Continuing our informative series, here is a good overview on motorcycle tyre making in five steps…
Motorcycle tyres are very important aspects of any motorcycle. Good quality tyres ensure rider safety and that he can enjoy his motorcycle to the maximum. Today, let us give you a fairly detailed overview about the sophisticated tyre-making process.
The process starts at the engineering labs, where designers develop new compounds, materials and tread patterns. After many hours of testing, new prototypes of compounds go to production (if they meet standards of course).
Tyre production is separated in 5 stages: Raw materials, extrusion, assembly, curing, and inspection (quality control). Every step of tyre production is tracked by professionals and latest computers. This ensures that the all products meet quality standards.
Tyre Making – Step 1
Mixing raw materials into usable compounds.
For example, well known tyre factory – Bridgestone, sources natural and synthetic rubber for its compounds. Natural rubber is “milky white latex” that comes from special rubber trees grown in Thailand. Natural components usually produce strong smell at the production plant, because rubber is natural fat and it starting decaying when mixing process begins. On the other hand, synthetic rubber based on petroleum, doesn’t have any significant acrid smell. Each rubber type has its own advantages for the various parts of motorcycle tyre.
Large pieces of natural and synthetic rubber start moving on a conveyor, while workers monitor the process. They also remove smaller chunks, which are unfit for tyres. Also rubber-processing equipment isn’t the only one, there are fabric-cutting units where different raw fabrics (polyester, Kevlar, nylon, Aramid, etc.) are similarly prepared.
These cuttings are joined together and are known as tyre plies. In addition, special secret materials are added to enhance tyre performance. Here are some of them…
- Carbon black is used for increasing durability and coloring.
- Sulfur is used for tyre hardening.
- Silica is another crucial component; it increases the wet grip.
Apart from this dozens of other unknown chemicals are used to fine-tune the properties of the compound.
All these materials are mixed in a giant vat under heat and solid pressure; process is closely monitored, and pressure is regulated. After this process rubber compounds look like long flat sheets.
Tyre Making – Step 2
In this process warm rubber sheets are pushed through special machines, which forms long strips of rubber. Extrusions vary depending on the tyre components being made (including carcass and sidewall layers).
After that steel cords are inserted in tyre carcass, they make up the tyre bead. Fabric and steel-belt plies, which were mentioned earlier, are created, and all tyre components are prepared for the final assembly.
Tyre Making – Step 3
Firstly, carcass assembly takes place on a large drum. Previously made carcass layer is rolled out, carefully measured and cut. Once the internal layers are formed, exterior tread layer is added.
This process is almost fully automated, however, there is still moderate level of human interaction during the assembly. The exterior tread layer is cut and molded by a machine operator. Once exterior layer is added, tyre is removed from the drum.
The result is a warm, elastic form known as a “green tyre.”
Tyre Making – Step 4
After the assembly, green tyres are moved over to curing chambers. The curing phase consists of three key elements – heat, pressure and time. In the mold chambers tyre tread pattern is applied to green tyres, they are pushed into the mold, and the tread pattern begins to get imprinted.
Temperature is raised to 170 degree Celsius (can be different for various type of tyres, up to 190 C), and chemical reactions begin to strengthen the tyre. Most bike tyres take about 15 odd minutes, but tyres for large trucks and heavy machinery may take up to 40 minutes.
Biggest tyres (made for world’s largest trucks like Liebherr T 282B) require one full day of “cooking” in the curing chambers. This process is completely automated.
After molding, tyres are cooled down. Small knobs, called spew, appear on the exterior of the tyre. They are created by purpose – allowing steam and air to escape. Before final inspection, most of the spew get removed.
Tyre Making – Step 5
Tyres are checked at every step of the creation process, but the most important is the last quality check. For final check each tyre is manually checked by professionals. They verify the shape, deformation or any other defects.
Also each tyre is checked by laser rays, to see if it is properly constructed. And finally, after that the tyre is tested on specifically designed road simulator that spins the tyre at various speeds. Usually less than 0.11% tyres do not pass these tests. Other 99.89% units are stored in large racks, waiting for worldwide distribution.
If you want to know further about the Tyre speed ratings, maintenance, etc, click on the following link..
Images: www.motorcycle-usa.com and www.motorcyclistonline.com