A testing room for the medical device manufacturer Zimmer – planned and turnkey implemented by Weiss Klimatechnik GmbH

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"We give new zest for life" – this is the motto of Zimmer, a globally leading Swiss manufacturer of personalized joint replacement systems. For nearly a hundred years, they have been producing, among other things, hip and knee prostheses, foot and ankle systems, hand and foot joints, to name just a few of their high-tech medical products. Quality – and this primarily means high demands on precision – is crucial in this industry. Inspection is carried out with 3D coordinate measuring machines in a measurement room planned and turnkey-built by Weiss Klimatechnik.

It is one of the most common surgical procedures overall: the implantation of an artificial hip or knee joint. Despite its complexity, it has long become a routine process in specialized clinics. A renowned manufacturer of such and many other demanding medical products is the Swiss company Zimmer, an international enterprise with a total of 8,000 employees – of which 1,000 are in Switzerland, where the headquarters are also located.

The quality of a shoulder joint, a femoral plate for trauma surgery, or a knee joint depends to an almost immeasurable extent on the precision of their manufacturing – after all, they are meant to replace a natural joint of an individual person. Every prosthesis produced here must therefore be reliably tested during final inspection and quality control – using extremely precise 3D coordinate measuring machines. These, in turn, are located in a special measurement room, which was planned and built by Weiss Klimatechnik.

Increased requirements

The decision for this expansion is partly related to the fact that the requirements for maintaining the climatic values in such a measurement room have recently been tightened internally, as Marc Baumeister explains. He is responsible as Manager of Technical Services at Zimmer, among other things, for the operation of the measurement room. The contact with Weiss Klimatechnik has existed for some time, as the company had previously implemented a calibration laboratory for Zimmer. Especially the extensive experience in the demanding fields of climate technology and cleanroom environments justified awarding the contract to Weiss Klimatechnik, according to Marc Baumeister.

The technical requirements for the measurement room of quality class III are specified in the VDI/VDE 2627 guideline. Parameters such as humidity and – especially critical – temperature are defined here. For example, the room where the measuring devices are located must be continuously climate-controlled so that temperature fluctuations do not exceed +/- 0.5 Kelvin within one hour. Measurements are taken at 20°C – deviations in the micro-range are critical for the workpiece being tested, as Marc Baumeister emphasizes.

Brought to temperature

If, for example, finished hip joints are to be measured under these conditions, they must first be brought to this temperature of 20°C to prevent distortion of the measurement result. Before the medical product enters the measurement room, it remains – depending on the model and size – at least five hours or a day in an anteroom. Only then do quality inspectors place the prostheses on special pallets for the 3D coordinate measuring machines in the actual measurement room.

The measuring machines follow specific measurement programs in the form of an actual and target comparison, which the inspectors run through for each individual product. The machine then prints a report for documentation – to verify the precision of production and traceability of each joint.

The turnkey measurement room, designed, assembled, and commissioned by Weiss Klimatechnik, accommodates ten measuring machines that run around the clock, each nearly three meters high and about one and a half meters wide. Each of them weighs, depending on the model, between two and three tons.

The room-in-room concept from Weiss Klimatechnik ensures constant room conditions, explains Hans-Joachim Weitzel, Project Manager in the Strategic Business Area Cleanroom at Weiss Klimatechnik, who is responsible for the project at Zimmer. The measurement room, evenly illuminated with 1,000 lux, is encapsulated by thermally insulated enclosure surfaces.

The compact climate unit from Weiss Klimatechnik, including control and regulation, is located outside the actual measurement room. The compact design of the manufacturer's climate systems saves space: the entire climate technology is housed in a small but accessible space.

Monitoring and documentation

Color signal lights and online monitoring of measurement data serve for supervision. Sensors continuously transmit temperature and humidity values and record them continuously, so that it is possible to trace and verify for each product that it was measured within the required specifications.

Zimmer is extremely satisfied with the conception and implementation by the Weiss Klimatechnik team, as well as with the results. The new measurement room allows for greater accuracy in measurement, in addition to the aspects of time and cost efficiency, as Marc Baumeister explains.

Previously, each measuring machine was located in its own room – distributed across the factory premises. Opening these rooms, for example, quickly changed the temperature. With the new large room, maintaining the temperature is significantly easier – the temperature does not change due to the short opening of the doors thanks to the heated airlocks. The previous situation often required measurements to be repeated due to excessive fluctuations. Being able to avoid this today greatly contributes to the efficiency of the entire testing process at Zimmer.