1,720,965 research outputs found
Drawing up an industrial CT system purchase specification: a Brazilian case study
No full textComputed tomography integration to the quality control loop of Brazilian industries has been continuously growing. Being capable of imaging internal structures of an object, hidden features formerly evaluated only after physically sectioning it became visible through computed tomography. Despite being an engineering technology to be considered in non-destructive
analysis and dimensional metrology, the task of selecting an appropriate CT measurement system is not trivial. This paper outlines a general methodology for defining the quotation bases of an industrial CT system suitable for in-line quality control of light metal parts, and thus assisting the buyoff activity
Experimental assessment of computed tomography dimensional performance using modular test pieces made of polyoxymethylene and aluminum
No full textComputed tomography for dimensional metrology has been part of the quality control loop for more than a decade. Because of the complex measurement-error cause system and the lack of appropriate guidance, usually no consistent uncertainty reporting has been made. Modular test pieces made of polyoxymethylene and aluminum have been devised, manufactured and used to investigate some influence factors intrinsic to CT-based data and their effects on evaluating features of size. The experimental planning and the most significant experimental findings, including the use of artefact reduction algorithms, are presented and discussed in this paper
Voxel dataset noise reduction algorithm based on CMM reference measurements for geometrical tolerance analysis of prismatic test pieces
No full textComputed tomography for dimensional metrology has been introduced in the quality control loop for about a decade. To make the tolerance verification consistent, GD&T evaluation programs have been developed, which make use of CT point clouds generated through segmentation. This important step in a CT measurement sequence is investigated under the perspectives of tolerance analysis and measurement uncertainty. Based on empirical master part reference measurements, voxel dataset noise can be rationally filtered out by applying point-based reduction algorithms. Their significance on dimensional and geometrical characteristics’ measurements is experimentally tested and discussed in this work
CT Measurement Realization Process: The Need for Advanced Correction Methods
No full textComputed tomography use as a dimensional metrology technique has increased steadily, despite the fact that the uncertainty has been rarely determined and expressed in measurements of production parts. This perception may be attributed in part to a limited way of employing the uncertainty concept. From this perspective, the conceptual integration of the product (and measurement) realization process with the uncertainty approach is first emphazised in this paper. The reasoning behind it is to employ different methods for uncertainty evaluation in a rational sense, where the accuracy required to the uncertainty evaluation process drives the method selection. For critical measurement cases, which can be identified in the proposed concept, the need for advanced correction methods, using master part reference measurements for point-based compensation, is presented, tested and justified for GD&T characteristics
Experimental investigation on the accuracy of fast CT dimensional measurements using the Multi-Feature Check standard
No full textX-ray Computed Tomography (CT) has gained significant traction across various industrial sectors as a dimensional metrology tool. However, despite its potential, dimensional CT scanning can be relatively slow, often hindering routine adoption for many applications. This work explores the feasibility of reducing measurement time while maintaining measurement accuracy, based on a trade-off between speed and measurement quality. Three distinct acquisition times achievable with a fast CT system were explored, namely 192 s, 112 s, and 68 s. Within these durations, CT settings are systematically fine-tuned and adjusted to uphold fixed acquisition times. In particular, the investigated scanning parameters were the number of projections, exposure time, and scan mode on fast CT measurements of dimensional and geometrical characteristics. This is conducted through an experimental approach utilizing a commercially available calibrated standard, commonly known as Multi-Feature Check, to evaluate measurement errors. Preliminary results indicate the feasibility of improving the measurement accuracy with reduced scanning times by an appropriate selection of scanning parameters. The design of experiments, key findings, and their implications are outlined and discussed in this study
CT applied as a reference technique for evaluating active lock-in thermography in characterizing CFRP impact damage test samples
No full textDetection of impact damages in CFRP test samples with active lock-in thermography is fast and non-tactile, but in general it does not easily reveal the 3D geometry of the quantity of interest. Computed tomography (CT) is a holistic technique capable of characterizing most of the occurring impact damages in CFRP samples, but due to measuring envelope limitation and timeconsuming data capturing it is inappropriate for mass production. On the other hand, recent developments have made possible quantifying 3D impact damage geometry properties through thermography. From this perspective, CT setting optimization for imaging CFRP test samples with induced impact damage is put under scrutiny in this paper, whose results will be important to validate thermography-based dimensional content
Experimental investigation of the influencing factors on the structural resolution for dimensional measurements with CT systems
No full textThis paper presents an experimental investigation on the factors influencing the metrological structural resolution (MSR) of CT systems. The investigation consists of structured experiments involving several CT data acquisition and processing parameters. The method used to assess the metrological structural resolution is based on the amplitude transfer function (ATF). Because of the intrinsic relation between structural resolution and noise, the extracted surface RMS deviation was also evaluated. The results show how dependent the MSR is on the influencing factors and provides useful functional relations between data acquisition and processing parameters, the MSR and the surface deviations. They also help demonstrating the applicability of the ATF-based method to characterize the metrological structural resolution of CT systems
CT-based dimensional metrology developments in Brazil: Current status and outlook
Full text linkSince the 1980s Computed Tomography (CT) has been used in many industrial sectors for non-destructive inspection, including flaw detection, failure analysis, and assembly analysis. Back to the 2000s CT has become a metrology tool for dimensioning and tolerancing analysis as well, in which some topics have gained attention of researchers, such as the traceability of a measurement result and the evaluation of the measurement uncertainty. In Brazil, the first two CT systems for dimensional applications were installed about a decade ago in two research centers. For years these two CT infrastructures for dimensional metrology allowed companies of different segments to benefit from the technique and made it possible for researchers to be involved in the field of CT for dimensional metrology. More recently, those promising initiatives have been drastically reduced for reasons such as the obsolescence of those CT infrastructures, despite the significant research efforts that have been observed in other venues. To reverse this negative outlook associated with the field of CT dimensional metrology in Brazil, this paper outlines an integrative framework for collaborative research and development in the subject, which encourages measures, e.g., to fund basic and applied researches, to train and educate people, and to support industries through measurement services and bespoke solutions
The concept of digital twin used to investigate geometrical variations in the production of pipe spools
Full text linkThe fourth industrial revolution comprises the digital transformation of manufacturing by means of an intensive integration of advanced information and communication technologies. The possibility of creating interactive virtual replicas of the physical entities to predict and detect physical issues and optimize processes is one of the key benefits of the manufacturing digitization. In the oil and gas industry, one of the essential activities that can take advantage of innovative digital technologies is the geometrical quality assurance of pipe spools. In this sense, this work focuses on the development of digital twins of pipe spools that embrace attributes of their physical counterparts to manage dimensional variation and to assist the geometrical quality assurance process. Based on data available in the design stage of the product realization loop, i.e., dimensional tolerance, it was possible to estimate the process capability and to predict, by sensitivity analysis, the behavior of the spool elements when assembling them to each other
- …
