In automotive tire manufacturing, rubber is the main raw material used in manufacturing. Rubber which is used for tire manufacturing is both natural and synthetic rubber. From the rubber trees, the natural rubber is found in liquid form from the bark. The liquid latex obtained from the tree bark is then mixed with acids which causes it to solidify to make the raw rubber. So, tire manufacturers require raw rubber and raw rubber is supplied to them in the shape of huge bales which are made from the rubber sheets that have been made after squeezing out the excess water from the above-explained rubber mixture. The second type of rubber is a synthetic rubber which is produced from the polymers found in crude oil. Butadiene is a kind of synthetic rubber polymer. Butadiene is often used in tire manufacturing and its synthetic combination with other materials decides the physical and chemical properties which further determines the performance of each component in the tire. The tire performance is judged by its rolling resistance, wear, and traction qualities. Further, instead of using just latex in the manufacturing industry, some manufacturers choose to use synthetic rubber because synthetic rubber is very durable and strong. Other than the automotive tires, it is often used in sporting goods also. For example, wire and cable insulation use synthetic rubber, but it might have more widespread use if the cost wasn’t greater than that of natural rubber. But various synthetic materials have been explored as of now and currently, synthetic rubber is derived from Isoprene. With the current innovation levels going on, the latest rubber compounds and technology would produce high-quality synthetic rubber from renewable resources that would replace approximately six gallons of crude oil required to produce one passenger car tire. In general, designs may vary by product and manufacturer but every tire has some percentage of natural rubber in it. The rubber is often blended with up to 100 different compounds. Some of these compounds are carbon black, silica, sulfur, and synthetic rubber and the combination of these compounds leads to the different performance characteristics for the tires. On the other hand, tread rubber is often a trade-off between various tire performance properties. By comparison, all-terrain tires that deliver excellent traction cannot be expected to deliver the tread mileage of a touring tire that has been engineered to operate on smooth surfaces.
Butadiene is often used in tire manufacturing and its synthetic combination with other materials decides the physical and chemical properties which further determines the performance of each component in the tire. The tire performance is judged by its rolling resistance, wear, and traction qualities.
What is rubber material compounding:
Compounding is bringing together of all the ingredients needed to mix a batch of rubber compound. Each component of a tire has a different application and may require a variation of ingredients to mix together to ensure the component can best perform its job. Mixing is the process of bringing all the ingredients together by applying mechanical work to blend them into a homogeneous substance. The mixing is done in three or four stages to incorporate the ingredients in the desired state.
How the tire manufacturing is done?
In a tire, the tread and the sidewall are prepared by extruding the uncured rubber compound through an extrusion process. The extrusion process shapes the tire tread or the sidewall profiles, so, the extrusion process is one of the most important operations in the tire manufacturing process. For extruding the rubber compound, a screw-type extruder is used. The extruder assembly is primarily a combination of an extruder barrel and an extruder head. Following the extrusion process, tires are made using a variety of blending, extrusion, calendaring, cutting, assembly, and inspection equipment. Once a compound is extruded, it is then passed through calenders. Calendering is a process that involves squeezing the compound into thin sheets using a calendering machine. An automotive tire is manufactured by a robotized machine called a tire building machine. The tire building machine assembles all sub-assembly parts like tread, sidewall, inner liner, body ply, bead, and cord body together in order to assemble the tires. At this stage, the tires are uncured and are referred to as green tires.
A tire is manufactured on a flat shape drum in a two-stage process. First, the inner liner is wrapped around a drum. Secondly, the first body ply is wrapped on top, followed by the second body ply. Then, the bead assemblies are positioned. Thereafter, the drum has a bladder which is inflated which moves inwardly from both the ends of the drum which forces the plies to cover the bead assemblies. Then from both sections, the sidewall sections are then pressed. Next, another machine is used to apply the belts, nylon cap, and tread material on top of the tire obtained from the first stage process as explained above. The tire still needs curing after the above process.
What is Curing Process?
In order to give the green tire its final shape, curing is done. It is a process where pressure is applied along with heat to the green tire set in the mold. After the mold is closed, the pressure is applied to make the green tire flow into the mold, which makes the tread pattern and sidewall lettering already engraved on the mold, embossed on the green tire. Within the set cycle time, the tire is cured and the mold is opened by releasing the internal pressure. Thereafter, the tire cooling is done by placing it on a PCI, or post-cure inflator that holds and inflates the tire until it fully cools.