Plastic Injection Molding

Our plastic injection molding process produces custom prototypes and end-use production parts in 15 days or less. We use aluminum molds that offer cost-efficient tooling and accelerated manufacturing cycles, and stock more than 100 different thermoplastic resins.

How Does Plastic Injection Molding Work?

The thermoplastic injection molding process at Protolabs is a standard process involving an aluminum mold with no heating or cooling lines running through it, which means cycle times are a bit longer. It allows our molders to monitor fill pressure, cosmetic concerns, and the basic quality of the parts. 

Resin pellets are loaded into a barrel where they will eventually be melted, compressed, and injected into the mold’s runner system. Hot resin is shot into the mold cavity through the gates and the part is molded. Ejector pins facilitate removal of the part from the mold where it falls into a loading bin. When the run is complete, parts (or the initial sample run) are boxed and shipped shortly thereafter.

injection molding service icon
  • 25 to 10,000+
  • Shipped in 15 days or less
  • Molds starting at $1,495
Common Applications
  • low-volume production
  • bridge tooling
  • pilot runs
  • functional prototyping
 

Watch: Knit Lines in Molded Parts 

See how knit lines in molded parts can impact overall functionality and how to reduce them.

on demand manufacturing injection molded machine

Molding Options: Prototyping or On-demand Manufacturing?

Consider part quantities, lifetime maintenance, level of inspection, and cost when determining which option is right for injection molding.


Design Guidelines

Our basic guidelines for plastic injection molding include important design considerations to help improve part moldability, enhance cosmetic appearance, and reduce overall production time.

 

VIEW GUIDELINES

Thermoplastic Materials

Choose from production-grade thermoplastic resins ranging from ABS, PP, PC and nylon to high-performance resins like PEEK and PEI. A number of colorant options are available and customer-supplied thermoplastics are also accepted.

 

VIEW MATERIALS

Resources

press operator examines liquid silicone rubber part

Free moldability analysis within hours

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