A workpiece spindle holds the workpiece and causes it to rotate at a defined speed during machining. Its design affects runout, rigidity, speed, torque, and thermal behavior. Therefore, the bearings, drive, cooling, lubrication, workpiece clamping, and sensor systems must be tailored to the machine tool and the machining process. The following answers explain the function, design, and selection of workpiece spindles for lathes, turning centers, and combined turning-milling applications.