Acetal Plastic: What You Need to Know About Its Features

Today, I want to talk about a plastic that I use for many projects. It is called acetal plastic. You may also hear it called POM. POM is short for polyoxymethylene. This plastic is strong and does not have much friction. It is great for solving problems. In this article, I will tell you everything about acetal. We will look at its special features and how we machine it to make many useful items. We will also look at the different kinds of acetal and what makes each one special. After you read this, you will see why this plastic is a top choice for so many types of work.

What Is Acetal Plastic?

Let me tell you about a great material I use a lot. It is called acetal plastic. Some people call it acetal, polyoxymethylene, or POM. It is a kind of engineering thermoplastic. This means it is a strong plastic that lasts a long time. It can be heated and shaped in many ways. Acetal is a semi-crystalline material. This means that some of the tiny parts inside the plastic are very neat and in order. This helps make the plastic strong and stiff. This plastic is a true workhorse in the world of materials.

I often suggest using acetal plastic for jobs that need a tough material with low friction. This means that parts made from acetal can slide by each other with ease. They do not wear out fast. It is also a good choice instead of metal in many situations. This is because it is strong but weighs much less. Another good thing about this plastic is its dimensional stability. This means it keeps its shape very well, even if it gets hot or damp. This makes it a great plastic material for making parts that need to be exact. We can machine it to make very specific shapes and sizes, and we know it will stay that way.

What Are the Main Features of Acetal Plastic?

When I need to decide if acetal plastic is the right material for a job, I think about its wonderful features. One of the first things I think of is its high strength and stiffness. This plastic is strong and does not bend easily. This makes it good for parts that need to be tough. Another important feature is its low friction. Parts made of acetal move smoothly against one another. That is why it is often used for items like gears and bearings. This low friction also gives it excellent wear properties. This means it lasts for a long time, even when it rubs against other parts.

Here is a quick list of some of the best things about acetal plastic:

• High Strength and Stiffness: This plastic can hold heavy things without bending.
• Low Friction: It has a slick surface. This helps reduce wear and tear.
• Excellent Dimensional Stability: It keeps its shape well, even when the heat or moisture changes.
• Low Moisture Absorption: It does not take in a lot of water. This helps it keep its shape and strength when it is wet.
• Good Chemical Resistance: It can stand up to many different chemicals, like solvents and fuels.
• Easy to Machine: We can cut and shape this plastic with great care to make detailed parts.

These useful properties make acetal plastic a material that can be used for many different jobs.

Homopolymer vs. Copolymer Acetal: What Is the Difference?

When you look at acetal plastic, you will find there are two main kinds. There is homopolymer acetal (also called POM-H) and copolymer acetal (POM-C). They may look the same, but they have some key differences. The main difference is in how they are made on the inside. A homopolymer is made of one type of unit that repeats. A copolymer has two different units that repeat. You can think of it like a chain. A homopolymer chain is made of all the same kind of link. A copolymer chain has two different kinds of links that repeat.

So, what type of acetal plastic is best for you? It really comes down to what you need to do with it. Homopolymer acetal is a little bit stronger and stiffer than the copolymer kind. You might know it by the brand name Delrin®, made by DuPont. It also has a slightly higher tensile strength. On the other hand, copolymer acetal has better chemical resistance. This is especially true when it comes to hot water and strong cleaning liquids. It also tends to have less porosity. This means there are fewer tiny holes in the middle of the material. This can be important for parts used in food processing. It is also important for medical uses where you do not want germs to grow.

Here is a table to help you see the differences:

How Do You Machine Acetal Plastic?

I have worked in the shop for a long time. I can tell you that it is very easy to machine acetal plastic. It cuts very cleanly. It also makes good chips, which helps the whole process go well. Because it is so stable, we can machine it to very tight tolerances. This means we can make parts that are very exact in their size and shape. But, you should keep a few things in mind to get the best results when you machine acetal.

One of the most important things is to use sharp tools. A sharp tool gives you a clean cut. It also makes the surface smooth. If your tool is not sharp, it can make too much heat. This heat can cause the plastic to melt or change its shape. Speaking of heat, you need to control it well. Acetal does not get rid of heat easily. So, you need to use the right cutting speeds to stop problems from happening. Sometimes, we use a little bit of coolant or cool air to help keep things from getting too hot. Another thing to look out for is that acetal can make long, stringy chips when you machine it. We have to make sure to clear these chips away. If we do not, they can get stuck in the machine.

Is Acetal Plastic Able to Resist Chemicals?

I get asked a lot about the chemical resistance of acetal plastic. The good news is that acetal is resistant to a lot of different chemicals. This makes it a very helpful material. It does well against things like hydrocarbons, solvents, and neutral chemicals. This means you can use it in places where it might touch fuels, oils, and other common industrial liquids. You do not have to worry about it breaking down.

But, it is good to know that acetal has some weak points. It is not a good pick for uses where it will be around strong acids or bases. These strong chemicals can harm the plastic. They can make it degrade. Also, normal acetal plastic is not very resistant to UV radiation from the sun. If you need to use it outside, you will need a special kind that has additives in it. These additives protect it from the sun’s rays. But for many uses indoors and in factories, the chemical properties of this plastic are good enough to do the job well. This plastic material is a great pick when you need good chemical resistance.

Can You Use Acetal Plastic for Making Food?

Yes, for sure! I have worked on many jobs where we used acetal plastic. We used it for parts in machines that process food. One of the main reasons for this is that many kinds of acetal are compliant with the rules from the FDA for food contact. This means they are safe to use in places where they will touch food. You will often see this plastic material used for things like parts on conveyor belts, parts for pumps, and other pieces of equipment in the food and drink industry.

On top of being safe for food, acetal has other features that make it a great pick for food processing. Its low moisture absorption is a big benefit. It means the plastic will not get bigger or change its shape in wet places. Wet places are common in this type of work. Also, its smooth surface with low friction is simple to clean. This is very important to keep things clean and safe. There are even special kinds of acetal that can be found by metal detectors or x-ray machines. This is a great safety feature. If a small piece of the plastic were to break off and get into the food, it would be easy to find and take out. This makes the food making process even safer. These features make acetal plastic a commonly used and trusted material in the food processing world.

What Are Some Everyday Uses for Acetal Plastic?

Because acetal plastic has such a great mix of features, you will see it used in a very wide range of places. I have seen it used in so many different kinds of work, from making cars to making consumer goods. Its high strength, low friction, and excellent dimensional stability make it a top material for many mechanical parts. It is often used to take the place of metal. This is because it works just as well but is lighter and often costs less.

Here is a list of some of the places where acetal is commonly used:

• Mechanical Parts: This is a very common use. You will see acetal used for gears, bearings, bushings, rollers, and valves. Its low friction and good wear resistance are perfect for these types of moving parts.
• Car Industry: In cars, acetal is used for things like parts for power windows, parts for door locks, and parts for the fuel system.
• Consumer Goods: It might surprise you to know that acetal is in many of the products you use each day. It is in things like zippers, parts for home appliances, and even some toys.
• Food Processing: As we talked about, acetal is a great pick for food processing machines. This is because it is often FDA compliant and easy to clean.
• Electrical Parts: Acetal is a good electrical insulator. So, it is used for things like connectors and bobbins in electrical work.

This is just a short list, but it gives you an idea of how much you can do with this plastic. Its special mix of acetal properties makes it a key material in many areas.

What Are the Downsides of Acetal Plastic?

I really like working with acetal plastic. But I also know it is not the right material for every single job. It is important to know its weak points so you can make a good choice for your project. One thing to know is how it acts in some chemical situations. As I said before, acetal is not resistant to strong acids or bases. If your job involves these kinds of chemicals, you will need to find a different plastic.

Another thing to think about is its poor resistance to UV radiation. If you leave normal acetal plastic in the sun for a long time, it can get weak and breakable. It can also lose its color and strength. There are kinds with UV protection, but this is something you must know if your part will be used outside. Also, it can be hard to glue acetal. Its low-friction surface is great for gears and bearings. But that same surface makes it hard for glue to stick. You often need to treat the surface in a special way to get it to stick well. Lastly, acetal is a tough material. But it is important to remember that it is still a plastic. It is not as strong as metal. For jobs with very high stress, metal might still be the better pick.

Why Is Acetal a Great Pick for CNC Machining?

From my time in the shop, I can tell you that acetal plastic is one of the best materials to use for Usinage CNC. The main reason is that it is so easy to machine. It cuts clean and makes chips you can expect. This makes the whole process go very smoothly. We can use a CNC mill or lathe to make very detailed parts with great accuracy and tight tolerances. This is because acetal has excellent dimensional stability. So, it does not change its shape while it is being machined.

Another great thing about acetal is the nice surface finish we can get right from the machine. If we use sharp tools and the right cutting settings, we can make parts that are smooth and ready to go. We do not need to do a lot of extra work to finish them. This helps save time and money. Because acetal is a strong and stiff plastic, we can make parts that have thin walls and small details. We do not have to worry about them breaking. All of these things make acetal a very well-liked and trusted choice for parts made with a CNC machine.

What Should I Think About When I Buy an Acetal Rod?

When I need to order an acetal rod for a new job, there are a few important things I always think about. I do this to make sure I get the right material for the work. The first thing is to choose between homopolymer acetal and copolymer acetal. As we talked about before, they have different features. So, you need to pick the one that is the best fit for what you need. If you need the most strength and stiffness, homopolymer might be the better choice. If you need better chemical resistance or are worried about porosity, then copolymer is probably the better pick.

Another key thing is the size and tolerance of the rod. Make sure you get a rod with the right diameter for your parts. This will help you waste less material. Also, look at the maker’s spec sheet for the dimensional tolerance of the rod. A rod with a tight tolerance will be more even in its size. This is important for machining parts with great accuracy. Lastly, if you are making parts for the food industry or any other use that needs special features, make sure the acetal rod you buy has papers to show it meets the right standards. This will let you know for sure that you are using a high-quality and safe plastic material.

Important Things to Remember

• Acetal, also called POM, is a strong and stiff engineering thermoplastic with low friction.
• It has excellent dimensional stability and does not take in much moisture, which makes it great for wet places.
• There are two main kinds: homopolymer (POM-H) and copolymer (POM-C). Each one has its own good points.
• Homopolymer acetal is stronger and stiffer. Copolymer acetal has better chemical resistance and less porosity.
• Acetal is easy to machine to tight tolerances. But it is important to use sharp tools and control the heat.
• It can stand up to many chemicals. But it is not good against strong acids, bases, or UV light.
• Many kinds of acetal are FDA compliant and safe to use with food.
• Common uses include gears, bearings, parts for cars, and consumer goods.