POM (Delrin/Acetal) CNC Machining Services
- Tolerances to ±0.01 mm
- Delivery in as Fast as 3 Days
- ISO 9001:2015 Certified
POM is widely recognized by two trade names: Delrin (DuPont’s homopolymer grade) and Acetal Copolymer (a generic copolymer grade), often used interchangeably in the manufacturing industry. POM is used for demanding products and parts such gears, medical delivery equipment, and other high-load mechanical applications.
RpProto offer 3-axis and 5-axis POM CNC machining services including milling, turning. Whether you need Delrin CNC machining for high-strength mechanical components, or acetal CNC machining for chemically resistant parts in food or medical environments, RpProto delivers precision-machined POM parts that meet your most demanding specifications — from rapid prototypes to production runs.
These three terms are often used interchangeably. What’s the Difference? There are important distinctions:
| POM (Generic) | Delrin (POM-H) | Acetal Copolymer (POM-C) | |
|---|---|---|---|
| Full Name | Polyoxymethylene | POM Homopolymer (DuPont) | POM Copolymer |
| Structure | — | Homopolymer | Copolymer |
| Tensile Strength | High | Higher | Slightly Lower |
| Chemical Resistance | Good | Moderate | Excellent |
| Thermal Stability | Good | Excellent | Better vs. acids |
| FDA / Food Safe | Grade-dependent | Select grades | Yes (POM-C) |
| Best For | General use | High-load mechanical | Chemical / food contact |
RpProto machines both POM-H (Delrin) and POM-C (Acetal Copolymer). If you’re unsure which grade is right for your application, our engineers are happy to advise.
| Property | POM-H (Delrin) | POM-C (Acetal Copolymer) |
|---|---|---|
| Density | 1.42 g/cm³ | 1.41 g/cm³ |
| Tensile Strength (Yield) | ~70 MPa | ~63 MPa |
| Flexural Modulus | 2,700 MPa | 2,500 MPa |
| Elongation at Break | 25–75% | 30–75% |
| Hardness (Rockwell M) | M80–M94 | M78–M90 |
| Coefficient of Friction | 0.1–0.3 | 0.1–0.3 |
| Water Absorption (24h) | 0.20–0.25% | 0.22–0.25% |
| Operating Temperature | -40°C to 120°C | -40°C to 110°C |
| Heat Deflection Temp | 136°C | 110°C |
| Dielectric Strength | ~20 kV/mm | ~20 kV/mm |
CNC Milling and CNC Turning
3-axis, 4-axis, 5-axis milling.
Standard turning & turn-milling compound.
| Tolerances | Standard ±0.1 mm; Precision ±0.01 mm |
| Surface Roughness (Ra) | Ra 0.8 μm – Ra 3.2 μm (as-machined) |
| Max. Part Size (Milling) | 1,200 × 600 × 500 mm |
Advantages of POM (Delrin/Acetal)
Exceptional Dimensional Stability
POM has one of the lowest moisture absorption rates among engineering plastics (0.22–0.25%), ensuring machined parts retain their dimensions even in humid environments. Ideal for precision-fit assemblies where dimensional drift is unacceptable.
Self-Lubricating & Low Friction
POM's inherently low coefficient of friction (0.1–0.3) reduces wear in moving components without additional lubricants. Perfect for gears, bearings, bushings, and sliding mechanisms.
High Strength & Rigidity
With a tensile strength of up to 70 MPa and excellent flexural modulus, POM rivals many metals in structural applications while being significantly lighter — enabling metal-to-plastic substitution.
Outstanding Fatigue & Impact Resistance
POM maintains its properties under repeated cyclic loading, making it one of the few plastics suitable for high-cycle mechanical applications such as snap-fit components and spring-loaded assemblies.
Chemical & Electrical Resistance
Resistant to fuels, solvents, and a wide range of organic chemicals. POM also has good dielectric properties, making it suitable for electrical insulation components across automotive, electronics, and industrial applications.
Why Choose RpProto for POM CNC Machining?
Flexible Production: Prototype to Volume
From a single prototype to 10,000+ production parts, RpProto scales with your project needs. No minimum order quantity. Volume pricing available for orders over 50 pieces.
Fast, Reliable Global Shipping
Parts ship from our facility within 3–7 business days. Expedited options available. We ship to the US, EU, UK, Australia, and worldwide via DHL, FedEx, and UPS.
Competitive, Transparent Pricing
Instant online quotes in under 2 minutes. No hidden fees. All pricing includes material, machining, and standard inspection. Surface finishing costs are itemized clearly.
ISO 9001:2015 Certified | RoHS Compliant | SGS Inspected | PPAP Available | NDA Protected
Managing POM Deformation in CNC Machining
POM is a crystalline thermoplastic with a relatively high thermal expansion coefficient. Without proper process controls, this leads to three common deformation failure modes — and here’s exactly how RpProto eliminates each one.
Flood Coolant + Low Speed
- Root Cause
Cutting heat causes local thermal expansion in the workpiece.
- RpProto Solution
We use flood coolant and low cutting speeds during critical operations to maintain workpiece temperature within acceptable limits.
Stress-Relief Annealing 80–100°C
- Root Cause
POM retains internal stresses from the extrusion/molding of raw stock, which can be released during machining — causing warping in thin-walled or large flat parts.
- RpProto Solution
For critical parts, we recommend (and provide) a stress-relief annealing step before final machining. Parts are heated to 80–100°C and cooled slowly to stabilize dimensions.
Soft Jaws + Vacuum Fixtures
- Root Cause
Excessive clamping force can distort thin-walled or hollow POM parts, causing them to spring out of tolerance after release.
- RpProto Solution
We use custom soft jaws and vacuum fixtures, and calculate safe clamping pressures based on part geometry and wall thickness.
POM (Delrin/Acetal) CNC Machined Parts: Industries & Applications
Automotive
Typical Parts: Gear wheels, door lock actuators, fuel system valves, clips
Why POM:High fatigue resistance, low friction, fuel resistance
Consumer Electronics
Typical Parts: Precision connectors, insulating brackets, slider rails
Why POM:Dimensional stability, good dielectric properties
Medical Devices
Typical Parts: Drug delivery mechanisms, surgical instrument components
Why POM:POM-C is FDA-compliant, biocompatible, low particulate
Food & Beverage
Typical Parts: Conveyor components, pumps, valve bodies
Why POM:FDA-grade POM-C, resistant to cleaning agents
Industrial Machinery
Typical Parts: Bearings, bushings, guide rails, pulleys, rollers
Why POM:Self-lubricating, wear-resistant, tight tolerances
Robotics & Automation
Typical Parts: End effectors, drive gears, linear guides
Why POM:Lightweight metal alternative, repeatable precision
Ready to Machine Your POM Parts?
From single prototypes to production-scale Delrin and Acetal parts — RpProto delivers precision CNC machining with fast turnaround and guaranteed quality. Upload your design now and get a quote in minutes.
Frequently Asked Questions: POM (Delrin/Acetal) CNC Machining
POM (Polyoxymethylene) is the chemical name for acetal resin. Delrin is DuPont’s branded homopolymer version (POM-H), known for its superior mechanical strength. Acetal Copolymer (POM-C) is a generic copolymer version with better chemical resistance and stability. Both are excellent for CNC machining; the choice depends on your specific load and environment requirements.
Yes. POM is one of the easiest engineering plastics to machine with high precision. At RpProto, we routinely achieve dimensional tolerances of ±0.05 mm for standard parts and ±0.01 mm for precision-critical features. POM’s low moisture absorption means machined dimensions are highly stable over time.
POM can deform due to thermal expansion from cutting heat, release of residual stresses in raw stock, or excessive clamping pressure on thin-walled parts. RpProto uses flood coolant, optimized cutting parameters, stress-relief annealing for sensitive parts, and custom fixtures to prevent deformation and deliver accurate, stable parts.
Acetal Copolymer (POM-C) in specific grades (such as Hostaform C 9021 or Ultraform N2320) is FDA-compliant and suitable for direct food contact applications. Standard POM-H (Delrin) is generally not recommended for food contact without confirming specific grade compliance. Please specify food-grade requirements when requesting a quote.
Standard POM CNC machining stock is available in natural (white/ivory) and black. Other colors such as blue, red, and green are available in POM-C upon request, subject to stock availability and minimum quantity requirements.
Standard lead time is 5–7 business days from design confirmation. Expedited production is available in as fast as 3 business days for qualifying geometries and quantities. Complex or large-volume orders may require additional lead time — our team will confirm during quoting.
Yes. We accept STEP, IGES, DXF, DWG, STL, SolidWorks (.sldprt), and Parasolid (.x_t) files. Upload your file on our instant quote page and receive pricing and DFM feedback within 2 minutes. For complex assemblies, you can upload a ZIP file with multiple parts.
There is no minimum order quantity at RpProto. We machine single prototypes, small batches, and high-volume production runs with equal care. Volume discounts are available for orders of 50 pieces or more.
POM offers better dimensional stability and lower moisture absorption than Nylon, making it preferred when tight tolerances must be maintained in humid conditions. Compared to PEEK, POM is significantly more cost-effective and easier to machine, though PEEK is superior in high-temperature and chemical-resistance applications above 120°C. RpProto can help you select the optimal material for your application during our free DFM review.
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