Outer lens Clear PC-Overmold
Overmolding for lamp assembly involves injection molding a soft elabtomeric material (like TPE or silicone)over a rigid plastic or metal substrate (suc as ABS, PC/ABS or aluminum) to create intgrated, ergonomic, or sealed components in one piece.
Prototype molds allow testing of this two-stage process (substrate molding, then overmolding) before full production.
Overmold Lamp Assembly Components
Substrate (Part A): The rigid, primary component (e.g., the lamp base or handle), often featuring undercut features or perforations to improve mechanical interlocking with the second material.
Overmold (Part B): The softer, thermoplastic elastomer (TPE), TPU, or silicone layer added to the substrate, often used for grips, seals (IP rating), or impact resistance.
Mechanical Interlocks: Engineered features like holes or undercuts in the substrate that the overmold flows into, providing superior bonding over chemical adhesion alone.
Prototype Molds and Process Description
Substrate Tooling: A prototype mold is created to mold the rigid substrate first.
Overmold Tooling: A second, modified mold (or the same mold with inserts) is used to create the overmold cavity.
Step 1: The substrate is molded.
Step 2 (Transfer): The substrate is placed into the second cavity (manual for prototypes, robotic for production).
Step 3 (Overmolding): The secondary material is injected, filling the gap between the substrate and the second cavity, often fusing while the substrate is still warm, says Protolabs.
Key Design & Prototyping Factors
Material Compatibility: The substrate must have a higher melting temperature than the overmold to prevent melting during the second shot, says Fictiv.
Gate Location: Gates for the overmold should ideally be placed in areas that are concealed on the final product.
Prototyping Method: For low-volume prototyping, two separate molds are often used to reduce initial mold costs.
Common applications include sealing LED housings for moisture resistance and adding soft-touch grips to hand-held lamps