What is Liquid Silicone Overmolding?

Liquid silicone overmolding is also known as two shot/2k molding, which is a two-part process where a layer of material (liquid silicone rubber or thermoplastic elastomer) is molded over another component, such as a housing, wire or handle and which is a process for molding silicone rubber onto a base material (plastic, metal). Typically the base component part is first placed in the injection mold and the hot molding material fills the area around the inserted part. The result is an assembled product.

In order to make the materials (Liquid Siliconer Ruber LSR, Plastic, Metal) be bonded together both chemically and physically, we can have the substrate and overmold material interlock in some mechanical capacity.

How is the Process of Overmolding Silicone Plastic Parts Accomplished?

The plastic part is placed into an injection molding tool at which point LSR material is shot into, onto or around the plastic part. When the overmolded materail cures or solidifies, and then the two materials become joined together as a single part.

And becuase liqiud siliocne rubber's property, it can be bonded to majority of plastic resins and metal, and the bond is highly durable can withstand flex movement at different temperature ranges.

The Benefits of Overmolding:

• Make handheld items easier and safer to use

• Protect from sharp corners or edges

• Have better sealing performance

• Better electrical resistance

• Defense against water, dust, and other contaminates and have a longer life cycle

Typical Overmolding Applications:

Silicone Rubber Over Plastic - When rigid plastic substrate is molded, a soft rubber or TPE is molded onto or around the substrate. This is often used to give a soft grip area to a rigid part or a silicone sealing/ gasketing onto a plastic part to connect the plastic part and silicone sealing permanent to improve sealing performance.

Plastic Over Plastic - After a rigid plastic substrate is molded,  another rigid plastic is molded onto or around the substrate. The plastics could differ in color and/or resin.

Plastic Over Metal - First a metal substrate is machined, cast or formed. Then, the substrate is inserted into an injection molding tool and the plastic is molded onto or around the metal. This is often used to capture metal components in a plastic part.

Rubber Over Metal - First a metal substrate is machined, cast, or formed. Then the substrate is inserted into an injection molding tool and the rubber or TPE is molded onto or around the metal. This is often used to provide a soft grip surface