Plastic Injection Molding

What is plastic injection molding?

Plastic injection molding is one of the fastest manufacturing techniques available. Liquid plastic is injected into a mold where it is cooled, solidifies, and is ejected. The same mold can be used countless times and the process of producing a part can take as little as a few seconds. Thousands of different plastic types are available and different polishes and textures can be applied, allowing for a huge degree of customization and flexibility.

Who is plastic injection molding for?

Plastic injection molding is great for those looking to produce relatively large quantities of parts or products quickly and economically. After the initial tooling cost, further costs are very low so it makes sense to use plastic injection molding for larger runs. If you only require a small number of prototypes, 3D printing is likely to be more economical. Unlike vacuum casting, a single mold can be used over and over again more than 100 thousand times, so usually only a single mold is required. The ability to mix different types of plastic (through co-injection molding) is another reason why people choose plastic injection molding. For other production techniques it may be difficult to produce designs with mixed materials. Common uses for plastic injection molding include pilot runs, low-volume production, and on-demand parts.


First of all, a mold is produced, usually CNC machined aluminum. The material comes in the form of pellets, which are melted down in a barrel. This liquid is then compressed and injected into the mold through the mold’s runner system, where it quickly solidifies. Ejector pins then eject the solid part into a loading bin, and the process can be repeated again. The length of time it takes for each part to be produced depends on its size and the material used. This ranges from just a few seconds for small designs up to one or two minutes for larger, more complex designs. It should be noted that the production phase is completely automated, so labor costs are kept to a minimum.