Polyoxymethylene (POM), known as acetal, polyformaldehyde and polyacetal, is one of the plastics that offers many advantages for CNC machining of parts. This plastic has gained popularity in various industries due to its exceptional properties, benefits and diverse uses. Its chemical resistance, dimensional stability, mechanical strength and low friction make it a reliable material for engineering applications.
So what is POM? Is CNC POM machining ideal for parts manufacturing? Read on as we provide more information about POM editing.
What is POM material?
POM is an engineering thermoplastic with several beneficial properties. Its properties include exceptional hardness, strength and rigidity. Although it can be produced in different shades, its high crystalline content gives it a naturally opaque white appearance. POM has a density between 1,410 and 1,420 g/cm³.
POM plastic is widely used to produce precise parts that require dimensional accuracy, high rigidity and low friction. Due to its low friction, POM is ideal for rotating or sliding components such as bushings, bearings and gears.
Like many other synthetic POM polymers, it is manufactured by different chemical companies using slightly different formulas and sold under many brand names such as Celcon, Tenac, Duracon, etc.
Properties of POM plastic
High performance plastic polyoxymethylene (POM) is used in many industries. Due to its special properties it is suitable for numerous applications.
Low friction and wear resistance
POM plastic is characterized by a low coefficient of friction, which explains its excellent self-lubricating properties. Because there is less wear and overall performance is higher, the reduced frictional resistance allows for smooth sliding or rotational movements.
Chemical resistance
POM is ideal for manufacturing products that come into constant contact with chemical solvents, such as pump parts, seals and fuel system components. This is mainly due to the remarkable resistance of POM plastic to various chemicals, solvents and fuels. It can withstand contact with numerous organic chemicals, alcohols, oils and fats without deteriorating significantly.
Low water absorption and dimensional stability
POM plastic exhibits remarkable dimensional stability and maintains its size and shape even under varying humidity and temperature conditions. Due to its minimal water absorption, it is not susceptible to moisture-related problems such as swelling, warping and other dimensional changes. Applications that require precise tolerances as well as consistent efficiency also rely heavily on the dimensional stability of the POM.
Easy to edit
The easy processing of POM plastic allows for precise and effective manufacturing processes. It is easy to shape, machine, turn and drill, making it easy to produce complex parts and complex designs. Due to this property, POM resin is often chosen for applications that require complex geometries and high precision.
Excellent creep/impact resistance
POM plastic has excellent creep resistance, which means it can withstand long-term mechanical stress without deforming. Due to this property, POM components can function perfectly even when they are constantly exposed to stress or deformation.
How is POM plastic processed with a CNC machine?
POM parts can generally be machined using one of two methods. The first method is to use standard editing methods. As a second method, a preprocessed POM article can be annealed.
To edit the POM, the first step in the process is to create a CAD file of the part and then convert it to CAM to then convert it into G code that CNC machines can work with. The next step is to cut the POM part into specific sizes so that it can be easily placed on the machine bed. After cutting the POM part to the correct size, place it on the machine base and hold it with a device so that it does not move during processing.
It is important to ensure that the POM part is securely clamped in place as CNC cutting tools move based on predefined coordinates and any change in the positioning or orientation of the part would negatively affect the quality of the part.
After ensuring that the POM part is stable, use professional cutting tools attached to the CNC machine to remove material from the part. The recommended cutting tool is a universal flat milling cutter, as it offers greater efficiency when machining plastics.
Finally, it is important that you vacuum the CNC machine frequently when machining POM. This ensures that material chips do not clog the end mill.
Advantages of CNC machining of POM plastic parts
POM CNC machining is an excellent option for producing high-quality custom parts in many industries as it offers the following advantages:
uniformity
CNC machining provides consistently high-quality POM components for large-scale POM production with consistently excellent dimensions. This automated method ensures that each component is consistently manufactured to precise specifications for industries that require reliable and accurate POM parts, such as medical or aerospace.
Rapid prototyping
Prototyping is an important step in product development because it often shows manufacturers what the final product will look like. Rapidly creating POM prototypes through CNC machining helps reduce the time it takes for new products to reach the market.
Part accuracy
Precision, accuracy and tight tolerances are the hallmarks of CNC machining. Therefore, POM components can be manufactured with great precision and accuracy using CNC machining as it supports complicated geometries and tight tolerances.
Improving design flexibility
Due to the rapid design iterations of CNC machining, POM components can be easily changed during development without the need for costly tool changes.
Reduction in post-processing time
The type of post-processing of a product depends on the manufacturing process used. POM products manufactured using CNC machining generally require less post-processing due to the high precision of the manufacturing process and the ease of machining of POM. This approach results in lower manufacturing costs and faster delivery times.
The most important challenges in POM plastic processing
The main problems in CNC machining are often cracks and deformations. There are two common types of cracks: one occurs directly during CNC machining, while the other occurs hidden and is usually caused by internal stresses.
However, using high-quality materials for POM machining can help significantly reduce the occurrence of these problems. For this reason, it is often advisable to use modified POM materials for machining and carry out trial production before the actual machining process to determine the purity level of the material before starting machining.
Causes and solutions for deformations in POM machining
Warping is a challenge CNC machine operators face when working with POM. Below are the four main causes of warping and their solutions.
heat cut
POM material has low thermal stability, is sensitive to heat, and deforms quickly due to insufficient cooling after manufacturing. To neutralize this heat, you must do the following:
- The tool must be sharp so that the heat generated during cutting is minimal;
- The cutting amount can be reduced and divided into several cuts.
- Increase the amount of soda.
The objective is to minimize heat generation and quickly dissipate heat generated during the cutting process.
Internal stress
Engineering plastics have a high coefficient of thermal expansion. Therefore, if there is a significant machining tolerance, deformation will occur due to the elimination of internal stresses. Here's how you can counteract this:
- Select and prepare materials carefully.
- Use symmetric POM processing to counteract the stress and deformation caused by processing when the amount of material removed is relatively large.
- Adjust the margin and try to insert the thickest material possible.
Bobby pins
When POM material is fixed, it deforms and returns to its original shape when released. One way to avoid this is to improve the contact area of the part:
- Change the shape of the clip. For example, the lathe covers the workpieces and fixes them with glue.
- Vacuum suction cups can be used for larger panels, but this requires a flat plate.
- Fix the smoothed surface with suction cups after fixing one side with glue and then sweeping.
elasticity
The elasticity of POM material is quite large. Due to the elasticity of the material, the component that comes into contact with the tool bends inwards during cutting. The cut and pressed part will be slightly deformed when the tool is removed. It is now necessary to make several tool compensation changes depending on the impact of the cut. Repeated cutting when processing a small amount of material reduces dimensional distortion caused by the elasticity of the material.
POM Parts Applications
POM parts are used in a wide variety of industries due to their durability and other beneficial properties. Below you will find the different areas of application of POM parts.
Electrical and electronic parts
POM is electrically insulating. Therefore, it can be used to make switches and connectors to protect electronic parts.
Medical equipment
Due to POM's biocompatibility, it is used in the medical industry to produce surgical instruments, drug delivery systems, and other medical devices.
Automobiles
POM plastic is used in numerous interior and exterior car parts, including fuel system components and window regulators.
household items
POM plastic components are widely used to produce handles, buckles, zippers and other parts for household items and appliances.
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Common questions
CNC machining of POM plastic is an attractive option for producing high-precision components with excellent mechanical properties and durability. The numerous possible uses in diverse industries show the importance of POM for modern production processes.
Although problems such as cracking and deformation occur during the process, the advantages of CNC POM machining far outweigh the disadvantages.
Common questions
What is the difference between POM and POM C?
POM-C, also called acetal copolymer, is produced in a process called copolymerization. The material has greater impact resistance, toughness and chemical resistance compared to POM due to the addition of a comonomer during the polymerization process.
What is the temperature range of POM?
Acetal, sometimes called POM (polyoxymethylene), is a semi-crystalline thermoplastic engineering material with an operating temperature range of up to 82°C (180°F). Acetal has excellent dimensional stability, high strength and rigidity, and is easy to machine.
How durable is POM?
POM is a very durable material with high impact resistance. The fatigue resistance of this material is so high that it is comparable to metal. When a lighter option is needed, it is used in areas where metal is typically used.
