Room volume of over 2,000 m³: 712 m² large cleanroom is suspended from the steel structure of a hall roof

Modular concept regarding area, cooling capacity, and air throughput can be expanded

When manufacturing high-precision electric motors for specific applications in the automotive industry, strict requirements for technical cleanliness must be maintained in the production rooms and processes. To be able to carry out these tasks in the future at their own plant in Herbolzheim, the drive manufacturer ebm-papst St. Georgen GmbH & Co. KG, a subsidiary of the ebm-papst Group, has now set up a cleanroom according to VDA 19 standards, which safely filters dust and dirt particles larger than 150 µm from the air. This significantly reduces the risk of defects in the manufactured motors. Since it was not possible to install supports in the room due to the planned orientation of the production lines, the commissioned Nerling Systemräume GmbH developed a special solution: The entire ceiling air conditioning system was suspended from the hall roof via a steel structure. At the same time, the cleanroom is designed to be modular, allowing expansion in terms of size, cooling lines, and air conditioning if needed.

“Our products must be manufactured according to high automotive quality standards. We pursue a strict zero-defect strategy,” says Henning Stemler, project manager responsible for implementing the cleanroom at ebm-papst St. Georgen in the Herbolzheim plant. “To meet these requirements for electric motors used in automotive drive solutions, residual dirt requirements regarding particle size and particle count must be adhered to during processes such as winding the stators, assembly, and final inspection.” Particularly, no particles larger than 150 µm should be introduced into the room from outside. Since comparable cleanliness standards were not previously known within the company, a dedicated cleanroom had to be established to meet these conditions.

Challenging installation situation due to numerous installations

All operating equipment was planned and built according to the “onion skin” principle regarding cleanliness. “The cleanest process must be the actual manufacturing process. Here, additional suction and/or cleaning are carried out at many points,” says Stemler. “The next ‘onion skin’ is the manufacturing system itself, which is further encapsulated.” The outermost layer is the cleanroom, which protects the material and equipment from external contamination and was built by the cleanroom specialists Nerling Systemräume GmbH. Since the current cleanroom area was fully occupied with production equipment and offices before the construction measures, ebm-papst first had to relocate all operating equipment and, in some cases, establish new offices elsewhere.

“At first glance, the entire installation situation seemed difficult because many installations were located within the planned system area,” explains Jan Kürbis, project manager at Nerling Systemräume. “The entire infrastructure such as ventilation, cooling, lighting, electrical and compressed air supply, network connections, and fire alarm systems had to be almost completely removed.” “The particular challenge was that, for example, no supports or auxiliary supports could be standing in the room. These would have been disruptive when setting up the machine lines.” Therefore, the cleanroom builders suspended the entire ceiling, including installations, air conditioning, and ventilation, from the hall roof structure. “Since the roof still had reserves regarding load capacity, we clamped the heavy load-bearing structure onto the hall steel framework.”

Cost savings and modular expandability through hanging construction

The ability to suspend the cleanroom from the existing hall ceiling was a decisive reason for ebm-papst to commission Nerling: “This method saved us costly foundation work and an elaborate steel construction, and at the same time allows us to expand the cleanroom modularly if needed,” says Stemler. Additional modules can further increase area, cooling capacity, and air throughput at a later date. Currently, the cleanroom has a total built-up area of 712.19 m² with a clear room height of 3.1 m and a room volume of 2,208 m³/h. Besides the production areas, the room also includes functional zones for a material supermarket with lockable chambers for individual parts, an outgoing chamber for finished goods, personnel access, and an analysis laboratory for residual dirt testing.

The cleanroom was completed within two months. Currently, two of the six planned production systems are installed, with a third system scheduled for the first quarter of 2013. The remaining space is reserved for already scheduled expansions of manufacturing capacity in subsequent years. “Currently, the testing phase for the new systems is underway,” says Stemler. “Several measurement series have already been conducted to determine the basic cleanliness of the room. As expected, they resulted in a positive outcome.”