Model-Based Feedforward Control of Part Height in Directed Energy Deposition

Wang, Qian; Li, Jianyi; Nassar, Abdalla R.; Reutzel, Edward W.; Mitchell, Wesley F.

doi:10.3390/ma14020337

Cited by 12 publications

(3 citation statements)

References 33 publications

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“…Another aspect to highlight is the possibility of reducing the computational operations with the developed measurement algorithm in SFS, which is advantageous if we compare it with other new approaches based on the dynamic modeling of melt-pool geometry [35]. Here, the modeling approximation, costly in terms of computation, will inevitably cause errors in estimating the build height in LMD.…”

Section: Lmd In-line Layer Height Measurementmentioning

confidence: 99%

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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%

Section: Woc Wetting Angle Measurementmentioning

confidence: 99%

In-Line Height Measurement Technique for Directed Energy Deposition Processes

Borovkov

Yedra

Zurutuza

et al. 2021

JMMP

View full text Add to dashboard Cite

show abstract

“…Earlier literature on AM control focused on the control of process parameters for direct energy deposition (DED), but recent researchers have been working on the process control of SLM process due to enhanced applications. The literature of the DED process presents the use of PID control, feedback control for clad height [14], predictive control for clad height and temperature [15], multivariable melt pool geometry and temperature control [16], feedforward control for clad height [17], model-based PI control to regulate temperature [18], and model-based feedforward control for part height [19]. In the DED, the powder deposition occurs via the deposition of a controlled amount of powder in the melt pool.…”

Section: Introductionmentioning

confidence: 99%

Feedback Control of Melt Pool Area in Selective Laser Melting Additive Manufacturing Process

et al. 2021

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Selective laser melting (SLM), a metal powder fusion additive manufacturing process, has the potential to manufacture complex components for aerospace and biomedical implants. Large-scale adaptation of these technologies is hampered due to the presence of defects such as porosity and part distortion. Nonuniform melt pool size is a major cause of these defects. The melt pool size changes due to heat from the previous powder bed tracks. In this work, the effect of heat sourced from neighbouring tracks was modelled and feedback control was designed. The objective of control is to regulate the melt pool cross-sectional area rejecting the effect of heat from neighbouring tracks within a layer of the powder bed. The SLM process’s thermal model was developed using the energy balance of lumped melt pool volume. The disturbing heat from neighbouring tracks was modelled as the initial temperature of the melt pool. Combining the thermal model with disturbance model resulted in a nonlinear model describing melt pool evolution. The PID, a classical feedback control approach, was used to minimize the effect of intertrack disturbance on the melt pool area. The controller was tuned for the desired melt pool area in a known environment. Simulation results revealed that the proposed controller regulated the desired melt pool area during the scan of multiple tracks of a powder layer within 16 milliseconds and within a length of 0.04 mm reducing laser power by 10% approximately in five tracks. This reduced the chance of pore formation. Hence, it enhances the quality of components manufactured using the SLM process, reducing defects.

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Gaussian-process based modeling and optimal control of melt-pool geometry in laser powder bed fusion

Ren

Wang

2021

J Intell Manuf

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Model-Based Feedforward Control of Part Height in Directed Energy Deposition

Cited by 12 publications

References 33 publications

In-Line Height Measurement Technique for Directed Energy Deposition Processes

In-Line Height Measurement Technique for Directed Energy Deposition Processes

Feedback Control of Melt Pool Area in Selective Laser Melting Additive Manufacturing Process

Gaussian-process based modeling and optimal control of melt-pool geometry in laser powder bed fusion

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