Product Description:

The 1MS376A-QB-A2 is a stator subassembly for frameless spindle motors, manufactured by Bosch Rexroth Indramat and assigned to the 1MB High-Speed Asynchronous Motors series. Supplied as an open kit, it fits directly into a customer-designed housing where liquid coolant circulates through its aluminum jacket to remove heat created during torque production. In automated machining centers or grinding heads, the unit forms the stationary portion of a high-speed spindle drive that must generate stable torque at low speed before accelerating to production speed.

It develops a continuous mechanical output of 6.0 kW at the reference point of 240 rpm, where the electromagnetic field produces a sustained shaft torque of 240 Nm. To achieve this operating point, the drive inverter supplies a phase current of 21.5 A, while short duty cycles can draw up to 70.7 A without exceeding the thermal limits of the winding. The torque constant is 12.06 Nm/A, so each additional ampere produces a predictable increase in torque that the controller can use for fine vector regulation. The motor design remains open because the stator is intended to be enclosed by the machine builder, and its 1.5 m pre-loomed cable includes 4.0 mm² power conductors plus 10 mm² strand wires sized for the stated currents.

Winding parameters shape dynamic behavior. An inductance of 15.69 mH limits current rise time, allowing smooth current phasing during rapid speed commands, while a resistance of 1.898 Ω contributes to copper losses that the aluminum cooling jacket must carry away. The unsealed protection rating of IP00 requires installation inside a sealed spindle housing and explains why no dedicated sound insulation is provided; in free air, the bare stator reaches 75 dB(A). Assembly uses M8 × 22 mm fixing threads, and motor length code A allows rotor inertia to be matched without changing the electrical data.