DHi's Hipercon Brand Metal Fiber Brush Technology

The story behind Metal Fiber Brushes (MFBs)

HiPerCon® Brand Metal Fiber Brushes (MFBs) possess unique performance characteristics giving them clear and demonstrated advantages over traditional carbon based or other metal fiber brushes commonly used throughout the world in an almost endless variety of motor applications. Our patent protected technology and key technical developments have allowed our team to broaden the range of applications that can be addressed by MFBs. MFBs offer many advantages in solving many of the traditional challenges associated with legacy sliding contact technologies including, but not limited to:

  • LIFE – Need for low wear rate (long lasting) electrical contacts
  • ENVIRONMENT – Need for Robust Contacts, insensitive to various conditions of operation
  • ELECTRICAL – Need for high power capacity plus low contact resistance for data signal and  control improvements
  • MAINTAINABILITY – Need for little to no maintenance without presence              of contact wear debris or lubrication requirements
  • RELIABILITY – Need for contacts that do not degrade quickly (and the need for reduction in wear debris)


Legacy Sliding Contact Technologies CANNOT solve these challenges 

The advantages of DHi’s HiPerCon® Brand metal fiber brushes have been proven to solve the above challenges:

  • Significantly reduced generation of wear debris – only 20% of monolithic solid brushes
    • Benefits: near zero wear particulate to clean, contaminate or inhale, reduced need to change brushes or clean the machines, lower opportunity for shorts
  • Ability to operate in various contaminates -  including gear oil
    • Benefits: provides undisrupted service in many cases, reduced cleaning maintenance and spare part expense.
  • High current density capabilities and low noise characteristics
    • Benefits: reduced potential for surge damage, minimization of points of failure, reduced number of required brushes, measured data rates of 100MB/sec, ability to multiplex data over power, and improved machine operations
  • Significantly longer operational life
    • Benefit: the potential for single slip ring purchase for life of turbine
  • Reduced friction & slip ring surface wear - lower constant spring forceS
    • Benefits: long life slip ring and long brush life 


Significant technological advances occurring in recent years include:

  • New techniques for brush manufacturing that promote:
    • far superior shape conformance and retention to tight physical tolerances,
    • consistently manufacturing brushes of different shapes and sizes to perform in severe mechanical, electrical, and magnetic environments, and
    • a wide range of brush sizes.
  • Improvements in MFB design and construction that address the need to minimize brush circulating currents resulting from non-aligned magnetic fields. This is particularly important for MFBs in homopolar machines and in other high strength and non-aligned magnetic fields.
  • New developments in brush lubrication strategies that extend brush and slip ring service life in severe environments where they are exposed to volatile contaminates and low humidity.
  • Advancements in oxidation suppression additives. These allow metal fiber brush use on various slip ring materials including copper and copper alloys without slip ring plating or the use of a cover gas.
  • Improved understanding and development of processes and strategies to mitigate the impact of brush current polarity on brush and slip ring service life.
  • Significantly increased understanding on optimizing the complete brush system design to fully utilize the brush performance capabilities.
  • Improved, quality-driven manufacturing processes providing first time quality to exacting standards. DHi has instituted a rigorous ISO-9000-2001 certified quality system.


Our modern MFBs were developed through extensive R&D efforts funded under the Federal government’s Small Business Innovative Research (SBIR) Program. Our first highly successful cooperative endeavor brought together HiPerCon, Defense Holdings, Inc. (DHi), the Naval Sea Systems Command (NAVSEA), and the University of Virginia. This effort led to an entirely new kind of brush that was proven to reduce wear and tear on the slip ring surfaces while minimizing costly maintenance and downtime issues. Slip ring MFBs developed by HiPerCon and DHi are currently installed in the submarine force 500kW Ship Service Motor Generators under SHIPALT’s 4415KP (SSN 21 class), 4429KP (SSN 688 class), and alteration SSBN TZ 0906KP (Trident). While the successful operation of MFBs in submarine applications proved their viability in a shipboard environment, that application scarcely began to utilize the full performance capabilities of metal fiber brushes. As a result, our team received additional SBIR contracts of all Phases (I, II, and III) for:

  • the U.S. Naval Air Systems Command for development of improved propeller de-icing systems for fixed wing aircraft,
  • The U.S. Air Force, in collaboration with NAVAIR, for the development of improved propeller de-icing systems for C-130 aircraft, and
  • The U.S. Army for development of improved main rotor de-icing systems for rotary wing aircraft (helicopters)


In addition to the Government SBIRs, and as a result of the successes with the military branches, our team also received SBIR Phase III contracts from Boeing, Sikorsky, and United Technologies Research Center (UTRC) for their Smart Rotor Programs supporting the U.S. Army, and for the Mission Adaptive Rotor Program supporting DARPA. Our technology was incorporated into a LORD Corporation program supporting the U.S. Army, which has successfully undergone flight testing certification at Fort Eustis, VA. 

HiPerCon’s MFBs have proven highly successful in homopolar motor applications where extremely high current capacity is required in support of Guina R&D of Australia, and offer significant promise when developing other types of extremely power dense motor and generator applications. 

Key performance attributes of slip ring metal fiber brushes include the following:

  • Current densities of up to 250amps/square inch are easily obtained.
  • Current densities of up to 1000amps/square inch have been obtained under select conditions.
  • Non-dimensional wear rates of 2 × 10-11 at sliding speeds of 100 meters/second in open atmosphere.
  • Extremely high tolerance to atmospheric and liquid contaminants.
  • Extremely low electrical noise across the brush slip ring interface.
  • Lower levels of acoustical noise.
  • Less than 1/5 the wear debris volume of carbon brushes.
  • Improved machinery efficiency due to a very low and stable voltage drop and lower frictional forces.