Inserts and overmolding

Insert injection molding is the process of molding or forming plastic parts around other parts, or inserts. The inserted component is most commonly a simple object, such as a thread or rod, but in some cases, inserts can be as complex as a battery or motor.

Insert Molding combines multiple materials and components into a single unit. The process makes use of engineering plastics for improved wear resistance, tensile strength and weight reduction as well as using other materials for strength and stiffness. 

Insert Injection Molding Benefits

CFR Thermoplastics inserts and bushings are used for reinforcing the mechanical properties of the plastic parts or thermoplastic elastomer products that are created through the insert injection molding process. Some of the benefits of insert injection molding, include:

  • Improves component reliability
  • Improved strength & structure
  • Reduces assembly and labor costs
  • Reduces the size & weight of the part
  • Enhanced design flexibility
  • Recyclability (is limited when metal inserts are used)

Insert Injection Molding vs Overmolding

Insert molding and overmolding are two distinctly different processes that produce their own unique types of products. The overmolding process is the process when one material (or CFR Thermoplastic part) is overmolded over a second material. The base layer is produced first and the additional plastic layer(s) are molded over and around the original part. This results in a single finished product. Overmolding creates a strong finished product with long service life and enhanced safety features.

Conversely, insert injection molding occurs when an insert is injected into the mold cavity prior to plastic injection molding. The result is a single piece with the insert encapsulated by the plastic. Plastic injection inserts provide a fast and cost-effective assembly process, producing parts with reduced size and weight.


Written by Theo Mimpen (March 2021)

Overmolded thermoplastic composite (CFR TP) tube

Overmolded CFR Thermoplastic tube