Combine Multiple Materials, Eliminate Assembly Process, Save Time / Money, Metal Threaded Inserts in Molded Plastic Parts, Single Piece Assembly

GC Mold and Engineering provides plastic injection mold solutions to industries of all types and sizes. For almost 40 years BMJ has designed, built, repaired and worked on almost every type of mold existing in the plastic industry.

Our state-of-the-art mold building facilities include high-speed CNC Milling and EDM Machining to create many types of molds, including complex specialty injection molds, such as two-shot molds, unscrewing molds, insert molds, stack molds, and many other types.

Insert Molding: Combining Elements of a Part

When a specific design requires combining multiple materials into one finished part, the cost-effective process known as insert molding may be the solution you need.

With Insert molding, a plastic part is formed or molded directly over or around metal or plastic components, resulting in a single piece assembly. A typical example is a plastic handle molded over a metal screwdriver shaft. This value-added molding operation eliminates the need for a costly additional assembly process.

The process was originally developed to place threaded inserts in molded parts and to form the plug around the prongs on the ends of electrical cords. It was found that molding directly over the metal parts saves time and money by eliminating an assembly step. Today, there are few design limitations or restrictions on material combinations.

Insert Molds: Design Considerations

Insert molding has become a common method for manufacturing mixed material parts. The basic design rules for insert molding are generally similar to those for standard injection-molded parts.

There are, however, a few design elements particular to insert molding that should be considered, that may affect the part’s design:

• Insert material used
• Pull and compression-strength requirements of the insert
• Leak resistance requirements of the finished part
• Axial forces, or torque, the insert will be subjected
• Voltage requirements for electrical applications

Each of these areas must be addressed before our engineers can select the proper plastic material, and build the mold to perform optimally with the materials. The design of the insert itself must also be considered, such as sufficient “anchors” incorporated into the insert’s structure to properly secure it into the plastic parts.

If you want to know more information about insert molding, please go to what is insert molding section.