Although some investigations on the wear behaviour of
brush seals can be found in the literature, not all aspects are yet
understood during the wear-in process of the seal in operation.
However, it is important to understand all aspects in order to en-
sure a long service life of the seal. The present paper gives an
overview of the procedure, the results and the knowledge gained
through the long-term rub tests carried out with a tungsten car-
bide coated rotor with the aim of determining the time required to
wear the seal in (”time-on-condition”). The total test duration
of the cyclic tests was approx. 100 h. The measurements have
shown that on the basis of the applied test procedure the initial
wear-in phase is completed after approx. 40 cumulated operat-
ing hours and only very little wear occurs afterwards. Further-
more, it could be shown that the major part of the wear occurred
within a short period of time within these 40 h and that the prop-
erties of the test cycle have a great inﬂuence on the wear-in time.
The coupling of the rubbing intensity with time is achieved by
measuring the transient rotor temperatures during rubbing.
The tests carried out have also shown that the inﬂuence of
the concentricity properties of the rotor can resulting in rotor
temperature deviations over the circumference (”hot spots”).