March 2021

36 n BELTS, BEARINGS AND CHAINS March 2021 www.drivesncontrols.com Dutch researchers aim to discover why bearings fail E very year, around ten billion bearings are manufactured. Given the harsh conditions to which they are often subjected, most are incredibly reliable, with about 90% outliving the equipment to which they are fitted. Only 0.5% of bearings fail in service, but this still means that some 50 million need to be replaced due to damage or failure every year. Each failure will probably have financial implications in terms of lost production, damage to adjacent parts, and the cost of repairs. There are numerous reasons why bearings can fail or be damaged. Around one third fail due to fatigue, while another third fail due to issues with lubrication. Contamination causes a sixth of bearing failures, while the balance is accounted for by other factors, such as improper handling and mounting, heavier or different loads to those anticipated, and poor fitting. When attempting to predict how – and, perhaps more importantly, when – a bearing will fail, many variables must be taken into account, including the application, the environment in which it will operate, the lubricants used, and the loads to which it will be subjected. When developing new bearings, verifying their performance and assessing how long they will last can be a slow, expensive and complex process. SKF is hoping to solve this problem at its RTD (research and technology development) centre in the Netherlands where it is building a facility to boost its knowledge of the mechanisms that cause bearings to fail. It will also use the facility – called Brave (Bearing Rigs for Accelerated Verification Experiments) – to develop new ways to predict the remaining useful life of these critical components rapidly, accurately and repeatably. “We needed a flexible testing facility where we could simulate different application conditions and see how a bearing system – including the materials from which it is made, and the lubrication employed – performs when operating under different loads and at different speeds,” explains Edwin Tummers, SKF’s team leader for experimental verification.“We also needed to be able to do that in a way that allows us to perform investigations on that system, so we can determine how defects are generated, how they progress, and how long the bearing will last until maintenance is required.” Brave will use several specially designed rigs to develop and verify bearing failure models. The functions of these rigs are categorised as“contaminate”, “initiate”and“propagate”, and they will be often used in sequence. Each set-up type can also be used in isolation, or in a mix-and-match approach, enabling a wide variety of tests to be performed. “With the contaminate set-up, for example, we can generate defects, such as dents, abrasion, electrical damage and corrosive damage in the bearings in different ways,” explains Urszula Sachadel, SKF’s team leader for bearing steels. “We can also apply different lubricants. In the initiate set-up, we can then run the bearings under certain conditions to create some initial damage. Finally, in propagate, we can determine how different load and speed conditions influence the rate at which this damage spreads”. In this way, SKF researchers will be able to screen many different bearing variants quickly to determine the best way to solve an application. Test procedures will be developed, controlled and monitored closely, and all of the data, regarding variables such as vibration, temperature and load history, will be recorded. This data can be analysed in detail during or after the experiments. “Using Brave, we will be able to quickly evaluate potential bearing solutions, screen them, and understand the impact of different manufacturing processes on their performance,”says Sachadel.“In the future, we can use the data we gather to support our development of artificial intelligence and machine-learning techniques to predict or improve the performance of our bearings. “We plan to look at the bearings after different stages of remanufacturing,” she adds, “to determine how the process affects their performance and how to boost it. We’re going to learn a lot of new things through Brave, which we look forward to sharing with our customers.” n A new facility in the Netherlands will examine in detail why bearings fail, and develop techniques for reducing failures and predicting and extending bearing lives. SKF’s Urszula Sachadel:“We’re going to learn a lot of new things through Brave, which we look forward to sharing”