Introduction to Polyoxymethylene

Polyoxymethylene (POM) is an engineering thermoplastic with excellent mechanical properties and dimensional stability. It is widely used in various industries, including automotive and consumer electronics. POM offers high strength, hardness, and rigidity even at low temperatures. It is characterized by its opaque white appearance, although it can be produced in different colors.

POM is synthesized using formaldehyde as a monomer and has the simplest chemical formula among all polymers. In this article, we take you through the diverse properties of this material in manufacturing, mainly from its definition, types, properties, and applications. The picture on the left is some pom products, that can be sampled for you through our online CNC machining service.

What Is Pom?

Polyoxymethylene (POM) is a premium, high-performance thermoplastic prized for its outstanding mechanical strength, excellent dimensional stability, and low friction properties. The advantages of POM make it popular as a general-purpose material in various industrial fields and widely used in various precision engineering applications.

What Is the History of Polyoxymethylene?

Polyoxymethylene (POM) has an interesting history that dates back to the 1920s. In 1929, a German scientist named Hermann Staudinger first synthesized polyoxymethylene and recognized it as a polymer. However, commercial production of POM did not begin until the 1950s when the American chemical company Celanese Corporation introduced it under the trade name “Celcon.”

POM’s development gained momentum in the following decades as its desirable properties became evident. Over time, POM production methods and formulations have evolved, resulting in improved performance and expanded applications. Today, POM continues to be widely used and appreciated for its durability, reliability, and versatility in numerous industrial applications.

What Is the Other Term for Polyoxymethylene?

Polyoxymethylene, commonly known as acetal or polyacetal, is a widely used alternative term for this high-performance thermoplastic material. The name “acetal” stems from the chemical structure of the polymer, which contains the acetal functional group (-O-CH2-O-). This term is often used in the context of engineering and industrial applications, emphasizing its strength, durability, and dimensional stability. Similarly, the term “polyacetal” refers to the polymerized form of formaldehyde, the monomeric unit used in the synthesis of POM. These alternative terms, acetal, and polyacetal, are frequently used interchangeably with polyoxymethylene in various industries to describe this versatile and reliable thermoplastic material.

What Is Polyoxymethylene Made Of?

Polyoxymethylene (POM) is composed of repeating units derived from the monomer formaldehyde. It is synthesized through a polymerization process that involves the reaction of formaldehyde molecules, resulting in the formation of long chains of polyoxymethylene. The polymerization process may also involve the use of co-monomers or additives to enhance specific properties of the resulting POM material. However, the fundamental building blocks of POM are derived from formaldehyde, allowing for the exceptional mechanical properties and dimensional stability that make it a preferred choice in engineering applications.

How Is Polyoxymethylene Made?

Polyoxymethylene (POM) is typically produced through a polymerization process known as formaldehyde polymerization or oxymethylene polymerization. This process involves the reaction of formaldehyde (HCHO) molecules, typically in the presence of a catalyst, to form long chains of polyoxymethylene. The polymerization can be carried out using different methods such as solution, suspension, or bulk polymerization. In these processes, formaldehyde undergoes a series of chemical reactions, including the formation of cyclic oligomers and their subsequent polymerization into linear chains. The resulting POM can then be processed using techniques like injection molding or extrusion to create various shapes and forms for different applications.

How Is Polyoxymethylene Processed?

Polyoxymethylene (POM) is processed using various techniques, with injection molding being the most common method. In the injection molding process, POM granules are melted and injected into a mold under high pressure, where they cool and solidify to form the desired shape. This method allows for the production of complex parts with precise dimensions and excellent surface finish.

POM can also be processed through techniques such as extrusion, blow molding, and machining. Extrusion involves forcing the molten POM through a die to create continuous profiles or sheets. Blow molding is used to produce hollow parts by inflating hot POM inside a mold. Machining techniques like milling, turning, and drilling can be employed to shape POM into specific dimensions. These processing methods take advantage of POM’s excellent machinability and dimensional stability, allowing it to be transformed into a wide range of components for different industries.

In addition to injection molding, extrusion, blow molding, and machining, there are other processing techniques used for polyoxymethylene (POM). One such technique is thermoforming, where POM sheets are heated to a temperature where they become pliable and can be shaped using molds or vacuum forming. This method is often employed to produce parts with complex geometries, such as automotive interior components and electronic enclosures.

POM can also be processed through rotational molding, a method commonly used for producing large, hollow parts. In this process, powdered POM is placed in a mold, which is then heated and rotated to evenly distribute the molten POM throughout the mold cavity. Once cooled, the mold is opened, and the final part is removed.

Another processing technique for POM is 3D printing. While not as widely used as traditional molding methods, advancements in 3D printing technology have enabled the additive manufacturing of POM parts.

It’s worth noting that POM has excellent dimensional stability, meaning it retains its shape and size even under varying temperature and humidity conditions. This property makes it suitable for precision machining processes, such as CNC milling or turning.

What Are the Characteristics of Polyoxymethylene?

Polyoxymethylene (POM) exhibits several notable characteristics that contribute to its widespread use in various industries. Firstly, POM possesses excellent mechanical properties, including high stiffness, strength, and impact resistance, making it suitable for applications that require structural integrity and dimensional stability. Additionally, POM has a low coefficient of friction and excellent wear resistance, which enhance its performance in moving parts and sliding applications.

Furthermore, POM demonstrates good chemical resistance to solvents, fuels, and many chemicals, making it suitable for use in environments where exposure to such substances is expected. POM also has low moisture absorption, which helps maintain its mechanical and dimensional properties under humid conditions.

POM’s thermal properties make it suitable for a wide temperature range, as it can withstand both high and low temperatures without significant degradation. Its electrical properties, including high dielectric strength and low dissipation factor, make it suitable for electrical and electronic applications.

Another noteworthy characteristic of POM is its ease of machining, as it can be readily machined into precise shapes using conventional methods. This attribute makes it a favorable choice for producing intricate parts with tight tolerances.

Overall, POM is a multifunctional industrial material that combines mechanical strength, dimensional stability, low friction, chemical resistance, thermal stability, and ease of processing.

What Color Is Polyoxymethylene?

Polyoxymethylene (POM) is typically available in a range of colors. The most common color for POM is white, which is the natural color of the polymer. However, POM can also be manufactured in various other colors, including black, gray, and different shades of natural or translucent hues. The picture below is an example of pom raw materials:

pom-raw-materials-image-800x600

What Does Polyoxymethylene Look Like?

Polyoxymethylene (POM) typically has a smooth and glossy appearance. The surface of POM components is often characterized by a polished finish, which enhances its aesthetic appeal. In its natural form, POM is translucent or slightly opaque, allowing some light to pass through the material. POM parts can exhibit intricate details and precise shapes, thanks to their excellent machinability and dimensional stability. The picture below is an example of pom parts:

pom-parts-image-800x600

What Are the Different Types of Polyoxymethylene?

There are two main types of polyoxymethylene (POM): homopolymer and copolymer.

1. Homopolymer POM

Homopolymer POM is made solely from the polymerization of formaldehyde monomers. It offers excellent mechanical properties, high stiffness, and exceptional dimensional stability. Homopolymer POM is commonly used in applications that require high strength and rigidity, such as gears, bearings, and automotive components.

2. Copolymer POM

Copolymer POM, also known as polyacetal, is produced by copolymerizing formaldehyde with a small amount of comonomer, typically an acetaldehyde derivative. The addition of the comonomer introduces certain properties and characteristics to the polymer. Copolymer POM exhibits improved resistance to thermal degradation, enhanced chemical resistance, and better resistance to hydrolysis compared to homopolymer POM. It is often preferred in applications involving exposure to harsh chemicals or higher operating temperatures.

Both homopolymer and copolymer POM offer excellent mechanical strength, low friction, dimensional stability, and good processability.

In addition to the two main types, homopolymer and copolymer POM, there are also various grades and modifications of polyoxymethylene available in the market. These variations are tailored to meet specific application requirements and can offer enhanced properties or characteristics. Some notable variations of POM include:

1. Impact-modified POM

This type of POM incorporates impact modifiers to improve its toughness and resistance to impact and shock. Impact-modified POM grades are commonly used in applications where resistance to impact or vibration is crucial, such as automotive interior components or sporting goods.

2. Reinforced POM

Reinforced POM grades are formulated with additives like glass fibers, carbon fibers, or other reinforcing materials to enhance their mechanical properties, such as strength, stiffness, and dimensional stability. These grades are suitable for applications that require higher mechanical performance, such as structural components in automotive or industrial applications.

3. Low-friction POM

Some POM grades are specially formulated to have lower coefficients of friction, reducing wear and enabling smooth movement in sliding or rotating applications. Low-friction POM is often used in applications like gears, bearings, and conveyor systems.

4. Food-grade POM

POM can be manufactured using materials and additives that comply with food contact regulations. Food-grade POM is suitable for applications in the food and beverage industry, such as food processing equipment, conveyor systems, or packaging components.

What Are the Properties of Polyoxymethylene?

In the table below, we summarize some common general properties of pom material :

What Are the Physical Properties of Polyoxymethylene?

The table below lists some physical properties of pom:

POM Physical Properties Table
Physical PropertyDescription
DensityPolyoxymethylene (POM) has a relatively high density, typically ranging from 1.41 to 1.43 g/cm³.
Melting PointPOM has a relatively high melting point, typically between 165 to 175°C (329 to 347°F).
Glass Transition TemperatureThe glass transition temperature of POM is around -50 to -40°C (-58 to -40°F), below which it transitions from a rigid to a more rubbery state.
Tensile StrengthPOM exhibits high tensile strength, typically ranging from 55 to 80 MPa (8,000 to 12,000 psi) depending on the grade.
Flexural StrengthPOM demonstrates good flexural strength, typically ranging from 80 to 125 MPa (11,600 to 18,100 psi).
Modulus of ElasticityPOM has a high modulus of elasticity, typically ranging from 2,000 to 3,200 MPa (290,000 to 464,000 psi).
HardnessPOM has a relatively high hardness, typically ranging from 80 to 90 Shore D.
Impact StrengthPOM exhibits good impact strength, allowing it to withstand sudden impacts or shocks without significant damage.
Coefficient of FrictionPOM has a low coefficient of friction, providing excellent wear resistance and making it suitable for moving parts and sliding applications.
Moisture AbsorptionPOM has low moisture absorption, typically less than 0.2%, which helps maintain its dimensional stability even in humid conditions.

What Are the Chemical Properties of Polyoxymethylene?

The table below lists some chemical pom:

POM Chemical Properties Table
Chemical PropertyDescription
Chemical ResistancePolyoxymethylene (POM) exhibits good resistance to solvents, fuels, and many chemicals, making it suitable for various industrial applications.
Hydrolysis ResistancePOM has good resistance to hydrolysis, allowing it to maintain its mechanical properties in humid or wet environments.
Thermal StabilityPOM displays good thermal stability, with the ability to withstand a wide temperature range without significant degradation.
Oxidation ResistancePOM has inherent resistance to oxidation, enabling it to maintain its properties in environments with exposure to oxygen.
UV ResistancePOM is relatively resistant to UV radiation, making it suitable for outdoor applications where exposure to sunlight is expected.
Electrical InsulationPOM exhibits good electrical insulation properties, including high dielectric strength and low dissipation factor.
Creep ResistancePOM has low creep tendency, meaning it resists deformation over time under a constant load or stress.
FlammabilityPOM has a relatively high ignition temperature and low flammability, making it a self-extinguishing material.
Chemical StabilityPOM is chemically stable under normal operating conditions, maintaining its properties over extended periods.
BiocompatibilitySome grades of POM are biocompatible, allowing for use in medical and healthcare applications with appropriate certifications.

What Are the Mechanical Properties of Polyoxymethylene?

The table below lists some mechanical properties of pom:

POM Mechanical Properties Table
Mechanical PropertyDescriptionExample Application
StrengthPolyoxymethylene (POM) exhibits high strength, providing excellent mechanical performance and load-bearing capabilities.Gears, structural components
StiffnessPOM is known for its high stiffness, allowing it to maintain its shape and resist deformation under applied loads.Bearings, precision parts
Impact ResistancePOM demonstrates good impact resistance, enabling it to withstand sudden impacts or shocks without significant damage or deformation.Automotive components, sporting goods
Wear ResistancePOM has excellent wear resistance, making it suitable for applications involving sliding or rubbing contact with other surfaces.Conveyor belts, gears, bushings
Fatigue ResistancePOM exhibits good fatigue resistance, with the ability to withstand repeated loading and cyclic stresses without failure.Springs, hinges
Creep ResistancePOM has low creep tendency, meaning it resists deformation over time under a constant load or stress.Snap-fit components, structural parts
HardnessPOM has a relatively high hardness, providing resistance to surface damage and wear.Pump impellers, valve seats
Tensile StrengthPOM demonstrates high tensile strength, allowing it to withstand pulling or stretching forces without breaking.Fasteners, handles
Flexural StrengthPOM exhibits good flexural strength, enabling it to resist bending or flexing without permanent deformation.Support beams, brackets
Fracture ToughnessPOM has good fracture toughness, which refers to its ability to resist crack propagation and withstand impact loads.Automotive crash components, safety helmets

What Are the Advantages of Polyoxymethylene?

Polyoxymethylene (POM) offers several advantages that make it a popular choice in various industries and applications. Here are some of the key advantages of POM:

1. Excellent Mechanical Properties: POM exhibits high strength, stiffness, and toughness, providing exceptional mechanical performance and load-bearing capabilities. It maintains its shape and resists deformation even under high loads or impact forces.

2. Dimensional Stability: POM has excellent dimensional stability, meaning it retains its shape and size over a wide range of temperatures and in humid environments. This property ensures precise and consistent performance in various operating conditions.

3. Low Friction and Wear Resistance: POM has a low coefficient of friction, which reduces wear and enables smooth movement in sliding or rotating applications. It exhibits excellent wear resistance, making it suitable for components subjected to repetitive motion or contact with other surfaces.

4. Chemical Resistance: POM demonstrates good resistance to solvents, fuels, and many chemicals, making it suitable for applications where exposure to harsh chemicals is expected. It maintains its properties and integrity in challenging chemical environments.

5. Electrical Insulation: POM exhibits good electrical insulation properties, including high dielectric strength and low dissipation factor. It is widely used in electrical and electronic applications to provide insulation and prevent electrical leakage.

6. Easy Machinability: POM is a highly machinable material, allowing for precise and complex part manufacturing. It can be easily shaped, drilled, milled, or turned, making it a preferred choice for components with intricate geometries.

7. Resistance to Moisture Absorption: POM has low moisture absorption, which helps maintain its dimensional stability and mechanical properties even in humid or wet environments.

8. Self-lubricating: POM has inherent self-lubricating properties, reducing the need for external lubrication in certain applications. This feature contributes to low friction, extended part life, and reduced maintenance requirements.

9. Good Thermal Stability: POM exhibits good thermal stability, allowing it to withstand a wide temperature range without significant degradation. It retains its mechanical properties at both low and high temperatures.

10. FDA Compliance: Some POM grades are approved for food contact applications and comply with FDA regulations. This makes them suitable for use in food processing equipment, packaging, and other related applications.

What Are the Limitations of Polyoxymethylene?

While Polyoxymethylene (POM) offers numerous advantages, it also has certain limitations that should be considered. Here are some of the limitations of POM:

1. Water Absorption: Although POM has low moisture absorption compared to many other plastics, it can still absorb a small amount of water over time. This absorption can affect dimensional stability and mechanical properties, particularly in humid or wet environments.

2. Environmental Stress Cracking: POM is susceptible to environmental stress cracking when exposed to certain chemicals or solvents. It is important to select the appropriate POM grade for specific chemical environments to avoid premature failure.

3. Thermal Degradation: POM has a relatively high melting point, but prolonged exposure to high temperatures can lead to thermal degradation. This can result in a decrease in mechanical properties and dimensional stability.

4. Not Suitable for High-Load Applications: While POM has good strength and stiffness, it may not be suitable for applications requiring extremely high loads or heavy impact forces. In such cases, alternative materials with higher strength properties may be more appropriate.

5. Limited UV Resistance: POM is relatively resistant to UV radiation compared to some other plastics, but prolonged exposure to sunlight can cause degradation and discoloration. Therefore, it is not recommended for long-term outdoor applications without suitable UV stabilization or protective coatings.

6. Flammability: POM is generally considered to have low flammability, but it is still a combustible material. It can burn when exposed to high heat or open flames, and the combustion process releases toxic gases. Adequate fire safety precautions should be taken when using POM in applications where fire risk is a concern.

7. Cost: Compared to some other engineering plastics, POM can have a higher cost, especially in its unfilled or specialty grades.

8. Limited Chemical Resistance to Strong Acids and Bases: While POM has good resistance to many chemicals, it may not be suitable for prolonged exposure to strong acids or bases, which can cause degradation or chemical attack.

What Is Polyoxymethylene Used for?

Polyoxymethylene (POM), also known as acetal or polyacetal, is a versatile engineering plastic with numerous applications across various industries. Here are some common uses of POM:

1. Automotive Industry

POM is widely used in the automotive industry for various components such as gears, bearings, fuel system components, door handles, seat belt components, and interior trim parts. Its high strength, stiffness, and resistance to wear make it suitable for demanding automotive applications.

2. Electrical and Electronics

POM is used in electrical and electronic applications due to its good electrical insulation properties. It is commonly used for connectors, switches, relays, circuit breakers, insulating bushings, and coil forms.

3. Consumer Goods

POM is found in a range of consumer goods, including zippers, buckles, handles, knobs, and buttons. Its durability, dimensional stability, and low friction properties make it suitable for various applications in the textile, luggage, and furniture industries.

4. Industrial Machinery

POM is used in industrial machinery for components such as conveyor system parts, rollers, sprockets, pulleys, and gears. Its resistance to wear, low friction, and ability to withstand heavy loads make it suitable for these applications.

5. Medical Devices

POM is used in the medical field for applications such as surgical instruments, orthopedic implants, drug delivery systems, and dental devices. Its biocompatibility, chemical resistance, and dimensional stability make it suitable for medical applications.

6. Plumbing and Fluid Handling

POM’s resistance to chemicals and low moisture absorption make it suitable for plumbing and fluid handling components such as valves, fittings, couplings, and pump impellers.

7. Sports and Recreation

POM is used in sports and recreational equipment due to its impact resistance, toughness, and low friction properties. It can be found in items such as ski bindings, bicycle components, archery equipment, and fishing reels.

8. Food Processing

POM grades approved for food contact applications are used in the food processing industry. They are used for components such as conveyor belts, food handling equipment, and packaging machinery parts.

9. Aerospace

POM is utilized in aerospace applications for components that require high strength, stiffness, and resistance to wear, such as gears, bearings, and structural parts.

10. Miscellaneous Applications

POM is also used in various other applications, including textile machinery, agricultural equipment, construction hardware, and musical instruments.

What Causes Polyoxymethylene to Be Blue?

Polyoxymethylene (POM), in its natural form, is not inherently blue. It is typically a white or off-white colored polymer. However, POM can appear blue under certain circumstances. Here are a few possible reasons for POM to exhibit a blue color:

1. Pigmentation: POM can be pigmented or dyed with various colorants to achieve different colors, including blue. Manufacturers may add blue pigments during the production process to give POM a desired blue hue.

2. UV Stabilizers: Some grades of POM may contain UV stabilizers or additives that help protect the polymer from degradation due to UV radiation. These additives can sometimes impart a slight blue tint to the material.

3. Environmental Factors: Prolonged exposure to ultraviolet (UV) light or certain environmental conditions can cause degradation or discoloration of POM. In some cases, this degradation can result in blue discoloration. However, it’s important to note that such discoloration is usually an indication of material degradation and may affect the mechanical properties of the POM.

4. Contamination: If POM comes into contact with substances or impurities that have a blue color, it can absorb or adsorb those pigments, leading to a blue appearance. Contamination can occur during processing, handling, or exposure to dyes or other colored materials.

It’s worth noting that the blue color in POM is not a universal characteristic and may not be present in all instances or grades of the material. The color of POM can vary depending on the specific grade, manufacturing process, additives, and environmental factors it has been exposed to.

Can Polyoxymethylene be 3d Printed?

Yes, polyoxymethylene (POM) can be 3D printed, although it is not as commonly used in 3D printing as some other materials. The 3D printing process for POM is typically achieved through a method called fused filament fabrication (FFF) or fused deposition modeling (FDM).

To 3D print POM, it is typically processed in the form of filament. The filament is fed into a 3D printer that heats and melts the material. The molten POM is then extruded through a nozzle onto a build platform, where it solidifies and forms the desired object layer by layer.

However, there are a few considerations and challenges when 3D printing with POM:

1. High Printing Temperatures: POM requires relatively high printing temperatures compared to some other commonly used 3D printing materials. The extruder temperature needs to be set within a specific range to ensure proper melting and flow of the material.

2. Printer Requirements: Due to the higher printing temperatures, 3D printers capable of reaching and maintaining those temperatures are necessary for printing POM. It is important to ensure that the printer is compatible with the higher temperatures required for POM printing.

3. Warping and Shrinkage: POM tends to warp and shrink during the cooling process, which can lead to dimensional inaccuracies and warping of printed parts. Adequate bed adhesion techniques, such as a heated bed or adhesion aids, may be required to minimize warping.

4. Filament Availability: POM filament may not be as widely available as filaments for other materials commonly used in 3D printing. It may be necessary to source POM filament from specialized suppliers or manufacturers.

5. Post-Processing Considerations: POM can have a smooth surface finish when printed, but additional post-processing steps such as sanding or polishing may be required to achieve the desired surface quality.

Does Ruitai Provide pom materials?

Yes, we are professional prototype parts manufacturers who can provide various POM raw materials for your design projects.

Are POM and Derlin the Same Material?

No, Polyoxymethylene (POM) and Delrin are not the same material, although they are related. Delrin is a brand name for a specific type of POM resin produced by DuPont, while POM is the generic name for the polymer itself.

POM is a high-performance engineering thermoplastic that belongs to the polyacetal family. It is characterized by its high strength, stiffness, good dimensional stability, low friction, and excellent wear resistance. POM is widely used in various industries for applications such as gears, bearings, automotive components, and consumer goods.

Delrin, on the other hand, is a specific grade of POM resin that is manufactured by DuPont. It is known for its exceptional mechanical properties and is often used in high-performance applications. Delrin has become a popular and well-known brand name for POM, similar to how “Kleenex” is a brand name for facial tissues.

Generalize

This article serves as a comprehensive introduction to Polyoxymethylene(POM), covering its definition, wide range of applications, and notable advantages. Additionally, we have included a section of frequently asked questions (FAQs) to provide further insights. If you have any inquiries or require additional information, please don’t hesitate to reach out to our team.

At Ruitai, we offer extensive manufacturing capabilities and provide value-added services to cater to all your prototyping and production needs. We are pleased to offer you a complimentary quote at your convenience. Feel free to get in touch with us for any inquiries or to discuss your requirements.

Disclaimer

We would like to emphasize that the data content presented in this article is intended for reference purposes only. The information provided is based on our current knowledge and is offered in good faith. However, Ruitai Mould cannot guarantee the completeness, accuracy, or validity of the information provided, either explicitly or implicitly.

Addressing Common POM Questions:

Q1: Is polyoxymethylene toxic?
A1: Polyoxymethylene (POM) is generally considered to be non-toxic. It has a low level of toxicity and is commonly used in food contact applications and medical devices.

Q2: Is polyoxymethylene a thermoplastic or a thermoset?
A2: Polyoxymethylene (POM) is a thermoplastic. Thermoplastics are polymers that can be melted and re-melted multiple times without undergoing significant chemical change. POM can be melted and reshaped when heated and solidified upon cooling, allowing it to be processed and recycled.

Q3: Is polyoxymethylene a vinyldiene?
A3: No, polyoxymethylene (POM) is not a vinyldiene. POM is a polymer composed of repeating units of formaldehyde (or its cyclic dimer, trioxane). It belongs to the family of polyacetals and is commonly referred to as acetal or polyacetal.

Q4: Is polyoxymethylene transparent?
A4: Polyoxymethylene (POM) is not transparent in its natural form. It is typically an opaque or semi-opaque material with a white or off-white color. However, POM can be modified with additives or processed to achieve varying levels of translucency, but it is generally not considered a transparent material.