It’s time the Indian tyre makers put more emphasis on green tyre research and development as green tyres are made of indigenously available renewable resources such as natural rubber, natural fibres, vegetable oil etc., says Dr. P. Thavamani, Director, Indian Rubber Manufacturers Research Association (IRMRA), in an interview to Rubber Asia. Excerpts:
What is the major tyre testing expertise evolved since the founding of IRMRA in 1959?
IRMRA completed more than 52 years of its service to rubber and allied industries and celebrated its Golden Jubilee in 2008-09. Established with an objective of fulfilling the scientific and technological requirements of rubber industries, IRMRA has been enriching its capabilities and capacities in the field of testing and analysis of raw materials, compound development and human resource development by way of imparting training and conducting workshops.
Although IRMRA is working closely with rubber companies, mainly small and medium enterprises, it is also engaged in research in tyre material development and process development. IRMRA has developed for the first time in India an electron beam-cured tyre.
IRMRA received fund under the 11th Five Year Plan to set up a Centre of Excellence for tyre research, testing and certification. This centre is equipped with state-of-the-art testing equipment such as: Endurance testing for passenger car and two/three-wheeler tyres, endurance testing for light and heavy truck/bus tyres, rolling resistance, UTM for plunger test, bead unseating, steering response, tyre stiffness, foot print image, tyre burst testing, tensile testing machine with video extensiometer, facilities for cut tyre and failure analysis, Abacus software for tyre modelling, tyre NVH analysis The tyre centre is being augmented with facilities such as: Shearograhpy, SEM with EDS, XRD, tyre profile testing. These facilities are required for materials testing, nano composite development and the tyre failure analysis.
What are the recent technological changes in tyre testing and development of important standards that are worthy of implementation by tyre manufacturers?
Major technological changes have taken place in tyre design from conventional bias or diagonal ply to steel-belted radial tyres, tubeless tyres, tyres with low aspect ratio, puncture-resistant tyres, flat tyres etc. and the testing standards also have evolved accordingly to ensure the performance, mileage, safety, reliability and longevity of tyres.
New tests like plunger test, rolling resistance test, chipping and chunking resistance test, steering response, tyre stiffness, foot print analysis, acoustic test etc, have been introduced in evaluating the performance of tyres. Although most of the national and international standards call for the testing of basic performance characteristics of tyres, the OEM specifications are much demanding with respect to quality, reliability and safety. Hence, the tyre manufacturers need to follow and meet the OEM specifications while validating their tyres rather than just go by requirement of standards.
What kind of technical benchmark is used while testing tyres? Are the present BIS specifications enough for the new technology tyres?
We use the national standard (Indian Standard – IS), and international standards such as ECE for Europe, ASTM and FMVSS for the US and other standards like SAE, ISO, etc. as benchmark while testing the tyres. Tyres being safety-related items, the Government of India has notified that the quality of each type of tyre must be tested and certified as per the respective Indian Standards so that BIS can issue licence for marking the tyres. This notification was supposed to be implemented by May 18, 2010. However, this timeline has been extended to November 18, 2010.
The following Indian standards address the basic fit, form and functional requirement of tyres and tubes as per the service conditions prevailing in India.
1) Specification IS 15627: Automotive vehicles – Pneumatic tyres for two and three-wheeled motor vehicles.
2) Specification IS 15633: Automotive vehicles – Pneumatic tyres for passenger car vehicles, diagonal and radial ply.
3)Specification IS 15636: Automotive vehicles – Pneumatic tyres for commercial vehicles, diagonal and radial ply.
4)Specification IS 13098: Automotive vehicles – Tubes for pneumatic tyres
However, the Indian standards are yet to specify the additional requirements like tyre uniformity, steering response, rolling resistance, wet traction, low pressure endurance, noise and the like which are required for better ride comfort, fuel efficiency, safety etc. of the high-end passenger cars, buses and trucks.
I hope that the Indian standards also would be revised and updated on a par with any other national/international standards once the system gets matured. The Indian standard has not yet addressed the environmental aspects such as preventing usage of hazardous raw materials, pollution from tyre wear, waste and disposed tyres.
What are the measures to improve rolling resistance, noise levels etc. that would make Indian tyres acceptable to the European and American standards?
In order Improve the rolling resistance and the noise of tyres, the Indian tyre manufactures have to focus on tyre design, construction and the composition of materials.
Tyre design
The radial designed truck tyres shows up to 30% lower rolling resistance compared with bias designed tyres. Even the radial tyre with dual tread design – cap compound with improved tread wear and the base compound with low hysteresis — would improve the rolling resistance around 5% over the radial tyre with single compound. Tyres with higher outer diameter and the low aspect ratio improve rolling resistance significantly.
Tyre materials
Although the natural rubber (NR) is the first choice for radial truck tyres because of its outstanding physical and mechanical properties and adhesion with steel cord, solution styrene butadiene rubber (S- SBR) is being extensively used in passenger car radial tyres to improve the rolling resistance and the wet grip. Use of dual fillers — carbon black and highly dispersible silica with silanes — provides optimum of rolling resistance, wet traction and tread wear. Since aromatic oil with high polycyclic aromatics (PCA) is banned in Europe, the tyres for exports should be free of toxic aromatic plasticisers. Steel is the choice for belt and the high modulus low shrinkage (HMLS) polyester has replaced the low modulus nylon cord in radial tyres. Radial tyres with less number plies in the carcass and steel cord adhesion compound with low hysteresis improve the rolling resistance significantly.
You are undertaking research not only in testing, but also in product and compound development. What are the major outcomes of your projects that are industry-relevant?
Apart from undertaking the testing, certification, training, consultancy etc., IRMRA has developed many critical products for the Defence establishments such as the Navy, the Air Force and the Army, Bhabha Atomic Research Centre ( BARC), the Railways, Hindustan Aeronautics Ltd., ( HAL), Indian Space Research Organisation (ISRO).
Product development, especially for the Defence and atomic research applications, requires an extensive literature search, product and process design, development of compound, testing of material at various stages, testing and validation of products under service conditions. We also do life prediction for such critical applications. Once the product is developed, then with the consent of customers, the technology is transferred to potential private supplier for ensuring the availability of product in required quantity to the Defence establishment. We have been awarded a very important Rubber Dam Project by the Agricultural Ministry under the National Agricultural Innovation Project (NAIP) funded by the World Bank. The project is being successfully executed and, on completion, the technology would be transferred to the potential private industries.
We are in discussion with the national and International tyre manufacturers for carrying out collaborative research to develop compounds and reinforcing material for tyres which can well suit the Indian road and off-the-road conditions. With addition of more testing equipment and research facilities, we hope to do more work in the area of tyre development in the coming years. What are the areas where Indian tyre producers should put more emphasis on the development of green tyre and contribute to sustainable mobility?
The green tyres are made of material from environment-friendly renewable resources. The green truck and passenger tyres are made, to a large extent, with NR. Trials with the epoxidised natural rubber (ENR) have shown the promise of obtaining an optimum traction with substantial reduction in rolling resistance. The reduction in rolling resistance improves the fuel economy and also reduces the carbon dioxide emission. Apart from rubber, reinforcement in green tyres are made with eco-friendly materials: Carbon black is being replaced with nano silica filler, the petroleum-based textile is being substituted with natural resource-based fibres like rayon, silk, glass fibre, steel cord with recycled steel and fossil fuel-based plasticisers with vegetable oils. Even the rubber chemical content is substantially reduced.
Since we produce natural rubber, natural fibres, vegetable oil etc, in our country, the Indian tyre manufacturers must focus on their green tyre research and development activities by using the indigenously available natural resource-based material for sustaining growth and conservation of environment.