Tyres are considered one of the most important components of an automobile, yet they are assumed to be one of the simplest too. While tyre manufacturing and technology may not appear too complicated, modern day tyres have evolved into a complex blend of synthetics and natural rubber-based compounds. Auto Tech Review was invited by one of the country’s leading tyre manufacturers – TVS Srichakra – to understand the nitty-gritty of tyre manufacturing and testing at its Madurai facility in Tamil Nadu.
Incorporated in 1982, TVS Srichakra Ltd operates manufacturing facilities in Madurai in Tamil Nadu and Pantnagar in Uttarakhand. The combined monthly production of these two facilities stands at 2.5 mn units and the company enjoys a robust supply relationship with various two-wheeler OEMs like Bajaj Auto, Hero MotoCorp, Honda Motorcycle & Scooter India, Suzuki Motorcycles India, TVS Motors and India Yamaha Motor, among others, as well as the aftermarket. The company markets its products under the ‘TVS Tyres’ and ‘Eurogrip’ brands. TVS Tyres’ Madurai facility is also home to an R&D centre that is recognised by the DST, Government of India as well as the test track, where we got an opportunity to test and sample a variety of products.
For the engineers and scientists at TVS Tyres, OEMs are the first acid test for proving the tyres they produce. Secondly, it is the customers who use the tyres. OEMs need to homologate tyres to the particular vehicles they produce – thus, tyre compounds, construction and mixtures are designed to suit their models. The TVS Tyres ideology is to closely observe the technology code comprising basic research, science, engineering and technology that is further categorised into platform development, which is the core of construction, material sciences and engineering of the tyres.
While closely examining material development, there are various exotic materials that go into the construction of a tyre. There are polymers within which are natural rubbers and synthetic rubbers. There are multiple rubbers in synthetics like styrene-butadiene, polybutadiene and functionalised polymers, which are reactive components. The application of these specific polymers and the compounds created are evaluated in a virtual environment much before the testing phase.
Science today has evolved to the extent that the company is able to predict the performance of a tyre by just modelling a simulation with respect to grip, durability, stress, surface pressure, wear and tear, among others. The methodology in reference is known as Finite Element Analysis (FEA) and TVS Tyres has exhibited strong research capabilities in this area. All products rolled out by the company first go through this simulation and testing phase and once validated, they are sent for sample production. This methodology has enabled TVS Tyres to streamline its manufacturing process and enhance its flexibility to customise tyres to OEM requirements with minimal margin for error in the trial and testing phase. The company also has a rapid prototyping technology that can create a 3D model of the tyre, which can be showcased to OEM customers. This has also facilitated a quicker turnaround time for design modifications in tyre patterns.
But not all testing is done by computers in a virtual environment. The company also has a high focus on real-world testing in actual road conditions. TVS Tyres has been working with experts at a local and global level from Japan, US and Europe to develop newer testing methods that closely simulate real-life conditions and meet customer requirements. The company also has an unflinching focus on process development, engineering, manufacturing and R&D departments, with focus on process technologies and the next level of automation with respect to manufacturing processes. While the company’s R&D department is running at 70 % automation, the quality assurance side functions at around 85 % automation. The company has so far injected substantial investments in its R&D capabilities and plans to invest in new force and stiffness testing equipment in 2019.
TYRE INNOVATION & TESTING
TVS Tyres has been consistently undertaking efforts to maximise riding safety for two-wheelers. The objective has been to give the rider confidence, when they are in a corner or when riding at speeds in excess of 70 km/h. Most technologies today are derived from passenger cars. Tyre makers catering to the four-wheeler market follow the magic triangle principle, which focusses on maximising wet grip, mileage and rolling resistance.
For two-wheelers, there are challenges – the surface is rounder, thus groove stresses are higher due to tyre surface flattening on contact. When it comes to the application of silica, the restraint is on the elongation ability of the material as it has limited flexibility. TVS Tyres has created a hybrid technology, using fundamentally functionalised polymers, which contain free radicals that react with silica and have the ability to react with carbon black. The result is not a full silica technology but a partial one that helps maximise the wet grip and rolling resistance performance of tyres. This has resulted in an improvement in stoppage distance on wet surfaces, bringing the stopping distance down from 60 m to 45 m. The company has also improved rolling resistance performance.
A research conducted by TVS Tyres’ R&D team revealed that this combination of compound gives the tyre lower rolling resistance, superior grip and ensures the tyres do not generate cracks in the long run, even after 40,000-50,000 km. It is interesting to note how the R&D team has managed to interact with the functional side of the polymer to provide the right combination. Named as the tangent delta, this phenomenon is the measurement of dynamic mechanical properties of the tyre. The equipment measures the strain versus the loss models. When a certain amount of strain is applied, corresponding properties are measured to derive the delta shift. At different temperatures, the tangent delta has significance. At 0° C, it indicates how good the compound is in reference to wet grip. The same tangent delta at 60° C renders the rolling resistance quality of the tyre. At 30° C, it indicates the grip properties of the tyre. Judging by the characteristics of the compound, the engineers in the R&D wing at TVS Tyres can predict the fuel efficiency and braking distance of the tyre.
We were able to sample the company’s Eurogrip and TVS Tyres brands at its test track in Madurai. The tyres were fitted on commuter segment motorcycles and scooters like the Honda CB Shine, Bajaj Platina and Honda Activa. We also got to sample the Protorq series fitted on a KTM Duke 390 and Bajaj Pulsar 200.
Braking performance and grip rendered by the tyres surpassed our expectations and the overall confidence they offer to the rider is commendable. It is interesting to note that the low rolling resistance is also due to lower frictional values, yet the grip these tyres provides exude a superior feel in contrast to competition. TVS Tyres has invested heavily on technology and research to ensure that the tyres they supply across their 3,000 strong dealer network are of top quality and with an inclination to application of Industry 4.0 in the future, the company is set to remain in the vanguard of tyre technology in the country.
Text: Joshua David Luther