POM Plastic Overview: Properties, Applications, and Processing

By: HDCMFG
October 18, 2024

Polyoxymethylene (POM), also known as Acetal plastic or Delrin, is a high-performance engineering thermoplastic widely used in precision parts manufacturing. Its unique combination of strength, low friction, and excellent wear resistance makes it a popular material for various industrial and consumer applications.

In this blog, we will explore the properties, applications, and advantages of POM plastic and how it compares to other materials. Whether used in automotive components or industrial machinery, POM’s versatility and durability are key reasons for its widespread use.

What is POM Plastic?

POM plastic is a crystalline polymer, known chemically as Polyoxymethylene, with an impressive balance of physical properties. It is available in both homopolymer and copolymer forms, with Delrin being a well-known brand of homopolymer POM. In its natural state, POM is typically opaque white.

The material’s structure gives it excellent dimensional stability, high mechanical strength, and low moisture absorption. This makes POM ideal for manufacturing precision parts requiring tight tolerances, such as gears, bearings, and bushings.

Key Properties of POM Material

POM plastic is prized for its impressive mechanical and physical properties. Some of its key features include:

High mechanical strength: POM exhibits excellent toughness and resilience, which makes it suitable for heavy-duty applications.
Low friction and wear resistance: Its smooth surface and self-lubricating properties reduce wear and tear, making it ideal for parts like gears.
Dimensional stability: POM maintains its shape even in extreme environments, with low thermal expansion and minimal moisture absorption.
Chemical resistance: POM resists most solvents, oils, and fuels.

Properties	Value
Density at 20ºC	1.41g/cm³
Tensile strength @ yield	67MPa
Elongation @ break	30%
Tensile modulus of elasticity	2800MPa
Ball indentation hardness	150N/mm²
Hardness (Shore D)	81 Scale D
Moisture Content	0.0200 – 0.290 %
Injection Pressure	82.7 – 124 MPa
Melting Temperature	165 °C
Service Temperature – long term	50 to +100
Acid resistance	yes
Alkali resistance	yes
Hyrocarbon resistance	yes
Chlorinated hydrocarbon resistance	Limited
Aromatic resistance	yes
Ketone resistance	yes

Common Applications of POM

POM plastic is used in a variety of industries, thanks to its versatility and durable properties:

Automotive industry: POM is used in fuel systems, gears, locks, and seatbelt components.
Industrial machinery: Bearings, gears, and structural components made from POM benefit from its low friction and high wear resistance.
Consumer goods: It is also found in zippers, kitchen appliances, and power tool components.
Medical industry: In medical devices like insulin pens and dental instruments, POM’s biocompatibility and stability under sterilization make it an excellent choice.

POM vs. Other Plastics

When compared to other engineering plastics, POM demonstrates several advantages:

POM vs. Nylon: POM offers better wear resistance and lower moisture absorption than nylon, making it a preferred choice for parts exposed to water or humidity.
POM vs. PTFE: While PTFE (Teflon) excels in chemical resistance and higher temperature tolerances, POM is stronger and easier to machine, making it more suitable for mechanical parts like gears.
POM vs. Polypropylene: POM provides superior strength and rigidity compared to polypropylene, which is more flexible and used for lightweight applications.
POM vs. PEEK: POM offers good mechanical strength and dimensional stability, but PEEK surpasses it in terms of high-temperature resistance and chemical resistance.

Property	POM	Nylon	PTFE	PEEK
Strength	High	Moderate	Moderate	Very High
Moisture Absorption	Very Low	High	Very Low	Very Low
Machinability	Excellent	Good	Poor	Good
Temperature Resistance	Moderate	Moderate	High	Very High
Chemical Resistance	Moderate	Moderate	Very High	Very High

Processing Methods for POM Plastic

The two main methods for processing POM plastic are injection molding and CNC machining. Injection molding is especially popular for producing large quantities of POM components that have complex shapes, as it provides reliable consistency and precise dimensions.

On the other hand, CNC machining is well-suited for creating precision parts with intricate details and tight tolerances because of how easily POM can be machined.

Limitations of POM Plastic

While POM is highly versatile, it does come with a few drawbacks:

Sensitivity to UV: POM tends to degrade when exposed to sunlight for long periods, which limits its use in outdoor settings unless UV stabilizers are added.
Heat limitations: POM can’t handle temperatures above 160°C for extended periods, making it unsuitable for some high-heat applications.
Recycling difficulties: POM’s thermal properties make it harder to recycle compared to some other thermoplastics.

Frequently Asked Questions (FAQs) About POM Plastic

1. Is POM plastic FDA-approved?

Yes, certain grades of POM are FDA-approved and are used in food-safe applications like kitchen appliances and medical devices.

2. Can POM plastic be 3D printed?

While POM plastic can be 3D printed, it is more commonly processed using injection molding or CNC machining due to its high accuracy requirements.

3. What is the difference between POM and Delrin?

Delrin is a brand name for homopolymer POM, which offers slightly higher strength and stiffness compared to copolymer POM.

4. What temperature range can POM plastic withstand?

POM performs well in temperatures up to 160°C for short periods, though prolonged exposure to high heat may affect its performance.

Conclusion

POM plastic is a reliable material used in a wide range of industries, from automotive to medical. Its strength, low friction, and durability make it ideal for precision parts manufacturing.

At HDC, we offer expert CNC machining and injection molding services for custom POM plastic parts, ensuring high-quality and long-lasting products for your specific needs.