ServicesMicro Molding


Some micro projects require specialty micro injection molding processes, such as overmolding. Overmolding involves two or more materials molded together to become one part. Examples include molding plastic over plastic or molding plastic over a preformed part, such as a metal insert. (See examples of common polymers and substrates below.)

MTD specializes in two types of overmolding:

Insert Molding

Insert molding is injection molding a polymer around, over, under, or through a substrate material.

Multi-Shot & Multiple Material Molding

Injection molding multiple (two or more) materials around, over, under, or through a substrate material.

Overmolded Catheter Tip

Made from Ultem, this surgical device measures .005″ wall thickness at overmolded section over the steel ring, and features +/- .001″ tolerances.

Overmolded Suturing Assembly

The overmolded assembly design has a spring OD of 0.11″ (0.28mm). The Ultem wall thickness is 0.012″ (0.30mm).

Carbon-Filled PEEK Device

The PEEK component is overmolded over a .031″ diameter stainless steel rod for a sports medicine device.

Benefits of MTD’s Overmolding Process

  • High part precision achieved by leading edge molding equipment, capable tooling, and robust validation procedures
  • Shot-to-shot consistency guaranteed by instrumented molds
  • Improved part functionality (i.e. creating a water-resistant seal)
  • Cost-effective high volume production achieved through robotics and automation
  • Ultra-precise positioning of overmolding tool inserts enabled by in-line camera systems
  • Avoidance of foreign materials such as glues and adhesives into the final medical device
  • Significant reduction or elimination of costly and cumbersome assembly operations that can lead to failure modes and high fall-out rates

Common polymers for overmolding:

  • ABS
  • HDPE
  • LCP
  • PEI
  • PMMA
  • PC
  • PP
  • PPA
  • PPS
  • PS
  • PSU
  • TPE
  • TPU
  • PEEK

Common substrates in micro overmolding:

  • Metal
  • Plastic
  • Tubing
  • Fabric/mesh
  • Delicate electronics
  • Batteries
  • Microfluidic chips
  • Delicate assemblies
  • Other biomaterials
Translate »
Share This