Product Description:

The 1MR310D-A118/S026 rotor is manufactured by Bosch Rexroth Indramat as part of the 1MB High-Speed Asynchronous Motors series. It is supplied as a rotor for a frameless spindle motor, where it works with a dedicated stator to convert electromagnetic energy into mechanical rotation for CNC machining centers and other high-speed automation platforms. By occupying the core of the spindle assembly, the rotor provides the torque-transmitting element needed for rapid cutting and drilling operations while supporting a compact machine layout. Its frameless format also allows the motor section to be integrated directly into the spindle assembly instead of using a separate motor housing.

This unit has motor length code D and fits a frame size of 310, giving it a fixed axial envelope within the spindle assembly. A configuration of 3 pole pairs sets the electrical relationship between drive frequency and rotor speed during operation. The bore is ground to 118 H6 mm, producing the interference required for concentric, slip-free mounting on the shaft. Service balancing is handled by an internal thread of M10, allowing trim weights to be added after assembly. Dynamic response is influenced by the rotor mass of 80 kg and a mass moment of inertia of 0.492 kgm², which affect the torque required for acceleration, deceleration, and speed reversal. These features support stable rotation at high speed while keeping the mounted rotor properly centered on the shaft.

The rotor uses a step interference fit design that works with a center bore of 119 mm to guide installation and seating. Its external diameter is 228.7 -0.05 mm, which helps maintain a precise air gap with the stator, and the overall rotor length is 330 mm. Axial retention is achieved with a threaded pin that follows the DIN 913 standard. The fit geometry and retaining method help keep the rotor seated during rapid speed changes, and they support smooth running by limiting unwanted movement at the shaft interface.