What is overmolding?
Overmolding is the process of melting and injecting a thermoplastic elastomer (TPE) onto a pre-existing rigid plastic part, or substrate. This process creates a chemical bond between the TPE and the rigid material. Example applications that utilize overmolding include:
- Grips on plastic power tool handles
- Lid seals on jars and bottles
- Anti-skid footpads on blenders and small appliances
How do you overmold?
There are two primary injection molding processes for overmolding:
- Two-Shot Molding: This processes utilizes one machine with a rotary mold and two injection barrels. The first barrel shoots the rigid plastic substrate. The mold then rotates 180 degrees, aligning the injection location with the second barrel. The second barrel shoots the TPE overmold material onto the existing substrate. The contact between the rigid plastic and the TPE creates a chemical bond between the materials, finalizing the consolidated, finished part.
- Insert Molding: This process uses two machines. The first machine shoots the rigid plastic substrate. The substrates are then transferred and inserted into a second machine where the TPE overmold material is injected onto the inserted substrate. Again, the contact between the two materials creates a chemical bond and a consolidated, finished part.
What are the benefits of overmolding?
The process of overmolding can:
- Improve ergonomics and aesthetics of finished parts
- Add value and differentiate the end product
- Eliminate the need for glues and adhesives
- Consolidate parts by enabling a lid to have its own functional seal
- Improve a part’s integrity and longevity by seamlessly connecting aspects of design versus relying on the connectivity of a substrate and a grip, or a substrate and a seal ·
- Expand design freedom by eliminating the need for mechanical interlocks
What materials can be used in overmolding?
At Audia Elastomers, we offer innovative TPE products that bond to a wide variety of resins, including:
- PA 6
- PA 6/6
- PP (Homopolymer, Copolymer, Random Copolymer)
- PE (HDPE, LDPE, LLDPE)
- Other T\thermoplastic elastomers
So whether you want to expand your product offerings, increase margins, or improve ergonomics, we can help. Let our dedicated team design the ideal solution to meet your specific adhesion and overmolding needs. Together we are bonded by a shared vision of bringing your product to the next level.