With NUM’s new brushless servomotor ranges for CNC machinery applications, machine builders can now use a single drive-to-motor cable for each motion axis. This reduces cabling, speeds installation/commissioning, and improves performance.

The SHX and SPX brushless servomotors are available in 75, 95, 126 and 155mm frame sizes and three different lengths, offering a wide choice of output power and speed ratings. Both ranges feature high mass moments of rotor inertia, optimised for machine tool feed axes, and combine excellent dynamic performance with smooth running. The SHX range is intended for cost-sensitive applications and includes models with continuous torque outputs from 1.2 to 20Nm. For applications demanding motors with maximum power-to-volume ratios and a high degree of protection (IP67), such as high-end machine tools, grinding machines and robotics, the SPX range offers units with continuous torque ratings from 1.4 to 23Nm.

Developed for use with NUM’s latest-generation NUMDrive X digital servodrives and Flexium+ CNC platform, both servomotors only require a single cable connection. An embedded digital interface scheme allows the encoder power and position feedback data – together with diagnostic information and thermal data from the motor’s temperature sensor – to be carried on just two shielded wires contained within the motor’s power cable.

Additional features include a choice of single- or multi-turn digital encoders with medium, 20-bit (1,048,576 positions per turn) resolution and ±60 arcseconds accuracy. Backed by the precision control capabilities of NUM’s new Flexium+ CNC kernel, this level of encoder performance facilitates very smooth interpolated move profiles and fine adjustment of speed, states the company. Both encoders are also available in safety versions.

In addition, each drive module can incorporate a variety of safe motion monitoring functions such as Safe Torque Off, Safe Stop 1 and 2, Safely-Limited Speed, etc., with all critical system operations overseen by a centralized safety PLC that forms an integral part of the Flexium+ CNC system.

As standard, SHX motors have varnish impregnated housings with an IP64 rating, and their shafts are protected to IP54. The SPX motors feature a special corrosion resistant coating, and both the housings and shafts have an IP67 rating. If even higher levels of shaft protection are required for applications involving direct exposure to fluids such as cutting oils, the motors can be pressurised by connection to a compressed air supply.

NUM estimates that for a typical high-end CNC machine installation involving 20m cable lengths, the new technology can reduce total motor cabling costs by as much as 20% per axis.


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