TPT March 2025

TECHNOLOGY

Boosting welding quality with robot assistance WIRESENSE, TouchSense and

A reversing wire movement, which takes place at around 100Hz, causes the electric motor in the drive unit to scan the metal surface with the wire. It is this high frequency scanning of the workpiece that provides the necessary levels of precision. Even if the surface being scanned is uneven, such as the sheets lying at an angle, the edge can still be detected and measured without any difficulty. “Our WireSense technology uses the scanning function of the reversing CMT wire movement to determine the exact position of the component and edge as well as air gap heights. Steel, stainless steel and aluminium sheets from 0.5 to 20mm thick can be scanned quickly and precisely,” added Mr Schlor. Every raising and lowering operation on the component can be recorded accurately relative to a reference point specified at the start of the scanning process. In just seconds the robot has compared the taught positions with those measured, or in other words it has checked the stored values against the actual position data. If it detects any differences, the course of the seam is adjusted accordingly in the robot’s coordinate system and the weld is produced in the right place. With WireSense the wire electrode becomes a height sensor, allowing air gaps to be determined on lap joints using the precisely measured sheet edge height. To achieve perfect results it is possible to specify in advance which jobs stored on the Fronius welding system should be called up for different air gap sizes. This allows the robot to always respond appropriately and weld with the welding parameters that are ideal for the air gap dimension in question, preventing welding errors. The key to high quality lies in teaching the correct welding path. The tried and-tested TeachMode assistance system helps the welder set the weld seam positions on the robot, making the programming process extremely easy. The reversing wire movement prevents the wire from bending in the event of contact with the component and saves the user from having to remove the deformed wire or re-measure the stickout.

The TouchSense assistance system has been specially developed for fillet welds. Before each weld, the robot automatically touches the sheets being joined at the start and end of the weld. It does not matter whether it is the wire electrode or gas nozzle that makes contact: the signal is always clearly assigned and correctly transferred. The low sensor voltage creates a short circuit when the torch touches the workpiece, which enables the robot to precisely determine the weld position and adjust the welding parameters dynamically. Another helpful feature is the immediate warning issued if a spatter bridge forms between the contact tip and gas nozzle, allowing this to be cleaned promptly to increase precision and quality in production. “Adding special controller software to our highly sensitive and dynamic CMT drive turns the welding wire into a sensor that can identify contours or air gap deviations on the component,” said Philipp Schlor, strategic product manager, industrial welding solutions, at Fronius International. To ensure precision control of the welding wire, the Fronius welding system simply needs to be equipped with a CMT-ready system. The Welding Package – the Cold Metal Transfer (CMT) welding process itself – is not required. CMT-ready systems consist of a wirefeeder on a wire drum or wire spool, a wire buffer, and a CMT Robacta Drive, in other words a second wirefeeder on the torch itself.

TeachMode are patented assistance systems for robotic welding designed by Fronius to improve weld quality and increase efficiency. The welding wire acts as a precise sensor for the robot and simplifies welding path programming or detects deviations in the component position as well as air gaps over the course of the seam. Using this data, the robot can then correct the weld path – adjusting it precisely based on the identified position points – to save material, time and costs, as rework and component rejects are no longer an issue. Despite increasingly advanced robot technology and almost seamlessly interconnected systems, inaccuracies and deviations repeatedly occur in industrial production. In some cases, minimal material differences or imprecise clamping devices can have a negative influence on the welding result and potentially cause time-consuming rework, costly component rejects, or huge cycle time losses. Integrators often resort to using optical measuring systems to avoid having to make time-intensive manual readjustments. But laser and camera systems are expensive to buy and maintain, plus require space, which restricts access to the component. Fronius has the answer in the form of high-tech solutions for the intelligent iWave, TPS/i and TPS/i TWIN welding systems that require neither a camera nor manual readjustment.

Fronius www.fronius.com

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MARCH 2025