Insert injection molding, also known as plastic insert molding, is one of the rare manufacturing methods that combines polymers and metal materials to create one component in one production run.
Users of plastic insert molding rely on this production method for the added strength from the metal portion of an injection molded component, but it also reduces the need for secondary operations saving customers throughout the supply chain on costs, time, and improving throughput.
Agape Plastics highlights key considerations of insert injection molding including why it’s used, design points, benefits, and more.
Why Agape Customers Use Plastic Insert Molding
When the regular injection molding process, whether it’s for a stock part or a custom operation, still doesn’t hit the mark in term of component strength or design flexibility, our customers will turn to plastic insert molding.
While there will be further discussion points to provide context on the why, from a high-level view, insert injection molding bolsters specific areas of the injection molding process by added threaded features, strengthening load points, embedding electrical contacts, and largely reducing post-mold assembly steps such as removing metal fasteners or add-ons.
Design Considerations
Engineering teams no longer only consider the polymer used in plastic insert molding, but the metallic aspects of the manufacturing service as well. This adds a whole new level of complication and attention to detail when crafting a design. And as such, there are a few design wrinkles that teams should focus on when crafting the blueprint for their project.
This starts with a form of mechanical retention merely because polymers and metals feature different material properties, they won’t naturally bond. Because of this, there needs to be a form of mechanical interlocking during the manufacturing process to ensure the metal insert remains in place while succumbed to the pressure that’s present during the injection. Best practices to achieve this include incorporating undercuts, grooves, through-holes, or diamond knurls into your inserts. Additionally, avoid sharp edges on inserts as they can create unnecessary stress that will crack the formed plastic.
Wall thickness will always matter for plastic manufacturing, whether it’s traditional injection molding or insert injection molding. With insert injection molding, however, ensure proper wall thickness with a ratio that accounts for half the diameter of the insert. Thermal management is also important and to account for this, the mold area around the insert can be slightly warmer than the rest of the cavity to prevent flow disruption.
Repeatability and scalability are just as important in plastic insert molding as they are in injection molding. And to ensure that both of those characteristics are achievable, incorporate symmetrical designs that either automated technology or human operators can account for and place the insert accurately.
Common Applications
A wide variety of industries use plastic insert molding for essential components that make up a piece of a larger product or piece of equipment. Agape provides a few common examples below.
- Threaded fasteners
- Electrical connectors
- Automotive sensors and switches
- Medical cables
- Surgical tools
- Device housings
- Consumer electronics
- Aerospace components
Benefits and Tradeoffs
Like every manufacturing operation, there are going to be benefits that are centric to the process itself, as well as tradeoffs when compared to different production processes.
Benefits
- Reduced assembly costs as secondary operations such as welding, fastening, and adhesion are outright eliminated since a metal insert is already incorporated into the plastic component.
- Because the plastic component contains a metal insert, the product receives enhanced strength, durability, and reliability.
- Most would think that by adding metal into a plastic component it would increase the weight, but since the insert is a small portion of the total part, both weight and size are reduced compared to utilizing traditional injection molding and adding secondary operations.
- Design flexibility increases with plastic insert molding ranging from highly compact to miniaturized designs.
Tradeoffs
Insert injection molding typically lowers total overall costs with the removal of assembly labor and independent fastening work, but it does add mold complexity to account for the insert. Weighing these two items against one another ultimately leads customers to decide if this operation is right for them.
Connect with Agape Plastics for More Information on Plastic Insert Molding Operations
Agape Plastics is one of the industry-leading custom injection molding manufacturers in the United States, but injection molding isn’t all that we can do out of our Grand Rapids, Michigan facility.
Our capabilities include custom insert injection molding which offer flexibility, alternative assembly options, and a variety of cost-saving activities. Our injection molding machines and quality equipment allow us to adapt quickly to industry advancements. Polymer technologies and molding processes have led to new products and processes.
No matter the industry your components are being manufactured for, our stringent quality management systems ensure your production run will hit the mark every time. Achieve better plastic insert molding operations and contact Agape Plastics today.