Structured light-based height control for laser metal deposition

Garmendia, Iker; Pujana, Joseba; Lamíkiz, Aitzol; Madarieta, Mikel; Leunda, Josu

doi:10.1016/j.jmapro.2019.04.018

Cited by 42 publications

(25 citation statements)

References 27 publications

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“…The advantage over a laser line scanning system is that the measurement can be made from an external fixed position without the need to introduce an extra movement, which adds complexity to the system and decreases its accuracy. The developed control strategy complements the work in [28], where a height control strategy based on the recalculation of the deposition trajectories according to the mean height of the previously deposited layer was presented. This paper presents a novel methodology to apply local corrections within the layer, based on the dynamic variation of the scanning speed as a function of the height of each region.…”

Section: Introductionmentioning

confidence: 84%

“…In order to perform the mean height correction considering the geometry of the part and the scanned data, the same procedure was used as in Reference [28], where the CAD model, in STL format, of the complete part was sliced from the mean measured height to the next height to be reached after deposition of the following layer (Figure 2b). As in this work, only one layer was deposited between scans and the height of the volume to be deposited corresponded to the theoretical layer height.…”

Section: Methodsmentioning

confidence: 99%

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Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

et al. 2019

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Recently developed concentric laser metal wire deposition (LMWD) heads allow metal addition processes which are independent of the deposition direction, thus enabling complex paths to be generated. The sensitivity of the process to height deviations has experimentally been observed to be greater with this type of head than with powder ones, therefore requiring more precise and local process control algorithms to be implemented. This work developed a methodology for measuring the part, layer by layer, using a 3D scanner based on structured laser light. Height corrections were applied to the mean and intra-layer height deviations by recalculating the deposition trajectories of the next layer to be deposited. Local height deviations were adjusted by varying the scanning speed, thus increasing the feed rate in the lower areas and decreasing it in the higher ones. Defects generated in the purpose, with height differences within the layer, were successfully corrected. A flat layer was re-established through the application of the control strategy. The internal integrity of the parts due to the scanning speed variation was analyzed, resulting in fully dense parts. The structured light measurement and height correction systems are found to be an affordable and time-efficient solution that can be integrated into an LMWD environment, thereby improving the process robustness.

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Section: Introductionmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

et al. 2019

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“…As concerning off-axis monitoring systems, recently Garmendia et al [ 25 ] proposed a closed-loop control system that allowed the adjustment of the height of the deposited layer and recalculate the deposition paths during repositioning. The monitoring was performed using a structured light scanner.…”

Section: Review Of Main In-situ Monitoring Systemsmentioning

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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“…I. Garmendia et al [17], [18] use a structured light-based 3D scanner to measure the height profile of the part from a fixed position relative to the build platform, arguing that this measurement method would be more precise than strapping a sensor to a robot moving over the part surface in a scanning pattern. A depth image was captured in-situ after a pre-set number of layers were built and a control strategy that added or deleted layers, based on current build height and information from the CAD model, was used.…”

Section: B Closed-loop In Dedmentioning

confidence: 99%

Towards Vision-based Closed-loop Additive Manufacturing: A Review

Moltumyr

Arbo

Gravdahl

2020

2020 3rd International Symposium on Small-Scale Intelligent Manufacturing Systems (SIMS)

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The use of additive manufacturing technology has grown considerably in the last decade. Starting from a futuristic idea, additive manufacturing has shown to be a great tool for rapid prototyping and has found its way into industry as a set of techniques for manufacturing highly customized parts. However, a great number of challenges remain if we are to have efficient and general additive manufacturing systems with high precision, low failure rates, and good strategies for detecting and dealing with part failures. In this paper, the current state-of-the-art on online monitoring and closed-loop control in fused filament fabrication and directed energy deposition with camera and laser scanning is presented. A discussion on the challenges and possible ways of enabling full online part geometry monitoring in AM with articulated manipulators and multi-axis deposition is also provided.Index Terms-Three-dimensional printing, Closed loop systems, computer vision.

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Structured light-based height control for laser metal deposition

Cited by 42 publications

References 27 publications

Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

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

Towards Vision-based Closed-loop Additive Manufacturing: A Review

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