Molded-In Inserts

Inserts are installed during the injection mold operation.

The insert is placed on a core pin in the injection mold and the plastic is molded around the insert. Proper pin size is important to retain insert in place.

Advantages and Disadvantages of a Mold-in Insert


  • Excellent holding strength
  • Excellent plastic flow around insert
  • No secondary assembly
  • Multiple inserts can be installed during the molding cycle
  • Longer cycle times - more costly
  • Plastic can get into the threads
  • Mold Damage possible if misloaded
  • Inserts need to be removed before plastic can be reground if plastic part is defective
  • Molded-in Stress & Possible Sink Marks