Manufacturing Metrology

Metrology is the science of measurement, which can be divided into three overlapping activities: (1) the definition of units of measurement, (2) the realization of units of measurement, and (3) the traceability of measurement units. Manufacturing metrology originally implicates the measurement of components and inputs for a manufacturing process to assure they are within specification requirements. It can also be extended to indicate the performance measurement of manufacturing equipment. This Special Issue covers papers revealing novel measurement methodologies and instrumentations for manufacturing metrology from the conventional industry to the frontier of the advanced hi-tech industry. Twenty-five papers are included in this Special Issue. These published papers can be categorized into four main groups, as follows: Length measurement: covering new designs, from micro/nanogap measurement with laser triangulation sensors and laser interferometers to very-long-distance, newly developed mode-locked femtosecond lasers. Surface profile and form measurements: covering technologies with new confocal sensors and imagine sensors: in situ and on-machine measurements. Angle measurements: these include a new 2D precision level design, a review of angle measurement with mode-locked femtosecond lasers, and multi-axis machine tool squareness measurement. Other laboratory systems: these include a water cooling temperature control system and a computer-aided inspection framework for CMM performance evaluation

Feature-based hybrid inspection planning for complex mechanical parts

Globalization and emerging new powers in the manufacturing world are among many challenges, major manufacturing enterprises are facing. This resulted in increased alternatives to satisfy customers\u27 growing needs regarding products\u27 aesthetic and functional requirements. Complexity of part design and engineering specifications to satisfy such needs often require a better use of advanced and more accurate tools to achieve good quality. Inspection is a crucial manufacturing function that should be further improved to cope with such challenges. Intelligent planning for inspection of parts with complex geometric shapes and free form surfaces using contact or non-contact devices is still a major challenge. Research in segmentation and localization techniques should also enable inspection systems to utilize modern measurement technologies capable of collecting huge number of measured points. Advanced digitization tools can be classified as contact or non-contact sensors. The purpose of this thesis is to develop a hybrid inspection planning system that benefits from the advantages of both techniques. Moreover, the minimization of deviation of measured part from the original CAD model is not the only characteristic that should be considered when implementing the localization process in order to accept or reject the part; geometric tolerances must also be considered. A segmentation technique that deals directly with the individual points is a necessary step in the developed inspection system, where the output is the actual measured points, not a tessellated model as commonly implemented by current segmentation tools. The contribution of this work is three folds. First, a knowledge-based system was developed for selecting the most suitable sensor using an inspection-specific features taxonomy in form of a 3D Matrix where each cell includes the corresponding knowledge rules and generate inspection tasks. A Travel Salesperson Problem (TSP) has been applied for sequencing these hybrid inspection tasks. A novel region-based segmentation algorithm was developed which deals directly with the measured point cloud and generates sub-point clouds, each of which represents a feature to be inspected and includes the original measured points. Finally, a new tolerance-based localization algorithm was developed to verify the functional requirements and was applied and tested using form tolerance specifications. This research enhances the existing inspection planning systems for complex mechanical parts with a hybrid inspection planning model. The main benefits of the developed segmentation and tolerance-based localization algorithms are the improvement of inspection decisions in order not to reject good parts that would have otherwise been rejected due to misleading results from currently available localization techniques. The better and more accurate inspection decisions achieved will lead to less scrap, which, in turn, will reduce the product cost and improve the company potential in the market

A Simplified Phase Display System for 3D Surface Measurement and Abnormal Surface Pattern Detection

Today’s engineering products demand increasingly strict tolerances. The shape of a machined surface plays a critical role to the desired functionality of a product. Even a small error can be the difference between a successful product launch and a major delay. It is important to develop tools that confirm the quality and accuracy of manufactured products. The key to assessing the quality is robust measurement and inspection tools combined with advanced analysis. This research is motivated by the goals of 1) developing an advanced optical metrology system that provides accurate 3D profiles of target objects with curvature and irregular texture and 2) developing algorithms that can recognize and extract meaningful surface features with the consideration of machining process information. A new low cost measurement system with a simple coherent interferometric fringe projection system is developed. Comparing with existing optical measurement systems, the developed system generates fringe patterns on object surface through a pair of fiber optics that have a relatively simple and flexible configuration. Three-dimensional measurements of a variety of surfaces with curvatures demonstrate the applicability and flexibility of the developed system. An improved phase unwrapping algorithm based on a flood fill method is developed to enhance the performance of image processing. The developed algorithm performs phase unwrapping under the guidance of a hybrid quality map that is generated by considering the quality of both acquired original intensity images and the calculated wrapped phase map. Advances in metrology systems enable engineers to obtain a large amount of surface information. A systematic framework for surface shape characterization and abnormal pattern detection is proposed to take the advantage of the availability of high definition surface measurements through advanced metrology systems. The proposed framework evaluates a measured surface in two stages. The first step focuses on the extraction of general shape (e.g., surface form) from measurement for surface functionality evaluation and process monitoring. The second step focuses on the extraction of application specific surface details with the consideration of process information (e.g., surface waviness). Applications of automatic abnormal surface pattern detection have been demonstrated. In summary, this research focuses on two core areas: 1) developing metrology system that is capable of measuring engineered surfaces accurately; 2) proposing a methodology that can extract meaningful information from high definition measurements with consideration of process information and product functionality.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/136999/1/xinweng_1.pd

Measuring the accuracy of digitization of contactless scanners

Cílem práce je praktické ověření a stanovení přesnosti digitalizace bezkontaktních 3D skenerů, které jsou dostupné na oddělení TUL / KSA, v souladu s postupy používanými pro kalibraci (přejímací zkoušky) těchto zařízení. Součástí práce jsou informace o laboratorním vybavení potřebném k implementaci praktické části práce (3D bezkontaktní skener Atos III Triple Scan, Metra-Scan, Ein-scan, REV scan, Leica AT901-MR, SW GOM Inspect), o principech optické digitalizace a tak zvaných akceptačních testech. Implementace doporučených postupů pro testování přesnosti optických 3D skenerů je realizována na kalibračním standardu (etalonu), jehož nominální rozměry jsou určeny měřením na souřadnicovém měřicím stroji (CMM). S využitím standardu je stanovena přesnost digitalizace jednotlivých skenerů, výsledky jsou zpracovány, analyzovány a konfrontovány s údaji poskytnutými výrobci zařízení.The aim of the thesis is practical verification and determination of the accuracy of digitization of contactless 3D scanners which were available at the TUL/KSA department in accordance with the procedures used for calibration (acceptance tests) of these devices. The steps involved in this thesis are, to gain knowledge of laboratory equipment needed to implement the practical part of the work (3D contactless scanner such as Atos III Triple scan, Metra-Scan, Ein-scan, REV scan, Leica AT901-MR, SW GOM Inspect), with the principles of optical digitization and the so-called Acceptance tests. This thesis requires a Calibration standard, which is also termed Etalon that will enable the recommended procedures for testing the accuracy of optical 3D scanners to be implemented and determination of the nominal dimensions of the standard i.e., by CMM. By using this standard, the accuracy of digitization of individual scanners is determined and the results are processed and the accuracy results are compared with the data provided by the device manufacturer

Dimensional stability of parts manufactured by additive technologies

Tato práce se zaměřuje především na analýzu dlouhodobé rozměrové a tvarové stability dílů vyráběných aditivní technologií (pomocí 3D tisku). Dále je pozornost věnována technologiím 3D tisku, principům použití, vlastnostem materiálů používaných pro 3D tisk a parametrům, které ovlivňují dlouhodobou rozměrovou stabilitu. Modely pro testování byly vyrobeny různými technologiemi 3D tisku, jako jsou FDM, PolyJet, SLS a SLA. Vzorky byly skenovány pomocí bezdotykového skeneru ATOS II 400 a vyhodnocovány v SW GOM Inspect Professional V8. Digitalizovaná data byla porovnávána jak s nominálním CAD modelem, tak především s naskenovanými daty, které byly pořízeny ihned po vytištění vzorků. Tímto způsobem byla provedena inspekce modelů 3 měsíce po vytištění, po roce od vytištění a po roce a testu 1 (cyklické zatížení vlhkostí a teplotou) a testu 2 (vystavení vzorků UV záření). Výsledky byly analyzovány jak s ohledem na stárnutí v čase, použité technologii a materiálu, tak z pohledu účinků testu 1 a 2.This thesis mainly focuses on an analysis of the long-term dimensional stability of parts produced by additive technology (using 3D printing). Firstly, the study about the 3D printing technology was done like how it works, which principle is used and which materials could be used for printing. Furthermore, the detailed study about the material properties and which parameters will affect for long-term dimensional stability. A year ago, models were already manufactured by different additive technologies such as FDM, Polyjet, SLS, and SLA. These models were scanned by using 3D contactless scanner ATOS II 400 and inspected by GOM Inspect Professional. An inspection was done with duration of time like 3 months, after a year and after a year with standard test-1 is called humidity and temperature and standard test-2 is called UV radiation. Then this analysis of measurement was compared with CAD and first day of models printing. Based on this analysis and from point of view of ageing with respect of time, which technology and material will have good dimensional and shape stability is discussed. Furthermore, some of parameters were taken into account such as an effect of the technology used, the 3D printer used and the effect of test-1 and test-2