Tire manufacture requires kneading, or mixing, of the rubber combined with other ingredients. This operation is performed on a Banbury mills.
The next process is through a variety of mills, in which the rubber is again passed through opposing rolls and heated by friction. These rolls use hot water or low pressure steam to elevate the temperature of the rubber.
The rubber is then diverted either to a tread tuber or sheeting mill. Tubers use unions on extruder screws. Unions are also required on the rolls of sizing mill or sheeter.
After the sheeter the rubber is processed through calendaring rolls which use unions for heating the rubber until it becomes workable. Calenders use various size unions.
In addition to the rubber, many tire plants make cord of polyester, glass fiber or steel. Water and steam unions are used on the equipment which manufacture these components.