Acétal vs. Delrin : quelle est la véritable différence entre ces plastiques ?

Acetal and Delrin. They look a lot alike, but they have some important differences. Picking the right one is very important for your project. In this article, I will explain it all for you. We will look at what makes each of these plastics special. You will learn which one is better for what you need. When you finish reading, you will be able to choose between Acetal and Delrin and feel sure of your choice.

What Are Acetal and Delrin Plastics Anyway?

Let me tell you about a very interesting and useful kind of plastic. Its name is acetal. You may also hear people call it POM. POM is short for polyoxymethylene. It is a kind of thermoplastic. This means you can heat it up and put it in a mold to give it a shape. Then, it cools down and gets hard. You can even heat it up again to change its shape. This acetal plastic is a special kind of polymer. It is made from long chains of tiny parts. The main part that repeats in these chains is a CH2O unit. This structure makes acetal a very crystalline material. That means its insides are very neat and organized.

Think of it like a stack of logs that are all lined up perfectly. This neat structure gives acetal some great features. Now, you have probably heard of Delrin® too. So what is it? Delrin® is a brand name for a type of acetal. A company named DuPont makes it. So, every piece of Delrin is acetal. But not all acetal plastic is Delrin. It is like how every soda is not a Coke, but Coke is a type of soda. There are two main forms of acetal: homopolymer and copolymer. Delrin is an acetal homopolymer. This means its tiny chains are made of only one type of piece, repeated over and over. I’ll explain what that means for how it works in a little bit.

There are other brands of POM too, like Kepital® POM. But Delrin is so well-known that many people use its name to mean all acetal plastic. This can make things a bit confusing. It is important to understand the difference. The difference between acetal and Delrin can make a big difference in your final product. When you are comparing acetal, you need to know if you are looking at a homopolymer like Delrin or an acetal copolymer.

Is Delrin a Type of Acetal?

Yes, it is. As I said before, Delrin is a type of acetal. To be exact, it is an acetal homopolymer. You can think of “acetal” as the main family name for a group of plastics. Inside that family, there are different types. One of those types is the homopolymer, and Delrin is the most famous one. The other main type is the acetal copolymer family. These are also acetal plastics. But they are made of slightly different things. This gives them different features.

So, when we talk about acetal vs. Delrin, we are really talking about the two main types of acetal. These are the homopolymer form, which is Delrin, and the copolymer form. This is a very important point to understand. A lot of the time, people will say “acetal” when they are talking about an acetal copolymer. And they will say “Delrin” when they mean an acetal homopolymer. This happens a lot in this line of work, but it is good to be exact. The difference between acetal homopolymers and copolymers is very important.

The acetal polymer family is a part of a bigger group called engineering thermoplastics. These are very strong and useful plastics. They can often be used in place of metal parts in plastic machining and other uses. The first step is to understand that Delrin is a certain grade of acetal. This helps you ask the right questions when you are buying your plastic material. Knowing the difference will help you pick the right material for your job.

What is the Main Difference Between Acetal and Delrin?

The biggest difference between acetal and Delrin is because of how they are built on the inside. Like I said, Delrin is a homopolymer acetal. Its tiny chains are made of just one kind of piece that repeats. This makes a very even, crystalline structure. This structure gives Delrin some real pluses in how strong it is. It makes the plastic very strong and stiff.

On the other hand, acetal copolymer has a different structure. Its tiny chains are made of two different kinds of pieces. This breaks up the crystalline structure just a little. It makes the copolymer acetal a little less stiff than the homopolymer. But this different structure also gives it some good things too. For one, it makes it better at standing up to some chemicals. It also means it holds its shape better, especially when it gets wet. This is called dimensional stability.

So, you have to make a choice. Delrin (the homopolymer) gives you more stiffness and strength. The acetal copolymer gives you better protection from chemicals and holds its shape better. There is not one single material that is “best” for everything. The right choice is based on what you need your part to do. It’s all about matching the material’s features to the job you need it to do. The big difference between the homopolymer and copolymer types of POM is very important.

How Does Porosity Affect Acetal and Delrin?

Porosity is a very important thing to think about when you work with acetal and Delrin. Porosity means there are tiny empty spots or holes inside the plastic. In an acetal homopolymer, like Delrin, these empty spots can sometimes show up in the middle of a thick part when it is being made. This is called centerline porosity. This porosity can be a problem. It can make the middle of the part weaker.

Why does this happen? It is all about how the material cools down. The outside of the part cools and gets hard first. As the inside cools, it gets smaller. If there is not enough melted resin to fill that space, little bubbles can form. This is what makes the porosity. I want to be clear that this does not always happen. But it is a risk with acetal homopolymer. This is especially true for parts that are big and thick.

Acetal copolymer is much less likely to have this centerline porosity problem. The way its tiny parts are put together helps it to cool down more evenly. This means you are less likely to have those weak spots in the middle of your parts. So, if you are making a thick part that needs to be strong from the outside to the inside, an acetal copolymer might be a better choice. The lack of porosity is a big plus for the copolymer in these situations.

Which Has Better Mechanical Properties: Acetal or Delrin?

When we talk about mechanical properties, we mean things like how strong, stiff, and tough a material is. This is where Delrin, the acetal homopolymer, is really great. Because its inside has a very even crystalline structure, Delrin is one of the stiffest and strongest thermoplastics you can find. It has very good tensile and yield strength. This means it can handle a lot of pulling force before it starts to stretch or break.

Delrin also has great fatigue resistance. This means it can be bent or stressed again and again and it will not break. Think about a clip on a backpack that you snap open and close all the time. That is a perfect use for a material that has good fatigue resistance. Delrin is also very hard and has a very low coefficient of friction. This makes it very slippery. Parts made from Delrin slide very easily against another metal or plastic. This is why you see it used for things like gears, bearings, and parts on conveyor belts.

So what about acetal copolymer? It is also a very strong and stiff plastic. But, it is not quite as strong or stiff as Delrin. Its flexural yield and tensile strength are a little bit lower. But, it is a tougher material. This means it can handle a bigger hit without cracking. So, if your part is going to get hit or dropped a lot, the copolymer could be the better choice. The better mechanical properties of Delrin are a big reason why so many people use it.

What is the Temperature Range for Acetal and Delrin?

The temperature range is another important thing to look at when picking between these two materials. Both acetal and Delrin can handle a wide range of temperatures. But there are a few differences. Delrin, the homopolymer, has a slightly higher temperature range where it can work. It can be used all the time in situations up to about 200 degrees Fahrenheit.

Acetal copolymer, however, is a little better at handling high temperatures for a long time. It also works better when it is in hot water. Over time, hot water and steam can damage Delrin. The copolymer is much better at standing up to this. This is why you will often see acetal copolymer used in parts for sinks and faucets, and in coffee machines.

Both kinds of acetal can handle cold temperatures very well. They stay tough and strong even when it gets cold. But if your part will be around very hot water or steam a lot, you should probably pick the acetal copolymer. For most other uses in dry, hot places, Delrin is a very good choice. It is very important to understand the temperature range for your part to work well.

Are Acetal and Delrin Resistant to Chemicals?

Chemical resistance is another area where we see a big difference between these two forms of acetal. Acetal copolymer is the winner in this area. It has very good resistance to many different chemicals. These include things like fuels, cleaning liquids, and strong cleaning agents. This is why copolymer acetal is often used in the car industry for parts in the fuel system.

Delrin, the acetal homopolymer, also has good chemical resistance. But it is not as good as the copolymer. It can be harmed by strong acids and strong cleaning agents. This is something to remember if your part will be near strong chemicals. The reason for this difference is because of what they are made of. The structure of the copolymer makes it hold up better in these kinds of places.

So, if you need a part that can stand up to many different kinds of chemicals, you should probably pick an acetal copolymer. This is a big plus for the copolymer in many uses. But, for many normal uses, the chemical and abrasion resistance of Delrin is more than good enough. It all comes back to knowing the kind of place your part will be used in.

What Are the Common Uses for Acetal and Delrin?

Because they have so many good features, you can find acetal and Delrin in many different products. Their low friction makes them perfect for parts that move. I have seen them used in all kinds of things, from gears and bearings to conveyor belts and rollers. Anything that needs to slide in a smooth and quiet way is a good use for an acetal material. The low coefficient of friction is a very big benefit.

You will also see a lot of acetal used in cars. Things like parts for the fuel system, covers for speakers, and parts for seatbelts are often made from acetal. Its strength, stiffness, and chemical resistance make it a great choice for these kinds of tough jobs. I have also seen it used for things like the frames of eyeglasses and for zippers.

The food and medical fields also use acetal quite a bit. It does not soak up much water and it can be cleaned to kill germs. This makes it great for things like equipment used in food processing and for medical tools. There are special types of both acetal copolymer and Delrin that are approved for use in the food and medical industries. These materials are a great choice to use instead of metals in plastic machining for many jobs.

Which is Better for Your Project: Acetal vs Delrin?

So, how do you pick one? The acetal vs. Delrin choice depends on the answers to a few main questions:

• How strong and stiff does your part need to be? If you need the most strength and stiffness you can get, then Delrin is likely the right choice.
• Will your part be near strong chemicals or hot water? If the answer is yes, you should think about using an acetal copolymer.
• How thick is your part? If you are making a thick part, an acetal copolymer could be a better choice to make sure you do not have problems with centerline porosity.
• Does your part need to be very slippery? Both materials have a low coefficient of friction, but many people think Delrin is a little bit more slippery. There are also special types, like Delrin AF 100, that have PTFE (Teflon) mixed in to make them even more slippery.

I always tell my customers to think very hard about what their project really needs. Do not just pick Delrin because it is a famous name. Think about the physical properties you need. The choice between acetal copolymer vs. homopolymer is about giving and taking. You need to decide which features are the most important for your part. The difference between acetal and Delrin is the key to picking the right one.

Where Can You Get Acetal and Delrin Parts?

If you need parts that are made from acetal or Delrin, you have a couple of choices. One of the most common ways to make parts from these materials is injection molding. In this process, the plastic is melted and then pushed into a mold. Injection molding is great for making a lot of parts very fast. Injection molding and plastic extrusion are both common ways to make parts.

You can also make parts by cutting them from large pieces of acetal or Delrin. You can buy these materials in the shape of rods, sheets, and tubes. Then you can use a machine to cut them into the final shape of your part. This is a good choice if you only need a few parts, or if your part has a very difficult shape.

It does not matter which way you choose. It is important to work with a company that knows these materials well. They can help you pick the right kind of acetal or Delrin for your job. They can also help you design your part so that you get the most out of the material’s good features. Getting advice from an expert can save you a lot of time and money.

Key Things to Remember:

• Delrin is a brand name for an acetal homopolymer. Acetal plastic can be either a homopolymer or a copolymer.
• Delrin (the homopolymer) is stiffer and stronger.
• Acetal copolymer has better chemical resistance and stands up to hot water better.
• Acetal copolymer is not as likely to have centerline porosity (weak spots in the middle).
• The right choice between acetal and Delrin is based on what your project needs.