Getting your bearings

The Timken Company supplies engineehttps://www.timken.com/red bearings that it manufactures for a wide range of industries including mining, food and beverage, pulp and paper, cement, marine and wastewater. A growing demand in recent times for these bearings comes from the production of wind turbines, which promises further growth in coming years as countries across the globe work towards meeting their green energy targets. Wind turbines require a larger type of bearing, up to 1,200mm in diameter, which presents a challenge when it comes to measurement for quality assurance and control purposes.

Key highlights

• A brand new CMM makes the measurement of large scale bearings for wind turbines simple and effective
• Upgrades to an older CMM further expand the productivity and compatibility of the measurement arsenal
• A mixture of scanning and touch probe measurements assures precision across many points

For inspecting these larger bearings at its Dudley factory, The Timken Company acquired an Altera^M 15.12.10 ceramic bridge coordinate measuring machine (CMM), which has a working envelope of 1,500 x 1,200 x 1,000 mm and is manufactured by LK Metrology, based in Castle Donington. Timken’s quality control department is further enriched by a Mitutoyo CMM with the ability to measure ball and roller bearings with bores up to 800mm in diameter, which was upgraded by LK Metrology. The upgrade includes a new controller as well as identical CAMIO 2021 software for measurement, programming, analysis, and reporting which allows operators to switch programs between both machines.

For bearings to operate optimally, a wide variety of geometric features need to be checked accurately, including the flatness, circularity/sphericity, radial run-out and track width meet the specified tolerances, which can be as small as ± 6 µm. These measurements are now achieved in computer-controlled cycles of roughly ten minutes, with high repeatability.

William Hayes, Quality Improvement Engineer at the Dudley factory commented, “We selected LK Metrology to provide the new inspection facility, as it was the only potential supplier to offer us a new, well-priced, high accuracy machine of the right capacity. The company was also proactive in offering to retrofit new control software to our Mitutoyo BN710 CMM, as we need two measuring machines to cope with our increasing production throughput.

“Another point in LK’s favour was that its CMMs are installed in Timken plants in other parts of the world, including in the US, so the supplier was not an unknown quantity. It would in theory be possible to exchange programs internationally, but in practice this is unlikely to happen as most of our other sites are mass production environments, whereas we specialise in producing small quantities of engineered bearings below 10-off.”

Hayes also explained how LK supplied new technology in the form of a Renishaw PH10MQ motorised tilt and rotate head and SP25M scanning probe with interchangeable styli. Together, these can take measurements at important discrete points, or scan large areas at high speeds. An example given is that the system is able to scan a circle at 1.2m/min, acquiring up to 1,000 measurement points every second as it does so. The SP25M’s probe is also able to measure lengths up to 400mm, allowing measurement of points that are more difficult to reach, compared to Renishaw’s traditional probes, which have a 100mm length limit.

Timken’s measuring cycles use a roughly halfway split of touch trigger probing and scanning. With both sensors built into the SP25M probe housing, this can be done without exchanging the probe. The high speed of inspection allows for a rapid feedback for adjusting production processes concerning the factors that can affect the bearings’ performance, such as size, position, profile and form.

Full training for the new CMMs at Dudley was also provided to two inspectors by LK Metrology, allowing Timken to get started without major delays. The latest version of LK’s CAMIO 2021 software also increases inspection productivity, giving a better insight into the measured components based on quality data. New inspection programs are prepared quickly by automatically detecting which surfaces of the CAD model should be used to measure a feature. Improvements have also been made to the programming workflow by extending the advanced picking function to touch points and scan paths on a CAD model and to indicate the selection of existing measured features.