Those following progress in precision manufacturing know well that products are becoming more precise. Taken to an extreme, robotically controlled machines are capable of producing components so small their features are observable only under magnification.
While cleanliness is an important criterion across the board in such instances, it is crucial when it comes to surgical instruments. An example is found in tubes produced by A.M.I. GmbH (Agency for Medical Innovations) in Feldkirch, Austria, and used in the manufacture of instruments designed to place implants in the human body. Welded and calibrated to perfection by means of drawing them through a die body, the tubes are 400 mm (15.74”) in length with an I.D. of 4mm (0.15”) and O.D of 4.5mm (0.177”). In this instance some 20,000 pieces are produced annually.
Calibration introduced a cleaning issue as the drawing compound and fine metal particles tend to remain on and inside the tubes. In another production step functional openings are laser cut, which produces additional metal dust particles. Absolute removal of these contaminants is essential to the proper functioning of the instrument and to fully protect patients receiving implants.
A.M.I investigated several process cleaning approaches. Steam degreasing did not do the job. Ultrasonic cleaning was believed to be an answer but as originally tried was unable to provide satisfactory results.
Working with Elma, A.M.I. combined positioning and modifications to the process cleaning cycle to improve the batch cleaning operation. Rather than lay the tubes into the ultrasonic cleaner tank they are placed in a nearly vertical position and held stable by a grid. A.M.I selected the two-chamber Elma X-tra Flex 2 oscillating ultrasonic cleaning system combined with a WLT hot air dryer from Tovatech. By introducing vertical oscillation in the bath further cleaning was accomplished in a much more efficient manner. The Elma Flex bath is operated at 80º C (176º F) over a 10-minute cycle at 25 kHz. After being rinsed tubes are dried at 110º C (230º F) under a high air flow rate so no particles remain. The entire process is accomplished in an ISO class 100,000 clean room.
Proof of cleanliness is provided by electron microscopy; tubes passing the test are then sterilized as finished instruments. The process is validated as reproducible by a local technical college, and is constantly inspected by random tests.
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What novel problem-solution approaches to process cleaning have your company instituted using ultrasonic energy? How important is thorough cleaning? What were the challenges and how were they resolved?
Tags: ultrasonic
