Introduction to rubber processing and safety issues - HSE

Tyre building terminology
Each tyre factory may use different terminology to describe the various components of the tyre and tyre-building
machine but the following are the most common.
Tyre components
Inner liner - the initial band of rubber strip which eventually forms the airtight inner impermeable surface of the tyre; in
conjunction with the wheel rim. The inner liner acts like an envelope and retains the air pressure required to support
the load.
Plies - these are strips of rubber reinforced with fine steel wires or synthetic (usually polyester, nylon or rayon) fibres,
known as cords. Their main purpose is to provide the strength in the tyre. In cross ply tyres the ply cords run
diagonally, or on a bias, across the tyre (from bead to bead) with the cord angle reversed on each layer of ply. In
radial tyres the ply cords runs straight across the tyre. Car tyres tend to use fabric plies to provide the required
flexibility, whereas in commercial tyres steel plies are more commonly used.
Details of rubber coated steel cord cut and jointed, also showing brass coated steel wires
Beads - these are brass plated, high tensile steel wire rings, coated in rubber, which form the inner edge of the
finished tyre; the beads anchor the tyre to the wheel rim.
Bead wire making machine
Chafers (or apex strips) - these are strips of rubber laid over the bead to cushion and protect it in service when it will
be in contact with the rim of the wheel.
Side walls - these are rubber strips placed over the chafers to form the side walls of the tyre.
Breakers (or belt plies) - these are reinforced rubber strips, placed between the top plies and the tyre tread.
Tread - this is an unreinforced rubber strip, which will be given the characteristic tread pattern during moulding. The
rubber is compounded to provided traction, skid and cut resistance, and long wear. In car and truck tyre production,