IMEKO Event Proceedings Search

   

Page 469 of 977 Results 4681 - 4690 of 9762

Yuki Ishizaki, Terutake Hayashi, Masaki Michihata, Yasuhiro Takaya
DEVELOPMENT OF NANOPARTICLES SIZING METHOD BASED ON FLUORESCENCE POLARIZATION

We suggest a novel nanoparticle sizing method based on fluorescence polarization analysis. Particle size evaluation can be achieved by measuring the rotational diffusion coefficient, which is sensitive to the particle size. We develop a rotational diffusion coefficient measurement system and a fluorescent probe, which is labelled to particle. In order to verify the feasibility of the proposed method, fundamental experiments are performed. We measure the rotational diffusion coefficients of gold nanoparticles, whose diameters are 5 nm, 10 nm and 15 nm, using the developed system. The measured rotational diffusion coefficients decrease with increasing the particle size. It indicates that nanoparticle size, which is below 15 nm, can be measured with at least 5 nm resolution.

Yingzhong Tian, Albert Weckenmann, Tino Hausotte, Alexander Schuler, Bin He
MEASUREMENT STRATEGIES IN OPTICAL 3-D SURFACE MEASUREMENT WITH FOCUS VARIATION

Focus variation is an optical contact-free method that allows the measurement of three-dimensional surface metrology using optics with limited depths of field and vertical scanning. It was documented in the ISO 25178-6 first time in 2010. As one method of image capture, it has very crucial influence to get an excellent quality image that some key parameters are selected correctly for different workpiece. Those key parameters are including the exposure time, contrast, filters and so on. In this paper, a few of applications were selected to demonstrate the capabilities of the system using different measurement parameters including measurements on cutting-insert tool, stainless steel ball, stepped workpiece and VDI standard workpiece with silver colour surface. Some principles were concluded for optical three-dimensional surface measurement with focus variation after comparing the practical results with different parameters, serving as measurement strategies.

Giovanni Moroni, Wahyudin P. Syam, Stefano Petrò
ON COMBINING CHAOS SEARCH AND LEVENBERG-MARQUARDT ALGORITHM FOR NON-LINEAR SUBSTITUTED GEOMETRIC FITTING PROBLEMS

Product quality is becoming a main concern in today manufacturing. As such, a dimensional metrology is strictly necessary. High accuracy result while reducing speed in measuring a product has to catch up with the improvement of metrology instrument which can capture many points in less time. Fitting algorithm of points cloud from measurement plays a critical role for the measurement accuracy and speed. In this study, non-linear least-square fitting of circle, sphere and cylinder are addressed without any prior knowledge of their nominal. These geometries have common use in practice, such as sphere for calibration and hole-shaft features in mechanical assembly application. The improvement of initial point guess for LevenbergMarquardt (LM) algorithm by employing Chaos Optimization (CO) method is presented. The results show that, with this combination, higher quality of fitting results in term of smaller norm of the residuals can be obtained while preserving the computational cost.

Bogdan Galovskyi, Matthias Flessner, Andreas Loderer, Tino Hausotte
SYSTEMATIC FORM DEVIATIONS OF ADDITIVE MANUFACTURED PARTS - METHODS OF THEIR IDENTIFICATION AND CORRECTION

Additive manufacturing becomes more widespread nowadays. Selective laser sintering (SLS) as one of the additive manufacturing methods has a high potential because of a wide range of raw materials. In most cases the accuracy of a SLS process depends on the scanner system of the manufacturing laser beam, parameters of the laser beam and working distance. In order to meet higher quality parameters and to provide manufacturing defects correction a measurement system should be integrated in the process.
A measurement system should be developed with considering harsh conditions in the process chamber and taking into account features of the measurement object. Thus only non-contact sensors could be applied. Measurement systems based on the photogrammetric principle are more applicable for such tasks.
In current paper presented the investigation which was conducted to determine optical compatibility of the measurement system with raw materials. Measurements were carried out with materials heated to an operating temperature and after a melting process. Also, the test samples of different shape were produced with the SLSMachine. The influence of the manufacturing angle was investigated. General recommendations about the compensation of this influence and for location of an object in the powder bed were formulated. This paper presents some research results necessary for detection and prevention of errors during the SLS process. It is an important experience for application and integration of a measurement system as a monitoring instrument during the SLS process.

Matteo Lancini, Ileana Bodini, Simone Pasinetti, David Vetturi
DEFINITION OF A MEASURABILITY THRESHOLD OF GEOMETRIC TOLERANCES IN RELATION TO MEASUREMENT UNCERTAINTY AND DIMENSIONAL PARAMETERS

In order to avoid final product malfunction and to allow for assembly integration, geometric specifications and dimensional tolerances are commonly used in mechanical design. However the feasibility of geometric specification measurement and verification is often neglected and the influence of measurement uncertainty in geometric tolerances evaluation underestimated. The authors propose updated results of a mathematical and numerical model, based on Monte Carlo simulations, developed in order to define a measurability threshold of geometric tolerances in relation to measurement uncertainty and geometric parameters, such as feature dimensions, meant to help the designer to define measurable geometric specifications.
Starting from EN ISO 14253-2:2011 and EN ISO 14253-3:2011 standards, a perpendicularity tolerance between a cylindrical feature and a planar one has been simulated. A mathematical model has been defined for each feature, in order to assess both misalignment and its uncertainty when starting from the estimate of geometric entities obtained from point coordinates measured by a Coordinate Measurement Machine (CMM).
Monte Carlo Analysis of these simulation underlined how geometric parameters, such as dimensions of the features involved, can act as magnifiers for measurement uncertainty when verifying a geometric specification: there could be cases where this magnification effect could lead to non-measurability of misalignment and non-verifiability of the geometrical specification requested.

Frank Welkenhuyzen, Denis Indesteege, Bart Boeckmans, Kim Kiekens, Ye Tan, Wim DeWulf, Jean-Pierre Kruth
ACCURACY STUDY OF A 450 KV CT SYSTEM WITH A CALIBRATED TEST OBJECT

Computed tomography is already a well established technology in medical and material analysis. Also for dimensional metrology applications, CT is a promising technique for measuring internal and external geometries. Nowadays, most industrial CT scanners, use 120 to 225 kV sources. To scan thicker and more absorbing materials, more power is needed. The Nikon Metrology XT H450 has a range up to 450 kV. However the accuracy of these new, more powerful machines has to be investigated. This accuracy study uses a calibrated reference object and simulations, to get a better understanding of the existing errors. This reference object is developed and produced by fixing CMM probing styli on a socket. It has been produced in several materials and used together with simulations to analyze the accuracy of single and multi-material CT measurements. For single material, accuracies up to 10-15 µm are achieved. In the case of multi material this accuracy deteriorates to 70-80 µm. Besides some mechanical errors which cause these deviations, the main factor is the edge detection.

Salah H. R. Ali
THE INFLUENCE OF STRATEGIC PARAMETERS ON ROUNDNESS ACCURACY DEVELOPMENT

Roundness is an essential geometrical feature in precision engineering metrology especially for quality control of the rotating parts. Talyrond machine becomes one of the main instruments i n roundness measurement . Talyrond HPR TR-73 fitting software data analysis can contribute significantly o n the measurement accuracy. The error characterization of TR-73 software is very important to find an optimum fitting solution in measurement . The final accuracy of a n object is influence by many different parameters.
In this paper, the impact of fitting strategic parameters as computational geometric techniques i n roundness metrology using TR-73 machine have been studied. Strategically geometric ten parameters included two types of fitting filters and four types of software algorithm techniques during four ranges of spectral wave numbers have been estimated experimentally and discussed in details. The experiments have been performed to establish reference data sets of roundness measurements for circular, cylindrical and spherical objects . Measurement results revealed that the accuracy of the maximum roundness have been improved using MZ fitting technique. Moreover, the average of roundness measurement became more accurate by about 65.6% and 57.3% using 2CR and Gaussian strategy respectively, which proved the effectiveness within application range. Thus, establishing references data sets are presented to help the designer and operator to satisfy the best fit for roundness error measurements in nano-scale metrology.

J. Sola, F. J. Brosed, J. J. Aguilar
UNCERTAINTY EVALUATIONOF A 3D VISION SYSTEM: COMPARISON OF MONTE CARLO SIMULATION WITHA CLASSICAL EXPERIMENTAL CALIBRATION

The Guide to the Expression of Uncertainty in Measurement has some limitations, especially for systems with complex mathematical models. In this article, two alternative methods to obtain the measurement uncertainty (Monte-Carlo simulation and calibration based on experimental measurement) are compared. These methods are widely used to calculate the measurement uncertainty of measurement systems. The advantages and disadvantages of these two methods are going to be studied estimating the uncertainty of the flatness measurement using a system based on laser triangulation. The measurement system captures images of the laser plane projected in the surface to be digitalized. The laser pointsin each image are identified and extracted and transformed into 3D coordinates to calculate the flatness of the surface. The influence of different factors will be characterized and the results of the estimation of the uncertainty with both Monte Carlo simulation and the calibration based on experimental measurement will be compared as well as the characteristics and requirements of each procedure.

Stanislaw Adamczak, Pawel Zmarzly, Ireneusz Piotr Chmielik
INVESTIGATING MATHEMATICAL MODELS OF WAVINESS MEASUREMENTS OF CYLINDRICAL ELEMENTS BY THE V-BLOCK METHOD THROUGH COMPUTER SIMULATIONS

The paper relates to the problem of an adaptation of V-block methods to waviness measurements of cylindrical surfaces. It presents fundamentals of V-block methods and a principle of their application. V-block methods also called reference methods can be successfully used to measure roundness and waviness deviations of large cylinders utilized in paper industry, shipping industry or in metallurgy. The paper describes a methodology of development of a mathematical model of roundness and waviness measurements by the V-block method. Next, a computer simulation was carried out that aimed at checking if proposed model is correct. Another aim of the simulation was to verify the concept of the adaptation of the V-block method to waviness measurements of cylindrical surfaces. . The results of the simulations show that if parameters of the V-block method are correctly chosen then a projection accuracy of both roundness and waviness is high.

Rajalingappaa Shanmugamani, Ramamoorthy B
DEFECT DETECTION AND CLASSIFCATION OF ZINC COATED PARTS USING MACHINE VISION

A machine vision approach is required for detection and classification of surface defects such as pitting, watermarks, rough surface and color tonality in zinc coated parts. Such an automated visual inspection scheme involves following steps: image acquisition, defect segmentation, feature extraction and classification. Image acquisition of a part with complex geometry and specular surface depends on the effectiveness of illumination. Various illumination techniques such as dark and diffuse with various incident angles were tested for capturing images with maximum contrast and information. Feature extraction of the defects was then carried out to capture the brightness, shape and spectral properties of the defects. Then feature ranking was calculated to obtain the best features for a real-time inspection. Supervised classification was then tested with Support Vector Machine (SVM) for defects other than tonality difference. The color tone is unique to an inspection batch and hence a change in tonality had to be detected inline. An unsupervised classification method was used as an extra step with in-line learning for this case. Challenges like complex geometry, specular reflection and real-time processing in building the machine vision system for real time inspection is solved by developing various image processing algorithms. The color tonality inspection is a unique problem faced in this application and that was addressed at two stages by both supervised and unsupervised classification techniques.

Page 469 of 977 Results 4681 - 4690 of 9762