Tyre manufacturers across the world are faced with several challenges including identifying materials that are not fossil fuel based. Michelin, on its part, is working on several new technologies. T Murrali caught up with Dominique Aimon, Vice President – Technical and Scientific Communication, Michelin Group recently to get his perspective on the challenges and Michelin’s solutions. Edited excerpts:
Q: I understand that about 75% of the raw materials to make tyres is fossil-based; what are the initiatives taken by Michelin to reduce dependence on these raw materials?
Aimon: We follow 4 – R’s strategy – Reduce, Reuse, Recycle and Renew – to drastically address the problem of shortage of raw materials in the future and reduce the impact of our activities on the environment. All that anyone does will have impact on 3 elements – depletion of natural resources, impact on human health and bio-diversity, and finally climate change. So the 4 – R strategy is not designed only to reduce the dependency on fossil-based material; it is also designed to make sure that we reduce CO2 emissions and thus also reduce the impact on human health and bio-diversity.
Q: Can you explain adopting this strategy to your products?
Aimon: First of all we look at lighter tyres; reduce the weight of the tyre, therefore the quantity of raw material is less, eventually reducing the dependency. Then we focus on ‘Functional Economy,’ which is equal to what Xerox has made for the copying machine. They realised it was much better to sell a copy than a photo copying machine; by doing that it’s a virtual circle where you try to improve the life of your product because you don’t want to change them since you pay for them yourself.
Q: How have you applied Functional Economy concept at Michelin?
Aimon: Functional economy is to reduce the dependability of the raw material that we are using. An important investment that we have done recently is Euro 400 million in a service company – Sascar, in Brazil, in order to develop this Functional Economy approach. Sascar was providing service for fleets consisting of about 70,000 trucks. The more we use technology in our tyre the more we realise that people don’t care about it. The problem lies in not extracting all the potential, which is essential to contain the dependency on fossil materials. Therefore, it calls for a good service to maintain pressure, wheel alignment etc., which can improve the longevity of the tyre by 15% to 20%. Sometimes it can save up to 7% of fuel per truck, which is a huge saving for a truck company.
Coming to functional economy, it means not selling the product but selling the function that the product is doing. Take for example an aircraft company, which does not have the time to cater to all functions since they have so many problems to address. The tyre plays a role in take-off and landing and when the aircraft is rolling; we offer to take care of the maintenance and setting of the tyres, monitoring performance while what they pay is based on per landing. Literally what they buy is landing. This is functional economy. Not only with Sascar but we have a programme which has been underway for 10 years now giving fleet solutions for trucks in different parts of the world. We manage their tyres; what the opertors buy is kilometre multiplied by tonne that is transported. The function of the tyre is to carry a load over a given distance.
Q: Who benefits the most in this concept?
Aimon: It’s a win-win-win situation for the fleet operator, Michelin and the planet; for the truck company the benefit at the end of the day is that it’s less expensive for them, roughly about 10%, which is a very good saving. Michelin maintains the tyres and so we are able to demonstrate the quality of our product and all the technology that we have put in the tyre. The fleet operators realise this is a better solution and the benefits spread by word-of-mouth. Every time a customer is satisfied it’s good for Michelin.
Q: Does this concept help in validating your new tyres?
Aimon: Yes, of course; people can see the benefits when we introduce new technology. We introduced this concept with earth movers too as most of the large mining companies might not take care of their tyres. As we cannot extract the value we have developed sophisticated technology; but we also realised that there are more technologies to be developed to be more efficient in this Functional Economy model. For instance, we install tracking equipment in the vehicle to analyse the drivers and suggest to the company on the ways and means to improve driving to conserve fuel. By this way we become a part of their initiative. At the end of the day we have a tyre that lasts longer and saves fuel, so less pollution.
Q: How do you reduce rolling resistance when you have no option to improve the road surface?
Aimon: Any tyre to effectively operate needs to develop the contact patch with the road; without proper contact patch there will be no grip eventually preventing the vehicle from stopping, guiding or accelerating. In order to develop this contact patch the tyre is round but the road is flat; therefore it is necessary to have the deformation of the structure – the tread which is round has to become flat in the contact patch. All these deformations will consume energy and the rolling resistance of the tyre is coming from these deformations of a global structure of the tyre, not only the tread. Part of the rolling resistance is coming from the deformation of the small contact of the tyre with the road and the deformation of the structure here but this is only 10% of the rolling resistance; 90% of it is from the deformation of the global structure.
Q: So how do you overcome these challenges?
Aimon: First of all, the shape of the tyre plays a vital role; tyres with biger diameters are better because they have less deformation to overcome. As the road is flat its radius is infinite while the same for a tyre is fixed. The larger radius tyre is closer to the infinite. So the smaller tyres will have more rolling resistance and are not efficient. Therefore, we have some advanced programmes with car makers to develop tyres that will be narrower but larger in diameter. The weight of the tyre will be the same though the shape will be different.
Next, we try to find materials that will absorb less energy. We invented the silica technology in 1992 to address global deformation of the structure of the tyre that operates at varied frequencies. When a vehicle runs at 80 kmph, the tyre does 20 revolutions per second so the deformation is done slowly; however, to establish grip it is necessary to deform the tyre in milliseconds. There was a design conflict between getting the grip and getting the energy efficiency. When we realised that there was small deformation at very high speed, and that rolling resistance was related to deformation at low speed, we were able to design a material which was absorbing plenty of energy for small deformation at high speed and not absorbing energy for wide deformation at low speed. This was done by replacing carbon black with silica and it was a tremendous breakthrough. Designing tyres always has design conflicts; if you ask the consumer whether he wants dry grip or wet grip, he may ask for both.
Q: In the case of off-road and certain special truck tyres there are options such as either cut-resistance or speed, so there will always be a conflict. . .
Aimon: Yes, we faced those issues as well. How can we have a tyre with a good wet grip and reduce rolling resistance? It is by studying in detail and understanding that physical conditions are different that we were able to design one using innovation.
Q: You also have challenges in terms of temperature, cut-resistance and steerability with each feature contradicting others. How do you manage?
Aimon: One of the enemies for truck tyres is heat, which leads to lot of problems. That is why we make tyres lighter so that they produce less heat. This is because the heat is coming from the quantity of rubber that undergoes deformation; lesser the rubber more flexible it is. The flexibility facilitates the deformation of the tyre. This was also the trick with radials. Before radials, the tyre was bias having cross-ply and therefore, the structure of the tyre in the sidewall was exactly the same as the structure of the tyre in the tread. But the function of the sidewall is completely different from that of the tread. However, it is necessary to have a stiff structure for the tread and flexible structure for sidewall to have a nice contact patch with the ground and a good cushioning effect. As the system is more flexible, less energy is lost in deforming and so the rolling resistance is reduced.
Q: Tell us about the initiatives you have taken to reduce the dependency on natural rubber?
Aimon: We will need natural rubber for the future but what we know is that we cannot have the evolution of natural rubber resources in line with the growing demand for mobility. That is why we will need additional possibilities to get the equivalents of natural rubber. Natural rubber is mainly polyisophrene and there are about 15,000 plants in the world that can produce this kind of a molecule. We have looked at many of them and have realised that is not the right way to go. In the long term there is going to be a shortage of natural rubber. That is why we have developed a programme with a biotech company – Amyris Biotechnologies in the US to transfer sugarcane or beet into the isophrene molecule which is polymerised into polyisophrene. Michelin holds the knowhow to transform butadiene to polybutadiene and this will be an additional capacity having an equivalent property of natural rubber. The project is called bio-isophrene and we are in the R&D phase now, then there will be a pilot phase in 3 years followed by industrial demonstration and ramp-up by 2020. What is important to keep in mind is that it is not a substitution for natural rubber, it is only additional capacity. Natural rubber will continue to grow; the problem is it grows in only some areas of the world.
Q: To what percentage will this compensate the natural rubber?
Aimon: On an average natural rubber accounts for 25% of the raw materials to make tyres in general; the trend is that it will be the same for certain products. Natural rubber or polyisophrene is very useful to make tyres for trucks and earth movers and it will continue to be so. Polyisophrene is only used in some parts of the tyres for passenger cars. Polybutadiene, the other elastomer used in tyres, cannot be used for the treads of truck tyres. Polybutadiene in a passenger car tyre is about 30% by weight, polyisophrene is about 10-15% and the rest is made up of nearly 200 components including steel, oil, and sulphur. However, truck tyres are made mainly of natural rubber. The need for natural rubber is higher for tyres that operate at higher pressures. For passenger car tyres that operate at lower pressures it is better to use polybutadiene.
Q: As and when you reduce the dependency on natural rubber in passenger cars you are depending on the raw material based on fossil-fuel; how can you be eco-friendly?
Aimon: Except that for butadiene we have a new programme called ‘Bio-Butterfly’ to produce butadiene from alcohol eventually to reduce the dependency on fossil material, to make tyres for passenger cars. The good news is that alcohol can be produced from any kind of biomass. We also have a recycling programme, ‘TREC-Alcohol,’ which can transform the old tyres into alcohol which can be transformed into butadiene and then polybutadiene for recycling.
Q: So the larger consumption of fossil-fuel is taken care of by this methodology?
Aimon: Yes, by the fact that we’ll find another alternative to cope with the shortage of additional capacity for equivalent of natural rubber; to use alcohol, derived from bio-mass or old tyres, to produce synthetic rubber – goes into the circular economy.
Q: Is Michelin working on new technologies like tyre pressure monitoring systems etc?
Aimon: Of course we are, and the driver for that is the Functional Economy. That is why we have introduced technologies like MEMS – Michelin Earthmover Management System for the mining industry. By putting some electronics on the tyre we can track instantaneously what is the level of temperature of the tyre in the mine. Temperature is the enemy, so we can tell the operators when to reduce speed, to control the temperature. We are working on these technologies to track the conditions in which the tyre operates.
Q: When you alert the driver to reduce speed, will it not take a beating on his cost of ownership? How do you tackle this?
Aimon: We demonstrate to people that they lose less time if they cool the tyre because changing the tyre on this sort of equipment consumes a lot of time. So it’s an optimisation of all parameters; the operating company is confused in the beginning but when they see the figures they are convinced.
Q: So do you constantly work with the wheel and steering system manufacturers?
Aimon: Here it is more of the global service that we provide to car manufacturers. The strength of Michelin is that we work with all the car companies, which gives us an overview of all the strengths and weaknesses of all the suspension systems that they don’t have; we practise on all kinds of suspensions. That’s why car makers come to us for help in handling the vehicle. The level of expertise we have built up by working with all car makers allows us to give them good advice on specific problems.
Q: Tyre manufacturers are also working on reducing the tyre noise – what are the components that contribute to this and how do you address them?
Aimon: There are two kinds of noise – the one that is outside the vehicle, which has an impact on pollution; and the one inside the vehicle, which is the comfort zone. The noise changes with the change in the type of road surface. Considering environmental issues many countries are bringing in regulations and Europe is pushing hard on that. Over the last 10-15 years we have halved the noise that the tyres make. We have been able to achieve this by working on the tread pattern shape; the rubber in different tyres may not have the same lengths and this is becoming more and more complicated. We have developed several software to manage the external noise. In the case of internal noise it is more of working with the car makers to try to make sure there is no resonance for some vibration frequency in any part of their vehicle with those of the tyres. It is all about optimisation.
Q: When you define the tread pattern, it also plays a role in aesthetics. You are challenged with three issues – one to reduce noise, second to enhance aesthetics and third to have good grip. How do you manage?
Aimon: Yes, as I told you designing tyres is solving design conflicts; the conflict between energy, efficiency, dry grip and wet grip. For dry grip, the best one is the slick tyre used by racers. However, this may not suit during rains. So this is the type of design conflicts we have to solve. The evolution that you see over the last 15 years is the sophistication of the tread. There are sipes in the tread pattern to cut the film of water and improve the wet grip. The problem is when you do that the block is more flexible and when dry it’s not good. In order to solve this issue we have invented the 3D tread pattern that interlocks with each other. By having 3D sipes the rigidity of the block is assured. This helps reduce the quantity of energy needed to make the deformation in the tyre. We have 6,600 people doing R&D for Michelin around the world.
Q: Does India contribute to your research?
Aimon: We don’t have a research centre in India but we do have people coming from abroad to study the condition of roads in India, to look at the tyres and see what has to be done.
