Design Complex Components with Insert Molding

Low-volume injection molding isn’t limited to just simple parts. At Proto Labs, we have the ability to manufacture complicated parts using side-actions, hand-loaded inserts, overmolding, and have now started beta testing our insert molding process.

Instead of a mold that produces a final part using two separate shots like overmolding, insert molding generally consists of a preformed part—often metal—that is loaded into a mold, where it is then overmolded with plastic to create a part with improved functional or mechanical properties.

A threaded insert is placed atop a mold core where plastic is molded over it to form the final component.

Threaded Inserts
One way insert molding is leveraged is with threaded inserts, which reinforce the mechanical properties of plastic parts’ ability to be fastened together, especially over repeated assembly. Self-tapping screws work well with softer plastics, but they can become easily worn and/or cross threaded, and fail to perform well, which results in damaged parts that need to be replaced.

insert molding

Insert molding allows you to build added strength into parts with prefabricated components like threaded inserts.

Bushings and Sleeves
Incorporating metal bushings or sleeves is similar to threaded inserts, requiring an operator to slide the threaded insert over a pin before plastic is molded. Bushings and sleeves are a great way to increase part durability for mating components that need more abrasion resistance due to moving parts.

Have a Design Ready for Insert Molding?
There are many applications where parts can benefit from insert molding aside from bushings or threaded inserts. A simple project review with Proto labs can verify if your project is suited for insert molding, which is currently in beta phase. If you have a project involving insert molding, please contact one of our application engineers at or 877.479.3680 with details regarding your design.

This entry was posted in Tips with Tony and tagged , , , by Tony Holtz. Bookmark the permalink.

About Tony Holtz

Tony is a technical specialist at Proto Labs with more than 10 years of experience ranging from CNC mill operator to mold designer to customer service engineer. While his formal education is in industrial machinery operations, he has extensive knowledge and experience in both traditional and advanced manufacturing processes and materials. Throughout his tenure at Proto Labs, Tony has worked with countless designers, engineers and product developers to improve the manufacturability of their parts.

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