THE FIRST STEP IN BRINGING THESE MATERIALS TOGETHER TO FORM A TYRE
First of all the rubber compound must be prepared for use on different tyre specification and for the different tyre components. All of the materials (natural/synthetic rubber, carbon black, sulphur and other chemical agents) are mixed together and pressed to form rubber sheets. This is done in a mill, which is commonly called a ‘Banbury mixer’, after the name of its inventor. The rubber sheets are then cooled and loaded into pallets delivered to the manufacturing process of the different tyre components.
Types of processes to shape Rubber sheet to form different components
There are two different processes to shape the rubber into the individual components of the tyre :
Calendering for the inner liner, body ply and belts, and extrusion for the tread, bead, fillers, and sidewalls.
Calendering means “pressing the rubber compounds between large rollers”. The calender is machine equipped with three or more steel rollers which revolve in opposite directions, forcing the rubber compound to adhere to the cords.
Extrusion means “forcing the rubber compound through a die”. The die is metal mould in the shape of the tyre component to be manufactured. This distributes the rubber volume into the appropriate final shape and dimensions.