From toy blocks to space shuttle turbine blades, plastic injection molding is a part of our daily life. But what is plastic injection molding? Why is it famous? And is it the right choice for your manufacturing needs?
Today, we will answer all your questions about plastic injection molding and ensure you make the right choice for your business. Let’s get started!
What is Plastic Injection Molding?
Plastic Injection Molding was first introduced by an American Inventor in 1872. He attempted to replace ivory billiard balls with plastic balls, which gave him a new product quality. Since the machine’s inception, injection molding has evolved from producing small plastic components like buttons to manufacturing complex medical equipment.
The plastic injection molding process includes injecting molten plastic into a precisely engineered mold or cavity. After the plastic cools & solidifies, it takes the shape of the final product. Due to its capability to produce parts in large volumes with high dimensional accuracy, plastic injection molding is widely used across various industries, such as automotive, consumer goods, electronics, and medical devices.
How does Plastic Injection Molding work?
Plastic pellets go into a hopper to start the plastic injection molding process. Then, they move into a barrel. Inside the barrel is a drill, which is like a giant screw. The drill helps push the plastic pellets forward. Heater bands outside the barrel heat it, turning the plastic into a gooey, melted state.
When the machine starts, the mold closes. The auger pushes the melted plastic into the mold under high pressure, like a giant plunger. In just a few seconds, the melted plastic fills the empty part of the mold, called the cavity. Coolant, usually water, flows around the mold to cool the plastic quickly, similar to how water cools an engine.
The plastic hardens into the mold’s shape in less than a minute. The mold then opens, and the new plastic part pops out. Once the part is out, the process can start all over again.
Why should you choose Plastic Injection Molding for your manufacturing needs?
Plastic manufacturing is growing fast in the United States. From 1980 to 2024, jobs in plastic manufacturing, like plastic injection molding, grew faster than all other manufacturing jobs, growing 1.5% more each year. There are many reasons why US manufacturers love plastic, especially plastic injection molding. Here are some of the benefits of plastic injection molding:
Mass Production
Injection molding is one of the speedy manufacturing methods worldwide, eventually making this process suitable for mass production in less time. One injection molding cycle usually takes less than a minute—sometimes, it only takes a few seconds! Each cycle can make many parts at once, meaning many parts can be made quickly.
Low Wastage
Compared to the CNC machining process, where a tool cuts the plastic from large blocks, plastic injection molding comprises less material wastage. For CNC, you might start with a 100g block to produce a component that weighs a few grams. However, out of 100 grams of raw material in injection molding, the average wastage would only be 20g. As a result, injection molding is an economical and environmentally friendly manufacturing process.
Complex Parts
Plastic injection molding can make very detailed parts. This means you need fewer parts to make something, saving time. You can make parts with threads or side holes by adding things like unscrewing fixtures and core pulls. This removes the need for extra steps in other processes. You can even mold your design or brand onto the part during manufacturing.
Low cost (in the long run)
Plastic injection molding wastes less material than other methods, like CNC machining, which makes it cheaper. Plus, plastic costs less than metals and rubber.
Recycling saves money, too. Leftover plastic can be ground up and reused. This leftover plastic is called “regrind.” If you have enough regrind, mix it with new plastic and use it again. You can also sell it to factories that make plastic parts that don’t need to look perfect, making the process even cheaper.
After you pay for the mold, it doesn’t cost much to run it. Over time, the mold can produce many parts, saving you money.
Consistent Quality
Plastic injection molding is a process you can repeat many times. You can make thousands of plastic parts in one day with a machine. All the parts will be almost the same.
If you design the mold well, pick the right materials, and plan the product correctly, the number of bad parts will be very low, less than one percent.
Plastic injection molding is a great choice if you need your parts to be consistent.
What plastic can be used for injection molding?
Plastic part makers use thermoplastics for injection molding. Thermoplastics are special polymers that melt when heated and harden when cooled. You can heat and cool them many times before they become unusable.
Thermoplastics come as small pellets for molding. These pellets can be mixed with colors, recycled materials, glitter, and other additives. Unlike thermoset plastics, thermoplastics won’t burn if reheated.
Here are the most common types of plastic used in Plastic Injection Molding:
Acrylonitrile Butadiene Styrene (ABS)
ABS is a tough and light material. It’s commonly used for making plastic parts through injection molding. For example, LEGO bricks are made from ABS.
Polycarbonates
Polycarbonates are clear, tough plastics that resist impacts and can bend very much without cracking. People use them for everything from eyewear lenses to medical devices and mobile phone screens. They’re even strong enough to be used in bullet-proof glass.
Nylon
Nylon is known for its unique electrical properties and durability. It’s a versatile thermoplastic used in everything from sports gear to industrial parts. Its strength and electrical qualities make it a go-to material in many fields.
Polypropylene
Polypropylene is a versatile material known for its flexibility. It offers excellent chemical resistance and won’t leach into food, making it a great choice for making food containers and utensils.
Polyethylene
Polyethylene is a great plastic for making things with injection molding. It’s very flexible, strong, and can handle hits without breaking. It doesn’t soak up much water and can be recycled, so it’s perfect for making plastic containers and bags.
Conclusion
Plastic injection molding is super important in today’s manufacturing world. Knowing about it is key if you’re starting a new product or trying to improve your current processes. Choosing the right companies to work with, like those that make the molds and those that do the molding, is important. Choosing the right partners helps you reach your production goals, ensure good quality, and stay ahead of the competition.
Frigate provides various injection molding services to meet your production needs. Check our website for everything we can do, or get a free quote today!
