Optimized multi-shot imaging inspection design

Brierley, Nick; Bellon, Carsten; Toralles, B. Lazaro

doi:10.1098/rspa.2017.0319

Cited by 12 publications

(8 citation statements)

References 26 publications

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“…To evaluate the detectability of defects within a CT Volume Brierley et. al [6] propose the following metric. Given the object surface mesh, multiple defects are incorporated into it.…”

Section: Defect Area-contrast-to-noise-ratiomentioning

confidence: 99%

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Automatic scan planning for CT scans

Kretzer¹,

Schielein²,

Sukowski³

et al. 2022

eJNDT

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Today, Computed Tomography is becoming increasingly important as a non-destructive testing technique in industry. The advantages of evaluating 3D information are manifold and system costs have fallen in recent years. However, these systems suffer from the disadvantage that performing a measurement is more complex and error-prone than pure radioscopic testing. Thus, users with more skill and experience are needed to get the most out of the scan. Nowadays, the process of parametrizing the CT scan is often completely manual and mostly performed by inspection engineers due to the high number of available parameters. These are spatial resolution, magnification, object and detector distances, number of projections and, most importantly, positioning of the specimen on the turntable. Choosing appropriate parameters is not trivial due to the interplay between required image quality and scan time. So, identifying optimal parameters can be a major challenge. The main goal of the scan planning is to solve the scan task dependably, process-safely if applicable, and efficiently with minimal investment of time. Simulation-based determination of the optimal parameters can enable objective parameters to be obtained that are less depended on expert users. This is especially important when a wide variety of objects need to be scanned. 3D printed parts, which can have a batch size of one under extreme conditions, serve as an example. The range of parts produced is extremely wide and complex, which leads to a complex configuration of the scan. Fraunhofer EZRT is developing software solutions to find an ideal scanning trajectory for a given scan task. For this purpose, CAD data of the part is used to simulate CT reconstructions and to evaluate the suitability of the parameters in focus of the task. For this, the image quality of the component, for metrological task e.g., and the detectability of faults inside the material, pores e.g., are considered. The user is given the ability to provide the parameter space especially with the regard to the geometry of the system. Also, the user can define quality criteria, pore sizes in different component locations e.g., which are considered in the optimization process. In the first step, those parameter sets are selected which have the best ratings on a projection basis. Subsequently, reconstructions are made on the remaining candidates, and these are evaluated. This approach saves computational time, the entire parameter space can be sampled, and a meaningful evaluation of the expected reconstruction can be performed.

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“…To evaluate the detectability of defects within a CT Volume Brierley et. al [6] propose the following metric. Given the object surface mesh, multiple defects are incorporated into it.…”

Section: Defect Area-contrast-to-noise-ratiomentioning

confidence: 99%

“…Afterwards the area-CNR (Contrast-to-Noise-Ratio) of each projected defect is calculated and combined to a single metric that describes the detectability of the indication. For a complete explanation, the reader is referred to [6].…”

Section: Defect Area-contrast-to-noise-ratiomentioning

confidence: 99%

Automatic scan planning for CT scans

Kretzer¹,

Schielein²,

Sukowski³

et al. 2022

eJNDT

View full text Add to dashboard Cite

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“…Additionally, it is worth noting that modelling techniques may be applied to the inspection process itself, as a means of technique development, inspection planning and optimisation, uncertainty estimation and improving data analysis [128][129][130]. Such modelling could potentially also be linked into the product manufacturing process chain digital twin, for example with predictions on likely regions of porosity being fed into inspection planning models, to enable optimal inspections [131]. The relevant modelling techniques here are raycasting, for computing optical wavelength inspection coverage as well as the primary (simply absorbed) radiation in X-ray transmission images, and Monte Carlo photon propagation, for modelling more complex matter interactions [132].…”

Section: Inspectionmentioning

confidence: 99%

Metal powder bed fusion process chains: an overview of modelling techniques

et al. 2021

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Metal powder bed fusion (MPBF) is not a standalone process, and other manufacturing technologies, such as heat treatment and surface finishing operations, are often required to achieve a high-quality component. To optimise each individual process for a given component, its progression through the full process chain must be considered and understood, which can be achieved through the use of validated models. This article aims to provide an overview of the various modelling techniques that can be utilised in the development of a digital twin for MPBF process chains, including methods for data transfer between physical and digital entities and uncertainty evaluation. An assessment of the current maturity of modelling techniques through the use of technology readiness levels is conducted to understand their maturity. Summary remarks highlighting the advantages and disadvantages in physics-based modelling techniques used in MPBF research domains (i.e. prediction of: powder distortion; temperature; material properties; distortion; residual stresses; as well as topology optimisation), post-processing (i.e. modelling of: machining; heat treatment; and surface engineering), and digital twins (i.e. simulation of manufacturing process chains; interoperability; and computational performance) are provided. Future perspectives for the challenges in these MPBF research domains are also discussed and summarised.

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“…In summary, despite its disadvantages, XCT of a 'powder challenge device' is viewed as the best inspection technique simply because it can locate trapped powder. This provides invaluable detail and context to AM part design, the powder removal techniques' effectiveness and could be used to inform predictive models [35] of problematic designs.…”

Section: Performance Of Powder Removal Techniques On Complex Devicesmentioning

confidence: 99%

Assessment of trapped powder removal and inspection strategies for powder bed fusion techniques

Hunter

Brackett

Brierley

et al. 2020

Int J Adv Manuf Technol

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The issue of trapped powder within a part made using powder bed fusion additive manufacturing (AM) is one of the 'dirty secrets' of AM, yet it has not received significant attention by the research community. Trapped powders limit the application of AM for complex geometries, including heat exchangers and dies with conformal cooling channels. Being able to detect and remove trapped powder from the build is a necessary step to avoid downstream processing and performance challenges. In this work, 'powder challenge geometries' with complex internal features were fabricated via laser powder bed fusion (L-PBF) and electron beam selective melting (EBSM) and were used to assess the effectiveness of several powder removal and inspection methods. Hand-held ultrasonic polishing was explored as a powder removal technique and was shown to effectively clear extremely elongated channels that grit-blasting (the current industry standard) cannot clear. X-ray computed tomography (XCT) and weighing were used to inspect and quantitatively assess the effectiveness of powder removal techniques on the challenge geometries. Using the lesser known 'vacuum boiling' powder removal process and the more common ultrasonic bathing process, trapped L-PBF powder was easily removed from the deep channels. Conversely, trapped EBSM powder was difficult to remove using ultrasonic polishing as the powder was sintered inside the channels. It was shown that the powder recovered by the ultrasonic polishing process had size distributions, surface chemistry, morphology and porosity similar to the virgin powder. It is suggested, on these bases, that the recovered powder could likely be recycled without detrimental effects on the process operation.

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Optimized multi-shot imaging inspection design

Cited by 12 publications

References 26 publications

Automatic scan planning for CT scans

Automatic scan planning for CT scans

Metal powder bed fusion process chains: an overview of modelling techniques

Assessment of trapped powder removal and inspection strategies for powder bed fusion techniques

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