Product Description:

The 1MR310D-A120 rotor is a removable rotating element developed by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. As a frameless spindle motor component, it mounts on the machine-side shaft and works with a separate stator to generate the magnetic field that drives high-speed grinding, milling, and routing spindles in CNC equipment. Its role is to provide the mechanical core for high circumferential velocity while keeping thermal mass and balance suitable for precision machining tasks during high-speed operation. It is intended for spindle systems that rely on precise concentricity and controlled thermal behavior.

The rotor has an inside bore of 120 mm for a rigid shrink fit on the machine shaft. Its outside diameter of 228.7 mm sets the working air gap, and an overall length of 330 mm provides the active surface needed to produce torque. Dynamic response is influenced by the mass moment of inertia of 0.492 kgm², which helps the drive accelerate the spindle without excessive current demand. The rotor uses 3 pole pairs, which sets the relationship between mechanical speed and inverter frequency during operation.

A balancing ring thread of M10 allows residual unbalance to be corrected at running speed. The rotor belongs to frame size 310, and its shoulder-to-shoulder dimension of 242 mm fixes the axial location between mounting shoulders. A protection rating of IP00 means the part must be installed inside an enclosed motor housing before use. The outer surface uses a step interference fit, both main and secondary bores use an H6 tolerance, and motor length code D corresponds to the lamination stack height used for the required power density. This arrangement supports accurate rotor placement within the spindle assembly and helps preserve the intended air gap during operation.