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Photogrammetry technology has been used for the digitalization of multiple dental implants, but its trueness and precision remain uncertain.The purpose of this in vitro investigation was to compare the accuracy (trueness and precision) of multisite implant recordings between the conventional method and a photogrammetry dental system.A definitive cast of an edentulous maxilla with 6 implant abutment replicas was tested. Two different recording methods were compared, the conventional technique and a photogrammetry digital scan (n=10). For the conventional group, the impression copings were splinted to an additively manufactured cobalt-chromium metal with autopolymerizing acrylic resin, followed by recording the maxillary edentulous arch with an elastomeric impression using an additively manufactured open custom tray. For the photogrammetry group, a scan body was placed on each implant abutment replica, followed by the photogrammetry digital scan. A coordinate-measuring machine was selected to assess the linear, angular, and 3-dimensional discrepancies between the implant abutment replica positions of the reference cast and the specimens by using a computer-aided design program. The Shapiro-Wilk test showed that the data were not normally distributed. The Mann-Whitney U test was used to analyze the data (α=.05).The conventional group obtained an overall accuracy (trueness ±precision) value of 18.40 ±6.81 μm, whereas the photogrammetry group showed an overall scanning accuracy value of 20.15 ±25.41 μm. Significant differences on the discrepancies on the x axis (U=1380.00, P=.027), z axis (U=601.00, P.001), XZ angle (U=869.00, P.001), and YZ angle (U=788.00, P.001) were observed when the measurements of the 2 groups were compared. Furthermore, significant 3-dimensional discrepancy for implant 1 (U=0.00, P.001), implant 2 (U=0.00, P.001), implant 3 (U=6.00, P.001), and implant 6 (U=9.00, P.001) were computed between the groups.The conventional method obtained statistically significant higher overall accuracy values compared with the photogrammetry system tested, with a trueness difference of 3 μm and a precision difference of 18 μm between the systems. The conventional method transferred the implant abutment positions with a uniform 3-dimensional discrepancy, but the photogrammetry system obtained an uneven overall discrepancy among the implant abutment positions.

Vat-polymerized casts can be designed with different bases, but the influence of the base design on the accuracy of the casts remains unclear.The purpose of the present in vitro study was to evaluate the influence of various base designs (solid, honeycombed, and hollow) with 2 different wall thicknesses (1 mm and 2 mm) on the accuracy of vat-polymerized diagnostic casts.A virtual maxillary cast was obtained and used to create 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were further divided into 2 subgroups based on the wall thickness of the cast designed: 1 mm (HC-1 and H-1) and 2 mm (HC-2 and H-2) (N=50, n=10). All the specimens were manufactured with a vat-polymerized printer (Nexdent 5100) and a resin material (Nexdent Model Ortho). The linear and 3D discrepancies between the virtual cast and each specimen were measured with a coordinate measuring machine. Trueness was defined as the mean of the average absolute dimensional discrepancy between the virtual cast and the AM specimens and precision as the standard deviation of the dimensional discrepancies between the virtual cast and the AM specimens. The Kolmogorov-Smirnov and Shapiro-Wilk tests revealed that the data were not normally distributed. The data were analyzed with Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05).The trueness ranged from 63.73 μm to 77.17 μm, and the precision ranged from 44.00 μm to 54.24 μm. The Kruskal-Wallis test revealed significant differences on the x- (P.001), y- (P=.006), and z-axes (P.001) and on the 3D discrepancy (P.001). On the x-axis, the Mann-Whitney test revealed significant differences between the S and H-1 groups (P.001), S and H-2 groups (P.001), HC-1 and H-1 groups (P.001), HC-1 and H-2 groups (P.001), HC-2 and H-1 groups (P.001), and HC-2 and H-2 groups (P.001); on the y-axis, between the S and H-1 groups (P.001), HC-1 and H-1 groups (P=.001), HC-1 and H-2 groups (P=.02), HC-2 and H-1 groups (P.001), HC-2 and H-2 groups (P=.003); and on the z-axis, between the S and H-1 groups (P=.003). For the 3D discrepancy analysis, significant differences were found between the S and H-1 groups (P.001), S and H-2 groups (P=.004), HC-1 and H-1 groups (P=.04), and HC-2 and H-1 groups (P=.002).The base designs tested influenced the manufacturing accuracy of the diagnostic casts fabricated with a vat-polymerization printer, with the solid and honeycombed bases providing the greatest accuracy. However, all the specimens were clinically acceptable.

Most of the available digital systems are designed to image teeth and soft tissue rather than dental implants. However, although some are marketed specifically to record implant position, whether these products are better for implant scanning is unclear.The purpose of this in vitro study was to compare the accuracy of an implant intraoral scanner (PiC camera) with that of an intraoral scanner (TRIOS 3) for 6 implants placed in completely edentulous arches.Two maxillary master models with 6 external hexagonal Ø5.1-mm implants were used, one with parallel and the other with angled implants. The reference values were obtained with a coordinate measuring machine. Ten scans were made per model (parallel and angled) and system (intraoral and implant) (n=10), after which the 3-dimensional coordinates for each implant were determined with a computer-aided design software program and compared with the linear and angular reference values. Statistical significance was determined with the Student t test (α=.05).Statistically significant differences (P.001) were found in both precision and trueness. The overall errors relative to the reference in the parallel implant-supported casts based on the implant scanner were 20 μm (P=.031) and 0.354 degrees (P=.087) compared with 100 μm (P.001) and 1.177 degrees (P.001) in the cast based on conventional digital scans. The global errors in the angled implant casts were 10 μm (P=.055) and 0.084 degrees (P=.045) for the implant digital scans and 23 μm (P=.179) and 0.529 degrees (P.001) for the conventional digital scans.The implant intraoral scanner delivered greater precision and trueness than the conventional instrument for imaging complete-arch implant-supported prostheses.

Wire and arc Additive Manufacturing (WAAM) is gaining a lot of popularity in industries due to its ability to produce metallic components with a high deposition rate compared to other Additive Manufacturing (AM) processes. Moreover, there is no material wastage in the form of scrap as in the conventional subtractive manufacturing process. In this study, deposition of layers is done using a Computer numerical controlled Gas Metal Arc Welding (CNC GMAW) based WAAM setup. ER70S-6 low carbon-alloy mild steel wire is chosen as filler wire. A single square bead and a square-shaped component of 9 layers are fabricated on a substrate A36 steel. Deposition on the preheated and normal substrate is considered for analyzing the control of dimensional stability of bead height and bead humping phenomenon. Coordinate Measuring Machine (CMM) results shown that bead deposited on a preheated substrate has more dimensional stability and reduced humping. The hardness and wear test of the fabricated components were also carried out. The result revealed that hardness increases to some extent from149 to 159 BHN in the built direction (vertical). The average hardness is somewhat greater than that produced by conventional methods. The wear test was carried out at two different loading conditions of 1 kg and 2 kg, the wear rate calculated shows that the wear is lower in the case of the WAAM fabricated component compared to other traditional manufacturing methods. Results also revealed that the rate of wear gets lowered when the load is increased.

In this study, residual stresses of cold-forged ball studs were investigated by the contour method with using widely available wire-Electro-Discharging Machine (wire-EDM) and Coordinate Measuring Machine (CMM). After the wire-EDM cutting, one of the steps of the contour method, it was revealed that the surface contour data was affected from the cutting step. Therefore, to increase the accuracy of the measured residual stresses, one of the ball studs were heat-treated to normalize residual stresses due to cold forging. The contour data of the heat-treated sample was subtracted from the as-forged surface contour to eliminate any cutting-induced artefacts. The final residual stress profiles suggested that the subtracting procedure minimized the cutting errors. In addition, a new classification approach for the cutting-induced errors for the contour method was introduced. According to final stress maps obtained by the contour method, it was revealed that high compressive residual stresses were obtained at the socket regions of the ball studs, as expected. Balancing tensile residual stresses were observed at the inner regions.

Additive manufacturing (AM) is an emerging fabrication method that has been frequently used to create personalized implants in the healthcare sector. Successful implementation of AM in the medical industry includes technological integration, interdisciplinary evaluation, and a reliable mechanism for accuracy assessment. While several detailed studies have been conducted in recent years to ensure the development of reliable implants, they mostly focus on traditional production methods, standard shapes, solid implants, and overlooked accuracy evaluation. These traditional implants are invariably dense, often ergonomically incompatible, and lack sufficient voids for new bone tissue regeneration in the implant. The advent of AM and its ability for customized mesh structures provide tremendous advantages, but also pose a profound conundrum for medical professionals responsible for evaluating and maintaining implant quality. Custom implants need to achieve a high degree of certainty that they fulfill aesthetic and precision requirements adequately. This study aims to design, fabricate, and evaluate a customized cranial implant that is accurate and aesthetically pleasing. Design, fabrication, and analysis are the three main phases of the methodology utilized to produce a realistic porous implant for cranial reconstruction. The design is acquired through mirror reconstruction in the medial modeling software, fabrication is accomplished using electron beam melting, and the fitting accuracy is achieved through expert assessment and coordinate measuring machine inspection. The structural analysis is also performed to investigate the dimensions of the pores and struts, as well as the structural consistency within the lattice specimen. The outcomes demonstrate that the cranial implant embedded with the dode thick structure exhibits adequate fitting accuracy, appropriate micro-hardness, sufficient compressive strength, and desirable cell attachment. In this investigation, the values of implant’s fitting accuracy, hardness, compressive strength, and porosity are observed to be 0.9773 ± 0.0437 mm, 343 HV, 67 MPa, and 75% respectively. Therefore, with the appropriate approach in cranial reconstruction, implant degradation can be minimized and aesthetic outcomes can be improved in skull surgical procedure for a healthier and better quality of life.

Surgical navigation systems have demonstrated improvements in alignment accuracy in a number of arthroplasty procedures, but they have not yet been widely adopted for use in total shoulder arthroplasty (TSA). We believe this is due in part to the obtrusiveness of conventional optical tracking systems, as well as the need for additional intraoperative steps such as calibration and registration. The purpose of this study is to evaluate the feasibility of adapting a less-intrusive dental navigation system for use in TSA. We developed a proof-of-concept system based on validated laser-engraved surgical tools recently introduced for use in dental surgery that are calibrated once when manufactured and not recalibrated at time of use. The design also features a notably smaller bone-mounted tracker that can be tracked from a wide range of viewing angles. To assess our system’s performance, we modified the dental surgical software to support guidance of a TSA procedure. We then conducted a user study in which three participants with varying surgical experience used the system to drill 30 holes in a glenoid model. Using a coordinate measuring machine, we determined the resulting drilled trajectory and compared this to the pre-planned trajectory. Since we used a model glenoid rather than anatomical specimens, we report on targeting precision rather than overall procedure precision or accuracy. We found targeting precision

Currently the measurement of surface texture in mechanical engineering is traditionally carried out using profilometers. Modern profilometers do not allow measuring of surfaces with complex shapes. This is due to the different sensitivity of the sensor and the discreteness of the movements along the axes of the Cartesian coordinate system. Coordinate Measuring Machines are devoid of such a drawback. However, stylus of the coordinate measuring machine has a diameter many times larger than the diamond stylus of the profilometer. Therefore, there is a mechanical filtering effect, that affects the results of measuring the parameters of the surface texture. In this paper a mathematical model of the contact of the spherical stylus and a rough surface based on analytical geometry is proposed. Influence of the diameter of the spherical stylus on the maximum measurement errors of a amplitude parameters are investigated. Seven amplitude parameters Rp, Rv, Rz, Ra, Rq, Rsk, Rku of the surface texture are modeled. Coordinate measuring machine and profilometer with stylus diameter of 2 μm measurement results are compared. it was concluded that the stylus diameter of the coordinate measuring machine when measuring the surface texture should be no more than 20 μm.

PURPOSE: The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS: A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS: Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION: Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

Optimization of a flatness error inspection activity on coordinate measuring machine (CMM) is a very crucial problem which demands minimization of a probe path for productive inspection. In the present work, the approach is explained to minimize the total probe travelling length and hence, the time of flatness inspection. Three sampling methods with eight sample sizes have been considered for this work. The ant colony optimization (ACO) algorithm based on travelling salesman problem (TSP) approach was developed in MATLAB environment to find the shortest probe paths. It was verified that the probe path depends on the sampling method used to measure the flatness. The sampling method giving the shortest probe path was selected as the best-suited method for a particular sample size. The results obtained by analyzing an illustrative example shows that the proposed approach is both effective and optimum.

The coordinate measuring machine (CMM) is one of the most widely used precision measurement machines in the machinery industry. In this study, the analysis and compensation of structural deformation in spatial coordinates effectively depicts the improvement of the spatial accuracy of the motion of a three-dimensional measuring machine in a measurement area. In addition to accuracy, it is also projected that the measurement can be carried out more efficiently. Therefore, the measurement speed of the CMM and dynamic characteristics of the structure are becoming increasingly important. Consequently, the measuring machine has better dynamic characteristics and meets high precision requirements. During measurement, the geometric errors generated by the machine are mainly because of its moving structure in the spatial position. In this study, the CMM is driven by aerostatic bearings; the boundary conditions and parameter settings of each component are established to obtain analysis results that are highly consistent with the actual machine characteristics. The finite element method is used as an analysis tool, including static deformation, modal, spectrum, and transient analyses. Because of the structural deformation and spatial geometric errors caused by the moving structure of the measuring machine, the relative deformation errors can be evaluated through the analysis of the spatial position error compensation to improve the measurement accuracy of the machine.

Purpose The purpose of this study is to improve the accuracy of a fused deposition modeling three-dimensional (3D) printer by identifying and compensating for position-independent geometric errors using a face-diagonal length test featuring a designed artifact and a Vernier caliper. Design/methodology/approach An artifact that does not require support when printing was designed and printed to allow performance of the face-diagonal length test. A Vernier caliper was used to measure the lengths of diagonals in the XY, YZ and ZX planes of the printed artifact specimen; this completed the face-diagonal length test. The relationships between position-independent geometric errors of the linear axes X, Y and Z and the measured diagonal lengths of the three planes were determined to identify geometric errors. Findings The approach was applied to a commercial fused deposition modeling 3D printer, and three position-independent geometric errors were rapidly identified. The artifact was re-printed after model-based compensation for these errors and the diagonal lengths were re-measured. The results were verified via coordinate measuring machine measurement of a simple test piece without and with model-based compensation for identified geometric errors. Furthermore, the proposed approach was applied to a commercial 3D printer. Research limitations/implications The measured diagonal lengths of the printed artifacts varied greatly. Thus, further studies should investigate the effects of printing materials and parameters on the length discrepancies of 3D printed artifacts. Practical implications A software-based compensation of identified position-independent geometric errors has to be used at commercial 3D printers for accuracy improvements of printed parts. Originality/value Thus, the approach is of practical utility; it can be periodically used to identify position-independent geometric errors and ensure that the 3D printer is consistently accurate.

A computer program for calculating cylinder parameters was developed based on a measurement strategy of five circles arranged along the cylinder axis. The parameters calculated by the program are: cylinder diameter, axis of inclination of the cylinder axis to the reference plane, deviations from the least squares reference cylinder (LSCY), the axis passing through the centers of the outermost measurement circles. The graphics of deviation from the cylinder dimension is shown in the Auto CAD system using the script command. The developed program complements the CMM software.

A rapidly advancing lean production industry demands quick manufacturing solutions with greater precision and accuracy. This paper proposes a framework for the accurate quantification of a die-casted wing using laser scanning and reverse engineering technique. In this technique, the wing upper and lower surfaces are scanned using a Coordinate Measuring Machine (CMM). This scanned data is then imported into CAD software to generate the surface using Free Form Reverse Engineering (FFRE). The model fitness test patronizes the curve fitting used for the surface generation. The generated surface and the original 3D CAD model are investigated using deviation analysis for inaccuracies originating due to manufacturing and data acquisition. The wing is further analyzed by the point data to 3D CAD model deviation analysis. The methodology adopted significantly minimizes the data acquisition and data processing error allowing deviation to be solely traced back to the manufacturing technique.

Drilled hole quality is a significant parameter for successful orthopedic surgery. The present investigation is an effort to reduce the delamination produced drilling with state-of-the-art hybrid drilling i.e. ultrasonically-assisted drilling. A comparative analysis has carried out as per experimental design to assess the ultrasonic drilling with conventional drilling. The novelty of the work is the use of coordinate measuring machine (CMM) for characterization of the delamination during bone drilling. The results revealed that ultrasonically-assisted drilling caused lesser delamination than conventional drilling. The maximum percentage delamination during conventional drilling was found to be 9.153% and 8.541% during ultrasonically-assisted drilling.

In order to implement 3D point cloud scanning of small hole structure, which could not be contacted or damaged, we propose a noncontact 3D measuring method. The system contains a laser triangulation displacement sensor, a Michelson interferometer system and a coordinate measuring machine, with the advantages of non-invasive scanning, fast measurement speed and high precision. Focusing on reconstructing 3D point cloud data, random sample consensus is used to separate surface data and hole data respectively from the raw dataset. Least square optimization determines the function of the cylinder, as well as hole diameter and inclined angle between the hole and the surface. In the experiment scanning a round hole, the estimated result has diameter error and angle error within 30 µm and 0.2°, respectively. Results manifest the effectiveness and feasibility of this system and express practicality in manufacturing industry.

Conventional implant impressions by using elastomeric impression material have been reported as a more reliable technique for a complete-arch implant record compared with intraoral scanner procedures. Photogrammetry technology may provide a reliable alternative to digital scanning or a conventional impression; however, its accuracy remains unclear.The purpose of this in vitro study was to measure and compare the implant abutment replica positions of the definitive cast with the implant abutment replica positions obtained by the conventional technique, photogrammetry, and 2 intraoral scanners.An edentulous maxillary cast with 6 implant abutment replicas (RC analog for screw-retained abutment straight) was prepared. Three impression techniques were performed: the conventional impression technique (CNV group) by using a custom tray elastomeric impression procedure after splinting the impression copings at room temperature (23°C), photogrammetry (PG group) technology (Icam4D), digital scans by using 2 different IOSs following the manufacturer's recommended scanning protocol, namely IOS-1 (iTero Element) and IOS-2 (TRIOS 3) groups (n=10). A coordinate measuring machine (CMM Contura G2 10/16/06 RDS) was used to measure the implant abutment replica positions of the definitive casts and to compare the linear discrepancies at the x-, y-, and z-axes and the angular distortion of each implant abutment replica position by using a computer aided-design software program (Geomagic) and the best fit technique. The 3D linear gap discrepancy was calculated. Measurements were repeated 3 times. The Shapiro-Wilk test revealed that the data were not normally distributed; therefore, the Kruskal-Wallis test was used to analyze the data, followed by pairwise Mann-Whitney U tests (α=.05).Significant y-axis linear and XY and YZ angular discrepancies were found among the CNV, PG, IOS-1, and IOS-2 groups (P.05). The PG group obtained a significantly higher distortion on the y-axis and 3D gap compared with all the remaining groups (P=.004). The 3D discrepancy of the CNV group was 11.7 μm, of the IOS-1 group was 18.4 μm, of the IOS-2 was 21.1 μm, and of the PG group was 77.6 μm. In all groups, the interquartile range was higher than the median errors from the discrepancies measured from the definitive cast, indicating that the relative precision was low.The conventional technique reported the lowest 3D discrepancy for the implant abutment position translation capabilities of all the implant techniques evaluated. The intraoral scanners tested provided no significant differences in linear distortion compared with the conventional method. However, the photogrammetry system tested provided the least accurate values, with the highest 3D discrepancy for the implant abutment positions among all the groups.

The present paper presented a mathematical approach based upon Buckingham pi theorem to estimate the volume of chipping while creating holes by rotary ultrasonic drilling on float glass specimen. The experimental validation is also carried out by performing L9 designed experimental trials at various combinations of drilling parameters. Coordinate measuring machine technique has been deployed to precisely quantify the chipping volume. The microscopic portray is used for chipping assessment. The result shows that the mathematical dimensional analysis is having good conformity with the experimental values. The minimum volume of chipping reported at the optimized parametric combination 4.73 mm3. It is figure out that the spindle speed and feed rate are showing similar trend in experimental and theoretical results. Hence, to enhance the utility of float glass, the researcher’s prime focus is to overcome the propagation of chipping nearby corners of the drilled glass. Drilling of brittle material such as float glass is noteworthy study to investigate. Hence using rotary ultrasonic drilling; float glass is drilled, and the chipping produced at hole edge corners is estimated in form of chipping volume. Also, Buckingham pi theorem mathematical-based model is proposed for chipping volume evaluation.

Properties of polymer gears were tested using coordinate measurement methods. This study is a follow-up to research on geometric accuracy of gears manufactured by injection molding. Spur gears were measured on a coordinate measuring machine running the GINA software by Klingelnberg. Measurement results were output in the form of measurement sheets which included values required in the DIN 3962 standard. The article also analyses the topography of test gear teeth. The topography was presented for a single tooth of the gear and determined on the basis of the measurements of 9 profiles distributed evenly over a specific profile assessment interval (interval Lα defined in the standard) and 7 tooth traces located within a relevant tooth trace assessment interval (interval Lβ defined in the standard). All gears tested in this study were placed outside accuracy class 12.

Gage Repeatability & Reproducibility (Gage R&R) is a useful technique in industry that is used to determine the adequacy of a measuring system. Generally, Gage R&R involves multiple operators taking multiple measurements of a particular feature. In this paper, Gage R&R of CMM is undertaken wherein the operator is replaced by three different factors which can affect the measurement like Location, Probe Diameter and Touch Speed. Internal Diameter, Overall Length, Parallelism and External Diameter of ten components were measured during the R & R study. The study revealed that percentage contribution of variance component due to Reproducibility was less than 2.18% thereby assuring that the change in location, probe radius or touch speed would not have a significant effect on the measurement of the features mentioned. This analysis would help industry to determine if measurement due to any of the above three factors is reliable.

The use of Digital Twin (DT) is adopted by manufacturers and have positive effects on the product manufacturing process. The aim of this paper is to define a Coordinate Measuring Machine (CMM) inspection DT model, based on inspection process digitalized functionalities, from one side, and Industry 4.0 opportunities (Digital thread, Big data, etc.), from the other side. A review about DT definition, is firstly presented. Secondly, we review related studies based on existing DT orientations and usages for CMM inspection. Thirdly, challenges related to the variation management are presented. Finally, a discussion about possible DT functionalities and opportunities is conducted then a CMM inspection DT model is presented.

Direct (forward) kinematic solution of the parallel robots is a challenging task for pure pose determination of the movable platform, which is crucial either in designing of the robot or its controlling. The availability of this solution is more critical especially in the case of using robot as a coordinate measuring machine (CMM). Solving direct kinematics (DK) problem of parallel robots is complicated as it is engaged with highly coupled nonlinear equations that are difficult to solve analytically to obtain exact answer. Hence in order to solve the mentioned problem, various approaches including empirical solutions e.g. using auxiliary sensors on the robot, neural network, and numerical methods are utilized. Meanwhile, numerical methods as the most cost-effective approach can acquire one unique accurate answer in a reasonable time. The aim of this article is to solve DK of a novel CMM parallel robot, which has three translational motions and a rotational around horizontal axis, using both analytical and numerical (Newton-Raphson scheme) approach along with comparing the results. After explaining the implementation procedure of methods according to the configuration of this robot, the results of simulations for both methods are presented and compared to each other. Moreover, inverse kinematics and direct kinematics are analyzed for the mentioned mechanism thoroughly. Results show that although analytical method gives more accurate answer especially for horizontal positions, numerical method solves the problem faster and also with acceptable accuracy.

Introduction This research has resulted in a system of sensors and software for effectively adjusting prosthetic alignment with digital numeric control. We called this suite of technologies the Prosthesis Smart Alignment Tool (ProSAT) system. Materials and Methods The ProSAT system has three components: a prosthesis-embedded sensor, an alignment tool, and an Internet-connected alignment expert system application that utilizes machine learning to analyze prosthetic alignment. All components communicate via Bluetooth. Together, they provide for numerically controlled prosthesis alignment adjustment. The ProSAT components help diagnose and guide the correction of very subtle, difficult-to-see imbalances in dynamic gait. The sensor has been cross-validated against kinetic measurement in a gait laboratory, and bench testing was performed to validate the performance of the tool while adjusting a prosthetic socket based on machine learning analyses from the software application. Results The three-dimensional alignment of the prosthetic socket was measured pre- and postadjustment from two fiducial points marked on the anterior surface of the prosthetic socket. A coordinate measuring machine was used to derive an alignment angular offset from vertical for both conditions: pre- and postalignment conditions. Of interest is the difference in the angles between conditions. The ProSAT tool is only controlling the relative change made to the alignment, not an absolute position or orientation. Target alignments were calculated by the machine learning algorithm in the ProSAT software, based on input of kinetic data samples representing the precondition and where a real prosthetic misalignment condition was known a priori. Detected misalignments were converted by the software to a corrective adjustment in the prosthesis alignment being tested. We demonstrated that a user could successfully and quickly achieve target postalignment change within an average of 0.1°. Conclusions The accuracy of a prototype ProSAT system has been validated for controlled alignment changes by a prosthetist. Refinement of the ergonomic form and technical function of the hardware and clinical usability of the mobile software application are currently being completed with benchtop experiments in advance of further human subject testing of alignment efficiency, accuracy, and user experience.

Measurement of roundness and contour is the essential process taking place in many manufacturing industries. Parts and components having round edges are typically produced in many industries for various applications like automobile shafts, gears, bearings and exhaust pipes. Incorporation of six sigma process can improve the quality of the measuring processes. Six Sigma methodology deals with using a strategy that attempts to reduce variation and to improve the quality through Six Sigma. This can be carried out by employing two different Six Sigma procedures. This article points out methods to reduce the lead time of Coordinate Measuring Machine inspection by introducing various measurement techniques and programming and design of holding fixtures. The methodology of execution of the measuring methods is initiated with the identification of problems, followed by analysis, identification, implementation and improvement. It is concluded that after the incorporation of the inspection lead time, there was considerable improvement in time spent for the entire measurement process.

Zero-point clamping systems are today an important component in manufacturing technology for minimizing set-up times and operating machines with maximum efficiency. There are various technological approaches to compensate for thermal influences on these clamping systems during machining. The thermal behaviour of two different zero-point clamping systems was analysed in a series of experiments at the Institute of Production Engineering at the Vienna University of Technology. Heat was brought into the system in a controlled manner and the resulting thermal displacements were measured using a coordinate measuring machine. Significant quality differences in reproducibility and accuracy were observed.

The present investigation reports the development of a force transducer for industrial applications with facile design and manufacturing objectives. The design of the force transducer is based on the analytical and computational approaches, followed by the experimental verification. Factors such as stress, strain and deflection of the force transducer were evaluated while conducting a rigorous assessment of the proposed force transducer. Al 7075 (T6) grade of aluminum alloy has been used as the material for fabrication of the force transducer with a nominal capacity of 2 kN. The fabricated force transducer as per the proposed design has also been investigated for geometrical and dimensional accuracy using precision coordinate measuring machine (CMM). Metrological characterization as per ISO 376: 2011 revealed that uncertainty of measurements is within 0.05 %, which includes relative uncertainty of the force transducer the factors such as repeatability, reproducibility, reversibility, interpolation, resolution, zero offset. Based on the above investigations, it has been found that the designed force transducer is of low cost ($ 200–$ 300), ease to manufacturing, and precise enough (0.05 % uncertainty of measurement) force transducer for force measurement up to 2 kN. The developed force transducer offers sensitivity up to of 0.2 N or better.

The present paper investigates the tool deflection in three dimensions for two different tool diameters during end milling operation and validates the experimental findings with the finite element results. Cutting forces (i.e., radial cutting force, tangential cutting force, axial cutting force) exerted by the tool on AISI 1045 steel substrate under different combinations of cutting parameters (viz. feed rate, cutting speed and depth of cut) were measured using a dynamometer. For more accurate prediction of tool deflection using finite element analysis (FEA), the tool-workpiece contact region was sliced into small segments for the equal distribution of cutting forces. In order to verify the experimentally measured inaccuracy in the cut profile using a coordinate measuring machine (CMM) under different sets of parameters, the experimental results were compared with the predicted values of FEA. From the results, it was observed that the cutting forces were comparatively larger in magnitude for the larger tool diameter. Also, the depth of cut was found to be the most influential parameter among all, whereas the effect of feed rate and cutting speed on profile error was found to be insignificant. Further, the results show good agreement between the predicted FEA simulated tool defection and experimental values.

Measurement of high precision components can be performed on-machine using a suitable measuring system or offline using a Coordinate Measuring Machine (CMM). The former approach is desirable, provi...

Computer aided inspection planning based on CAD coordinate measuring machine is the basic key technology, which occupies a very important position in the quality system. Nowadays, the research of integration technology has made a lot of achievements, but the research on information integration of system and system lags far behind the information integration of machining. How to use the part information and measurement-related knowledge provided by the product model to automatically generate optimal testing procedures and testing instructions for use is the basic task of the oriented intelligent system. This paper aims at the development of intelligent CMM inspection planning system based on 3D, from the overall analysis and design of the system to the extraction of detection geometric information, sampling planning, detection path planning and automatic generation of quack measurement program and other related key technologies will be studied. This paper briefly analyzes the relevant factors that determine the number of sampling points and summarizes the point requirements for the distribution of sampling points, and in view of the shortcomings and limitations of various methods of sampling point distribution on the general surface, a sampling strategy with adaptive step size is proposed, which solves the problem of sampling planning on the general surface. In the specific implementation of sampling planning, it is divided into two ways: edge-based and face-based geometric element measurement and sampling. Considering the requirements of distribution points, specific sampling algorithms are designed respectively, focusing on the analysis of the differences between edges and faces.

Estimates of the measurement uncertainty are crucial, without which precision measurements are useless from a practical point of view. Dimensional compliance with geometric product specifications (GPS) plays a key role in decision-making in manufacturing engineering. Without rigorous uncertainty assessment, manufacturers risk making incorrect decisions. Coordinate measuring machine (CMM) measurements are suitable when complex measurement tasks of a workpiece must be made, such as measurements of positional tolerances or repetitive measurements. Here, we attempted to solve problems related to the thermal influences in the assessment of uncertainty in Coordinate Metrology. Task-specific experiments based on the identification of residual errors using a hole plate standard calibrated by Physikalisch-Technische Bundesanstalt (PTB) were performed to compare the measurement uncertainty results in the different temperature ranges. The thermal issues of CMMs include measurements of the temperature of the environment and CMM errors, estimation of the uncertainties of the thermal errors of the CMM, and reduction of the uncertainties related to thermal errors of CMMs. Computation of the thermal errors must account for environmental influences and internal heat sources of the CMM. Assessment of the uncertainty of thermal errors covers almost all factors related to the uncertainty of the CMM. The state-of-the-art technique for determining the uncertainty of the measurements is discussed.

The parts with freeform surfaces are extensively employed in the production industries. Consequently, the quality inspection of sculptured surfaces becomes increasingly important. Typically, the Coordinate Measuring Machine (CMM) is utilized for inspection of these irregular geometries because of its precision. Certainly, the complex and non-rotational geometry makes it difficult to obtain the freeform surfaces. The meticulous analysis will indeed require the explicit reconstruction of the measuring surface. In view of the fact that only a well-chosen sample of inspection points and their locations can accurately define the measurand, the development of an appropriate sampling strategy becomes crucial. This work proposes a novel adaptive sampling plan for the precise extraction of surface form. It recursively and adaptively computes the relevant sampling scheme to achieve an effective inspection using the CMM. The input to the algorithm is a random sample size depending on the inspection point spacing and measuring surface dimensions. This algorithm employs a knot vector–based segmentation, followed by curvature-based grading of the segmented patches. A newly established formulation is utilized to assign a specific sample size for each segment. The points within each patch are allocated by exploiting distinct point distribution algorithms. This algorithm intends to abbreviate the variance between the reference and generated surface obtained through the specific sampling plan. Indeed, the befitting sampling policy provides the least error between the two surfaces. The outcome in the present study demonstrates that the proposed algorithm can significantly reduce the inspection points as well as maintain the precision of surface modeling.

A precise determination of the center of radial distortion (CoD) improves the characterization of the distortion introduced by the lens, and hence, supports a better description of the perspective projection process. Nonetheless, its value is often neglected and approximated by the center of the image. In our research, we aim to determine a lens CoD with high accuracy using derivative instruments. To that end, we introduce a method that bounds the region containing the CoD within one pixel of uncertainty by characterizing the residual of a straight line (RSL) fitting process. The procedure is further refined to obtain an estimate for the CoD position by first inferring straight lines (ISL) crossing it and then finding the intersection between these lines. Later on, we explore the introduction of the division model assumption (DMA) for lens distortion in the estimation of the CoD. The RSL approach becomes relevant as we compare the ISL and DMA methods with alternatives from the literature as it provides a reference value containing the CoD. In our experiments, we take images of a straightness gauge by moving a camera with a coordinate measuring machine at regular and accurate steps. At each location, we estimate undistorted lines at different orientations of the camera and find the CoD from their intersections. Our approach permits the establishment of the CoD with high accuracy for a camera lens with radial distortion.

The article presents the methods of study of geometric parameters of a working tool of a rail-milling train after revealing after the process of controlled operation of milling the polygon-shaped transverse profile of R65 rails not meeting the requirements of the standard. Those methods were tested in the case of rail-milling train of RFP-01 model. To eliminate the causes of formation of a poor-quality transverse profile, the specialists of JSC VNIKTI conducted a series of studies to establish the actual profile and incline of a working tool of milling wheels which are plateholders with carbide plates. A plate-holder from each milling wheel was randomly selected. The geometric parameters of plateholders were measured with a coordinate measuring machine. As a result of measurements, clouds of points of working surfaces of plate-holders were obtained. To compress and recognize images, a singular n × 3 matrix decomposition was used, where n is the number of rows equal to the number of points in the cloud, the columns are the coordinates X, Y, Z. The next step was to split the point cloud into triangles using the Delaunay triangulation algorithm. Using the above methods, plate-holders’ cutting lines were obtained that form the actually shaped rail profile. The cutting lines were aligned relative to the vertical axis with the R65 rail profile as per the condition of achieving the minimum root-mean-square deviation. As a result, the reasons for poorquality shape of R65 rail profile after milling were established, and recommendations were formulated for their elimination.

In the ultra-precision manufacturing of large optics, industrial robots have the potential to become an intelligent and economical choice of surface polishing. However, the transport of the workpieces between the polishing platform and the measurement instrument seriously limits the manufacturing efficiency. Therefore, an in-situ measurement system based on the monoscopic deflectometry is developed to determine the form quality of the optical lenses during rough polishing. Stray light reflected from the lower surface of transparent lenses may degrade the measuring quality, thus an effective absolute phase retrieval algorithm is developed to decouple the superposed fringes associated with the upper and lower surfaces. Then, the form of the upper surface under polishing can be reconstructed to guide the subsequent polishing. Experimental results demonstrate that the accuracy of the method is comparable to that of the coordinate measuring machine, consequently the manufacturing efficiency and reliability of large optical workpieces can be greatly improved.

Purpose To compare the implant replica position accuracy on a duplicated complete edentulous maxillary implant definitive cast made either using conventional procedures or material jetting additive manufacturing (AM) technology using a coordinate measuring machine (CMM). Material and methods A complete edentulous maxillary cast with 6 implant replicas was prepared. The definitive cast was duplicated using two manufacturing procedures namely conventional (CNV group) and additive manufacturing procedures (AM group). On the CNV, an AM Co-Cr framework and a custom AM custom tray with a polyether impression material were used to obtain an impression of the definitive cast at room temperature (23°C). On the AM group, the definitive cast was digitized using a laboratory scanner. The standard tessellation language (STL) file was exported and used to manufacture the polymeric AM specimens using a multijet printer following manufacturer´s recommendations. A new digital implant replica was located on each corresponding housing of each AM specimen. A total of 10 specimens per group was obtained. A CMM was selected to measure the position of each implant replica on the definitive cast, CNV, and AM specimens. Linear and angular discrepancies were computed for each specimen. Thus, the Mann Whitney U test was used to analyze the data (p = 0.05). Results There was no significant difference in x-, y-, and z- linear and XZ angular discrepancy between both groups. However, the AM group revealed a significantly higher median YZ angular discrepancy than the CNV group (p = 0.007). Conclusions Material jetting AM technology demonstrated no significant difference in trueness and precision values of the linear and angular implant replica positions when compared to the conventional technique.

In this research, the effect of pulse currents on the weld geometry and angular distortion in pulsed GTAW (PGTAW) process in 3 mm thick SS-304 autogenous butt weld joint was investigated. Welding method uses pulse current and continuous current. The mean current and welding speed were kept constant with the peak current and base current were varied. During pulsed GTAW process, the arc condition was captured directly using a charge-coupled device (CCD) camera. Weld geometry was carried out using a digital microscope. Distortion was measured using Coordinate Measuring Machine (CMM). The results show that the peak current and base current have an influence on weld geometry and angular distortion. The weld geometry on pulsed GTAW was produced wider of weld bead width than continuous GTAW. However, angular distortion on continuous GTAW was higher than pulsed GTAW. Pulsed GTAW can widen the weld bead by 0.57% - 25.09%, but can reduce distortion by 15.15%-88.17%. As compared with weld geometry to the continuous GTAW, the widest result occurs at peak current 212A and base current 40A. The smallest of distortion on pulsed GTAW was achieved at peak current 138A and base current 80A.

Laser powder bed fusion (LPBF) is one of the most potent additive manufacturing processes. One of the constraints for a broader industrial use of this process is the limited knowledge of its dimensional performances and geometrical behavior, as well as the inability to predict them as a function of material, process parameters, part size, and geometry. The objective of this study is to enrich knowledge of the geometric dimensioning and tolerancing (GD&T) performances of the LPBF process and to evaluate the distortion prediction capabilities of the ANSYS Additive Print® software. To this end, a selected topologically optimized part with three different support configurations was manufactured using an EOSINT M280 printer and AlSi10Mg powder. After printing, the parts were scanned using a coordinate measuring machine (CMM) and a micro-computed tomography (μ-CT) system. The GD&T calculations were carried out according to the ASME Y14.5 (2009) standard. The distortions measured by the CMM and μ-CT techniques were 0.195 mm and 0.368 mm, respectively (95% interval). After the software calibration and two numerical sensitivity studies, the same stereolithography files used to print the parts were downloaded into the ANSYS Additive Print® software to calculate distortions caused by the process. The differences between the experimentally measured and the ANSYS-predicted distortions for a 56 mm × 58 mm × 137 mm part fell within a 0.134 mm range at a 95% interval. The fidelity of the numerical predictions, the impact of the support structures, and the differences induced by the CMM and μ-CT measurement uncertainties are presented and discussed.

The purpose of the study was to test new method for in vitro evaluation of dental material wear with 3D digitization procedure. Thirty dental crowns, made of polyetheretherketone and veneered with composite material, were subjected to wear test. The crown surface was digitized using coordinate measuring machine before and after the performed wear test. Mesh 3D models were reconstructed and average and maximum depth of lost material and volume loss was calculated (GOM Inspect 2016 software). Mean average depth value amounted 12±7 µm, maximum depth value was 42 µm, while mean volume loss was 0.0024 mm3. The smallest measured values were 4 µm for depth value and 0.0003 mm3 for volume loss. Coefficient of variation was very high for all tested parameters (>50%) as a result of data inconsistency. Within the limitations of applied methodology, the possibility of using coordinate measuring machine in measurement of dental material wear was confirmed.

Closed hydrostatic rotary table is one of the key units in an ultra-precision machine tool, while the main component of the rotary table is the rotor system, consisting of two thrust plates and a rotor. The kinematic errors of the rotary table are directly affected by the geometric errors of the rotor system. However, geometric errors of the rotor system are difficult to evaluate, due to the closed structure of the system. In this paper, a strategy to evaluate geometric errors of rotor system, using ultra-precision CMM (coordinate measuring machine), is presented. The method is based on coordinate conversion and least squares principle. In this approach, two sets of open structures are established, by dividing the rotor system into two parts. The profiles and cylindrical feature of the components of the rotor system are directly scanned by CMM. Following the compensation of the data from the CMM, the parallelism and perpendicularity errors can be evaluated. Furthermore, based on the aforementioned compensation algorithm, an optimization method for improving assembly precision of the rotor system is proposed. The result shows perpendicularity error between the two thrust plates and the rotor to be 14 μm and 21 μm, respectively, and the parallelism error between the two thrust plates to be 28 μm with measurement uncertainty of 0.5 μm. Additionally, the experimental result on the optimization method of guiding the assemblage of rotor system indicates that the parallelism error reduced to 12.1 μm, noting a 57% improvement.

Purpose Three-dimensional (3D) printing is increasingly used to produce orthopaedic components for hip arthroplasty, such as acetabular cups, which show complex lattice porous structures and shapes. However, limitations on the quality of the final implants are present; thus, investigations are needed to ensure adequate quality and patients safety. X-ray microcomputed tomography (micro-CT) has been recognised to be the most suitable method to evaluate the complexity of 3D-printed parts. The purpose of this study was to assess the reliability of a micro-CT analysis method comparing it with reference systems, such as coordinate measuring machine and electron microscopy. Design/methodology/approach 3D-printed acetabular components for hip arthroplasty (n = 2) were investigated. Dimensions related to the dense and porous regions of the samples were measured. The micro-CT scanning parameters (voltage – kV, current – µA) were optimised selecting six combinations of beam voltage and current. Findings Micro-CT showed good correlation and agreement with both coordinate measuring machine and scanning electron microscopy when optimal scanning parameters were selected (130 kV – 100 µA to 180 kV – 80 µA). Mean discrepancies of 50 µm (± 300) and 20 µm (± 60) were found between the techniques for dense and porous dimensions. Investigation method such as micro-CT imaging may help to better understand the impact of 3D printing manufacturing technology on the properties of orthopaedic implants. Originality/value The optimisation of the scanning parameters and the validation of this method with reference techniques may guide further analysis of similar orthopaedic components.

The aim of this study was to evaluate the accuracy/dimensional stability of High-rigid vinyl polysiloxane, polyvinyl siloxane, and polyether impression materials in full arch implant-supported prosthesis. Custom acrylic trays were made on a stone replica of the reference die. Two groups were present in this study: splinting and nonsplinting. A total of 30 samples of 15 for each group were made. Impressions were made and poured with type IV dental stone to obtain experimental casts and were evaluated for dimensional stability and accuracy by measuring with a coordinate measuring machine (CMM) in three dimensions (X, Y, and Z), and a verification jig was fabricated to check the accuracy both clinically and radiographically. Differences in measurements were analyzed using independent t-tests, analysis of variance, and chi-square tests. In terms of dimensional stability, the lowest mean deviation was found in casts made from open tray splinting and nonsplinting and within the impression materials (p > 0.05). But, significant differences (p > 0.05) were obtained with splinting over nonsplinting in terms of accurate fit of the verification jig. This study concludes that polyether material showed less deviation from the reference model, followed by High-rigid VPS and PVS. As results were statistically not significant, all the three impression materials can be used for making full-arch implant-supported prostheses. Splinting obtained more accurate casts over nonsplinting.

This study presents a method of measurement of the form error of the tip ball in the tactile probing systems of a coordinate measuring machine (CMM) by using a rotating reference sphere. The measurement of the form error of the CMM probe tip was conducted without the use of additional external measuring instruments or sensors. The form errors of the probe tip ball and the reference sphere were separated from the probing coordinates of CMM by rotation of the reference sphere. The effectiveness of the proposed method was evaluated based on an uncertainty analysis. The uncertainty in measurement of diameter of the probe tip ball was estimated to be less than 0.5 μm.

The use of lattice structures produced using additive manufacturing (AM) is of great interest to the aerospace and medical industries because of their potential for strength/weight optimization. However, their use is often limited due to challenges in qualification. Recent standards proposed for the definition and verification of lattice structures created using AM attempt to address these gaps. In this work, a lattice component is designed using a repeated unit cell and theoretical supplemental surfaces (TSS), brought forth in ASME Y14.46, are used to define the bounding geometry of the component. Two planes and a sphere are used to define a datum hierarchy that will be used to qualify the component. A measurand is defined by a spherical TSS and is later used to evaluate the quality of datum registration. The component is produced using a laser powder bed fusion process and then measured using focus variation microscopy, X-Ray computed tomography, and a coordinate measuring machine (CMM). The three data sources are then registered using a refined sampling registration based on the CMM points. The effect of CMM data acquisition strategy on the quality of the registration is then examined. Results show that CMM planning based on optical measurements of the component, as opposed to the designed geometry, show significant improvement in the quality of registration. This work highlights the importance of sampling location in tactile measurements of components produced using additive manufacturing and recommends that definition of inspection locations/methods be integrated into the design cycle of AM parts.

The paper presents the results of measuring the gearbox housing with the ATOS optical measuring system, the TRITOP system and the "TESA micro-hit 4-5-4" coordinate measuring machine. The aim of the study was to determine the differences in modern measuring systems and whether these differences affect the final measurement result when controlling parts of a complex configuration. At the beginning of the paper, the way of functioning of the used measuring systems and the results of research in this area are described. GOM Inspect software used for the ATOS and TRITOP measuring systems, while PC DMIS software used for the coordinate measuring machine. The analysis of the obtained results showed that there are significant differences in the measurement results and that the measuring systems used can't be applied with the same success to the measurement of parts of complex configuration such as the gearbox housing.

This work investigates the dimensional accuracy of PMMA parts, manufactured using the CO2 laser machine. Basic geometries like cylinder and cuboid were used for investigation of dimensional accuracy. Two parts of PMMA having different dimensions of cylinder and cuboid were cut and then the dimension of each part was measured using Coordinate Measuring Machine (CMM). To check the dimensional accuracy of the fabricated part, the nominal dimension was subtracted from actual measured dimension. After the experiment, it was found that the machine accuracy is less when the dimension of the part is less, when dimension increases, accuracy of the machine increases.

Modern measuring instruments as highly technological, precise, multi-functional tools today are complex systems, and estimation of their uncertainty turns into a non-trivial task of science. To provide information about the probability of results, their convergence, and reproducibility, it is necessary to analyze the task-oriented measurement uncertainty. As an approach to determining the uncertainty of complex systems, to avoid the need for professionally experienced personnel and expensive “artifacts” used for evaluation, there is a method of a so-called virtual measuring instrument. In this method, the measurement process is simulated, taking into account the influence of the main disturbance parameters and conducting statistical analysis using the Monte Carlo approach. All characteristics of virtual modules repeat the properties of real devices but allow quick and qualitative evaluation of environmental parameters' effect on the accuracy, as well as the uncertainty of measurement. It allows us to evaluate the correctness of the result under the present conditions. The measurement uncertainty is usually caused by several major sources. Uncertainty depends on the method of measurement, but there are still common factors, i.e. uncertainty caused by measuring instruments, methods, operators, and environment. Among environmental influences, it is important to highlight – the change of light and temperature, which can vary widely variate at the production process, and at the same time have a crucial impact on the uncertainty of measurement. The paper presents a virtual measurement instrument method and its known implementations.

The article presents the analysis of the influence of various fixtures of the Y-axis slide of the CMX 70U machining center measured in a coordinate measuring machine. As a result of a series of measurements of designated geometric features, specific deviations have been determined, and on their basis statistical calculations have been performed. The further part of the article shows the analysis of the theoretical body deflection under the influence of the force of gravity performed using the MES method in CREO Simulate.