Product Description:

The 1MR241H-A098 rotor is produced by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. It is a dedicated rotary element for frameless spindle assemblies in which the stator is mounted directly in the machine housing and the rotor is mounted on the shaft. By eliminating a complete motor casing, this design shortens the power train and supports high-speed milling, drilling, and grinding operations that require a compact drive envelope inside automated production cells. This arrangement is common in machine tools where spindle packaging space is limited. Because the rotor works as part of a built-in spindle motor, the surrounding machine structure supplies the support, bearing arrangement, and enclosure needed for operation.

The rotor uses Frame Size 241, which sets the outside diameter and stack height so it aligns with a matching stator bore. An inside bore of 98 mm allows the shaft or drawbar to pass through without secondary machining. This through-bore layout supports spindle designs that need a central passage for tooling or clamping hardware. The magnetic steel laminations and copper squirrel-cage conductors bring the rotor mass to 39.5 kg. The distributed mass creates a polar moment of inertia of 0.227 kg·m², which affects acceleration torque during spindle ramp-up. Because no protective housing is supplied, the component carries a IP00 rating and must be installed in a clean, fully enclosed motor cavity for safe operation.

The rotor has a permissible rotational limit of 9000 rpm, enabling the spindle to cut or grind hard materials without losing surface finish quality. The rotor core uses a step interference fit so it clamps tightly onto the shaft and maintains concentricity under centrifugal stress. A secure shaft fit helps limit vibration at elevated speed and supports stable running in precision spindle assemblies. Length designation H indicates the active lamination stack depth, which helps match thermal capacity to the intended duty cycle. Its classification as a Rotor for 1MB Frameless Spindle Motor indicates compatibility with 1MB stator kits that share the same frame code.