Molding silicone rubber - manufacturing processes for high volume and mass production of silicone rubber parts and products

Silicone rubber is a unique synthetic elastomer that is made from a cross-linked polymer which is reinforced with silica. Some if characteristics include: stability at both high and low temperatures, no taste or smell, translucent and hence easy to color, wide hardness range, chemically resistant, weather resistant, high level of sealing performance, electrical properties and resistant to compression. There are four main molding methods: liquid injection molding, compression molding, transfer molding and extruding (or "extrusion" / "extrusion molding") (Dow Corning, 2007).

Similar molders are used in all of these processes. Preforms are rough pieces of unvulcanized rubber that are placed in the compression mould, the cylinder of the injection molding machine, or in the pot of the transfer mould. Strip preforms are especially suited to injection molding. For injection and transfer molding, preforms can be of any shape that is convenient for feeding the injection cylinder or transfer pot. Transfer molding offers several advantages over other methods by providing: shorter production cycle, maintains closer dimensional tolerances than compression molding, provides uniformity and fast mold setup although non of the processes are better than LIM for avoiding flash and eliminating the excess waste of material.

[Read the entire article]

This is an article written for Protosil.