Product Description:

The 1MR240B-A072 rotor is manufactured by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. It is used as the rotating element in 1MB frameless spindle motors, where it works with a matching stator to convert electrical energy into mechanical output for machining centers, grinding spindles, and other precision automation equipment. Because it is a frameless rotor, it is intended to be integrated directly into the spindle assembly rather than installed as a complete standalone motor. Its geometry provides the magnetic and mechanical interface needed for compact, high-speed spindle designs.

With a frame size of 240 and motor length code B, the rotor pairs with a stator section suited to tight axial envelopes. When operated at a nominal winding voltage of 122 V and a rated current of 46 A, the assembled spindle delivers 6.5 kW of continuous mechanical power at 1000 rpm and produces 62 Nm of shaft torque. This combination supports spindle layouts that need stable continuous output without excessive installation length. The winding has an inductance of 1.665 mH and a resistance of 0.213 Ω, helping the drive control current rise while limiting copper losses. The inside rotor diameter is 72 mm and the outside diameter is 163.9 mm, which sets the air gap for magnetic flux. An M6 pressure-oil connection thread is machined into the shaft, and the step interference fit helps keep the sleeve secure during thermal cycling.

Dynamic behavior is influenced by a rotor moment of inertia of 0.078 kg·m² and a mass of 19 kg, which balance speed response with bearing load. During rapid acceleration or deceleration, the inverter can supply a peak current of 101.1 A, and the torque constant of 1.57 Nm/A links current directly to available spindle torque. That relationship helps the spindle respond quickly to changing speed commands during short-duty bursts. Frequent speed changes place alternating mechanical and thermal loads on the rotating assembly, so stable alignment is important in high-speed spindle service.