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Plastic Injection Molding Or Plastic Machining

ByAnthony Hendriks

Apr 15, 2015
Plastic Injection Molding Or Plastic Machining

People involved in the manufacturing industry perform many different operations. Plastic “injection” molding and machining of plastic components are the two most common processes and contrary to popular belief that these two are similar processes, they are very different. To help you better understand the differences between plastic machining and plastic injection molding, you need to know what they actually are.

Plastic machining is a process of reducing the size of plastic components from a large shape, just as shaving slivers from a tree with a knife. The plastic injection molding is a process that heats up plastic pellets to their melting point and injects them into a cavity. The plastic pellets are cool when rigid, but viscous (or melted) at higher temperatures. As plastic pellets cool, they harden in the shape of the cavity. So, how are these two plastic machining services different?


Plastic Machining Is More Expensive When it comes to price, plastic machining services are less expensive than plastic injection molding. It can cost up to 20 times plastic molding and yet sometimes, machining of plastic components is the cheaper option. The cost of creating the initial mold varies in both processes, creating the cost difference. From $5,000 to over $150,000, the cost of initial mold varies greatly. If you need only a few parts and you will spend only a little money on the initial mold to create them, the plastic injection molding process might be less expensive.

Plastic Mold Cannot Be Easily Changed If you are in need of hundreds of fewer parts, plastic machining services is the right solution. After you create a plastic mold, it cannot be easily changed. Therefore, the cost of creating the mold is higher than the cost of plastic machining services. But if you are dealing with larger orders, plastic injection molding is a better choice. However, there are always exceptions.

Plastic Machining Is More Accurate Than Plastic Molding The precision is the key. With plastic molding, except results within .13 mm of specifications, while with machining, the results are highly accurate within .02 mm of specifications. There are a lot of industries and operations that require this level of accuracy. If high-quality final product is needed, plastic machining services is a better option, because the process of transferring plastic into a mold usually leaves some imperfections.

If you are choosing between plastic injection molding and plastic machining services, here is what you need to consider:

  • For manufacturing hundreds of fewer parts – plastic machining;
  • To avoid the high costs of creating initial mold – plastic injection molding;
  • For high level of accuracy and better quality of finished products – plastic machining.

By Anthony Hendriks

The life of the party, Anthony is always up for spending some time with family and friends, when not blogging of course! Ever since a child, his love for books of mystery, race cars and travelling keeps on growing so it's difficult for him to single out that one all-time favourite hobby. If there's one thing he hates, though, it's having pictures taken but you already guessed that from his choice of plant photo for the blog.