Mixing

The constituents are weighed out and combined by a mixing process which must blend the ingredients thoroughly in a repeatable way. This is achieved either by an internal mixer, where the compound is mixed by two meshing rotors in an enclosed case; or by open mill mixing, adding the ingredients carefully into the “nip” between two steel rollers, typically of 30″ diameter.

The result of either process is a batch of uncured rubber compound. This is allowed to settle for a time before undergoing Quality Assurance tests. Once passed, it can be formed into suitable shapes for moulding.