Product Description:

The 1MR310B-A108 is the rotor component used in Bosch Rexroth Indramat's 1MB High-Speed Asynchronous Motors series. As a dedicated rotor for a frameless spindle motor, it provides the rotating mass that couples directly to the machine tool spindle, supporting the surface speeds required in automated milling, drilling, and grinding processes. Its construction allows seamless integration into liquid-cooled stator assemblies to maintain thermal stability during continuous service.

With a frame size of 310, the rotor sits centrally in the corresponding stator channel and uses a step interference fit that locks the shaft along a 177 mm contact zone to minimize slip under high torque. The outside diameter is held to 228.7 mm with a -0.05 mm tolerance, while the overall length reaches 265 mm, placing the magnetic core safely within the 273 mm minimum spindle housing length. Code B in the motor length table indicates the axial buildup used for this variant. A measured mass of 65 kg and a polar moment of inertia of 0.477 kg·m² balance dynamic start-stop profiles against bearing loads, enabling rapid acceleration without excessive overshoot. These physical properties support the elevated rotor surface velocities demanded in finishing operations.

Assembly features ensure accurate seating and oil circulation once the rotor is inside the machine tool. A ground bore of 108 mm with an H6 tolerance accepts the matching spindle shaft, while the adjacent spindle fit is 108 mm s6 over a 180 mm engagement to keep radial runout low. The secondary spindle step measures 107.8 mm t6 for back-to-back alignment with tool adapters. Dynamic balance correction can be performed through an M10 thread provided for the balancing ring, and lubrication is routed through an M6 pressure-oil port that feeds the bearing set. Magnetic symmetry is maintained by the rotor's 3 pole pairs, completing the electromagnetic circuit established by the stator.