Product Description:

The 1MR240F-A087 is a dedicated rotor component produced by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. Within a frameless spindle assembly this rotor mates with a stator to convert drive current into mechanical rotation for CNC machining centers, grinding heads, and other precision automation tasks. By supplying a balanced, high-speed rotating mass, the part supports the compact, liquid-cooled spindle concept that characterizes the 1MB series.

The rotor is built to a 240 frame size, indicating an outer lamination diameter that matches stators in the same dimensional class and provides sufficient flux area for high torque density. An internal 87 mm bore allows the unit to slide over a precision spindle shaft while still leaving wall thickness for mechanical strength. Dynamic behavior is influenced by a 0.12 kg·m² inertia; this moderate value shortens acceleration times without sacrificing stability at rated speed. The steel stack and squirrel-cage conductors bring the total rotating mass to 29.9 kg, a figure that must be considered during spindle bearing selection. Length designation in the motor’s code is F, defining the active axial stack height so drive engineers can match coolant flow and magnetic loading to the chosen stator.

Service and mounting features complete the rotor’s integration into the spindle. Two dedicated hydraulic oil ports count 2, permitting controlled hydraulic expansion of the bore during assembly or removal and minimizing shaft damage. The rotor is machined with step interference fit, a geometry that establishes defined seating positions and maintains concentricity under high centrifugal forces. A sealing ring sized AS568A-88.49 × 3.53 mm protects internal passages from coolant ingress. Its classification as a Rotor for 1MB Frameless Spindle Motor guarantees interchangeability across 1MB stators of equal frame and length codes without additional balancing.