An apparatus and process for grinding out faults on the surface of a ferromagnetic workpiece includes the step of placing a grinding device on the workpiece, magnetizing the workpiece by a magnetizing device, sensing surface faults in the magnetized workpiece by first and second sensing elements placed above first and second check points and grinding the sensed surface faults of the magnetized workpiece by the grinding device. The workpiece is operatively and repeatedly transported in one direction with respect to the first and second elements and the grinding device, and repeatedly returned in a direction opposite to the first direction. The ground workpiece is tested for faults at the first and second check points, and the first and second checkpoints are arranged behind and in front of the grinding device, respectively, with respect to the opposite direction of movement of the workpiece. The workpiece is additionally ground in dependence of the fault detected at the first check point, and repeatedly ground
