The RAC Spindle Drive Controllers series from Bosch Rexroth Indramat comprises digitally controlled AC main spindle drive controllers intended for numerically controlled machine tools, providing high stiffness and a wide constant-power speed range for demanding spindle applications.
Across the RAC2, RAC3, and RAC4 variants, the platform supports Indramat 2AD asynchronous main spindle motors and 1MB frameless spindle motors, covering continuous output power ranges that span roughly 10 kW up to 93 kW depending on the controller and motor combination. The series includes an internal spindle positioning capability with a dedicated position control loop that can index the spindle on command and can also run the spindle as a precision servo axis (C-axis) using high-resolution feedback for accurate low-speed control. RAC controllers are designed for direct connection to three-phase industrial mains and manage braking energy through regeneration back to the supply network, with integrated mains contactor and emergency-stop behavior described for the controller architecture. Commissioning and integration are built around a plug-in AS programming module for storing parameter sets, selectable command/feedback interfaces (analog ±10 V, 16-bit digital, or SERCOS), optional encoder and synchronization inputs for spindle feedback, and optional extra functions such as incremental encoder output, RS-232 parameter handling, and discrete position selection via a digital position setpoint interface.
