You have your next big idea in mind but it needs a little extra something. Something to push it past your competitors, something to make it unique, and to keep it at the head of the pack. Would a metal part integrated to your injection molding put it over the top? How about two materials used in conjunction to create something never thought of before? If both of these concepts sound amazing, yet you don’t know what either is, we’ll step you through insert molding vs overmolding and why you should consider them on your next project:
What is Insert Molding?
Insert molding is a process in which plastic is injected into a mold that contains a pre-placed insert. The final part coming out of the mold is a single molded plastic piece with an insert surrounded by the plastic. The inserts placed inside the mold and molded over can be made of metal or different types of plastic.
The benefit of insert molding can be seen across many industries. From automobiles, cookware, household appliances, medical instruments and devices, cabinet knobs, electrical components and more, insert molding offers low cost opportunities to reduce part size, increase component reliability, and increased strength of each part.
The process of insert molding is very similar to standard injection molding, with the extra step of adding the insert into the mold before the final plastic injection process is completed. The step of adding the insert, regardless of its material, can be done manually by a technician or with some form of automation.
What is Overmolding?
Overmolding is a process where a single part is molded using two or more different materials in some combination. The first material used in the overmolding process is often referred to as the substrate, and it is partially or fully covered by subsequent materials during the overmolding process.
The overmolding process doesn’t require the substrate, or base material, to be plastic. It can be a machined metallic part, a separate injection molded component, or something as simple as a threaded metal insert or electrical connector. The secondary overmold materials typically are a plastic or rubber, depending on the base substrate. Each material must be carefully selected to ensure a chemical compatibility, as well as a thermal compatibility. The secondary material melting point shouldn’t be higher than the base substrate, which may cause an issue during the injection process.
Overmolding is currently being utilized in many different applications and industries, and can seen in daily life in toothbrushes, tool hand grips, shampoo and conditioner bottles, and razors for shaving. Each of these examples can utilize a plastic over plastic, rubber over plastic, or plastic and/or rubber over metal to create a unique product in many colors and textures. In some products, overmolding does contain more than two materials to create the final products. Scissors are a great example of a product using three different materials in specialized cases.
Both of these process have benefits that can help reduce the cost of your next project while adding additional strength and durability. Insert molding may take the place of a secondary operation to add logos, badging, and threaded inserts to reduce the overall manufacturing cost. Overmolding may replace a secondary process to bond components together, and make your product better for your intended customers. Both can be flexible to colors and materials if properly selected to meet the desired end result. The environment the product will operate in and how it functions will also help to dictate if either process will be a good choice.
If you have a potential design idea, but aren’t 100% sure if it will work, we’d like to discuss it with you. When you’re ready to collaborate with our elite team, call (425) 339-0288 or email mattp@sealectplastics.mystagingwebsite.com.
Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.
In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.
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