Der ultimative Leitfaden zur Materialauswahl für Spritzguss: Die Wahl des richtigen Kunststoffs für Ihr Projekt

Picking the right material for your injection molding project is the biggest choice you will make. It changes how your part looks. It changes how your part works and how long it lasts. It also changes the cost and the speed of making your product. In this article, I will show you a simple way to pick the perfect plastic, one step at a time. You will learn about different materials. You will learn what their features mean. And you will learn how to find the right one for your job. This guide will help you make a smart choice. It will save you time and money.

Why is Material Selection in Injection Molding So Important for Your Project?

When you are making a part, you have an idea in your head. You know what you need the part to do. The material selection process is how you make that idea come to life. If you pick the wrong injection molding material, your part might break in a very easy way. It might bend when it gets hot. Or it could get hurt by simple chemicals. This is why material selection in injection molding is a very big deal. It is not just a small detail. It is the base of your whole project.

You can think of it like building a house. You would not use the same material for the strong base of the house as you would for the glass windows. Every part has its own job. For plastic parts, it’s the same thing. A gear that goes inside a machine needs to be strong. It needs to last a long time without wearing out. A food box needs to be safe. It needs to have good chemical resistance. The material you choose must be right for the job the part has to do. A bad choice here can make problems with the mold. It can end in a product that does not work. A good material selection makes sure your injection molded parts work great from the start.

What Are the Most Common Injection Molding Plastics I Should Know About?

When you first see all the different materials for injection molding, it can feel like too much to handle. There are thousands of choices! But there is good news. Just a few common injection molding plastics are used for most jobs. I have learned that learning about these simple materials is the best place to begin. These are sometimes called commodity materials. That is because they are easy to find and don’t cost too much.

Let’s look at some of the most used ones. This injection molding material comparison chart will give you a fast look.

This is only a place to start. There are many types of each kind of plastic. For instance, you can get materials like ABS with glass fibers added in to make them stronger. Or you can get materials like Nylon that are better at working in a high temperature. The important part is to start with a good idea of what these common materials do well. After that, you can find the exact type that is right for your mold and your product.

How Do I Check Materials by Looking at Their Mechanical Properties?

After you know what your part will do, you need to check its mechanical properties. This might sound hard, but it is really just about how strong and tough a plastic is. The property that people talk about most is tensile strength. You can think of tensile strength as the power a material has to be pulled on and not break. If you are making a part like a handle or a hook, you will need a material with high strength.

But tensile strength is not the only thing that is important. You also have to think about impact strength. This is how well the material deals with being dropped. You also need to know its flexural strength. This is how well it deals with being bent. Does your part need to be hard like a rock? Or does it need to bend just a little bit without breaking? These are the kinds of questions that help you with your material selection.

When you check different materials, look at these numbers. A material like Polycarbonate has a very high impact strength. That is the reason it is used for safety glasses. A semi-crystalline material like Nylon has a nice mix of strength and the ability to bend. This makes it great for parts that have to move. Looking at the mechanical properties helps you pick the best material. It helps you make sure your plastic products are strong enough for use in the real world. You must pick the right material so that a weak part does not come out of the mold.

What About Heat and Chemical Resistance in the Material Picking Process?

I have worked on many parts that have to last in tough places. Some of them go under the hood of a car. They sit right next to a very hot engine. Other parts are used in a lab. In a lab, they might be cleaned with strong chemicals. This is where heat resistance and chemical resistance become a very important part of the choice. If you do not think about this, your part could melt. It could get soft, or it could just fall apart.

Heat resistance tells you the hottest temperature a plastic can take before it starts to lose its shape. This is a very important thing for parts used in electronics, cars, or tools for cooking. For a job in a high temperature place, you need a plastic material that can handle the heat. Materials like PEEK or special types of Nylon are made for this. When you are picking your injection molding material, make sure its heat resistance is higher than the hottest temperature your part will ever be in.

Chemical resistance is also very important. Will your part touch things like oils, acids, or cleaning liquids? If it will, you need a material that will not break down. Polypropylene is well-known for its very good chemical resistance. That is why it is used for containers and tools for labs. Some plastic materials are easily hurt by certain chemicals. You should always check the chemical resistance of a material against anything it might touch. A bad reaction can ruin a product. So, this step in the material selection process is one you just cannot skip. The mold itself will not be changed, but the part it makes will be.

Are Electrical Properties a Big Deal for My Injection Molded Parts?

For a lot of products, you do not need to think about electricity. But if you are making cases for electronics, connectors, or any part that will be close to electricity, then electrical properties are the most important thing. Most plastic materials are natural insulators. This means they do not let electricity pass through. This is a very good thing for keeping people safe.

The main property to check for is called “dielectric strength.” This number tells you how good a material is at stopping electricity. A material with a high dielectric strength can take a lot of voltage before it breaks down and lets electricity through. This is the reason plastic is used to cover wires and to make cases for power tools. The electrical insulation properties keep the person using it safe.

When you select materials for an electrical job, you must pick a plastic with the right insulation properties. Some materials also have special things added to them to make them anti-static. This is important for keeping delicate electronic parts safe. Do not forget about these electrical properties. Making sure your material meets the rules it needs to follow for electricity is the secret to a safe and good product. The design of your mold might even need a few small changes to make sure the electrical performance is the best it can be.

How Does My Material Choice Change the Design of the Injection Mold?

The material choice you make has a big effect on the design of the steel mold. I have seen jobs get late because a team picked a material that was hard to use. They did not think about how it would change the molding process. Every plastic acts in its own way when it is melted down and pushed into a mold. This material behavior is a very important thing to know.

For example, some materials shrink more than others when they get cool. The mold must be made just a little bit bigger to make up for this shrinking. If the person making the mold does not know what plastic you are using, they cannot get the size of the finished part right. They must know the rate of material shrinkage before they start to cut the steel for the mold.

You also need to think about how the material flows. Some high-strength materials are very thick and sticky, almost like honey. They need bigger channels inside the mold so they can flow in the right way. Other materials are thin like water. They can fill a very fancy mold with a lot of details. This property is called viscosity. The design of the mold changes with the specific material you have picked. This includes the gate, which is where the plastic goes in. It also includes the runners, which are the channels it flows through. You should always tell your mold maker your last material choice before they begin to build the mold. This makes sure of good ease of molding.

What Should I Look for on a Material Data Sheet?

The material data sheet is your best friend when you are in the selection process. It is a paper with details from the company that sells the material. It shows all the important properties of a plastic. When you first see it, it can look like a long list of numbers that are hard to understand. But if you know what to look for, it can tell you all you need to know to compare materials.

Here are the important things I always check on a material data sheet:

• Mechanical Properties: Look for tensile strength, flexural modulus (this shows stiffness), and impact strength (this shows toughness).
• Heat Properties: Find the “Heat Deflection Temperature.” This number tells you the heat resistance of the material.
• Flow Properties: Look for the “Melt Flow Index” or “Melt Flow Rate.” This gives you an idea of how easy it is for the material flows into the mold. A bigger number means it flows more easily.
• Shrinkage: The data sheet will tell you what to plan for with the shrink rate. This is very important for the person who is designing your mold.

Do not be scared to ask for help reading a data sheet. Your injection molding services helper can explain it to you. This sheet is the way to be sure that the material performance will match what you need. Before you make your final choice on your injection molding material selection, get the data sheet. Make sure the numbers match what your part needs.

How Does the Cost of the Material Change the Whole Injection Molding Project?

Of course, we always have to think about the material cost. It is easy to make the mistake of picking the cheapest plastic you can find to save some money. But my story from the beginning shows that this can be a mistake that costs a lot. The price of the plastic itself is only one part of the whole cost of your injection molded products.

A cheaper plastic might be harder to use in the mold. It could need longer cycle times. This means the injection molding equipment has to run for a longer time. This makes the cost for each part bigger. A cheaper material could also lead to more bad parts, or molding defects. You have to throw these bad parts away. A material that costs a little more but has good ease of molding can actually lead to a lower final price for each part. This is what we call cost-effective injection.

My advice is to think about what you get for your money, not just the price. You should find the cheapest material that does everything it needs to do. Does it have the right tensile strength? Does it have the right amount of chemical resistance? Do not give up quality just to save a little money on a pound of plastic. The main goal is to find the best material that gives you a great product at a good price. Your mold will also last for a longer time if you use a good, reliable plastic.

Can I Use High-Performance or Special Kinds of Materials in My Mold?

Sometimes, a normal plastic just will not be good enough for the job. For very hard jobs, like in airplanes, medical tools, or fast cars, you might have to look at high-performance materials. These are special plastics that are made for very tough places. They give you great strength, very high heat resistance, and the best chemical resistance.

A good example is high-performance materials like PEEK (Polyether Ether Ketone). This material is so strong and so good with heat that it is often used to take the place of metal parts. Using materials such as polycarbonate with glass fillers added can also make it much stronger. These materials cost more money. They can also be harder to use in a mold. But for the right job, they are worth the cost.

Another thing that is getting more popular is using biodegradable and recycled materials. A lot of companies now want to make their products in a way that is good for the earth. There are many great choices you can make with recycled plastic. They still offer good mechanical properties. There are also new biodegradable plastics. These can break down after some time. Using these materials may be a great choice for your company. But you must make sure the material meets everything it needs to do before using it in your mold.

How Do I Stay Away From Common Mistakes When Picking a Material for Injection Molding?

After many years of working on plastic manufacturing jobs, I have seen the same mistakes happen again and again. Choosing the right material can be easy if you stay away from these common mistakes. The biggest mistake is not knowing for sure what your part needs to do before you start looking at the plastics you can choose from. You have to know the kind of place it will be in.

Another mistake is picking a material by looking at only one of its properties. A plastic might have a great tensile strength. But if it has bad chemical resistance and your part is going to be around oils, it will not work. You have to look at the whole picture. You should always get a suggestion from someone who knows a lot if you are not sure. They have seen before how the material reacts inside a mold.

Last, do not forget to think about how the part will look and feel. The way the plastic surface looks, its color, and how it feels are all part of the material selection. Some materials, like ABS, have a nice, shiny look when they come out of the mold. Other materials might look dull. The perfect material is one that works great, looks great, and can be made without any problems in the mold. You should take your time. Learn about it. And test it if you can. This will help you select the right and most fitting material.

Key Takeaways to Remember

Here is a quick list of the most important things from this injection molding materials selection guide.

• Know What You Need First: Before you look at any plastic, write down what your part needs. What is its job? What place will it be in? This is the most important step in selection of the right material.
• Look at Everything: Do not just think about one thing, like tensile strength or cost. A good choice looks at mechanical properties, chemical resistance, heat resistance, and price all together.
• The Material Changes the Mold: Your material choice has a direct effect on the design of your mold. Always make your final choice on the material before the mold is built.
• Use the Data Sheet: The material data sheet is your guide. Learn to read it to check different choices. Make sure the material meets your needs.
• Don’t Just Pick the Cheapest: The cheapest injection molding material is often not the best deal in the end. Think about how long it takes to make a part, how many bad parts are made, and how long the product will last.
• Ask for Help: If you are not sure, ask someone who knows. A good plastic seller or injection molding partner can give you advice to help you find the suitable material for your project.