Brief Introduction about Pneumatic Tire Construction

Authors Bio:
Hi, I am Pradeep Sharma. I have completed my Mechanical Engineering from University of Pune, Maharashtra(India). Currently, I am working with Mahindra & Mahindra Company at Nasik.

Introduction:

Pneumatic tires are manufactured according to relatively standardized processes and machinery. Annually, over 1 billion tires are manufactured in around 450 tires factories in the world. Tire factories start with bulk raw materials such as rubber ,carbon black and chemicals and produce numerous specialized components that are assembled and curred.

Construction of Tire:

The tire is an assembly of numerous components that are built up on a drum and then cured in a press under heat and pressure. Heat facilitates a polymerization reaction that cross-link rubber monomers to create long elastic molecules, which permits the tyre to be compressed in the area were tyre  contact the road surface and spring back to its original shape under high frequency cycles.

Components used in tire assembly:

1. Inner Liner:

The inner liner is an extruded rubber sheet compounded with that result in low air permeability. The inner liner assures that the tire will hold high pressure air inside, without diffusing air gradually through the rubber structure.

2. Body ply:

The body ply is a calendered sheet consisting of one layer of rubber, one layer of reinforcing fabric and second layer of rubber, earliest textile used was cotton and later materials include rayon, nylon, polyster.Passenger tires typically have one or two body plies, it give strength to tire structure .Truck tires, off-road tires, and aircraft tires have progressively more plies.

3.    side wall:

Sidewalls are non-reinforced extruded profiles with additives to give the sides of the tire  good abrasion and environmental resistance. Additives used include antioxidants and antiozonants.Sidewall extrusions are nonsymmetrical provide a thick rubber area.

4. Bead:

Beads are bands of high tensile-strength steel wire encased in a rubber compound. It is coated with special alloys of bronze or brass. Coating protect the steel from corrosion. Beads inflexible and inelastic ,and provide the mechanical  strength to fit the tire to the wheel. Bead rubber includes additives to maximize strength and toughness.

5. Apex:

The apex is a triangular extruded profile that mates against the bead.

6. Belt package:

Belt are calendered sheet consisting of a layer of rubber , a layer of closely- spaced steel cords, and a second layer of rubber. The steel cords are oriented radially in radial tire construction, and at opposing angles in bias tire construction. Belts give the tire strength. Passenger tires are usually made with two or three belts.

7. Tread:

Tread is a thick extruded profile that surrounds the tire carcass. Tread compound include additives to impart wear resistance and traction in addition to environmental resistance.

8. Side wall carcass:

This part of the tire serves as the load bearing framwork that forms the tire’s body shape.The carcass are made of rubber coated fabric as well as steel cords that are placed in radial direction.It contains the inflation pressure that helps out to support the load and the overall absorbing of impact.

9. Inner liner:

The inner liner is the area of tire that is made of special rubber that attaches to the carcass.It is designed to withstand a high resistance to air migration.

Materials used in Tire Manufacturing:

• Natural rubber is the basic elastomer used in tire making.
• Styrene-butadiene co-polymer is a synthetic rubber which is often substituted in part for natural rubber based on the comparative raw materials cost.
• Polybutadiene is used in combination with other rubbers because of its low heat-buildup properties.
• Halo-butyl rubber is used for the tubeless inner liner compound, because of its low air permeability. The halogen atoms provide a bond with the carcass compounds.
• Carbon black, forms a high percentage  of  the rubber compound. This gives reinforcement and abrasion resistance.
• Silica, with carbon black is used in high performance tires, as a low heat build up reinforcement.
• Antioxidant and antiozonants prevent  sidewall cracking due to the action of sunlight and ozone.
• Textile fabric reinforces the carcass of the tire.