metal-impregnated graphite brush

  • 1Diamond tool — A close up of the segment of a diamond saw blade A diamond tool is a cutting tool with diamond grains fixed on the functional parts of the tool via a bonding material or another method.[1] As diamond is a superhard material, diamond tools have… …

    Wikipedia

  • 2Duplicating machines — were the predecessors of modern document reproduction technology. They have now been replaced by digital duplicators, scanners, laser printers and photocopiers, but for many years they were the primary means of reproducing documents for limited… …

    Wikipedia