Real-time laser process monitoring system with fibre integrated sensors
Detection of events during laser material processing is done with sensors from lateral and coaxial perspectives. Making use of the fibre that delivers the processing laser beam however is new. In laboratory tests the detection of back radiation through the processing fibre has been demonstrated in some applications. A robust detection of quality relevant features in an industrial environment still needs to be developed taking into account all environmental influences that can occur. While the advanced technology has improved productivity, the remaining problem is to detect weld defects quickly, reliably and cost-effectively in on line mode because post process detection accounts for scrap and economic losses.
The successful implementation of suitable sensors and detection algorithms will deliver data that can be used for process analysis. The identification of robust correlations between signals and welding defects then sets up an ICT based decision system to either adapt processing parameters or to stop the manufacturing task for manual re-inspection. Once accepted by the assessment partners, the validation phase of the assessment can demonstrate the possibility of reducing or even eliminating post welding quality checks.
ACTFAST demonstrates its capability to monitor and detect changes in laser welding power, and also the surface cleanliness of the components to be welded can be detected. The goal of the project was to improve the quality assurance of Sodecia’s automotive shift fork components that form part of the dual clutch transmission assembly. These components are manufactured in a hot-rolled, high strength low-alloy steel and all welds are partially penetrating butt welds. The main defects seen in these welds are lack of penetration defects as well as accuracy of the weld placement on the joint line.
The outcome of the project has been a successful step forward in reducing the part scrappage rate by providing indication via FFBD and visible light signals whether a weld process could be successful, and therefore the laser process can be inspected and corrected.
Optoskand AB (supplier), Sodecia Group (user), The Welding Institute -TWI- (research partner)