A review on in situ monitoring technology for directed energy deposition of metals

Tang, Zijue; Liu, Weiwei; Wang, Yiwen; Saleheen, Kaze Mojtaba; Liu, Zhichao; Peng, Shitong; Zhang, Zhao; Zhang, Hongchao

doi:10.1007/s00170-020-05569-3

Cited by 149 publications

(55 citation statements)

References 218 publications

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“…This technique is promising for the measurement of layer height in LMD as key data for the stability of the deposition and for the control of the process. Recently, this has been a trend included in reviews that talk about the challenges to be addressed with monitoring technologies [34].…”

Section: Lmd In-line Layer Height Measurementmentioning

confidence: 99%

In-Line Height Measurement Technique for Directed Energy Deposition Processes

Borovkov

Yedra

Zurutuza

et al. 2021

JMMP

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Directed energy deposition (DED) is a family of additive manufacturing technologies. With these processes, metal parts are built layer by layer, introducing dynamics that propagate in time and layer-domains, which implies additional complexity and consequently, the resulting part quality is hard to predict. Control of the deposit layer thickness and height is a critical issue since it impacts on geometrical accuracy, process stability, and the overall quality of the product. Therefore, online feedback height control for DED processes with proper sensor strategies is required. This work presents a novel vision-based triangulation technique through an off-axis located CCD camera synchronized with a 640 nm wavelength pulsed illumination laser. Image processing and machine vision techniques allow in-line height measurement right after metal solidification. The linearity and the precision of the proposed setup are validated through off-and in-process trials in the laser metal deposition (LMD) process. Besides, the performance of the developed in-line inspection system has also been tested for the Arc based DED process and compared against experimental weld bead characterization data. In this last case, the system additionally allowed for the measurement of weld bead width and contact angles, which are critical in first runs of multilayer buildups.

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Section: Lmd In-line Layer Height Measurementmentioning

confidence: 99%

In-Line Height Measurement Technique for Directed Energy Deposition Processes

Borovkov

Yedra

Zurutuza

et al. 2021

JMMP

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“…Experimental determination is time-consuming and costly due to the large number of the process operating parameters. Typically, thermocouples and infrared thermography are used to determine temperature fields [ 12 , 13 , 14 , 15 , 16 ]. However, it is not possible to directly measure the object temperature using thermography.…”

Section: Introductionmentioning

confidence: 99%

Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process

2021

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The work is devoted to the development of a model for calculating transient quasiperiodic temperature fields arising in the direct deposition process of thin walls with various configurations. The model allows calculating the temperature field, thermal cycles, temperature gradients, and the cooling rate in the wall during the direct deposition process at any time. The temperature field in the deposited wall is determined based on the analytical solution of the non-stationary heat conduction equation for a moving heat source, taking into account heat transfer to the environment. Heat accumulation and temperature change are calculated based on the superposition principle of transient temperature fields resulting from the heat source action at each pass. The proposed method for calculating temperature fields describes the heat-transfer process and heat accumulation in the wall with satisfactory accuracy. This was confirmed by comparisons with experimental thermocouple data. It takes into account the size of the wall and the substrate, the change in power from layer to layer, the pause time between passes, and the heat-source trajectory. In addition, this calculation method is easy to adapt to various additive manufacturing processes that use both laser and arc heat sources.

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“…Monitoring methods can be also classified, by regarding the topological setup, as on-axis (coaxial) and off-axis with respect to the laser beam. Equipment with different technical characteristics can detect different aspects of the process, and by combining different systems, more sophisticated analyses can be carried out [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Coaxial Monitoring of AISI 316L Thin Walls Fabricated by Direct Metal Laser Deposition

et al. 2021

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Direct metal laser deposition (DMLD) is an additive manufacturing technique suitable for coating and repair, which has been gaining a growing interest in 3D manufacturing applications in recent years. However, its diffusion in the manufacturing industry is still limited due to technical challenges to be solved—both the sub-optimal quality of the final parts and the low repeatability of the process make the DMLD inadequate for high-value applications requiring high-performance standards. Thus, real-time monitoring and process control are indispensable requirements for improving the DMLD process. The aim of this study was the optimization of deposition strategies for the fabrication of thin walls in AISI 316L stainless steel. For this purpose, a coaxial monitoring system and image processing algorithms were employed to study the melt pool geometry. The comparison tests carried out highlighted how the region-based active contour algorithm used for image processing is more efficient and stable than others covered in the literature. The results allowed the identification of the best deposition strategy. Therefore, it is shown how this monitoring methodology proved to be suitable for designing and implementing the right building strategy for DMLD manufactured 3D components. A fast and stable image processing method was achieved, which can be considered for future closed-loop monitoring in real-time applications.

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A review on in situ monitoring technology for directed energy deposition of metals

Cited by 149 publications

References 218 publications

In-Line Height Measurement Technique for Directed Energy Deposition Processes

In-Line Height Measurement Technique for Directed Energy Deposition Processes

Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process

Coaxial Monitoring of AISI 316L Thin Walls Fabricated by Direct Metal Laser Deposition

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