Tectra Automation recently supplied and integrated the drive componentry for the first bevel head servomotor-driven CNC plasma cutting tables manufactured by CNC Clear Cut in Rosslyn, Pretoria. The Bosch Rexroth servo drive train, which interfaces with the CNC control through the Ethernet-based SERCOS 3 communications protocol for real-time machine response, provides an enhanced cutting accuracy and throughput for superior three-dimensional metal profiles.

“The high-end plasma cutting tables have used traditional servo motors in the control of the cutting axes,” comments Paul van Niekerk, CNC Clear Cut. “While these motors were fit for purpose, they did not have the accuracy, speed and controllability of the Bosch Rexroth servomotor with integrated SERCOS 3 communications.”

Apart from being the supplier of the servomotors, servo drives and planetary gearboxes, as well the aluminium profiles for the torch bridge, Tectra Automation integrated the drive train, including engineering, programming, coding and fine tuning. Tectra Automation sized the servomotor requirements according to the torque, speed and inertia specification of each machine cutting axis.

“The servo system with integrated SERCOS 3 protocol improves machine output, enhancing production, productivity and quality of the finished product by providing an instantaneous instruction relay between the CNC control and the servo system across SERCOS 3,” explains Georg Venter, Divisional Manager, Electric Drives and Controls, Tectra Automation. “SERCOS 3 also offers a high immunity to electrical noise, which, given the electrical nature of plasma generation, was an invaluable aspect of attaining a more precise, higher-quality plasma operation.”

CNC Clear Cut has, to date, built two plasma tables utilising this servo system configuration. The first machine incorporated a sophisticated bevel cutting head, which allows machinists to swivel the plasma arc, for the cutting of, for example, precise three-dimensional cone profiles. This requires two motors synchronised for the longitudinal axis; a single motor for the cross axis; a motor for the cutting torch height; and two motors for the control of the bevel action. Five planetary gearboxes were used with the servo motors. The second machine did not incorporate the bevel mechanism, and thus was comprised of four servomotors requiring three planetary gearboxes.

Tectra Automation is a member of the Hytec Group of Companies, the sole importer and official OEM partner of Bosch Rexroth in Africa.