Tires – Visit of the Dunlop two-wheeler factory in Montluçon – The manufacturing of a Dunlop motorcycle tire in pictures

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Visit of Dunlop’s two-wheeler factory in Montluçon

Tires - Visit of the Dunlop two-wheeler factory in Montluçon - The manufacturing of a Dunlop motorcycle tire in pictures

Where can you find a motorcycle and scooter tire manufacturer in France? In Clermont-Ferrand, at Michelin? No: in Montluçon, at Dunlop! Site visited the French tire manufacturer belonging to the Goodyear group: follow the guide !

The making of a Dunlop motorcycle tire in pictures

The manufacturing process begins with the "mixing" of the different components (natural and synthetic rubbers, silica, carbon black, sulfur, oil, baking agents, etc.). These are three huge – and loud! – "mixers" 60 meters long powered by 2000 hp engines which take on this task, sometimes several days long. Several screens indicate to the operators the values ​​to be monitored (temperature, quantity, etc.) and the productivity. The losses, quantified in kilograms of mixture lost and in euros, are also clearly displayed: we are in Auvergne !

Since a reorganization decided in the early 2000s (just after the takeover of Dunlop by Goodyear in 1999), the plant has specialized, among other things, in the mixing activity: 65% of the 400 tonnes daily that the Montluçon site is capable of supplying (250 tonnes per day on average currently) are used to supply all the group’s factories.

In the form of 200 kg plates, the “mix strips” are then sent to the “Extrusion” part of the plant. The result is a strip 0.9 to 1 cm thick which can be wound in the form of reels 90 meters long – the equivalent of 45 tires – or packaged in the form of a cartridge. Here, the industrial tool seems more sophisticated and computer assistance more important: two checks by weighing followed by a laser check are automatically carried out on the belt.

Then come the phases of preparation and making, where all the elements are gathered. Two people are responsible in particular for making the steel beads that are found in each bead of the tire (the lower end which is blocked inside the rim). It is this assembly of steel wires that gives – and maintains – the round shape of the tire. A little further on, the belt is made either from aramid cables coated with rubber, or from steel wires. At Dunlop, we use the so-called JointLess Belt (JLB), which consists of making this reinforcement in one go to avoid overlapping of the layers. With the key "weight gain and better dynamic responses", assures the manufacturer.

On its most sophisticated motorcycle tires, which use several types of rubber such as the, Dunlop has been using its own technology since the beginning of the year. JointLess Tread (JLT) to make the tread. Here again, as for the JLB, the key concept lies in the continuous winding of the components in order to ensure the homogeneity of the surface in contact with the ground. Very proud of this "in-house process", the tire manufacturer has invested a whopping 6 million euros in the development of his JLT machine, ie a third of the total investments attributed to Montluçon over the past three years. Hence a certain reluctance to let us examine this machine in detail, a good part of which was camouflaged during our visit. !

One of the 640 employees of the factory – there were 5,700 in 1971! – at work. During our visit, an information screen indicated that 480 of these employees had an attendance rate of 100% since the start of the year, which made them eligible for an endowment of four Dunlop / Goodyear tires of their choice! "It works very well, it allows our employees to identify and get involved", the managers of Montluçon tell us about this method launched to improve productivity.

After the preparation stage, the product – called "green tire" – is practically finished: basically, it only remains to cook it! This firing will allow it to go from plastic to elastic state via vulcanization. The tire is introduced into a press, where a mold will give it its final shape and form its sculptures, as well as all the inscriptions on its sidewalls. The operation takes between 10 and 20 minutes at a temperature of around 180 ° C. The cooling then takes place at room temperature. According to the head of this workshop, the curing time and temperature have a huge influence on the dynamic capacities of the tire, in particular its grip..

As soon as it comes out of the press, the tire is immediately analyzed by an operator who checks in particular the correct order of the inscriptions. It is then transferred to the "verification / inspection" service where three people take care of examining it more closely (as with the light truck tire in the photo above). The correct balancing of the tire is thus precisely checked: static on 100% of the products, dynamically on all 17-inch tires – the dimension most commonly used in motorcycles. The technician finally examines the interior "to the touch" before validating. According to Dunlop, only 3% of tires would be declared non-compliant after this battery of tests and would be scrapped. The rest is now ready to be sent to points of sale … and to put on your motorcycle or scooter !

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