How to build a radial tire.
Tires are not just round and black they are sophisticated products
that can take years of research and development to produce. If you have
ever wondered how tires are made, the following is a roadmap for the
construction of a radial tire:
Start with Rubber and Additives
Tire construction starts when raw chemical additives such as sulfur,
carbon black and solvents are combined with natural and synthetic
rubber. The process takes place in a large machine called a banbury.
In addition to mixing and grinding, the banbury heats the rubber to
make it workable in preparation for further applications. The raw
product emerges in the form of long, flat bands of rubber, which are
then worked in rolling mills.
Six Main Components
It takes several machines to shape the rubber into the individual
components of the tire: tread, ply, belts, beads, sidewalls, and
inner-liner.
- The tread rubber is extruded through a tuber, then measured,
cooled and cut into precise lengths.
- Sidewalls are also extruded through tubers, along with the white
rubber for a white sidewall or white lettered tire if required.
- The ply is produced in a calender mill, which combines thin sheets
of rubber with nylon or polyester cord fabrics. The large sheets are
cut to width, rolled and transported to the assembly area where all
the components will come together.
- At the same time as the raw rubber is transformed into the tread
and plies, the creel room equips the tire with its basic strength.
Fine steel wire goes into the manufacture of belts for the
steel-belted radial tire. Rubber from the mills and steel from the
creel room are molded together into wide flat sheets, cut on the bias,
rolled, and moved to the tire-building machine.
- The innerliner is a impermeable layer of rubber on the inside of a
tire which creates a airtight chamber when fitted to the vehicle
wheel. This layer eliminates the need for a innertube.
- The last major component of the tire is the bead. The beads are
created out of wrapped steel wire, covered with rubber and formed into
hoops. The bead anchors the fabric plies of the tire and seats the
tire firmly on the wheel.
The Green Tire
The six components (tread, ply, belts, sidewalls, liner and beads)
come together on the tire-building machine. These six components are
assembled into what is known as an uncured, or green, tire in two
stages.
- The carcass of the tire, including beads, plies, sidewalls and
liner, is constructed on one side of the machine.
- The tread and the underlying belts are assembled next to the
carcass on the other side of the machine.
The two subassemblies are then joined together and the result is a
green tire.
Vulcanization
The next phase is vulcanization, the molecular transformation of the
soft, gummy green tire into the tough, and longwearing, modern passenger
tire. The green tire is placed in a curing mold and is subjected to
intense pressure and high heat internally and externally for a specified
period of time. Simultaneously, the tread pattern is imprinted onto the
rubber. When it comes from the mold, the tire is ready for final finish
and inspection.
Final Finish and Inspection
For showroom quality, any excess rubber is trimmed off the cured
tire. Every tire is thoroughly inspected. The tire then undergoes
various uniformity checks to assess ride and comfort quality. Once the
tires have passed all the checks and inspections, they are sent to the
distribution warehouse for shipment.
