Molded silicone rubber raw materials are molded into products by heating and pressurizing in the closed mold cavity. Generally, the method is to make the powder rubber block into a blank with a shape similar to the product, put it in the cavity of the heated mold, then close the mold and pressurize it to form, cure or vulcanize, and then demould the product. This method is especially suitable for the molding and processing of thermosetting products.

Generally, according to the type of polymer processed and the shape of products or semi-finished products, the extruder, head and die, as well as the corresponding auxiliary devices such as setting and traction are selected, and then the extrusion process conditions such as screw speed, head pressure, material temperature, setting temperature and traction speed are determined. In the extrusion process, the materials generally have to be plasticized, but the setting method is different. For example, extruded plastics often need to be cooled and shaped to cure, while semi-finished products of extruded rubber need to be further vulcanized.

Difference between molded silicone rubber and extruded silicone rubber:

1. Molded rubber compound  is cured by plate vulcanization press machine, while extruded rubber compound is cured by extrusion machine.

2.Molded rubber compound is to add double 2,5 vulcanizing agent or odorless vulcanizing agent, while extruded rubber compound is to add double 2,4 vulcanizing agent or platinum vulcanizing agent. There are great differences between the two vulcanizing agents and can not be mixed;

3. Both molded silicone rubber and extruded silicone rubber can reach food grade. Molded silicone rubber need to add odorless vulcanizing agent, the extruded silicone rubber need to add platinum vulcanizing agent.

4. The curing time of molded silicone rubber is about 5min, and the curing time of extruded silicone rubber is only a few seconds;

5. The molded silicone rubber are mainly use for production of silicone rubber products, like gaskets,O-rings,seals,etc ,while the extruded silicone rubber are mainly use for silicone rubber tubes,strips.

6. The molded silicone rubber is limited by the size of the product. However, the extruded silicone rubber is produced through the extrusion process can be produced without restriction all the time.

7. In terms of the shelf life of both two rubbers without vulcanizing agent can be effectively stored for 1 year. If the vulcanizing agent is added, the molded rubber compound can be stored for 1 month, and the extruded rubber compound can only be stored for 2-3 days at most. Because the vulcanizing agent is easy to volatilize in the air, the rubber must be stored in a dry and cool place!