Product Description:

The 1MR241H-A111 is a rotating component manufactured by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. Supplied as a bare rotor, it is intended for direct integration into high-speed machine-tool spindles, where its laminated steel core and copper squirrel cage convert stator magnetic fields into shaft rotation. Delivering the moving part separately allows the surrounding spindle assembly to use application-specific cooling, bearings, and housing geometry while keeping a standardized rotor architecture. This format is used where the spindle shaft and surrounding stator are designed as part of the machine structure rather than as a complete housed motor.

The rotor belongs to frame size 241, which aligns its outside diameter with 1MB stator segments of the same designation. Its central bore is machined to 111 mm, allowing shrink-fit mounting on a hollow spindle shaft or space for through-spindle coolant lines. Dynamic response is influenced by a polar moment of inertia of 0.227 kg·m², which supports stable rotation while still permitting speed changes at high operating frequencies. A total mass of 39.5 kg adds thermal capacity and helps delay temperature peaks during extended high-speed operation. Mechanical retention is provided by an outer surface with a stepped interference fit, which helps maintain concentricity during repeated thermal cycling.

The rotor uses motor length code H, so the active iron stack extends farther axially than shorter codes and increases torque potential without changing the radial envelope. Because the operating principle is asynchronous, the rotor induces current in its bars instead of using permanent magnets, which avoids rare-earth magnetic materials and supports overspeed operation. It is classified as a Rotor for 1MB Frameless Spindle Motor, and the pre-ground rotor bore supports accurate mounting on the spindle shaft. That arrangement is common in compact spindle systems where radial space is limited and balance quality is critical at elevated speed.