Centerless grinding is a process for grinding cylindrical workpieces and is used for mass production of items such as cylinder rollers, tapered rollers, pump shafts, hydraulic spacers, cross pins, drills and much more.
The workpiece is not clamped between two centers, which is why the process is referred to as centerless grinding. The workpiece is instead located in the so-called grinding zone between the grinding wheel and the regulating wheel on a workpiece support. The rotating grinding wheel and regulating wheel put the workpiece into rotation and remove material (see illustration).
The grinding pressure from the grinding wheel  presses the workpiece  against the regulating wheel  and the workpiece support . The rotating regulating wheel provides the counterpressure required for grinding.
Yet while the regulating wheel and the grinding wheel rotate in the same direction, they have different rotational speeds. The regulating wheel rotates at a lower speed, serving as a brake for the workpiece. In addition, the regulating wheel supports the workpiece and, by determining the angle of the rotational axis and rotational speed, determines the throughfeed speed for the workpiece during traverse grinding.
The rotating workpiece sits atop the workrest blade during grinding. This impacts the quality of the grinding process in relation to its thickness, the support angle β and material used in the contact surface.
In principle, differentiation is made between two centerless external cylindrical grinding processes: plunge grinding and throughfeed grinding.