Insert molding is a plastic injection process that incorporates metal or other non-plastic materials into a plastic product, replacing the need for fasteners and reducing overall part size and weight. The process is used to produce a wide variety of products in industries like automotive, medical and consumer electronics. The benefits of insert molding are numerous, but there are some things to keep in mind when deciding on whether or not this is the right process for your product.
Metal inserts are placed in the injection mold before the molten plastic is injected, and the molded product is then formed around the insert. Injection molds are designed to prevent the injected plastic from covering any areas that should be exposed by the insert or substrate, so the final product is a single, seamless piece. Metals that are often inserted into plastic include bronze or brass bushings in rotating parts, metal handles for medical instruments, and electrical connectors and strain reliefs.
The same design guidelines for insert molding apply as with standard injection molding: Maintain proper draft angles, ensure consistency in wall thicknesses, eliminate undercuts, and avoid unnecessary part features or superfine surface finishes where possible. In general, any component that needs to fit into a larger plastic component should be considered for insertion molding, as long as the size and material are compatible.
Inserts can either be incorporated at the time of the injection molding process, or they can be loaded in the post-molding phase. The former allows for the benefits of insert molding to be realized at the time of manufacture, while the latter usually involves a separate operation after the initial injection molding and can help reduce manufacturing costs.
Some of the key advantages of insert molding are the reduction in assembly and labor costs, increased part reliability, reduced part size and weight, and enhanced strength and functionality. Insert molded parts can also be more durable, as they are less likely to be damaged by vibration or shock.
Another advantage of insert molding is the ability to create functional, tight-tolerance threaded inserts without using a secondary process such as soldering or threading. This helps to ensure that the threaded portions of a part remain strong and reliable throughout the life of the component.
If a part is cost sensitive, it’s important to understand the increase in unit price that insert molding will cause before pursuing it. An injection molding company can help you determine whether or not inserts are a good choice for your project by carrying out a cost-benefit analysis.
Whether it’s a simple metal handle for a medical instrument or a complex component in an electrical device, Crescent can help you decide if insert molding is the best option for your product. From concept through prototype, we can manage your entire project, including mold design and fabrication, sourcing of the inserts, and even custom manufacturing if necessary. Contact us today to learn more about our insert molding services.