How to improve tire uniformity?
Tire uniformity is an integral part of the tire and wheel assembly process. At Eurofit, the research team is continuously working on creating the perfect tire and wheel assembly (TWA). Innovation is key, as Eurofit’s customers are looking for solutions that are both cost-effective and of high quality. The latest development is a new machine for measuring High-Speed Tire Uniformity (HSTU). So far, in Europe, these machines work only in lab settings for research and testing purposes. At Eurofit, however, the newly developed HSTU machine works in a one hundred percent industrial production setting at OEM level performance. This machine is able to measure the uniformity of a TWA at a speed of 120 km/h in only 24 seconds with respect to customer parameters to eliminate potential vibrations in a car.
When driving our car, we want maximum comfort. This requires optimum quality of all car parts, especially the tires and rims. Therefore, carmakers and their TWA suppliers, such as Eurofit, use uniformity measurement as a way to identify TWAs which do not perform at the required level, with a focus on the tire. Tire uniformity refers to the dynamic properties of tires as defined by a set of measurement standards and test conditions accepted by the global car manufacturing industry. These standards include the parameters of among others, radial/lateral and tangential harmonics force variations, lateral forces/radial, and lateral run-out geometry and sidewall bulge.
Low and high speed
For years, tire uniformity testing has been performed at low speeds (about 8 km/h). Today – as cars have become lighter, TWAs have become larger, and customer expectations on comfort have grown – testing at high speeds is instrumental in delivering the right TWA for premium and sports cars. This issue became a topic for the Eurofit research team when Daimler wanted TWAs for its new S-Class cars that needed high-speed testing to deliver on the car’s premium quality standards. During this time, no European machine supplier was ready to show a running High-Speed tire uniformity process for TWA.
From 0 to 120 km/h and back including the movement of the TWA through the machine in 24 seconds
The team started working on a prototype, based on lab models and turned it into a fully functioning, production-ready machine that can perform an HSTU test in just 24 seconds at a speed of 120 kilometers per hour. In traditional lab settings, the same test would take approximately 15 minutes for each TWA. One important challenge for the team was the way the TWA is attached to the machine. In lab settings, this is done manually with bolts. The Eurofit team developed a patented fast speed clamp system to secure the TWA. This system also addressed a very low tooling impact on the readings by the testing machine itself, which is a common problem with traditional TWA testing machines. In addition, the new machine offers a wider variety of testing capabilities, especially in the field of forces that influence a TWA while driving at the most sensitive speeds.
Today, the HSTU machine is extensively tested, among others, by checking around thousand TWAs for testing high premium models and sports cars at Daimler.
The new machine plays an essential role in further boosting the quality of new cars. The better the comfort of a new car and a positive impression by the first (test) drive, the less a customer is inclined to go back to the dealer to complain, and the higher the chances of a satisfied customer. This way, dealers and carmakers avoid the cost of possible recalls or warranty claims and work on their brand.
The High-Speed tire uniformity machine project, situated in Böblingen, close to Stuttgart, Germany, illustrates Eurofit’s strong commitment to develop and deliver efficient and effective solutions to its customers. All for the purpose of creating the perfect TWA.