Compression molding is a rubber processing method in which raw rubber materials are formed into products by heating and pressing in a closed mold cavity. Products using the molding process include: miscellaneous parts, sealing rings, oil seals, etc.

Generally, a powder-like rubber block is first made into a blank with a similar shape to the product, and placed in the cavity of a heated mold, then the mold is closed and pressurized to form and solidify or vulcanize, and then demolded. Products, this method is particularly suitable for the molding process of thermosetting products.

advantage:

1. Can be made into any shape

2. High precision, beautiful product shape

shortcoming:

1. Generally, it can only be made with a length less than 600 mm

2. Long production cycle and low efficiency

3. The production process will produce a lot of burrs and waste

4. The mold is expensive and the development cycle is long

Extrusion (Crowdingout), generally according to the type of polymer processed and the shape of the product or semi-finished product, select the extruder, die and die, as well as the corresponding auxiliary devices such as shaping and traction, and then determine the extrusion process conditions such as Screw speed, head pressure, material temperature, as well as setting temperature, traction speed, etc. In the extrusion process, the materials generally have to be plasticized, but the shaping methods are different. For example, extruded plastic often needs to be cooled and shaped to make it solidify, while the semi-finished product of extruded rubber needs further vulcanization. The products that use the extrusion process are; rubber sealing strips, hoses, and rubber-sheathed cables.

advantage:

1. Can be infinitely long

2. Fast production cycle and high capacity

3. Very little waste

4. The mold is cheap, and the development is convenient and fast

shortcoming:

1. Can only be made into strips

2. The precision is a little bit difficult, and some shapes are difficult to produce

In summary, the molding and extrusion processes have their own advantages and disadvantages, and the products are different, and the selected process is also different.