Automated welding: the basis for sustainable hopper manufacturing
With a strong partner at its side, HORSCH introduced a new process for welding hopper seams – with clear quality advantages and additional improvements with regard to occupational safety.
Large, thin-walled hoppers with weld seams that are up to three meters long place high demands on the manufacturing process. For suppliers, this did not only mean long welding and grinding times, but also considerable physical strain on the employees. Against this background, HORSCH focused on how to improve the quality and process of welding the hopper seams. "We repeatedly examined the hopper issue and wondered what we can optimize," says Florian Forster (project manager, quality management). Since mid-2022, he and his team have been working specifically on a solution.
Within the scope of a final thesis, the economic efficiency of automated welding was analysed. At the same time, Quadrus Metalltechnik – a long-standing partner with experience in robot welding – started contacting equipment manufacturers and evaluating technical concepts. After an extensive analysis, it was clear that approximately 85% of a Pronto hopper could be welded automatically by means of robots. Quadrus, therefore, decided to invest in a corresponding robot system. "Quadrus was a key team player right from the start," Florian Forster emphasises. "Without this partner, we wouldn't have been able to implement the project – especially regarding their technical expertise in this sector."
Optimised process, better results
Manual welding requires long seams that have to be welded section by section. "A three-meter-long weld seam cannot be welded manually in one go; you have to pause," Florian Forster explains. The start of the weld seam remains visible and has to be ground afterwards to achieve an even appearance. With the robot, this step is eliminated because the seam is welded in one continuous pass.
Sensors also play a key role in ensuring consistent quality. An integrated laser scanner first scans the component geometry and precisely identifies the weld seam position. Only then does the robot follow the programmed welding path – always maintaining the same distance to the component. This ensures reproducible results and a consistent work pattern.
With automation, the welding process itself was adapted, too: the hoppers are now processed by means of the CMT method which requires significantly less heat and minimises distortion in the thin sheet metal. The robot maintains a stable distance and creates a straight line so that for most components, single-sided welding from the outside is sufficient. The previous manual welding on both sides is therefore no longer necessary.
The new process eliminates all grinding work. Grinding always carried the risk of unintentionally removing base material or weakening the weld seam. Now, the material remains completely intact reducing potential sources of error. The results speak for themselves: the weld seams are significantly more even in appearance, easier to assess, and have less pores – which has a positive effect on the corrosion behaviour. All in all, the result is a consistently high quality.
Occupational safety also benefits significantly. "Welding involves hazards – heat, arc radiation, smoke, fumes," Florian Forster points out. As the robot takes over these steps and grinding work is eliminated, this workload is taken off the employees.
Statements from Quadrus
Alexander Ram about the challenges and the co-operation.
“One of the biggest challenges was to achieve the required precision in thin sheet metal sector. We are talking about tenths of a millimetre to ensure the burn-through of the root of the weld seam fits perfectly. This starts with the tack-weld templates and extends to the sensor settings. In our co-operation with HORSCH, we constantly had to adjust the geometry if the robot couldn't reach a certain area.
In the beginning, we did not know if it would even work at all. Now we proved that it does. And now it's about optimizing even further what we already have.”
Andreas Buron about working on the new plant and setting up the welding process
"For me, the project was very interesting because the hopper system with all its sensors is on a completely different level than the robot welding systems I had programmed previously. We had training courses for it, and due to close coordination with HORSCH, we were able to build the process step by step.
Choosing the right sequence of weld seams is also important to minimise distortion. And when you see what you can do with a system like this, it's truly impressive."
Functionality and tests
Currently, two different Pronto hoppers are welded by the robot plant as standard, and a third is in the programming phase. Quadrus handles the complete offline programming: HORSCH provides the hopper’s STEP file. Quadrus integrates them into the 3D software of the robot cell, defines welding parameters, specifies the weld seam paths, and creates the robot program. The program is then re-taught online at the plant to precisely adjust the weld seam positioning.
Before series production started, the first machines with robot-welded hopper underwent intensive durability testing at the circular test facility in Schwandorf. Only then did they start with a smaller batch – first 20 machines, then 50. The machines with the robot-welded hoppers have now been in working in the field for some time. "The customers are absolutely enthusiastic," Florian Forster reports.
For the coming year, the production of 350 to 400 hoppers with this process is planned. At the same time, HORSCH and Quadrus are working on extending the process to other hoppers, e.g. those used for the Maestro. This does not only involve programming but also design modifications to make components suitable for robot processing. The project is designed for the long term: higher production volumes, consistently high quality, and reduced staff requirements in a sector where skilled workers are hard to find. "We want to position ourselves for the future," Florian Forster summarizes.