High-Precision Engineering Plastic for Low-Friction Parts
POM (Polyoxymethylene), also known as acetal or polyacetal, is a high-performance engineering thermoplastic known for its high stiffness, low friction, excellent wear resistance, and dimensional stability.
These properties make POM particularly suitable for precision mechanical components such as gears, bearings, bushings, rollers, fasteners, and moving assemblies.
Why Engineers Choose POM
Unlike general-purpose plastics primarily selected for appearance or cost, POM is often chosen for mechanical performance.
Its combination of stiffness, wear resistance, low friction, and dimensional stability makes it suitable for parts that move, slide, rotate, or maintain precise mechanical relationships.
Maidder provides custom POM plastic parts through CNC machining and injection molding, supporting projects from functional prototypes and engineering validation to repeat production.
POM has naturally low friction characteristics, making it well suited for moving components and sliding surfaces.
Typical parts include:
- Gears
- Bearings
- Bushings
- Rollers
- Sliding components
Excellent Wear Resistance
POM performs well in applications involving repeated mechanical movement and surface contact, helping reduce wear over extended service periods.
High Strength and Stiffness
Its mechanical strength and rigidity allow POM to handle structural loads while maintaining part geometry.
Excellent Dimensional Stability
Low moisture absorption and good dimensional stability help POM maintain accurate dimensions, making it a strong choice for precision components.
Good Creep Resistance
POM maintains its shape effectively under sustained mechanical loads, making it suitable for functional parts exposed to long-term stress.
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POM-C vs POM-H: What Is the Difference?
POM is generally available in two major material families: POM-C (copolymer) and POM-H (homopolymer).
Understanding the difference is important when selecting POM for precision components.
POM-C — Acetal Copolymer
POM-C provides a balanced combination of:
- Good dimensional stability
- Chemical resistance
- Low moisture absorption
- Good wear resistance
- Reliable machinability
It is commonly selected for precision CNC machined components and general engineering applications.
POM-H — Acetal Homopolymer
POM-H generally provides:
- Higher stiffness
- Higher mechanical strength
- Good fatigue resistance
- Excellent wear performance
It is often selected for mechanically demanding parts such as gears, bearings, and high-load components.
POM Manufacturing Options
POM performs particularly well in both CNC machining and injection molding, making it suitable for projects ranging from precision prototypes to high-volume production.
POM CNC Machining
POM is one of the most commonly selected engineering plastics for precision CNC machining because it machines cleanly while maintaining good dimensional stability.
- Precision prototypes
- Functional testing parts
- Gears and pulleys
- Bearings and bushings
- Rollers
- Fixtures
- Mechanical components
- Low-volume production
POM CNC machining offers:
- Good dimensional accuracy
- Smooth machined surfaces
- Excellent machinability
- No mold tooling required
- Fast prototype turnaround
- Suitable performance for functional testing
For engineering teams developing mechanical products, CNC-machined POM parts can also be useful for validating fit, movement, wear, and assembly before production tooling.
POM Injection Molding
POM injection molding is suitable for medium- and high-volume production of precision mechanical plastic components.
- Gears
- Clips
- Fasteners
- Connectors
- Mechanical housings
- Bushings
- Automotive components
- Consumer product mechanisms
Injection molding provides:
- Injection molding provides:
- Consistent part geometry
- Complex feature capability
- Excellent repeatability
- Low unit cost at production volumes
Because POM is a semi-crystalline plastic with meaningful molding shrinkage, mold design and processing conditions should be carefully controlled when dimensional accuracy is critical.
From CNC Prototype to Injection Molded POM Parts
POM is particularly useful for products containing mechanical movement.
During early product development, CNC machining can produce functional POM components without investing in tooling.
These parts can be used to evaluate:
- Assembly fit
- Gear engagement
- Sliding movement
- Mechanical loads
- Wear behavior
- Functional tolerances
Once the design is validated, the project can transition to injection molding for repeat production.
This allows engineers to identify mechanical or assembly problems before committing to production tooling.
Common Applications of POM Plastic
POM is widely used where mechanical precision, wear resistance, and low friction are more important than transparency or cosmetic appearance.
Gears & Transmission Components
POM is commonly used for:
- Spur gears
- Worm gears
- Pulleys
- Sprockets
- Transmission components
Its low friction and wear characteristics make it suitable for repeated mechanical movement.
Bearings & Bushings
POM is frequently selected for:
- Bushings
- Bearings
- Guide components
- Sliding blocks
- Rollers
These applications benefit from its low friction and dimensional stability.
Automotive Components
Typical applications include:
- Clips
- Fasteners
- Mechanical connectors
- Interior mechanisms
- Fuel-system-related components where an appropriate grade is specified
Electronics & Electrical Products
POM can be used for:
- Precision mechanisms
- Connectors
- Insulating components
- Switch components
- Printer mechanisms
Industrial Equipment
Applications include:
- Machine components
- Rollers
- Guides
- Fixtures
- Valve components
- Mechanical assemblies
Consumer Products
POM is also found in:
- Zippers
- Handles
- Hinges
- Locking mechanisms
- Appliance components
- Moving product assemblies
When Should You Choose POM?
POM is a strong candidate when your part requires several of the following characteristics:
High dimensional accuracy
Low friction
Repeated movement
High wear resistance
Good stiffness
Low moisture absorption
Mechanical durability
Smooth sliding performance
For components such as gears, bushings, bearings, rollers, clips, and precision mechanisms, POM is often more appropriate than general-purpose plastics.
POM vs Other Engineering Plastics
POM vs Nylon
- Better dimensional stability
- Lower moisture absorption
- Low friction
- Precision mechanical performance
- Higher toughness in certain applications
- Good fatigue performance
- Strong wear performance
- Different temperature or structural characteristics depending on grade
POM vs ABS
- Better wear resistance
- Lower friction
- Better suited for precision mechanisms
- Better dimensional stability in many mechanical applications
- Better cosmetic surface options
- Easier painting and finishing
- Suitable for housings and consumer products
- More economical for many general applications
POM vs PC
POM is generally preferred for gears, bearings, sliding components, and mechanical mechanisms.
PC is generally preferred where high impact resistance, transparency, and toughness are priorities.
FAQs
What is POM plastic?
POM (Polyoxymethylene), also called acetal or polyacetal, is a semi-crystalline engineering thermoplastic known for high stiffness, low friction, wear resistance, and excellent dimensional stability.
What is POM plastic used for?
POM is commonly used for gears, bearings, bushings, rollers, clips, fasteners, connectors, and other precision mechanical components.
Is POM the same as Delrin?
Not exactly.
POM is the overall polymer family, while Delrin® is a trade name associated with specific homopolymer acetal (POM-H) materials.
A simplified way to understand the terminology is:
POM → Polyoxymethylene material family
Acetal → Common generic name for POM
POM-C → Acetal copolymer
POM-H → Acetal homopolymer
Delrin® → Brand name used for POM-H materials
When selecting a material for production, the exact resin grade should be confirmed based on mechanical, dimensional, chemical, and regulatory requirements.
What is the difference between POM-C and POM-H?
POM-C is an acetal copolymer offering balanced chemical resistance, dimensional stability, and processing characteristics. POM-H generally provides higher stiffness and mechanical strength.
Is POM good for CNC machining?
Yes. POM has excellent machinability and dimensional stability, making it a popular material for CNC-machined precision parts, prototypes, gears, bushings, and mechanical components.
Is POM suitable for injection molding?
Yes. POM injection molding is widely used for repeat production of precision mechanical components, particularly parts requiring low friction, stiffness, and wear resistance.
Is POM suitable for gears?
Yes. Its combination of low friction, wear resistance, stiffness, and dimensional stability makes POM a common material choice for plastic gears.
Can POM replace metal parts?
In suitable applications, POM can replace certain metal components to reduce weight, corrosion, friction, and manufacturing costs. The decision should be based on actual load, temperature, wear, and tolerance requirements.
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