass in high-volume production.
Why choose BFY Mold for POM parts?
- 0.1% defect rate guarantee
- 30-day tooling delivery
- Free DFM analysis
