Product Description:

The 1MR375B-A170 is a rotor assembly manufactured by Bosch Rexroth Indramat for integration into the 1MB High-Speed Asynchronous Motors series of frameless spindle units. As the rotating element inside a high-speed machine-tool spindle, the rotor converts magnetic fields from the stator into mechanical torque. It provides the constant acceleration and deceleration cycles required in automated milling, drilling, and grinding systems.

This rotor belongs to frame size 375, a diameter class that matches compatible stator laminations and housing components. Its outside cylindrical surface measures 273.7 mm with a -0.05 mm tolerance, maintaining a tight air gap for efficient electromagnetic coupling. A through bore of 170 H6 mm accommodates the spindle shaft while following standard ISO tolerance bands. The design uses a step interference fit, meaning two nested diameters create progressive press zones that secure the rotor without adhesive. Dynamic response is influenced by a moment of inertia of 1.39 kg·m², giving the drive predictable acceleration profiles during tool changes. An M10 balancing-ring thread at the rotor face allows fine correction of residual imbalance, and the shoulder diameter of 197 mm provides a positive axial stop against the shaft collar. The motor length code B indicates the medium axial length variant within the 1MB platform.

The primary spindle interface is ground to 170 s6 mm, while the secondary coupling surface follows 169.7 t6 mm; these tolerances ensure concentric seating on both the drive-side and tool-side extensions. Overall rotor length is 430 mm, meeting envelope limits inside standard cartridge housings, and the assembly supports a minimum spindle length of 437 mm so that clamping nuts and sensor rings clear the stator end windings. A secondary bore diameter of 169.7 H6 mm aligns coolant tubes or drawbars, and the balancing-ring thread works with these fits to keep vibration within machine-tool limits during sustained 20,000 rpm operation.