© Lukas Zwiessele | ebm-papst

Insight into our testing centerFeeling giddy: Test bay impeller strength, spin and cycle test

Impellers are an essen­tial part of a fan. Depending on the mate­rial used – plastic or metal – different loads can shorten the service life. That’s why ebm-papst sets its speed to maximum in the Hollen­bach testing center, even taking them up to breaking point.

In the testing center in Hollen­bach, fans are pushed to their limits and beyond with real-life envi­ron­mental influ­ences. New prod­ucts, sizes or compo­nents pass through the test stations in a total of six test fields over an area of approx­i­mately 2,500 square meters. In this series, we take a closer look at each of these test bays. The third focuses on impellers made of metal and plastic.

In the testing center, ebm-papst not only tests complete fans, but also their indi­vidual compo­nents, such as impellers. Their dura­bility is inves­ti­gated in the “Impeller strength, spin and cycle test” bay designed specif­i­cally for this purpose. The tests are carried out on new prod­ucts – during and after devel­op­ment – and when intro­ducing new sizes of existing fan series.

In the cycle test, metal impellers have to run many start-stop cycles and prove their load capacity. (Photo | Lukas Zwies­sele | ebm-papst)

All three impeller tests are ramped-up tests, meaning that the test spec­i­mens run at a signif­i­cantly higher speed than they are later approved for. The load is compressed into a shorter period of time. In this way, the load in the field can be simu­lated from the speed and dura­tion. There­fore, the engi­neers iden­tify possible weak­nesses very quickly, before the impellers are released to do real work.

Impeller strength test bay

In the impeller strength test bay, plastic impellers are mounted on a total of 11 test benches and oper­ated for 28 days in a row. The focus here is on the special prop­er­ties of the plastic mate­rial: How does it behave over time when centrifugal force and thermal loads act on the fan? After the 28 days, the experts in Hollen­bach test the plastic impeller: How strong has the mate­rial been? Has the tip gap between the impeller and housing changed thereby? Here, the engi­neers are guided by stan­dard values and their own expe­ri­ence. This ensures that the effi­ciency and noise gener­ated by the impeller do not enter a crit­ical range over its oper­ating time.

The spin test bay is made for metal …
as well as plastic impellers. (Photo | Lukas Zwies­sele | ebm-papst)

Spin and cycle test bay

The spin test bay features test benches for metal and plastic impellers in different sizes, including for compact fans. Assem­bled on test benches, this is where the maximum oper­ating speed and the destruc­tion speed are deter­mined, so it can easily come to breaking point here!

The test cabi­nets contin­u­ously carry out start and stop cycles on metal impellers to iden­tify the maximum oper­ating speed and detect poten­tial weak­nesses in the mate­rial. The test rigs for the cycle test have a drive power of 36 kW and 45 kW, respec­tively, and can thus run at maximum speeds of 15,000 rpm and 6,500 rpm, respec­tively. And this with impellers of sizes 450 to 1,250.

Mr Kemmer, how do the loads on the metal impellers differ?

Exclu­sive insights into all test fields

Learn more about how ebm-papst puts fans to the test in the indi­vidual test fields. Each article with exciting insights, videos and pictures!

Required fields: Comment, Name & Mail (Mail will not be published). Please also take note of our Privacy protection.