NUM develops brushless servomotors for more performance and less cabling

NUM estimates that for a typical high end CNC machine installation involving 20 m cable lengths, the SHX and SPX brushless servomotors can reduce total motor cabling costs by as much as 20% per axis. Available in 75, 95, 126 and 155 mm frame sizes and three different lengths, the SHX and SPX offer machine builders a wide choice of output power and speed ratings to match different machinery applications. Both motor ranges feature high mass moments of rotor inertia, optimised for machine tool feed axes, and combine dynamic performance with very smooth running, even at low speeds. The SHX range is intended mainly for cost-sensitive applications and includes models with continuous torque outputs from 1.2 to 20 Nm. 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 23 Nm. SHX and SPX brushless servomotors have been developed for use with NUM's latest-generation NUMDrive X digital servodrives and Flexium+ CNC platform. An innovative 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. All SHX and SPX brushless servomotors offer a choice of single- or multi-turn digital encoders with medium, 20 bit (1,048,576 positions per turn) resolution and ±60 arc-sec accuracy. With the precision control capabilities of NUM's Flexium+ CNC kernel, this level of encoder performance facilitates very smooth interpolated move profiles and fine adjustment of speed. Both encoders are also available in safety versions that return position and redundant position data to the servodrive using a secure certified protocol, and comply with the EN 61800-5-2 functional safety standard to SIL 2. NUM is also currently developing a range of high resolution 23 bit digital encoders featuring an accuracy of better than ±45 arc-sec, for applications demanding ultra precise positioning. 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. All SHX and SPX brushless servomotors are available with plain or keyed shafts, an optional electrically actuated permanent magnet holding brake, and a choice of stator winding configurations. Designed for use in ambient temperatures between 0 and 40ºC, the motors can also be operated at up to 55ºC with appropriate power de-rating.