Plastic Injection Molding: What Is It and How Does It Work?

Worldwide, the plastic injection molding process is a market worth $260 million dollars. Projects suggest it will continue to grow in the future.

The continued growth of this market is largely due to its versatility. Plastic injection molding can to make everything from aerospace and automotive parts, to medical equipment, to toys and phone cases.

You probably have something within arm’s reach that was made with injection molding!

Keep reading to learn more about this process and how it works.

Features of Plastic Injection Molding

Injection molding has been around since the 19th century and is the ideal method for producing complex parts at a low cost. It’s best for objects that are within 60 cubic inches in size.

One of its key selling points is the ability to create precise designs. It’s great for intricate parts and you can incorporate a lot of features at very small tolerances.

Despite being intricate, parts made with injection molding are highly durable. You can add fillers to the injection mold to reduce the density of the plastic, thus making the item stronger.

Plastic injection processes offer a great deal of options when it comes to colors and types of plastic. Have a look at some of the plastic varieties you can use:

  • Antistatic plastic
  • Biocompostible plastic
  • Chemical resistant plastic
  • Infrared transmitting plastic
  • Thermoplastic rubber

Advanced techniques such as repeated injection can create parts out of multiple materials and insert molding can add additional plastic parts over existing parts.

Finally, plastic injection molding reduces labor and material waste. A plastic injection molding machine produces items with consistent quality at a consistent rate. It furthermore eliminates a lot of human error and is almost waste-free, as the leftover bits of plastic can be repurposed for later projects.

Molds come in different materials and with different expected lifespans. A prototype mold is inexpensive and is best for testing out a design. It may not produce more than 1,000 items.

Conversely, a mold built for long-term use will cost more but be more durable.

How It Works

In a nutshell, the machine injects melted plastic into a mold, where it hardens into the desired shape.

The process starts with plastic in granule, powder, or pellet form. It flows from a feed hopper into a barrel containing a screw. The frictional action of the screw heats up the barrel to melt the plastic.

Once the plastic is at the right temperature, the machine uses high pressure to inject it through a check valve and into a closed metal mold. Aluminum is a popular choice of metal for these.

Inside the mold, the plastic cools and hardens into the shape of the inside of the mold. Once it’s cool, an ejector pushes the completed product out of the mold.

Take a look at rapid injection molding methods for prototype molds!

Plastic Injection Molding Companies

If this sounds like the ideal technique for your next plastic project, the next step is to look for a great plastic injection molding service. Prototech Asia provides rapid prototyping services to help you speed up your product’s access to its market.