Improved QC Inspection for Large-Scale Bearings

The Timken Co. plant in Dudley, England, recently recorded an increase in demand for large bearings – up to 1,200-mm diameter – for wind turbine construction, and anticipates further growth for such applications as green-energy programs take shape in various parts of the world. The plant is an established manufacturer of engineered bearings for mining equipment, food and beverage processing operations, pulp and paper manufacturing, cement production, marine systems, and wastewater processing.

To conduct quality inspections on the larger bearings Timken acquired an Altera^M 15.12.10 ceramic bridge coordinate measuring machine (CMM), with axis travels of 1,500x1,200x1,000 mm manufactured by LK Metrology.

Timken's QC department also uses a Mitutoyo CMM capable of measuring ball and roller bearings with bores up to 800 mm in diameter. This machine was upgraded by LK at the same time, with a new controller and identical CAMIO 2021 software for measurement, programming, analysis, and reporting, so that inspectors are able to swap programs conveniently between both machines.

Dozens of high-precision geometrical features need to be checked on each bearing to ensure that flatness, circularity, radial run-out, and track width meet specified tolerances – some of which are within ±6 µm.  At Timken in Dudley, this is achieved quickly, repeatably, and automatically on the CMMs in computer-controlled cycle times of around 10 minutes.

"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,” recalled William Hayes, quality improvement engineer at Dudley. “Also, the company was 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 favor was that its CMMs are installed in Timken plants in other parts of the world, including in the U.S., 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 specialize in producing small quantities of engineered bearings below 10-off."

Hayes explained that LK also supplied new technology, specifically a Renishaw PH10MQ motorized tilt-and-rotate head and SP25M scanning probe with interchangeable styli. Together, these tools are able to take measurements at important discrete points, as previously, or to scan large areas very quickly.

For example, the system is able to scan a circle at 1.2 m/min, acquiring up to 1,000 measurement points every second. Another benefit of the SP25M probe is the possibility to accurately measure with stylus lengths up to 400 mm, allowing difficult-to-access areas of a component to be reached, whereas traditional probes have a stylus length limit of 100 mm.

The change in functionality from touch trigger probing to scanning is fully programmable. In the case of Timken's cycles there is approximately a 50:50 split between the two modes of operation. They are performed by the SP25M probe, as there are two sensors built into the single housing, so there is no need for probe exchange.

The wealth of data collected then is available for very accurate reports concerning deviations in size, position, profile, and form that can affect bearing performance. Higher-speed inspection also makes it possible for metrology to provide prompt feedback for adjusting production processes.

Within 10 days of the new CMM installation at Dudley and the simultaneous upgrading of the smaller machine, two of Timken's six inspectors had already undergone training by LK Metrology engineers and were checking bearings on both CMMs.

The latest version of LK's CAMIO 2021 software has the advantage of helping to increase inspection productivity, enhance the quality of data collected, and allowing the inspectors to gain more insight into the components being measured. New inspection programs are prepared quickly by automatically detecting which surfaces of the CAD model should be used to measure a feature.

Other improvements have 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.