Product Description:

The 1MR312B-A060 rotor is supplied by Bosch Rexroth Indramat for integration into the 1MB High-Speed Asynchronous Motors series. As a dedicated rotor for a frameless spindle motor, it forms the rotating magnetic element that works with an external stator to deliver the high surface speeds used in machine tool and automation spindles. Because it is supplied in kit form, the assembly can be built directly into the spindle housing to shorten the power train and reduce runout. This arrangement also allows the spindle to use the machine's own bearing system and housing instead of a separate motor enclosure.

In mechanical terms, the unit has a protection class of IP00, so it must be installed inside an enclosed spindle that provides its own sealing and grounding. The motor uses an open kit design, which means there is no external casing and the surrounding machine structure handles cooling. A frame size of 312 identifies the compatible stator diameter and bearing set. The through-shaft has a 60 mm bore for drawbars or coolant tubes, and the rotor is secured by a step interference fit to maintain concentricity at speed. Electrical connection is made through a single connection cable, which avoids slip rings and simplifies routing. Motor length code B indicates the active stack height and influences the available torque curve.

For service conditions, the rotor tolerates coolant pressures up to 6 bar, allowing liquid circuits to remove loss heat without leakage. Acoustic emission is limited to 75 dB(A) when the spindle runs at rated speed. Ambient operation is permitted up to 40 °C, and installation altitude is limited to 1000 m so cooling air remains effective. Because an encoder is not included, the machine must provide separate feedback hardware for position or speed monitoring.