Where do the tests take place?
There are acoustic test rooms at all of ebm‑papst's major production sites. The acoustic test room in Landshut is located in Plant 1 and has been brought up to date in terms of hardware and software in recent years. The room is set up as a resource for development and organized in such a way that trained measurement technicians can use it independently. Key to this is the specifically developed software. It controls the tests and provides a standardized evaluation. This shows whether the measured values correspond to the specifications, and where a closer look is worthwhile because measured values deviate.
Who is involved?
Andreas studied mechanical engineering and works in the Function and Design group in Landshut. Sound testing became his subject because acoustics - in other words, how a product sounds - is now one of the most important characteristics of fans. He was part of the team that planned and implemented the modernization and reorganization of the rooms. In addition to his own tests and evaluations, together with the Head of Team Laboratory Markus, he supports the work of other developers who use the rooms as a resource. Evaluation is not only carried out on the finished product and, above all, not just for one-off use. That's why Eugen from the Pre-Development Function/Design team uses the acoustic test rooms during the development phase to check design and function. For the Pre-Development Life Time Testing area, Michael uses the modern conditions to assess the noise properties over the entire service life of a fan. During the various test runs, the developers are supported by the expertise of Martin and other permanent employees at the testing facility.
Sound tests are an essential part of the development process and quality control
What is it all about?
Each and every fan and blower produces noise that is simultaneously emitted from several sources. One element is generated by the rotor, bearing and fan wheel. The other part is generated by the air flow. The products from Landshut are often installed in the immediate vicinity of people: This means that especially for Landhut's core competency, heating technology, low-noise operation is one of the most important features. Apart from the fact that noise testing is firmly embedded in the development process, the team in Landshut is systematically building up knowledge about noise generation and noise avoidance. Andreas explains: “The more accurately we understand the noise generation mechanism, the better and faster we can find corrective measures and further optimization options.”
What does the team do?
People describe sound as “volume” and “pitch”. Both can be evaluated using sound performance measuring: the energy of the sound waves determines the volume and their frequency, the pitch. It is the most common measurement in the acoustic test rooms. To do so, the test engineers often set up ten or more microphones at standardized distances and positions around the product. They then conduct tests at various speeds and operating conditions. The software compares results and specifications and shows deviations. The next step is to analyze: What exactly does the deviation look like? Which component could be causing this deviation? How would it have to change so that the frequency becomes lower, for example, or the energy in the sound waves decreases?
What’s the benefit?
The sound that ebm‑papst products generate - or rather do not generate - is a very important sales argument. At the same time, the sound tests are a kind of X-ray eye with which the team can look into the running product. This also helps with quality inspections and complaints. Certain frequencies can be assigned to specific components. For example, a sound test can be used to detect the condition and a possible defect in a ball bearing without having to be destroyed.
"Very accurate knowledge of how sound is generated in the products gives us a valuable head start in the development of exceptionally quiet products."
Andreas, Function and Design, R&D