The art of good measurements: installing an automated system

Recently, a large program was executed at the Philips plant in Turnhout, Belgium, aimed at doubling the CDM yield and drastically lowering the manufacturing price per lamp. Part of this aimed at improving throughput times on the High Speed Lamp Line. Leak testing of lamps, which formerly took two days and was carried out by employees, is now fully automated and carried out inline – with excellent results.

Paul Oeyen, Project Leader, Philips Turnhout, explains.

“Previously, we’d always have a number of lamps resting ‘in quarantine’ for two days, awaiting final leak inspection,” says Paul Oeyen, Project Leader, Philips Turnhout. “A leaking lamp will contain air i.e. nitrogen with some oxygen. A well-manufactured lamp contains only nitrogen. We’d wait for two days until enough air had seeped into the lamp, so we could check if it would oxidize metal components when we increased the temperature.”

“The requirement of detection limits is high. The leak rate we want to detect is very small (1 x 10-8 millibar-liters per second). To automate this process, a specially designed, highly sensitive leak tester onto an industrial line had to be built.”

Fully automated, in-line measuring system

“Products are now automatically tested on the HSLL manufacturing line. With the new test, the nitrogen is infused with a very small amount of tracer gas and sent to a vacuum chamber. If there’s a leak, a little gas leaves the lamp and the tracer gas is detected by a mass spectrometer. The procedure is fully automated and accuracy has increased. This has allowed us to cut costs and we’ve earned the investment back several times over. We also no longer need staff to check every lamp individually at the end of the line.”

“The device Philips Engineering Solutions has built for us is an impressive feat of engineering, which continues to meet our demands. Excellent job!”

Front view of the leak tester in the HSLL production line showing the lamp chambers.

Image: Rear view of the leak tester in the HSLL production line showing the machine lay-out and the mass spectrometer used for the actual measurement.
Image (top): front view of the leak tester in the HSLL production line showing the lamp chambers.

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