GMN's metal insert molding capabilities

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By Richard Smylie | Jan 28, 2016
GMN Automotive metal insert molding

When a part needs to hold up against heavy wear and tear, a basic nameplate may not meet demanding project requirements. In these cases one of the technologies that GMN utilizes is metal insert-molding, a process in which both metal and plastic are used together. This capability is especially popular in the automotive industry because it creates pieces that are robust enough to withstand both external and internal environments.

Metal insert molding can replace traditional methods for combining metal and plastic together, including adhesive bonding or crimping. While both of these methods offer adequate bonding for flat surfaces, the advantages of metal insert molding far outweigh those of adhesive bonding and the crimping method.

The metal insert-molding process is an alternative method that overcomes the many difficulties found when combining metal and plastic. The first step of metal insert-molding is decorating the metal with mechanical and chemical finishes for cosmetic requirements. Next, heat activated adhesive is applied to the back of the metal. The part is then trimmed and the metal is formed into the desired shape. The metal piece is inserted into the mold before the plastic is then injected. Finally, the part is cooled and trimmed again if needed.

Metal is chosen for many reasons. First, mechanical finishes can be applied that give the appearance of movement on the part from reflecting light. These finishes include spin, brush, strip and coin graphic patterns. Metal is also used because it’s a strong material that holds its shape and many projects require the feel and weight of authentic metal. While metal provides both cosmetic and functional purposes, plastic is used predominately as a lightweight material that can support the piece as a structural component used to attach the part to its final application.

The advantages of metal insert-molding are broad. This technology allows for a line to line fit between the metal and plastic to create an absolute bond and complete support on the back of the part. The strength of the metal allows for a thicker section of plastic tabs or clips on the back of the part without the risk of heat sink through the top surface of the metal. The combined metal and plastic components can also be machined for a cleaner fit without compromising on the look of the part. The plastic material also traps and covers the raw edge that is created when the parts are cut out.

Metal insert molding is a popular technology that offers both functional and cosmetic benefits for decorated trim components.