Tire manufacturing

Soil protection, fuel savings and long tire life– pushing this performance to the maximum for one tire is an extreme challenge! MICHELIN pulls off this feat every day thanks to innovation and a continuous search for high performance, as well as the quality of its manufacturing processes.

To satisfy Michelin quality requirements, the various manufacturing stages follow a rigorous, methodical process combined with continuous quality control at all stages of rollout. 

• The preparation of semi-finished tires
• Assembly
• Curing of the tire
• Final verification

A tire is of infinite complexity due to its composition and the technology applied.

Natural and synthetic rubber, carbon black, metal cables, textile fibers and chemicals are some of the component elements of a tire.

The first stage consists of preparing these elements of the semi-finished product to form the tire components, which are the rubber, textile and metal plies and the beads.

Confection

MICHELIN agricultural tires are manufactured by professionals based on a complex, rigorous process. The assembly of the intermediary (semi-finished) products is split into two phases: confection and finishing.

Confection consists of successively laying the various semi-finished product elements onto a drum the same diameter as the tire, as shown in the diagram opposite.

Illustration

1- Laying of the interior rubber

2- Laying of the casing ply

3- Laying of the bead fillings

4- Turning up of bead fillings onto beads

5- Presentation of the bead

6- Laying of the foot rubber

7- Pose of the protectives

8- Pose of the flanks

Finishing

1. Finishing then enables the casing to be given the shape of the future tire. This is conformed to the tire template by inflating the drum and bringing the two beads together simultaneously. The crown textile or metal crown plies that will form the tire locking ring are then fitted. The tread is added and completes the assembly. At this stage, the future product is called an uncured tire. The product tack ensures its cohesion.

Illustration

1- Start of conformation

2- End of conformation

3- Laying of the first crown ply

4- Laying of the second crown ply

5- Laying of the tread

6- Removal of the uncured tire

The tire materials change from a plastic to an elastic state by means of the curing process. This phenomenon, called vulcanization, creates the composite structure between the various elements of the casing. Tires are vulcanized in special presses, using the combined action of heat and pressure.

The pressure compresses the tire from the inside and applies it against the mold walls to ensure it takes on the shape and tread patterns.

See the illustration

1- Laying of the uncured tire in the curing mold

2- Closure of the mold

3- Pressurizing (cold molding)

4- Steam curing

5- Removal from mold: the mold opens like the petals of a flower

From receipt of the raw materials to the time tires leave the plant, every stage is rigorously controlled.

Monitoring and control systems ensure the conformity of the manufacturing processes to Michelin quality requirements.

After curing and before shipment, agricultural tires undergo one last verification. The verifications made are of several kinds: visual, ultrasound, uniformity and architecture.