Hard disk drives with FDB-Technology

PM DM develops electronically commutated BLDC motors.
While almost everyone is familiar with computer hard disks, only few know that the heart of the hard disk is an electrically commutated DC motor, which is known as a spindle motor.

If we consider the memory capacity of modern hard disks, it very quickly becomes clear that the requirements placed upon the spindle motor are quite considerable. Every spindle motor has an application-specific hydrodynamic bearing system to ensure the best possible quality and reliability.
A particular technical challenge is the design of the FDB (Fluid Dynamic Bearing) systems.

PM DM uses micro annular gear pumps of the magnetic hermetic series for this purpose. These pumps dispense few microliters of the fluid directly into the fluid dynamic bearing system. A slight end-off-cycle suck-back enhances dosing accuracy and generates a clean drop separation. The integrated programable microcontroller allows an easy integration into the overall control.

Decision criteria for this pumps

  • high accuracy (precision and trueness) of the dispensing process
  • suck-back of the liquid for a clean drop separation
  • compact design and low weight
  • integrated programmable micro controller allows easy integration into overall control


Applied pump




< Back to overview