POM Material: A Versatile Engineering Plastic

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This guide explores POM material’s properties & uses in industries like automotive & consumer goods, revealing its significance for manufacturers.

Introduction

POM material is a semi-crystalline thermoplastic, boasting high mechanical strength, dimensional stability, and low friction, ideal for various applications including gears and precision parts.

Its cost-effectiveness, versatility, and functional performance make it indispensable in manufacturing, offering reliable functionality and design flexibility across industries from automotive to medical devices.

What is POM Material

Definition and Composition

POM, or polyacetal, is a semi-crystalline engineering thermoplastic derived from formaldehyde (CH2O)n. Its molecular structure includes a carbon atom bonded to two -OR groups, giving it both crystalline and amorphous regions.

This unique composition contributes to its notable properties, including good dimensional stability.

Types of POM Ｍaterial

• POM-H (Homopolymer): This is the standard POM variety, known for its well-balanced mechanical properties, good chemical resistance, and natural white color.
• POM-C (Copolymer): This type offers even higher chemical resistance and improved long-term dimensional stability compared to POM-H. However, it has slightly lower mechanical strength.

Improving POM Material with Additives

Additionally, POM can be modified with various additives like:　

• Glass fibers: Enhance stiffness and dimensional stability
• Lubricants: Improve wear resistance and sliding properties
• Flame retardants: Increase fire resistance

These modifications result in a wider range of POM materials suitable for specific applications.

Properties of POM Material

TL;DR: The following chart provides a summary of the content for an easy read.

Category	Property	Description
Mechanical	Strength and Durability	High
	Impact Resistance	Good
	Friction	Low coefficient
	Wear Characteristics	Excellent
Thermal	Melting Point	High
	Temperature Resistance	Good
	Thermal Expansion	Low coefficient
Chemical	Resistance to Chemicals and Solvents	Good
	Hydrolysis Resistance	Good
Electrical	Dielectric Strength	Good
	Insulating Properties	High

Mechanical properties

POM is strong, durable, and tough, capable of withstanding stress without deforming. It offers decent impact resistance
,especially in cold conditions, and excels in low-friction and high wear scenarios, perfect for parts requiring durability in moving contacts.

Thermal properties

With a high melting point and consistent performance at temperatures up to 100°C, POM maintains its shape and 
strength when exposed to heat. Its low thermal expansion rate ensures size stability despite temperature changes.

Chemical properties

Resistant to many chemicals including alcohols and hydrocarbons, POM is not compatible with strong acids and bases. It stands up well against hydrolysis, remaining stable in hot and humid conditions.

Electrical properties

POM has strong dielectric properties, effectively preventing electrical leaks, positioned well as an electrical insulator with high resistance to electrical conductivity.

Applications of POM Material

Automotive Industry

• Interior Components: POM’s strength and abrasion resistance make it ideal for instrument panels, bushings, seat adjusters, armrests, door handles, and knobs.
• Fuel System Parts: POM’s toughness and chemical resistance suit fuel lines, rails, pump housings, valves, and sensor components.

Consumer goods

• Handles and Knobs: POM’s durability and resistance to deformation suit doorknobs, cabinet hardware, appliance knobs, levers, and tool handles.
• Zippers and Fasteners: Its low friction and resilience make POM ideal for zipper sliders, teeth, coil springs, and snaps.

Engineering Applications

• Gears and Bearings: POM’s stability and low friction fit gears, low-load bearings, and bushings.
• Valve Components: Its chemical resistance suits valve seats, seals, bodies, and housings in various engineering applications.

Medical Devices

• Surgical Instruments: POM’s biocompatibility and sterilizability suit handles and housings for surgical instruments.
• Dental Applications: Its resistance to sterilization makes POM suitable for disposable dental tools and orthodontic retainers.

Advantages and Disadvantages of POM Material

Advantages of POM Material

• High mechanical strength: POM is a tough and rigid plastic, making it suitable for parts that need to bear significant loads without deforming.
• Excellent dimensional stability: POM retains its shape well even under varying temperatures and moisture conditions. This makes it ideal for precision parts.
• Low coefficient of friction: POM has a slippery surface, reducing friction and wear in moving parts. This makes it useful for gears, bearings, and rollers.
• Ease of machining and fabrication: POM can be easily machined using conventional tools and techniques. It can also be welded, threaded, and polished.

Disadvantages of POM Material

• Poor chemical resistance: POM can be degraded by strong acids, bases, and solvents. This limits its use in environments with harsh chemicals.
• High moisture absorption: While not as high as some nylons, POM can absorb moisture over time, which can affect its dimensional stability and mechanical properties.
• Limited UV resistance: POM can degrade when exposed to ultraviolet light for extended periods. This makes it less suitable for outdoor applications.
• Flammability: POM is flammable and will burn if exposed to an ignition source. It may not be suitable for applications with fire safety requirements.
• Brittle at low temperatures: POM can become brittle and more susceptible to cracking at low temperatures.
• Difficult to paint and bond: POM’s low surface energy makes it challenging to make paints and adhesives adhere well. Special surface treatments may be required.

POM Material: Limitations and Considerations

Limitations Due to Water Absorption

Water absorption in POM leads to dimensional changes and weakened mechanical properties, requiring alternative materials for high-load or outdoor applications to ensure long-term performance.

Environmental Considerations

Exposure to chemicals or fluctuations in humidity and temperature affects water absorption in POM, potentially degrading the material.

Design Considerations

Maintaining uniform part thickness is vital for preserving dimensional stability and mechanical properties in POM. Surface treatments and alternative materials like PEEK can further mitigate water absorption issues, improving reliability.

POM Material Compared to other materials

POM Compared to Metals

Properties	POM	Metals
Weight	Lightweight	Heavier
Corrosion Resistance	Excellent	Variable
Friction	Low	Higher, may need lubricants
Strength	Stiff, less strong than metals	Very high
Thermal Conductivity	Low	High

POM outperforms metals in several aspects: it’s lightweight, corrosion-resistant, and exhibits low friction properties.

Nonetheless, it falls short in terms of strength and thermal conductivity when compared to metals.

POM Compared to Other Plastics

Properties	POM	Other Plastics
Stiffness	Higher	Variable
Friction	Low	May be higher
Chemical Resistance	Good	Ranges widely
Impact Strength	Good (esp. low temps)	Some plastics higher
Temperature Resistance	Moderate	Some plastics higher

POM exhibits distinct characteristics compared to other plastics. It boasts higher stiffness, ensuring precise part dimensions, and low friction for smooth movement. Additionally, POM offers good chemical resistance, making it suitable for harsh environments.

However, it falls short in impact strength when compared to some plastics, especially at low temperatures, and has limited temperature resistance, making it less ideal for high-temperature applications.

POM Compared to Engineering Polymers

Properties	POM	Engineering Polymers
Cost	Affordable	Typically higher
Machinability	Easy	Can vary
Stability	Excellent	Varies, some exceptional
Temp Resistance	Moderate	Generally higher
Chemical Resistance	Moderate	Often superior
Strength (High Temperatures)	Lower	Usually remains strong

POM stands out in comparison to engineering polymers. It offers advantages such as affordability, easy machinability, and excellent dimensional stability.

However, it has limitations including lower temperature resistance, limited chemical resistance, and reduced strength at elevated temperatures compared to engineering polymers.

Conclusion

Polyoxymethylene (POM), a versatile engineering plastic, offers high strength, stability, and ease of production. Its low friction and cost-effectiveness make it ideal for various components. However, limitations such as poor chemical resistance and brittleness in cold temperatures must be considered.

Despite these drawbacks, POM remains significant due to its balanced properties, finding use in gears, bearings, and other applications across industries, providing a competitive edge in cost-sensitive production environments.

Discover High-Performance Materials at Unionfab

Unionfab, a top-tier 3D printing company in the industry, offers a range of materials beyond POM, including high-performing PLA, PEEK, and Stratasys ULTEM™ 9085, allowing you to select the optimal solution.

Whether opting for 3D printing or traditional manufacturing techniques like CNC machining or vacuum casting, Unionfab seamlessly integrates your chosen material into the production process.