LAG deploys welding robot on bulk truck line

Prompted by a shortage of professional welders, commercial vehicle manufacturer LAG, from Bree, Belgium, to take the step two years ago to automate welding of aluminium tanks. Together with Valk Welding, LAG has optimised the welding process at a number of crucial points where, after a start-up period of some months, the welding station forms a reliable link in the bulk truck line. “Now that the robot takes care of the mundane welding, we can use our professional welders for more complex welding. With this, we produce more welding work with the same number of employees,” tells Manufacturing Engineering Supervisor Gareth Bonnell, Process Engineer Jos Clijsters and Manufacturing Manager Leon Bokken.


LAG builds about 300 tanks a year in a large number of variations over this production line. Previously, these were manually welded at various stations. The move to line production, where the tanks are fed on a rail in a fixed cycle time past each station for a specific operation, meant a change in the design and the preliminary process for LAG. Each operation must be equivalent for each type at all times, was LAG’s goal.

What did that mean for welding?

More welding jigs were needed in order to use a welding robot to weld the front, back, cylindrical tube, reinforcing ribs and manholes of the tanks. Gareth Bonnell: “In addition, a welding robot doesn’t consider large gaps in the weld, therefore you have to be more aware of tolerances. That meant we had to adapt the preliminary process to make sure the gaps were within the tolerances.” Adaptive welding has since been developed and marketed by Valk Welding in the form of “Arc Eye Adaptive Welding”.

High reliability

LAG asked several robot integrators to be able to provide a large installation in which the aluminium tanks could be robotically welded with high reliability. “After all, stoppage of welding production means that the entire line would then come to a standstill”, Gareth Bonnell emphasises. “Valk Welding, with their knowledge and experience in the field of welding robot technology was able to fill in the complete picture, both hardware-wise and software-wise. In doing so, their methodology of offline programming allows line production to not have to be interrupted for programming.”

Aluminium welding process

“Aluminium is always a somewhat more difficult material to weld, moreover, due to the large distance between barrel and robot torch, the feeding of the welding wire requires the necessary attention. To enable accurate wire feeding, Valk Welding has developed its own solution, where the wire motor is integrated into the robot torch. With this VWPR QE Servo Pull robotic torch, the welding wire can be fed short on the welding seam according to the push-pull principle. Together with the Spiral Weaving MIG process of Panasonic, this has been extensively tested at Valk Welding. The fact that Valk Welding has everything in house, also in the field of welding wire supply, is a strong advantage”, says Gareth Bonnell.

Track welds precisely with Arc-Eye laser sensor

To make it possible for the welding torch to continue to follow the weld seam precisely over long lengths, Valk Welding deploys the Arc-Eye CSS laser sensor which, mounted on the robot torch, scans the weld seam in real time and, if necessary, corrects the trajectory of the welding robot.
“Initially, we were sceptical due to the fact that the reflections on the aluminium would interfere with the scanning image, but the Arc-Eye turned out not to be sensitive to this. So, the weld seam tracking works perfectly”.

Effectiveness increased

“Within this line, we can now flexibly produce a large number of variants. Because not all variants have been programmed yet, we are now constantly adjusting programs. Despite this, the effectiveness has been greatly increased because the welding robot has taken over most of the monotonous welding work from the hand welders. With the bulk line we are now at maximum efficiency. We will therefore now also look at how we can do the same for the other lines”, Leon Bokken looks ahead.

Valk Welding built a welding robot installation in which the welding robot on a YZX gallows construction moves together with the robot control. The welding fume extraction unit and the welding wire drum moving along with the height displacement over a 17 meter long track to reach all positions optimally.

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