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Radial Tire Production Radial tire manufacturing starts with many kinds of raw materials -- pigments, chemicals, some 30 different kinds of rubber, tire cord fabrics, bead wire, etc. The production process begins with the mixing of basic kinds of rubber with process oils, carbon black, pigments, antioxidants, accelerators and other additives, each of which contributes certain properties to what is called a compound. These ingredients are mixed in giant blenders called Banburies. They blend the many ingredients together, producing a black, gum-like material that will be milled again later for use in a tire. The rubber material can take several forms. Most often it is processed into carefully identified slabs that will be trucked to breakdown mills located in tire building areas of a manufacturing plant. These mills feed the rubber between massive pairs of rollers, over and over, mixing and blending the material to prepare the different compounds for the feed mills, where they are slit into strips and carried by conveyor belts to become sidewalls, treads, or other parts of the tire. Still another kind of rubber coats the fabric that will be used to make up the tire's body. The fabrics come in huge rolls, and they are as specialized and critical as the rubber blends. Several kinds of fabrics are used: polyester, rayon or nylon. Most of today’s passenger tires have polyester cord bodies. Another key component is the tire’s bead. Shaped like a hoop, the bead’s backbone is formed from high-tensile steel wire, which will fit against the car's wheel rim. The strands are aligned into a ribbon and coated with rubber for adhesion, then wound into loops that are wrapped together to secure them until they are assembled with the rest of the tire. Radial tires are built on a round drum or cylinder that is part of a tire-building machine. The tire-building machine pre-shapes radial tires into a form very close to their final dimension to make sure the many components are in the proper position before the tire goes into a mold to be cured or vulcanized. When building a tire, the tire builder starts with a double layer of synthetic gum rubber called an innerliner. The innerliner makes it possible to seal air in a tire and eliminates the need for an inner tube that once came inside each tire. Next come two layers of ply fabric, which are sometimes referred to as the cords. Two strips called apexes stiffen the area just above the bead. Next, a pair of chafer strips are added. They are called chafer strips because they resist chafing from the wheel rim when mounted on a car. Now the tire builder adds the steel belts that resist punctures and hold the tread firmly against the road. The tread is the last part to go on the tire. After automatic rollers press all the parts firmly together, the radial tire, now called a green tire, is ready for inspection and curing. The curing press is where tires get their final shape and tread pattern. Hot molds like giant waffle irons shape and vulcanize the tire. The molds are engraved with the tread pattern, the sidewall markings of the manufacturer and those required by law. Each press cures two tires at a time; they operate around the clock, twenty-four hours a day. Passenger tires are cured at over 300 degrees for 12 to 25 minutes, sometimes much longer as in the case of large earthmover tires. As the press swings open, the tires are popped from their molds onto a long conveyor that carries them to final finish and inspection. Inspection is both visual and internal. Some tires are pulled from the production line and X-rayed. Additionally, quality control engineers regularly cut apart randomly chosen tires and study every detail of their construction that affects performance, ride or safety. This is how all the parts come together: the tread and sidewall, supported by the body, and held to the wheel by the rubber-coated steel bead. But whatever the details, the basics are fundamentally the same: steel, fabric, rubber, and lots of work and care, design and engineering. Tire Ingrediants
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