Liquid Silicone Overmolding Metal Parts Injection

Liquid Silicone Rubber (LSR) overmolding is a manufacturing process that integrates flexible silicone with rigid metal components, resulting in highly functional and durable parts. This technique combines the unique properties of LSR—such as flexibility, thermal resistance, and chemical inertness—with the strength and stability of metal. It’s widely used across industries for creating components that require enhanced performance, precision, and aesthetics.

The Overmolding Process

1. Metal Part Preparation:
   The first step involves preparing the metal inserts. Cleaning is essential to remove oils, dirt, and residues that could hinder adhesion. Surface treatments like sandblasting or the application of primers can enhance bonding between silicone and metal.
2. Mold Design and Setup:
   A custom mold is created to securely hold the metal inserts while allowing liquid silicone to flow and bond with the metal during injection. Mold design must account for thermal expansion differences between the materials and ensure proper alignment.
3. LSR Injection:
   The material flows around the metal inserts, filling cavities and forming a strong mechanical or chemical bond. Elevated curing temperatures solidify the silicone in place, integrating it with the metal.
4. Demolding and Final Steps:
   Post-processing is minimal due to the accuracy of the process, although minor trimming or quality checks may be performed.

Benefits of LSR Overmolding

1. Strong Adhesion:
   The process ensures a robust bond between LSR and metal, creating parts that can withstand high mechanical stresses and environmental conditions.
2. Design Flexibility:
   LSR’s low viscosity and excellent flow properties enable the creation of intricate designs, thin walls, and complex geometries.
3. Durability:
   The combination of silicone and metal produces components with high resistance to extreme temperatures, UV radiation, chemicals, and wear.
4. Enhanced Functionality:
   Overmolded parts benefit from silicone’s insulating, sealing, and cushioning properties, making them ideal for applications requiring shock absorption, thermal insulation, or watertight seals.
5. Cost and Time Efficiency:
   Overmolding eliminates the need for secondary assembly processes like gluing or fastening, reducing production time and costs while minimizing potential failure points.

Applications

• Automotive: Used for seals, gaskets, vibration dampeners, and connectors.
• Medical Devices: Ideal for biocompatible parts like surgical tool grips and seals.
• Consumer Electronics: Found in device casings, wearables, and connectors.
• Industrial Equipment: Used for protective covers, grommets, and shock absorbers.