A Pragma Group Company

Metal fibre brushes (MFB)

Defense Holdings, Inc.® (DHi) HiPerCon, LLC® of Charlottesville, VA have teamed to extend the use of their revolutionary, patented Metal Fiber Brush (MFB) technology to the grounding of the shafts of rotating power plant offering.

  • Reduced maintenance costs
  • Increased service life and online availability
  • Enhanced performance
  • Improved environmental tolerance


DHi provides full-spectrum engineering and life-cycle support for metal fiber brushes which have unique performance characteristics:

  • Current densities of up to 250 Amps/sq inch are easily obtained.
  • Current densities of up to 1000 Amps/sq inch have been obtained under select conditions.
  • Less than 1/5 the wear debris volume of carbon brushes.
  • Non-dimensional wear rates of 2 x 10-11 at sliding speeds of 20 meters/second in open atmosphere. In all side by side testing, MFB’s had at least twice the service life of carbon brushes.
  • Extremely high tolerance to atmosphere contaminates.
  • Extremely low electrical noise across the brush slip ring interface.
  • Lower levels of acoustical noise.


DHi’s MFB shaft grounding device is a cost effective means of preventing bearing damage that often is the result stray currents induced in the shafts of electric motors. Without shaft grounding devices current can pass through the motor bearings and end up etching the races and causing premature failure. This problem is particularly acute in variable frequency drive (VFD) motors. VFD motors are used increasingly for many applications including productions lines, printing, fresh water and fire pumps because of the energy savings that they can provide. DHi’s patented MFB technology offers a brush system that can withstand severe operational environments with a very long life.

DHi grounding brushes can:

  • Demonstrate a service life of more than 10 years or 9.1 Billion shaft revolutions at shaft speeds up to 20 meters/sec
  • Operate with up to 1,5 mm of shaft runout
  • Be easily adapted to any motor using standard mounting options and requires only offer a very small footprint
  • Run directly on a steel shaft without modification
  • Be easily replaced during operation.
  • Carry 40 amps continuous current in a single brush
  • Have a total system resistance of only about 3.7mΩ when operating on a bare steel shaft
  • Operate in oil soaked environments