TARRC: EXPANDING TESTING FACILITIES

For over thirty years access to the expertise of TARRC’s technologies and state-of-the-art facilities have been available to the tyre and associated industries through the research centre’s independent consultancy service Rubber Consultants. The consultancy has been assisting companies since 1984 to improve their businesses by offering them world-class elastomer testing and R&D services. It has established a unique portfolio of in-house services available for the elastomer and polymer industries as well as suppliers to these businesses. Rubber Consultants has a global customer base with clients from the tyre, automotive, aerospace, railway, oil & gas, medical & healthcare, pharmaceutical, packaging and the construction sectors.

TYRE TESTING

Paul Brown has been responsible for tyre material development and testing at TARRC for well over 20 years. He explains how the testing carried out for clients through the consultancy breaks down into two areas. The first is that required to show product conformity including but not exclusively testing to the ECE regulations for the UK retread industry for their process type approval. The second is product development testing for suppliers to the tyre and motor industries. Some of this testing is in response to motor vehicle manufacturers requirements whilst other tests can be early-stage development of new ideas.

The other associated area involves tyre tread compound testing where the development compound is applied to a prepared casing using industry standard retreading techniques. Subsequent testing involves a combination of on vehicle services trials, trailer based trials and laboratory based rolling resistance measurements. This work both lies within TARRC’s own research areas looking at sustainable materials and is used by suppliers to the tyre industry to acquire promotional data for their product; be that polymers, fillers or other ingredients.

TYRE WEAR

Tyre abrasion studies and the development of accelerated tyre tread wear testing at TARRC date back to the 1950s when there was not much knowledge about these matters. Recently, a project was commenced with the aim of applying novel techniques developed at TARRC to study the study of wear mechanisms. Scientists at TARRC now believe they can explain why the simple laboratory abrasion tests fail to predict in-service wear; the wear mechanisms are demonstrably different.

Examination of worn tyre treads and abrasion test samples using TARRC’s ‘net-vis’ technique has highlighted morphology differences between them, thus providing an insight into the possible mechanism of tyre road wear and why laboratory tests are unreliable. This work has initiated a new project on the influence of rubber filler interaction on the longevity of green tyres and aims to achieve better understanding of wear mechanisms active in tyre tread compounds during on-road testing and in laboratory abrasion testing, ultimately improving existing laboratory test methods to better reflect road wear processes.

TYRE TESTING FACILITIES

TARRC’s scientists and technologists have at their disposal some of the most comprehensive independent tyre testing facilities in the world. These are complemented by state-of-the-art analytical laboratories where analysis of tyre construction and tyre component formulations can be performed as well as compliance testing under the REACH directive including PAH testing.

The facilities include:

• UKAS and VCA accredited tyre test rigs for endurance testing to ECE Regulations 30, 54, 108 and 109.

• A 2-station passenger test rig comprising an endurance hub with a top speed of 350kph and 2 tonne capacity and a second hub for carrying out force and moment measurements to determine how the tyre will react and perform under different service conditions. These F&M data are used in modelling tyre behaviour.

• 2-Station commercial vehicle tyre test rig with 60mph and 6.5 tonne load capacity, primarily used for endurance testing of commercial vehicle tyres to the ECE Regulations.

• Instrumented single station rig for rolling resistance measurements to ISO Standards: ISO 18164 with a 5 tonnes load and 60mph speed capacity. This rig has a high-torque drive suitable for testing high rolling resistance tyres, such a solid tyres, at speeds up to 25mph

• Pendulum skid resistance tester to test with a range of test surfaces from well defined abrasive paper to roadway, testing to BS EN13036-4:2011

• Road trailer for accelerated wear testing and wet and dry traction properties

• Fleet testing offering a range of severity of service for wear trials of commercial vehicle tyres

• Tyre testing laboratory is approved by the Vehicle Certification Agency for type approval of passenger and CV tyres

• Retreading facilities for the conventional hot-cure retreading of both truck and passenger tyres. This is used to produce multi-section truck tyres for wear testing . There is also the facilities for precured retreading of commercial vehicle tyres.

EU TYRE LABELLING

Since June 2012, for selling within the EU, tyre manufacturers have been required to provide data in relation to the performance of their tyres through testing and labelling. The aim of the regulation is to increase safety, promote fuel-efficient and safe tyres, decrease noise levels and allow consumers to make informed purchasing decisions. Currently these only apply to new tyres.

The label classifies tyres from A (the highest performing) to G (the lowest performing). Information must be available in technical promotional literature such as leaflets and brochures, including on manufacturers’ websites. This has to be done for every new tyre within scope of the regulation sold on the EU market.

Tyre labelling has influenced tyre development within the industry to give lower rolling resistance without compromising the other performance properties. One of TARRC’s key projects in this area has focussed on developing sustainable tyre materials resulting in tread materials for better wear resistance, lower rolling resistance and raised wet grip. Using Malaysia’s Ekoprena, a sustainable modified natural rubber, technologists have produced pre-cured retreads at factory-scale mixing. Ekoprena treads match the service life of the control formulation (a premium retread formulation) in medium severity wear. Development and testing are ongoing to further optimise formulations.

FUTURE DEVELOPMENTS

The tyre industry has always been necessarily slow to change due to the safety-critical nature of the product: the tyre is the only contact between vehicle and ground. However, the development of electric and autonomous vehicles will put different demands on tyres compared to today’s vehicle fleet. With the more efficient electric motors and the removal of drive train losses, the importance of the tyre rolling resistance is much higher. Currently, vehicle range is an important brake on the up-take of fully electric vehicles thus any improvement in tyre rolling resistance increases the attractiveness of this technology. Driverless vehicles, with communication to the other vehicles in the area will greatly reduce the demands on the passenger vehicle tyre by eliminating the need for high inputs to the tyre: harsh accelerations (braking, accelerating and cornering) should be a thing of the past once the vehicle control systems are beyond the frailties of the human mind.

Future truck tyres may not be as different from today’s tyres as the principle demand of load-bearing remains. Sure, each component will be optimised for weight and the influence on tyre rolling resistance, but the need to be able to retread truck tyres, for both environmental and economic reasons will limit just how far the tyre can be developed away from the current technology.