In-process height control during laser metal deposition based on structured light 3D scanning

Review on adaptive control of laser-directed energy deposition

“…In these geometry signatures, the widths and heights of the deposited layers 15 and the profile of the molten pool 9,10 can be monitored by a single industrial camera, and the entire outline of the deposited layers are commonly obtained by a 3-D camera. 16,17 To improve the calculation speed and efficiency, Tang et al 18 used a laser-based areal topography measurement sensor to measure the surface and developed a depth image method to process the data and extract the 3-D features. Moreover, a 3-D scanner of structural light was used to measure the height of the deposited layers from an external fixed position by Garmendia et al 17 However, the strong metal vapor in the 3-D reconstruction method based on structural light may contaminate the optical device and affect the monitoring results.…”

“…16,17 To improve the calculation speed and efficiency, Tang et al 18 used a laser-based areal topography measurement sensor to measure the surface and developed a depth image method to process the data and extract the 3-D features. Moreover, a 3-D scanner of structural light was used to measure the height of the deposited layers from an external fixed position by Garmendia et al 17 However, the strong metal vapor in the 3-D reconstruction method based on structural light may contaminate the optical device and affect the monitoring results. A new method to extract the 3-D structure based on the position information of the electron beam speckle was proposed to overcome the deficiency of structural light monitoring.…”

“…Generally, the layer-to-layer control focuses on the control of height. For example, Garmendia et al 17 proposed a method to modify the number of layers to ensure accuracy of the deposition height and developed a new computer-aided manufacturing program that can calculate the subsequent scanning track according to the measured height and reduce the error between the actual value and the measured value. Moreover, Arrizubieta et al 88 developed a powder flow control system to regulate deposition height with the method of layer-to-layer control because the response speed of the powder feeding rate is slow and not suitable for online control.…”

Strategy Development for the Manufacturing of Multilayered Structures of Variable Thickness of Ni-Based Alloy 718 by Powder-Fed Directed Energy Deposition

“…Although there are nowadays specific modules in several Computer Aided Manufacturing (CAM) software packages for the AM process, their effectiveness is unclear. It is necessary to develop a specific CAM program depending on the complexity of the deposition geometry, which adapts the trajectory to the "rules and monitoring system" of each additive manufacturing system, as done by Garmendia et al [22]. Additionally, the strategy of deposition is critical for obtaining a good geometry, as demonstrated by Kono et al [23].…”

Accuracy Evaluation of Dense Matching Techniques for Casting Part Dimensional Verification

“…In the last few years, 3D optical scanners [ 5 ] are replacing laser trackers as the most used measuring equipment for the dimensional quality control assessment of machined and casting parts. Modeling and calibration issues are mentioned in [ 13 , 14 , 15 , 16 ], whereas some examples of application are studied in [ 17 , 18 ] and even accuracy performance is determined for lighting conditions in [ 19 ]. Although their accuracy is still a bit lower (±30 µm/m) than laser-tracker technologies (±15 + 6 µm/m) for high accuracy applications, casting part verification methodologies have been adapted to these technologies as they offer a volumetric view of the part compared to its nominal CAD definition.…”