Product Description:

The 1MR242N-C071 is a rotor assembly built by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. It is designed to be integrated into frameless spindle motors used in machine-tool and automation systems where compact envelopes and high rotational speed are critical. As the rotating element of the motor, the rotor works with a separately supplied stator to generate the torque and surface speed required for metal cutting, grinding, or high-speed positioning.

The rotor belongs to frame size 242, giving it a fixed outside diameter that matches the corresponding stator bore. Its central bore measures 71 mm, allowing the spindle shaft to pass through while leaving room for a coolant tube or sensor wiring. During operation, the rotor may reach a mechanical speed of up to 16,000 rpm; this limit sets the ceiling for spindle surface speed and influences bearing selection and dynamic balance quality. The rotor has 2 magnetic pole pairs, which set the electrical frequency used by the stator field and the relationship between input frequency and mechanical speed. The rotational energy stored at rated speed is determined by a mass moment of inertia of 0.135 kg·m², which affects acceleration, deceleration, and the spindle controller's tuning parameters.

Total rotating mass is 36.9 kg, a value that must be considered when calculating bearing load and handling requirements. The shaft-to-hub interface uses a step interference fit, ensuring a secure press fit between the rotor and shaft without additional locking hardware. The active core uses length code N, which influences the achievable torque and the thermal dissipation path. The outer diameter is ground with allowance so that, after thermal expansion at running temperature, the rotor maintains the specified air gap to the stator without risk of contact.