The role played by tyres in shaping up a vehicle’s overall behavior is often overlooked by many a customers. After all a tyre is the only medium of interaction between the vehicle and mother earth, meaning several parameters of an automobile’s performance such as ride, handling, grip, stopping distance, fuel economy, etc., are functions of tyres.
We have always wondered what goes into making raw rubber into beautiful black circular things that facilitates motoring. We made a quick trip to TVS Srichakra’s (makers of TVS Tyres, Eurogrip and TVS Eurogrip branded tyres) Madurai plant to find out the answer. Here is a brief outline of the 2 & 3 wheeler tyre specialist’s R&D functions and tyre manufacturing process. Since the business hinges on the patented technologies and highly confidential methods, we were not allowed to photograph the facilities.
So what goes on at TVS Srichakra R&D?
TVS Srichakra conducts most of its research and development in-house at its plant. The R&D facility is responsible for a wide range of functions such as new product development (both current and future), new material development, new compound development, new process development, new technology development, vendor development, improvement projects, regulatory homologation, manufacturing equipment testing, simulation, customer complaint redressal, and knowledge repository and management.
New material development includes a continuous experimental process which investigates suitability of various alternative raw materials for tyre reinforcements (tyre cords, carbon black, steel, etc.), polymers and chemicals used. Compound development is also given prime importance since it’s the compound which dictates the tyre behavior. Process development involves devising an optimum recipe for tyre manufacturing whenever a new compound, material or construction type (for example radial) is introduced. Rapid prototyping, benchmarking, testing and evaluation are the functions which go without saying.
R&D department also actively involves in deciding the specifications of manufacturing equipment, testing them and releasing them for commissioning. The engineers also fix the acceptable quality norms of each and every step of the process which is then ensured by the quality control department. This department randomly collects samples from both raw materials and processed products to check for their compliance with prescribed standards.
The R&D facility houses elaborate testing, machining and simulation equipment details of which are kept confidential for obvious reasons. Apart from in-house facilities, the company also enlist helps from various research organizations world wide and hire test riders from Japan and Europe as consultants cum liaisons to better understand the needs of its OEM customers.
Tyre research and development is a multi-pronged activity which is capital and knowledge intensive. As S. Gopalakrishnan, VP, R&D, humorously puts it, preparing compound for tyre is comparable to preparing dough for roti and then cooking it! So optimum recipe, ingredients and temperature conditions are arrived at after hundreds of trials and repetitions.
How are the tyres manufactured?
Here is a concise step-wise process that is adopted by TVS Srichakra to manufacture cross ply tyres for two and three wheelers.
Arrival of raw material
The process starts with receiving raw materials from the vendors and storing it at a purpose-built warehouse using color coded inventory management system with badge numbers. Hazardous materials and items that require controlled environment are stored in specialized chambers within the warehouse.
Once the quality control team tests random samples of all the raw materials and gives a go ahead, they are readied to be transported to next stage of the process. If defects are detected, the entire batch of the materials are transferred to rejection area from where it is sent back to vendors.
Second step involves preparing the compound as per the specification prescribed by R&D department for the particular product in question. Raw materials required for compound such as rubber, carbon black, chemicals, adhesives and the like are mixed as per computer controlled proportioning system and the mixture is then heated to specified temperature.
The mixture thus obtained undergoes a multistage rolling to achieve homogeneous composition and then stored temporarily before heading towards next stage. Elsewhere at the facility, steel beads which give structural rigidity to side walls and nylon ply fabric which form the inner layer of the tyre are prepared.
Green tyre assembly
The compound is then fed into a roller which puts out a fine roll with specified width which ultimately forms the outer layer of the tyre. The rolls, beads and nylon ply are then assembled by trained personnel with the help of specialized tools and equipment (tyre building drums and machines). This process results in what is called as green tyre (the rubber is still soft). Compound’s ability to deform is important till this stage after which it’s cured (toughened by subjecting it to controlled temperature and pressure in a mould).
Curing inside moulds
The green tyre is now ready to take its final shape as it’s fed into moulds which incorporate the tread pattern, branding, serial number plate and other specifications that can usually be found on the sidewalls. A rubber bladder is inserted inside the green tyre before it goes into the mould. As the pressure and temperature are applied as specified by the R&D department, the green tyre gets cured and adopts its final shape.
Ever wondered what is the purpose of numerous small spikes on brand new tyres that wear out during initial use? They are actually results of entrapped air escaping through pores within the mould! Depending on the type of the tyre, there is a post production process which removes these spikes before shipping.
The hot tyre which comes out of the mould is them mounted on drums and kept inflated for prolonged duration. This process is called as Post Curing Inflation (PCI) which is crucial for the final product to retain its shape permanently.
How is production quality implemented?
Apart from ensuring the quality of raw materials, the quality control department tests random samples of semi-processed materials after each and every step to check things go as per planned. The finished tyre is subjected to mandatory plunger test (a random tyre is selected and force required to pierce it is checked to see if it complies with the standards), endurance tests, inflation tests, bead test (tyre is run at a 35% angle under low pressure to check if it comes out of the rim), balancing test and so on.
- It’s the compound that generate traction, not the treads.
- The basic requirement of the treads is to form a channel or groove to displace water away from the tyre’s foot print (contact patch). The design and trajectory of treads are primarily there for aesthetic reasons.
- Difference between tube and tubeless tyres lies in a special leak proof coating on the inner layer of the tyre.
- Tyres are continuously tested for endurance and driveability with a dedicated fleet of vehicles.
TVS Tyres future plans
TVS Tyres is working on numerous future products and the most significant of them are motorcycle radial tyres. If things go as per planned, the upmarket radial tyres for compact sportsbikes will be launched within this year.