Product Description:

The 1MR375D-S125 rotor is supplied by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. It serves as the rotating element in a frameless spindle assembly where torque is generated electromagnetically and transmitted directly to high-speed machine tool spindles. In this role, the rotor combines a shrink-fit construction with rust-protection varnish so that it can be mounted to a customer-specific shaft while resisting corrosion during coolant-rich machining cycles.

The rotor employs a cooling mode of IC3W7; an external liquid circuit draws heat from internal channels to keep motor temperatures low during continuous duty. Its frame size of 375 aligns the rotor diameter with stators of the same series, providing a standard mechanical envelope for retrofit or new-build spindles. An inside rotor diameter of 125 mm allows the user to clamp the component onto thick hollow shafts often found in high-power milling heads. The mechanical speed limit is 6000 rpm, which is the maximum permissible surface velocity before centrifugal forces exceed the shrink-fit retention stresses. The electrical design uses 3 pole pairs, so synchronous speed changes in 166.7 Hz increments when the stator field frequency is adjusted, giving predictable speed-to-frequency mapping.

A rotational inertia of 1.73 kg·m² moderates acceleration rates, matching the energy storage needed for large-cutter starts without overloading the drive. The steel laminate stack and shaft sleeve weigh 134 kg, a value that must be considered when selecting spindle bearings and lift equipment. With a protection class of IP00, the rotor itself offers no housing and must be used inside a sealed motor frame that provides isolation from the surrounding environment. Thermal class 155 (F) sets the maximum allowable insulation temperature, helping preserve varnish integrity when coolant flow or ambient conditions push the stator toward its thermal limit.