Pneumatic and electric automation solutions provider Festo has sold about 450 Servo-Pneumatic robot welding-gun solution systems in South Africa since the product was launched in February 2012, Festo automotive industry head Charles Hulme tells Engineering News.

“The first local use of the Servo-Pneumatic system was at vehicle manufacturer BMW South Africa’s Rosslyn plant, in Pretoria, in February 2012, on BMW’s new F30 3-Series line,” he states, adding that it was also the first time that the customised Servo-Pneumatic control technology was used on robotic welding systems in South Africa.

He explains that Festo’s Servo-Pneumatic system controls the welding gun mounted on a welding robot.

“The product has also had international success, as Festo has, to date, sold about 9 000 units to carmakers and automotive component producers, such as BMW, Volkswagen, MA Automotive and Linde + Wiemann,” Hulme points out.

Hulme says the requirements for customised welding-gun control solutions are constantly increasing.

“It is not just the quality of spot welds that play an important role. Equally important is the flexibility and speed of the welding gun. Festo has developed the Servo-Pneumatic drive and controller system to meet these specific customer requirements,” he states.

He adds that the Servo- Pneumatic system offers more than precision control and regulation of welding guns. “Each spot weld from the welding gun, can be set to an individual force and the opening gap of the welding arms can be controlled proportionally. The freely programmable opening width means that the welding gun no longer has to be fully opened when moving around disruptive edges.”

Hulme notes that the opening width of the welding arm can be freely programmed using the Servo-Pneumatic cylinder and that the pressure level in the compensation cylinder can be adapted depending on the welding gun’s position.

Further, he highlights that Festo developed a controller software program specifically for the Servo-Pneumatic welding guns.

“The ability to control the welding force results in a significant improvement in the quality of the spot welds. The commissioning software is required during initial startup in the welding-gun workshop to calibrate the gun. The software ceases to be required once the welding gun is attached to the robot arm. All application data, such as electrode position, welding force and compensating pressure, are controlled by the higher-level controller by fieldbus communication,” he notes.

He adds that the controller can monitor the welding process through the feedback of the current sensor values.

“Different interface capabilities also facilitate high levels of communication flexibility. Communication can take place through various bus systems such as Interbus, Profibus and Profinet. A computer can also be connected through a serial interface with the system,” Hulme points out.

He notes that better control means the welding gun is not subjected to the rebound impact of the electrodes, which, therefore, results in noise reduction in the factory, better quality workmanship and less breakdowns, thereby ensuring improved production volumes and no lead time.