Investigation of Integrated Additive Manufacturing from Feedstock to Part Quality: Development of an in-situ monitoring technique for the detection of flaws in WAAM depositions
TWI Industrial Member Report 1183-2024 [pdf / 4,847KB]
By Capucine Carpentier andKyriakos Flentzeris
Industrial Need
WAAM is a complex process. Deviations from optimal deposition parameters, random changes in environmental conditions, feed rate and energy input may lead to the formation of flaws. In addition, different equipment, feedstock quality variations, and working conditions can ultimately obstruct the final quality of a build. In such cases, late detection of unacceptable flaws may lead to unnecessary rework or, even worse, to render a build or a batch into scrap.
WAAM stakeholders, apart from seeking ways to improve deposition quality, are also fuelling the demand for developing systems that can allow early flaw detection. Therefore, stakeholders require a system capable of determining when a flaw can jeopardise the final performance and preferably offer feedback and reassurance for the quality of each layer.
In-situ monitoring and flaw detection is a complex mission with obstacles that the NDE society has to resolve before commercialising and integrating any inspection system into a WAAM machine. Ultrasonic (UT) inspection technology keeps advancing and has been proving its value to the welding industry for decades. However, developing an ultrasonic in-situ inspection procedure for WAAM applications has to account for and consider additional factors.
Key Findings
The study conducted has demonstrated that in-situ ultrasonic inspection is possible and effective in detecting flaws and changes in component growth during the WAAM manufacturing process. The instrumentation choice allowed for ultrasonic wave propagation through the build with a good signal-to-noise ratio. The temperature affected the time of flight of the observed signals but without prohibitive results. Changes in build thickness with each new deposition and the tungsten rod lack of fusion (LOF) replica were detected.
Impact
Overall, this trial was an important milestone to pave the way for further research and advancements in in-situ monitoring and inspection of WAAM depositions.