D&M Plastics LLC has been a provider of injection molding services since 1972. According to company folklore, in 1993, we became the first ISO-certified custom injection molder in the United States. Currently, D&M has ISO 9001 and ISO 13485 certifications.

We pride ourselves on excelling at:

  • Designing for manufacturability
  • Creating out-of-the-box solutions to meet our customers’ specific needs
  • Providing creative solutions to solve our customers’ most challenging injection molding dilemmas in the medical, electronics, defense, aerospace, and automotive industries
  • Providing fast turnaround times and quick response to customer requests
  • Maintaining strict material management and quality assurance processes
  • Maintaining a companywide focus on quality
  • Maintaining a safe working environment

What Is Overmolding?

Overmolding is the process of adding a second layer of plastic over a premolded plastic part, often referred to as the substrate. Overmolding is usually done with a material that is softer and more flexible than the substrate.

Overmolding is typically used to achieve one or more of the following:

  • Improve the tactile feel of the substrate
  • Improve the aesthetic appearance of the part
  • Improve shock resistance
  • Produce a multi-colored part
  • Provide electrical insulation when the substrate is metallic
  • Create a seamless joint between two parts without using fasteners or glue

Material Considerations

Of note, it is important to ensure that the plastic material for overmolding is chemically compatible with the substrate. When the overmold material does not chemically bond well with the substrate, the two materials can be mechanically bonded by incorporating holes or ribs on the surface of the substrate.

In addition to substrate compatibility, other factors that influence the choice of the overmold material include the thickness of the finished part, as well as physical and aesthetic features such as:

  • Hardness
  • Flexibility
  • Tactile feel
  • Visual appeal

Thermoplastic elastomers (TPE) are commonly used for overmolding. The other commonly used materials may include:

  • ABS
  • Acetal copolymer (POM)
  • Acrylic
  • HDPE
  • PBTR
  • PEEK
  • PEI
  • Polycarbonate

Insert Molding vs. Overmolding

Insert molding and overmolding are similar processes. Just as with overmolding, insert molding is used to give the substrate some additional features that improve its function or properties.Insert molding involves placing a metallic part—such as a bushing, fastener, clip, or pin—into a mold and then injecting plastic so that it surrounds a portion of the metallic part and forms a single unit.

The application for the finished part determines whether insert molding or overmolding is the preferred technique. Both techniques provide the following benefits:

  • Insert molded or overmolded parts are more robust and durable than similar parts made by mechanically assembling the individual units.
  • Both processes are cost-effective since there are no secondary assembly steps
  • Molding avoids the use of adhesives.

Overmolding and Insert Molding From D&M Plastics

D&M is well equipped for fabricating sophisticated, highly engineered, molded parts with strict tolerances. We have the ability to injection mold horizontally and vertically. D&M has extensive experience with molding high-performance plastics.

We work closely with our customers at every step of manufacturing, from initial design to high-volume production. D&M strives to provide the best service, fastest turnaround times and the highest quality in the industry at competitive prices.

Please contact us to learn more about D&M’s capabilities or request a quote for your injection molding project.