Overmolding vs Insert Molding

Which Plastic Molding Process is Right for Your Applications – Overmolding or Insert Molding?

When it comes to plastic injection molding processes, many people find themselves researching the differences to determine which process is right for their application. One of the most commonly researched processes are overmolding and insert molding.

As an industry-leading resource for plastic injection molding, we have covered the topic of overmolding vs insert molding to help you quickly & easily identify which process is best for your product.


Plastic Overmolding

Overmolding is when one material being is molded over a second material.

The base layer is molded first and the additional plastic layer(s) are molded over and around the original part – resulting in a single, finished product.


  • Strong Finished Product
  • Long Service Life
  • Enhanced Safety
  • More Cost Efficient than Post-Molding Fabrication

Product Examples:

  • PCB
  • RFID
  • Phones
  • Power Tools & Hand Tools
  • Car Steering Wheels

*Special Notes:

To avoid plastic molding defects like distortion, gaps and stress fractures, molds must be meticulously designed and the overmolding process must be performed with utmost precision.

Whether you are using metal or plastic resins, proper material selection is critical to ensure materials bond together chemically and mechanically – without experiencing molding defects like melt or distortion.

Insert Molding

Insert Molding Injection Molding

Insert Molding is when plastic is injected into the mold cavity and insert piece (or pieces) prior to plastic injection molding. The resulting product is a single piece with the insert encapsulated by the plastic.


  • Faster Assembly Time
  • Reduced Part Size
  • Reduced Part Weight
  • Cost-Effective

Product Examples:

  • Filters with Fine Mesh Inserts
  • Vacuum Hose Connectors
  • Automobile Air Ducts
  • Heavy Equipment Components
  • Medical Syringes

*Special Notes:

Depending on the size, shape & geometry of the part, a multi-cavity mold may be manufactured to increase production.

Secondary, post-molding operations are sometimes necessary to complete the assembly.

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