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Additive Manufacturing: Directed Energy Deposition 2
1:30pm - 2:30pm
Session Chair: Prof. Stephan Barcikowski, University of Duisburg-Essen, Chemical Technology, Germany
Location:Room 2 ICM
1:30pm - 1:45pm
In-situ clad geometry measurement in wire laser metal deposition process
Iker Garmendia, Jon Flores, Carlos Soriano, Mikel Madarieta
Wire Laser Metal Deposition (w-LMD) is a promising technique that could generate significant cost reductions. However, process control still needs to be developed to ensure product quality. Due to the high temperature of the melt pool and the resulting light radiation, current commercial equipment can only measure the geometry of the clad after the process or between the deposition of different layers, which affects the heating and cooling cycles of the part and the manufacturing time. In this work, a measurement system based on a side mounted vision camera and laser light projection is developed, which allows an in-situ measurement of the clad geometry data. This enables to know the nozzle-to-part distance, the surface where the successive layers are deposited, or bead parameters related to the quality of the deposition.
1:45pm - 2:00pm
Structure-borne acoustic process monitoring of laser metal deposition
Irene Buchbender, Christian Hoff, Jörg Hermsdorf, Volker Wesling, Stefan Kaierle
Laser Zentrum Hannover e.V., Germany
Acoustic emissions have been used as a means for process monitoring and non-destructive testing in welding to determine process characteristics, detect anomalies and infer the quality of the welded part. While air-borne noise has been studied extensively, research on the application of body-borne sound in the process monitoring of laser metal deposition remains limited. This paper examines the use of structure-borne sound for in-process monitoring of the deposition of the Nickel-based Superalloy CMSX-4. Due to the low weldability of the material and its susceptibility to hot-cracking, there arises a need for an in-process, non-destructive method for monitoring cracking. A high-frequency-impulse-measuring device (QASS GmbH) up to 50 MHz was attached to the substrate mount. The frequency data of the signal over time was evaluated by analysing the Short-Time Fourier transform (STFT) of the raw acoustic data, the acoustic characteristics of the process were determined, acceptable thresholds set and cracking detected.
2:00pm - 2:15pm
Studies on the direction-independent temperature measurement of a coaxial laser metal deposition process with wire
Avelino Zapata, Christian J. Bernauer, Melanie Hell, Michael F. Zaeh
Technical University of Munich, Germany
Among the Directed Energy Deposition (DED) processes, the Laser Metal Deposition with wire (LMD-w) combines the advantages of a high precision and a high deposition rate. Recently, optical systems have been developed that form an annular laser spot, facilitating a direction-independent process. However, when a pyrometer is coupled to the optical system, also the measurement spot assumes the form of a ring. This work studies the inline temperature signal of a pyrometer with a ring-shaped measurement spot for the LMD-w process. High-speed videos are used to interpret the signals based on process observations. The two modalities of a single and a two-color measurement are compared regarding their reliability. The measurement setup is varied to study the influence of different process conditions on the signal. At last, a configuration is identified that allows a valid measurement. The reliable inline temperature measurement opens the opportunity to monitor and control the process.
2:15pm - 2:30pm
Process development for laser hot-wire deposition welding with high-carbon cladding material AISI 52100
Laura Budde, Marius Lammers, Jörg Hermsdorf, Stefan Kaierle, Ludger Overmeyer
Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany
An increase in wear resistance and thus an increase in service life is of great importance for many components. The production of hybrid components with high-carbon steel as cladding material offers the possibility of achieving these goals. However, materials with a carbon equivalent of more than 0.65 are considered difficult to weld due to their tendency to crack. In this study, a laser hot-wire deposition welding process with bearing steel AISI 52100 as cladding material is used to investigate the influence of laser power, wire feed speed, scanning speed, overlap ratio and wire preheating as well as interactions of these parameters on process stability, the formation of cracks and pores, the cladding waviness and the dilution. Layers of eight adjacent weld seams are welded onto an austenitic stainless steel. A stable process is observed for most parameter combinations except for samples with low wire feed speed and major wire preheating.