Developing a method to characterize spring-applied brakes with regard to the load spectrum dependent properties failure probability and circumferential backlash

Customer: Industry

Beside the permanent magnet brake, the spring-applied brake is the most frequently employed type of brake in industrial drive systems. Compared to each other, each version has specific advantages over the other, qualifying them for characteristic applications:

Permanent magnet brakeSpring-applied brake
+ great dynamics and torque density + overall friction work over its lifetime
+ exact positiong by connections w/o play and/or wear+ flexible mounting options and easy assembly
+ w/o residual torque+ low purchasing cost
→ especially precision and High-speed applications:  Servo-, robotic and medical Technology→ especially safety relevant applications: e.g. elevator and crane systems, intra-logistic systems

Efforts in brake technology are aimed at

  • extending maintenance intervals or avoid them completely as well as
  • Increasing the lifetime of the brakes.

In addition, spring-applied brakes are increasingly employed in applications that have traditionally used permanent magnet brakes given their attractive price. Thus, requirements have tightened on

  • fail-safe performance and
  • circumferential backlash.

Up to now, there is no uniform procedure to characterize spring-applied brakes with regard to these properties, so that a suitable/applicable method has to be developed. The challenges in doing this consist of

  • identifying effective load collectives (fig.: test stand brake process, simulative investigations),
  • integrating these in a shortened and reproducible manner into relevant component interfaces (fig.: wear test stand, test stand reversed fatigue strength),
  • not falsifying any relevant damage processes and
  • ensuring the transferability of the test results to the application.