Product Description:

The 1MS312B-4A-A1 stator is produced by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. As the stator of a 1MB frameless spindle motor, it forms the electromagnetic core for high-speed milling or grinding spindles used in automated machining centers. Its open kit design allows direct integration into a machine housing, while the three-phase asynchronous principle creates the rotating field needed to drive the matching rotor. This format suits spindle assemblies in which the motor components are built directly into the mechanical structure instead of being installed as a complete housed motor.

This B-length stator uses liquid cooling through an aluminum cooling jacket to control winding temperature during high-speed operation. The cooling circuit can handle up to 6 bar of pressure, so the external cooling system must regulate flow. Because the unit is an Open (Kit Motor) assembly, it has an IP00 rating, so the machine must provide the required enclosure and purge air. Heat is carried away through the jacket instead of relying on free air around the stator body. Eight M8 mounting points, each 23 mm deep, secure the stator to the spindle sleeve, and a single M8 ground thread of the same depth provides protective bonding. The 1.5 m connection loom and B length leave room for routing inside cartridge housings.

Electrical interfaces exit as a single bundle at the stator end, which keeps the internal spindle wiring grouped in one location. It includes 3 power leads for the main connection, and the cable bundle has a diameter of 22 mm. The phase conductors use 16 mm² copper, matching the ground cable cross-section for protective bonding. Two NTC thermistors use sensor wires sized at 0.5 mm², giving the drive temperature feedback during operation. The separate thermistor pair helps the control system respond to rising stator temperature before the windings reach an unsafe level.