The main HPGR manufacturers are Polysius, KHD, and Koppern, all originating from

Germany. Polysius favours a high aspect ratio design – large diameter, small width, and provides for a larger operating gap and reduced wear, while both KHD and Koppern prefer a low aspect ratio. Each of these companies has spent considerable time and resources to improve the technology to reduce wear and develop superior rolls which include the use of studs, segments, edge protection inserts, and advanced materials of construction.