Almost all fabrication of structures today involves welding. Fatigue is a major cause of failure especially in welded structures, reflecting the fatigue performance of many welded joints. Whether welding together a few relatively simple parts or fabricating large, complex structures, weld fatigue is one of the most-common failure modes if the part or structure is subjected to fluctuating stresses. Therefore, the quality of welds is a top priority for manufacturers especially in automotive industry.
A robot welding unit tackling the challenges of weld quality was developed under FIMECC MANU programme. In the solution robotic control unit harnessed with machine vision system and algorithms checks if the welds, holds, bolts and other structural details are exactly in right place compared to the CAD drawing of the part. There is an adaptive feedback loop from the control unit to robot welding unit and necessary corrections can be made online.
The developed solution turns the quality checking of weld profiles in automated production systems into digital era. The solution enables adaptive correction of the welding parameters (e.g. corrections in welding path or parameters) to realize a weld with desired geometry to fulfill the high quality and fatigue strength requirements. Current solutions just check the component and in case of welding failure the component is rejected. This causes huge amount of material and production losses.
Automated operator-free robot welding solution also improves significantly the efficiency of production lines offering competitive advantage for Finnish manufacturing industry. For example in automotive industry, which is the one of the target segments of the developed solution, robotisation is a key contributor in keeping European car manufacturers competitive against the thread caused by cost pressure coming from Far-East. In addition to manufacturing, also quality control has to be done automatically by special measurement unit. The products are complex and multiple different car types are built in the same production line. There is no additional time for recalibrating the measurement systems or doing manual work for moving parts to the quality checking units. Therefore, automated quality control and inspection systems are needed.
The solution creates prerequisites for high productivity and quality welded structure manufacturing. The benefits of the developed solutions can be counted in savings in material and production losses and improved productivity. The automated quality checking in automotive industry has significant impact by reducing risk of calling back cars due to failures in suspension systems. In case of call back cases the losses are counted in tens of millions euros.
Quality is proportional to the weld performance in conditions of use. With the developed solution the resulting product service properties can be ensured reliably and accurately. As a result costs arising from poor quality, such as reclaim, scrap and downtime costs, can be minimised. For Mapvision, the manufacturer of the online visual inspection solution, this means one additional competition factor in automotive production line biddings.
- Antti Knuuttila, Oy Mapvision Ltd.
- Matti Kutila, VTT
Oy Mapvision Ltd., VTT Technical Research Centre of Finland Ltd.