Product Description:

The 1MR270C-A120 is a rotor component manufactured by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. As a rotor for frameless spindle assemblies, it forms the rotating element that works with a separate stator to deliver high-speed cutting, drilling, or grinding in automated machine tools. Integrating this element into a direct-drive spindle removes transmission losses and supports precise speed regulation required by modern CNC equipment. Because it is supplied as a rotor only, the surrounding spindle structure must provide the supporting bearings, housing, and cooling path.

This rotor is built on frame size 270, giving it a diameter large enough to withstand radial forces while fitting matching stators of the same series. An inside bore of 120 mm allows the work-side shaft or tool holder to pass through without reducing structural stiffness. The maximum mechanical speed is 12000 rpm, which permits high surface-speed machining while keeping centrifugal loading within the intended operating range. Dynamic response is influenced by a rotor inertia of 0.258 kg·m², balancing quick acceleration with rotational stability during speed changes. Because the protection class is IP00, the part has no built-in enclosure and must be installed inside a housing that supplies its own sealing and cooling.

Motor length code C identifies the axial dimension used with a corresponding C-length stator so the magnetic air gap and thermal path remain correct. A rotor mass of 53.3 kg must be considered when selecting bearings, handling methods, and the spindle support structure during assembly. The step interference fit on the shaft journal provides a secure, slip-free connection to the hub after thermal installation. The unit is classified as a Rotor for 1MB Frameless Spindle Motor and is intended for integration into modular, liquid-cooled spindles rather than standalone motor assemblies. This layout supports compact spindle designs where the motor is built directly into the machine head.