Solid silicone cold runner injection mold

Liquid Silicone Rubber (LSR) overmolding

A solid silicone cold runner injection mold is a specialized type of mold used in the manufacturing of silicone rubber products. In this type of mold, the runner system, which is a network of channels that guide the liquid silicone material into the mold cavities, is made from solid silicone material. This is in contrast to traditional hot runner molds where the runner system is heated to keep the material in a molten state.

solid silicone cold runner injection mold

solid silicone cold runner injection mold

The use of solid silicone in the runner system offers certain advantages, such as reduced material waste and easier cleaning, as there is no need to flush out molten material. This type of mold is often used for applications where cleanliness and minimal material waste are crucial, such as in the medical or food industry.

Liquid Silicone Rubber (LSR) overmolding is a specialized manufacturing process that involves the application of liquid silicone rubber onto a substrate or an existing component to create a protective or functional outer layer. This process is used in various industries, including automotive, medical, electronics, and consumer goods, to enhance product performance and durability. While LSR overmolding offers many advantages, such as excellent heat resistance, flexibility, and biocompatibility, there are common issues that manufacturers may encounter during the overmolding process. This article delves into the details of LSR overmolding and explores some of the common issues and their solutions.

Understanding LSR Overmolding

LSR is a high-purity, platinum-cured silicone rubber that is known for its exceptional properties, making it a preferred material for overmolding applications. The overmolding process involves the following key steps:

  1. Surface Preparation: Proper preparation of the substrate or the existing component is crucial. It should be cleaned and, in some cases, primed to ensure good adhesion of the LSR.
  2. Mold Design: The mold used for LSR overmolding needs to be designed to accommodate the substrate and allow the LSR to be injected or dispensed onto it. The mold’s design should also prevent flash and promote the proper flow of LSR.
  3. Injection or Dispensing: Liquid silicone rubber is either injected into the mold or dispensed directly onto the substrate using specialized equipment. The choice of method depends on the specific requirements of the project.
  4. Curing: LSR overmolding typically involves curing the silicone rubber at elevated temperatures to accelerate vulcanization and hardening. The curing process may use either compression or injection molding techniques.
  5. Demolding: Once the LSR has cured and solidified, the molded part is removed from the mold, often requiring the separation of the substrate and the LSR.