Product Description:

The 1MR310B-A094/S026 is a rotor subassembly manufactured by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. As a frameless spindle motor component, it mounts directly on a machine-tool shaft to create a compact high-speed drive. Its geometry, running clearances, and threaded features support an interference fit with the mating spindle, so torque is transferred without keys or external couplings. This arrangement is common in precision grinding and milling centers where low runout and a short powertrain are important.

A balancing ring thread of M10 allows correction weights to be added after assembly to meet vibration limits. A 30° entry chamfer guides the rotor onto the shaft and helps protect the spindle seat during installation. The primary inside diameter is 94 mm, and fit class s6 is used on that seating zone to provide the required interference after thermal expansion. The minimum spindle engagement length is 273 mm, which provides enough overlap to distribute shear stress along the rotor body. A stepped fit is used on the second seating zone, and length code B indicates the axial package size, while a relief angle and shallow relief depth help reduce extraction force during disassembly.

The secondary fit zone uses class t6, which tightens the tolerance toward the drive end while helping limit hoop stress in the rotor sleeve. The rotor outside diameter of 228.7 mm sets the radial build and supports a uniform air gap inside the stator bore. Balancing elements are secured with a pin made to the DIN 913 standard for thread compatibility. Tool clearance at the shoulder is limited by an undercut width of no more than 5 mm, and the matching under-seat chamfer completes the geometry without adding extra material. The stepped interference-fit layout separates the contact areas, which helps during removal when the rotor must be pulled from the spindle.