Insert molding is a specialized type of injection molding that combines different materials into a single finished part. While 2 shot molding allows multiple types of plastics to be combined, insert molding allows the inclusion of metal components in a plastic part. For example, you could have a plastic cabinet-door knob with a metal fastening screw embedded during the molding process instead of having to assemble it later.

A wide range of metal components can be used in the insert molding process, including screws, limiters, threaded fasteners, magnets, filtering screens, tubes, clips, mounting brackets, and more. These components can be made from stainless steel, brass, copper, aluminum, nickel, or bronze. Your injection molding company will work with you to select the best combination of metal and plastic based on the part’s requirements.

Good design practices include carefully crafting molds to ensure proper retention of the metal in the plastic part. Some inserts may need to be heated prior to being molded to reduce the thermal difference between the plastic and the metal, which could cause quality issues.

Why Use Insert Molding?

There are several reasons to choose insert molding:

  1. It reduces the post-molding assembly required with separate metal elements, which can be costly. Separate installation of these components adds motion waste, increases production time, and involves additional equipment and labor. Insert molding saves those assembly and labor costs.
  2. It enables designers to integrate features into plastic parts that will make them stronger, more durable, and more reliable than native plastic areas. For example, installed metal compression limiters will strengthen fastening areas and eliminate creep potential.
  3. It allows enhanced product design by integrating features not possible with plastic alone: for example, a stainless steel screen insert can provide a filtration area in a plastic part.
  4. It is useful in metal to plastic conversion to make parts more efficient. There is increasing demand across industries to produce parts in plastic instead of metal — to lower weight, reduce production costs, and eliminate corrosion. Insert molding allows retention of essential metal elements within a plastic part.


Industries with Applications for Insert Molding

Many industries can benefit from insert molding, such as:

  • Automotive and Trucking: Metal to plastic conversion parts reduce weight and improve fuel economy
  • Medical: Plastic parts with metal components are used in a wide range of medical and surgical devices
  • Consumer Products: Insert molding has applications in an array of industries from electronics to HVAC systems
  • Aerospace: Insert molding is used for parts for aircraft interiors, controls, communications and guidance/navigation.

Insert molding provides you with the best of both worlds: it retains the strength and functionality of metal parts by embedding those elements into a more economical and efficient plastic part. Viking Plastics has extensive experience designing insert molding solutions to meet a variety of challenges.

For more information about insert molding, click here.  To consult with the Viking Plastics team about using this process for your project, contact us or request a quote.