Understanding POM Plastic: A Guide to Polyoxymethylene and Its Applications

This is a detailed overview of POM plastic, which many may not be familiar with. In today’s blog article, we will try to answer all your questions regarding POM plastic, including its composition, primary attributes, key applications, which thermoplastic elastomers engineering plastic it competes with the most, and some of its drawbacks. To further develop your existing knowledge on the subject, we believe that addressing these aspects will allow you to grasp POM plastic’s design and the engineering principles behind its multifaceted applications.

Let’s start by defining POM plastic, its structure, and the comparison between copolymer and homopolymer acetal. This is important because before understanding the importance of POM plastic, it is essential to learn how it is made. On the topic of properties, we will focus on its mechanical properties, which make it stand out among other plastics, and why it is dominant in several different applications. Other properties of interest are its dimensional stability, low friction, and wear resistance, making it a desirable engineering component in various industries.

As such, POM plastic has a representative outlook on the number of industries adopting it and its applications—the automotive, electronic, and engineering sectors, among many others. This allows us to explore POM in greater detail, covering its most common contribution to specific injection-molded components, shafts, and bearings.

We dedicated ourselves to explaining POM as a plastic in the previous sections. From this point on in our work, we will provide an approach to POM plastic that, for now, we have just once mentioned — the perspective of POM plastic within the context of other engineering thermoplastics. We will also discuss the comparative considerations in which the advantages of acetal alternatives over thermoplastic and molding considerations and machining are discussed and guide you through considerations on whether acetal copolymer or acetal homopolymer should be selected.

Understanding these challenges can help you position yourself best regarding the scope and pivotal limitations in the content, which include creep and rigidity issues, moisture absorption, and environmental and chemical resistance issues of POM plastic. This integration creates insight into how POM plastic can be helpful in various applications.

We hope this paper will be an excellent asset for the readers and users of POM plastic. Let’s begin by looking at this homo polymer in detail, along with its varied applications.https://pom-material.com/blog/discovering-the-pom-plastic-polyoxymethylene-and-acetal-applications/

What is POM Plastic?

What is POM Plastic

In engineering, polyoxymethylene (POM), also called acetal and polyacetal, is mainly used in many of these industries’ sectors due to its thermoplastic nature, reinforced by its vast number of acetal properties. It also contains a repeating unit of formaldehyde, which defines its overall set of characteristics.

Definition of POM and Its Composition

POM, also called Polyoxymethylene, belongs to the family of engineering thermoplastics, such as plastics characterized by high usage temperatures and excellent mechanical and thermal properties. It is a thermoplastic polymer consisting of composite units of formaldehyde, one of its structural features. In more simple terms, the molecular structure of POM is based on a monomer constitutive [-CH2O-]n, wherein n stands for the number of molecular units that are composed in a number to form a compound. Some of the Key features of POM thermoplastics are;

Mechanical Properties: Due to its impressive strength, stiffness, and firmness, it is ideal for use in situations with excellent load-bearing applications.
Dimensional Stability: POM’s ability to absorb moisture is well-staged, which means that the material’s shape and size remain intact despite changes in environmental circumstances.
Low Friction: POM is a low-friction material that can be used in situations requiring less wear and smooth sliding motion.
Chemical Resistance: POM can withstand contact with many substances, such as solvents, fuels, and other chemicals.
Good Electrical Insulation: POM’s reasonable ability to act as an insulator can be advantageous in electric and electronic areas.
Temperature Resistance: Since POM has a high temperature at which it melts, it makes it possible for the polymeric material to exist under different temperatures without losing its mechanical performance.

Due to the attributes mentioned above, POM plastic is widely applied in the automotive, electrical, and various consumer goods industries.

Differences Between Copolymer and Homopolymer Acetal

Acetal plastics consist of two broad categories, copolymer and homopolymer; even though many of their properties overlap, some interesting features characterize the uniqueness of each, which makes them ideal for a particular application. The acetal copolymer and homopolymer differ in the following manner.

Copolymer Acetal:

Composition: A typical copolymer acetal consists of polyocodemeloxanine (POM) and one or more comonomers, such as ethylene oxide or glycol. Thus, it is classified as a mixture of acetal resins.
Tensile Strength: The copolymer possesses better tensile strength during acetal testing than the homopolymer.
Impact Resistance: Copolymer acetal is commonly used in applications that require mechanical shock resistance due to its better impact resistance properties.
Chemical Resistance: While copolymer acetal’s chemical resistance is good, it does not stand up to the strength of homopolymer acetal when exposed to strong acids.
Processing Temperature: The melting point of copolymer acetal assists in the ease of molding, making it easier to work with.

Homopolymer Acetal:

Composition: The only resin utilized in homopolymer acetal is called polyoxyethylene POM.
Creep Resistance: Applications exposed to a constant force for long durations where weight the weight-to-volume ratio is crucial can afford to utilize homopolymer acetal as it has optimal creep resistance.
Dimensional Stability: A polymer that maintains its length and shape with a change in temperature under environmental constraints is considered to have a high level of stable homopolymer acetal.
Chemical Resistance: When considering chemical compatibility, homopolymer acetal can’t be ignored. Their plurality gives them a broad range of applicability, including, but not limited to, strong acids.
Processing Temperature: Molding does not imply a high cost, but that is the situation with homopolymer acetal. The extensive initial precipitation causes the high cost of devices。

As with all matters of copolymer and homopolymer acetal for specific applications, this is an excess of all issues of consideration. Such a form in which the thickness of each of the voided members of the set may be measured may not be comprehensive. Always ask a material supplier or a specialist for assistance so you won’t have the more serious consequences of using the wrong acetal for your customized applications.

How POM is Produced

Polyoxymethylene plastic (often referred to as acetal) entails a multi-step manufacturing process to assure its consistent quality, me as a technical person will explain this process.

Formula: This process begins to produce POM with the polymerization of Formaldehyde, which can be done through acid catalysis or base catalysis. This involves treating novel formaldehyde with acid or base (that acts as an initiator), which results in polymer chains.
Melt Extrusion: At this stage, the polymer granular is in the form of tiny pellets. They are put into a melting process where temperature and pressure are controlled and blended. Using a die, molten material is molded into a linear, flat, consistent shape.
Cooling and solidification: For the excised POM to retain its properties, it must cool rapidly, causing it to harden. This process is attained by cooling the shape in the bath or pumping it through rollers. Rapid cooling is key, as it ensures that the desired qualities of POM are retained.

Consistent control of parameters is key to ensuring that a final POM product meets the expected standards in terms of quality and performance during production. The Process parameters consist of:

Melt Temperature: This refers to the temperature at which the POM pellets are melted during extrusion.
Extrusion Pressure refers to the pressure applied to the molten POM to force it through a die and mold it into the desired shape when it emerges.
Cooling Rate: The speed at which the POM shape, which has been extruded, solidifies the polymer by cooling it.
Polymer Molecular Weight: Average length of polymer chains; polymer size affects POM’s mechanical properties.

Production parameters can be more or less specific depending on the manufacturer of the POM and the properties needed. It is advisable to consult suppliers or experts on materials to avoid the wrong selection or application of POM.

Key Properties of POM Plastic

Polyoxymethylene (POM) has many synonyms, such as Delrin and Acetal. It is an engineering polymer typically used in a variety of applications. Below, we will examine some of its uses and properties in greater depth.

High Mechanical Strength: The material has excellent rigidity and strength and can readily be used for applications that require heavy support while considering the load limits.
Low Friction and Wear Resistance: Due to its self-lubricating factors, POM has low overall wear, which allows it to be used in applications that involve movement, such as engines, where it is subjected to substantial pressure and speed.
Dimensional Stability: Even when used around extreme temperatures, POM maintains its size and does not expand or shrink excessively.
Chemical Resistance: POM is not prone to rust and corrosion, so it can withstand a multitude of solvents and cleaners. It can also be used in extreme areas.
Electrical Insulation: POM can be used in highly charged areas because it has excellent insulating characteristics.
Low Water Absorption: POM, being mainly used in active areas where there is high temperature, can be kept in its form with low absorption of a particular substance, which overall strengthens its design.
In essence, POM contains excellent properties that help it sustain its focus structure at high temperatures, preventing it from significantly aging.

Owing to these significant attributes, POM is used in a wide range of industries, including automotive, electrical, consumer goods, and industrial sectors.

Understanding the Mechanical Properties

POM’s mechanical properties are critical for maximizing its possible uses as an engineering plastic. Also known as polyoxymethylene or acetal, POM has good mechanical properties that allow it to be used in many applications.

POM has high tensile strength, allowing it to carry large loads without deformation or yielding. It has also been shown to possess good fatigue resistance, allowing it to be used in contexts with repetitive or cyclic loading and stress applications with repeatable poms. In addition, POM has good stiffness, which helps it retain its dimensions when affected by mechanical forces. POM also has a low friction coefficient, which allows for ease and efficiency in motion and less wear and tear on components, facilitating a longer life.

These mechanical properties make POM very appealing to automotive, electrical, consumer goods, and industrial applications. POM’s ability to hold on to its mechanical and dimensional attributes even when subjected to environments with high humidity is added to its capabilities and dependability. Because of its heat resistance, POM can tolerate high temperatures while maintaining its mechanical characteristics even in rough conditions.

Understanding the mechanical attributes of POM allows engineers and designers alike to utilize POM’s strengths and produce robust and efficient solutions. Be it injection-molded parts across many industries, as a precision bearing and parts, or as a substitute for other thermoplastics, the engineering characteristics of POM promote it as an appealing material.https://pom-material.com/pom/

Low Friction and Wear Resistance

POM, which stands for polyoxymethylene and acetyl, has low friction and resistance to wearing out, which means it can be helpful in many applications, such as gears and automotive parts. POM shows excellent potential when bearing in mind its low coefficient of friction and wear resistance and its technical parameters:

Coefficient of Friction: POM’s coefficient of friction, which is usually between 0.20 and 0.35, makes it perfect for applications that require low friction.
Wear Resistance: POM has a very high wear resistance, meaning it can handle multiple contact points in motion without damaging itself.
Wear Rate: For POM, wear rate is defined as the quantity of material worn away per distance, and that distance is the distance performed by sliding and rubbing.
Surface Hardness: A hard surface layer of POM acts as a barrier to wear, permitting POM to retain its shape and function over long periods.

Due to its distinct features, POM is a go-to material for engineers and manufacturers. It functions significantly in sliding, rotating, and bearing mechanical joints due to its Low friction coefficient and high resistance to wear and tear.

Applications of POM Plastic

With its exceptional properties, POM plastic finds wide-ranging applications across various industries. Here are some key areas where POM plastic is commonly utilized:

Typical Applications for Injection-Molded POM

Injection-molded POM parts are commonly used for their low friction surfaces and good wear resistance. Some of its specified applications include:

Gears: Owing to the good frictional and tensile properties of POM, gears made of POM offer better power transmission & are more efficient in operation.
Bearings: POM is a self-lubricating and wear-resistant material that can locate bearings with minimal friction.
Sliding Mechanisms: POM is suitable for sliding elements and ensures open and consistent movement due to its relatively low friction coefficient and good dimensional integrity.
Automotive Components: POM offers good elastic and mechanical properties and resistance to several chemicals and fuels. That’s why It is widely utilized in many applications in automobiles, such as components of fuel systems, interior and exterior parts, and electrical connectors.

Uses in the Automotive Industry

POM plastic is used for quite some functions in the automotive industry, which include:

Fuel system parts: POM’s chemical and fuel resistance enable it to be used for fuel system parts such as fuel pumps, caps, and connectors.
Interior and Exterior: POM is utilized in interior components such as door handles, seat harness buckles, and window regulators, as well as in exterior elements such as grilles and mirror housings.
Electrical connectors: POM is also preferred for electrical connectors and housings due to its electrical insulation and dimensional stability.

Role in Precision Parts and Bearings

Sometimes referred to as acetal or Delrin, polyoxymethylene (POM) is a key component in producing precision parts and bearings for the automotive industry. This makes it a unique high-performance engineering plastic in construction.

Precision Parts:

Due to its excellent dimensional stability and low coefficient of friction, POM can make precision parts that can be manipulated smoothly and accurately within specific tolerances. This allows us to create intricately detailed yet powerful and robust parts for various applications.
Another advantage of POM is that its moisture absorption rate is considerably low. This allows it to maintain shape, making it less likely to swell, warp, or break.
Regarding POM, some essential considerations when molding or machining include tooling design, cooling rates, and stress concentration to prevent sharp edges.

Bearings:

One of the problems with lubrication is that the materials used usually have a very high friction coefficient. Still, with POM, this is completely avoided as POM naturally lubricates itself and has a very low friction coefficient, which makes it suitable for bearings.
Moisture gain is also low from this material, thus making POM bearings extremely strong and reliable.
The use of incap POM bearings is a good choice as they have a low tilt and oscillation, which increases comfort.
Though POM has advantages, some factors, such as load capacity, temperature constraints, and surface properties, should be considered when making POM bearings.

Utilizing the peculiar characteristics of POM, manufacturers can fabricate precision parts and bearings with exceptional performance, durability, and reliability. Appropriate materials and design considerations guarantee long service life in harsh automotive applications.

Comparing POM with Other Engineering Plastics

In comparing POM (polyacetal) with other engineering plastics, one has to consider each of their properties and performance aspects. Here, our focus will be on what places POM about other thermoplastics about critical parameters such as:

Mechanical Strength: POM has very high mechanical strength, which makes it stiffer and tougher than other engineering plastics.
Wear Resistance: POM’s low friction coefficient and high wear resistance make it appropriate for sliding and rubbing surface contact applications.
Chemical Resistance: POM has excellent resistance towards many chemicals such as solvents, fuels, oils, etc.
Moisture Absorption: Compared to other thermoplastics, POM exhibits low moisture absorption. Thus, Wu You Haiwen Zhang Koen Rummens of the Thomas B illustrates fewer dimensional changes while retaining good stability over time.
Thermal Properties: POM is thermally stable with a high heat deflection temperature and good creep resistance.

It is worth noting that the properties of POM include a relatively high concentration of wear resistance and moderate chemical resistance, which makes it an excellent candidate for engineering applications. It is crucial to adequately analyze and understand the primary requirements of the application to select the right material.

Advantages Over Other Thermoplastics

Considering the significance of thermoplastic polymers, nay I boldly say that POM (polyoxyethylene) is one of the leaders in this area. Highlighted, but not limited to, are the outstanding mechanical properties, wear, and chemical resistance that POM has.

POM has the following salient features peculiar to it and not found in other thermoplastics if several considerations are taken into account:

Mechanical Properties: POM is widely used today thanks to its excellent combination of strength, toughness, and stiffness, which are necessary for high-load-bearing applications. It also has a low friction coefficient, enhancing its durability and sliding characteristics.
Wear Resistance: POM’s wear-resistant properties allow it to endure multiple impacts, friction, and sliding. This is beneficial for applications in hostile environments.
Chemical Resistance: POM is resistant to harsh solvents, fuels, and even oils. Thus, it can withstand extreme working conditions while maintaining durability and being operable in many working environments.

Hence, these properties distinguish POM from other thermoplastics on the market. However, the best material choice requires careful consideration of the application parameters.

Considerations for Molding and Machining

Several issues must be taken into consideration when machining and molding Polyoxymethylene. The foremost step is ensuring that the molding machine can inject sufficient pressure and accurately control the temperature to achieve optimal results. A POM melt temperature of 190-230 degrees Celsius (374-446 degrees Fahrenheit) is typical. The recommended temperature for a mold is about 80 to 100 degrees Celsius (176 to 212 degrees Fahrenheit. To avoid warping or shrinkage, the polymer must also cool down adequately.

POM may be cut planar faces with conventional tooling for turning, drilling, and milling. Nevertheless, the tools must be sharp, while the rotation speeds must be optimal for cutting the POM while generating minimal heat. Accumulation of the chips created during machining should also be avoided, and the evacuation of chips during the machining cycle should be completed to avert damaging the workpiece.

Overall, during the machining of POM, the potential of changing size should be noted. POM is a great dimensionally stable material because of its low moisture absorption. However, a controlled environment should be maintained to reduce swelling and/or other adverse issues from occurring and changing the size of POM.

In conclusion, these simple requirements outlined above should be considered together with the proper guiding techniques for molding and machining POM to use poloxamer thermoplastic material in many applications successfully.

Choosing Between Acetal Homopolymer and Copolymer

There are several considerations that you have to take into account when deciding whether you should go for acetal homopolymer or copolymer. These factors will be seen below.

Mechanical Properties: Acetal homopolymer offers high strength, stiffness, and hardness, making it useful in applications where dimensional stability and rigidity are essential. On the other hand, Acetal copolymer provides better toughness and enhanced impact resistance, making it easier to use in more flexible applications while resisting stress cracking.
Chemical Resistance: Most solvents, fuels, and lubricants are resistant to both homopolymer and copolymer; however, to ensure compatibility, consider what chemicals will be used in the application when selecting an acetal grade.
Moisture Absorption: Acetal trimer has better Dimensional stability than acetal copolymer as it has a higher degree of dimensional stability, hence if much exposure to humidity and water is present in the application, using acetal beers would be better for the application.
Processing Conditions: Their broader processing range makes acetal homopolymers easier to use when molding complex, intricate parts. However, they may lose dimensional accuracy, as their tolerance levels for some applications may be affected. So, in cases where a high degree of accuracy and tighter tolerances are required, acetal homopolymer would be the better choice.

When considering different grades of acetal, it is essential to refer to the technical datasheets of each grade, keeping in mind its performance indicators, such as tensile strength, flexural modulus, impact strength, or melt flow index. Moreover, it is essential to communicate with material suppliers or professionals to confirm that the acetal grade selected meets your application and performance requirements.

Challenges and Limitations of POM Plastic

While POM (Polyoxymethylene) plastic offers a range of desirable properties, it is essential to know its challenges and limitations to make informed decisions regarding its usage. Here are some key considerations:

Understanding Creep and Rigidity Issues

Creep is a phenomenon in which a POM plastic (or any material) exhibits deformation over time under a constant load or stress. When designing components that will be subjected to stress or require load bearing for an extended period, additional measures must be incorporated to prevent this. As the creep resistance of POM plastics is not as high as that of most engineering plastics, careful designs and stress analyses should be conducted on critical points.

Conversely, rigidity would be the stiffness or the amount of deformation a material can endure. POM plastics have a high rigidity, providing a high degree of dimensional accuracy and a defined shape for external forces. There is a risk, though, that rigidity can equal a form of brittleness when the temperature is altered, primarily lower temperatures. As a result, the temperature ranges for operation and the need for impact resistance for the application will help predict the survivability of the POM plastic component during actual work.

For an absolute and clear understanding of POM plastic’s specific creep and rigidity behaviors, preferred technical data sources can be those provided by established suppliers or other professionals with vast experience and working knowledge of POM plastic.

Effects of Moisture Absorption

Moisture absorption is a significant factor to consider when evaluating the performance and durability of POM plastic components. It can change the material’s physical and mechanical properties, potentially affecting its functionality and structural integrity. Understanding the impact of moisture absorption on POM plastic is crucial to ensuring its suitability for specific applications.

When POM plastic absorbs moisture, several effects may occur, including:

Dimensional Changes:Moisture absorption can cause POM plastic to expand or contract, leading to dimensional changes in the component. This can result in warping, distortion, or poor fit in mating parts.
Reduced Mechanical Strength:Moisture absorption can weaken the mechanical properties of POM plastic. It may decrease tensile strength, impact resistance, and fatigue resistance, compromising the component’s structural integrity and overall performance.
Degradation of Physical Properties:Moisture exposure can degrade the physical properties of POM plastic, such as stiffness, hardness, and creep resistance. These changes can impact the component’s ability to withstand mechanical stresses and long-term loading.

To mitigate the effects of moisture absorption on POM plastic components, several measures can be taken:

Proper Storage and Handling:Ensure POM plastic components are stored in a dry environment and protected from excessive humidity. Proper packaging, sealing, and handling practices can help prevent moisture absorption.
Material Selection:Consider using POM plastic grades with improved moisture resistance, such as those specifically designed for low moisture absorption or enhanced hydrolysis resistance.
Surface Treatments and Coatings:Applying surface treatments or coatings to POM plastic components can help reduce moisture absorption and improve resistance to environmental factors.

To obtain specific information on the moisture absorption behavior of POM plastic grades, consult reputable material suppliers, industry professionals, and technical datasheets. Conducting thorough research and analysis while considering corresponding technical parameters such as water absorption rates and dimensional stability will help ensure POM plastic components’ proper selection and performance in moisture-prone environments.

Frequently Asked Questions (FAQ)

Q: What is polyoxyethylene, and how is it related to acetal plastic?

A: Polyoxymethylene, or acetal plastic, is a high-strength engineering thermoplastic characterized by excellent mechanical properties, good dimensional stability, and low moisture absorption. Due to its high stiffness and abrasion resistance, it is widely used in various applications.

Q: What are the key material properties of POM homopolymer?

A: POM homopolymer is known for its high tensile strength, hardness, and excellent dimensional stability. It also exhibits low moisture absorption, good thermal properties, and abrasion resistance, making it a versatile engineering material.

Q: How does anionic catalysis polymerize POM?

A: POM is polymerized using anionic catalysis, which involves the polymerization of formaldehyde or its derivatives, such as acetic anhydride, to form long-chain polyacetal polymers. This process results in a material with excellent mechanical and thermal properties.

Q: What are the advantages of using POM in injection molding?

A: POM is widely used in injection molding due to its high strength, excellent dimensional stability, and low moisture absorption. These properties ensure that molded parts maintain shape and function under stress and environmental conditions.

Q: What are some typical applications for injection-molded POM materials?

A: Applications for injection-molded POM include automotive components, electronic housings, precision gears, and consumer goods. POM is used in these applications for its high strength, stiffness, and excellent wear resistance.

Q: How does POM compare to other acetal resins regarding mechanical properties?

A: POM typically offers better mechanical properties, such as higher tensile strength and stiffness, than other acetal resins. This makes it suitable for demanding engineering applications where durability and reliability are critical.

Q: What are the different POM grades available, and how are they used?

A: POM grades vary based on their formulation and intended application. Some grades offer enhanced thermal properties, while others provide improved abrasion resistance or low friction. These grades allow designers to choose the most suitable material for specific applications.

Q: Why is POM considered a crystalline polymer?

A: POM is characterized as a crystalline polymer due to its highly ordered molecular structure, which contributes to its excellent mechanical properties and thermal stability. This crystalline nature is key to its widespread use in engineering applications.

Q: What role does acetic anhydride play in making POM materials?

A: Acetic anhydride is often used as a formaldehyde derivative in the production of POM. It aids in the polymerization process by reacting with formaldehyde to form the acetal polymer, resulting in a material with excellent mechanical and thermal properties.

eSIM Tech Research