Papers by Keyword: CMM

Abstract: Currently in Thailand, original equipment manufacturers (OEM) who produce precision-machined parts face a serious problem about product rejection from customers. This is because measuring results from the OEM supplier differ from the measuring results from the OEM buyer. Normally, for precision-machined parts, OEM suppliers and OEM buyers use CMM machines as an inspection tool. One major cause of the difference in measurements is that suppliers and buyers use different CMM machine, operators and measuring methods. In order to mitigate the difference in measurements, the standard guideline for measuring precision-machined parts by CMM machines needs to be improved. In this research, the guideline was developed by studying the best practices of five successful companies, who could minimize rejection due to the differences in the CMM machine operators and measuring methods. Validation results indicated that when manufacturers who had precision problems used this guideline, the product rejection could decreased significantly.

Abstract: Reverse design based on CMM (Coordinate Measuring Machine) measuring has been used in the engineering design widely because of its higher quality, shorter manufacturing cycle and lower cost. The flexible rod is widely used in tension mechanism because of its large adjustable range, high tensile strength and good flexibility. The reverse design of a flexible rod based on CMM measuring is researched in this paper. The structure of the flexible rod was analyzed. The CMM digital measuring of the part has been completed and the data of measuring results is processed. The reverse 3D modeling and design of the flexible rod have been accomplished.

Abstract: The paper presents a stage of the research concerning the development and improvement of a low cost small flexible coordinate measuring machine (CMM) that could be used in the future both in research and industry. Its main advantage could refer to the low cost (only about 30 ÷ 40% of the cost of a CMM in the category on the market, having similar dimensions) in conditions of high performance criteria. This could be possible due to the fact that they were implemented some recycled components in the construction of the robotic drive axes of the machine structure, low cost scanning devices and low cost mechanical systems for fixing and adapting the scanning devices. The research stage presented in the paper is essential for the later stages of research to develop an integrated concept: low-cost, flexibility, precision and efficiency, all criteria referring to a small portable scanning CMM, with possible application in any domain. Specifically, the described research stage refers to evaluate the implementation of some scanning systems, type non-contact low-cost and modern displacement transducers, on the principle of emission of LASER radiation, in terms of scanning accuracy. The reason is that currently these systems are used more and more in the CMMs construction.

Abstract: In manufacturing system, 3D Coordinate Measuring Machines (CMM) are widely used for inspection services where the product should be subjected to the verification of design specifications. It is usually necessary to know the accuracy of 3D CMM equipment during the verification process of the product quality in mass production. To insure and increase the accuracy of 3D CMM the international series standards ISO 10360 are used. This paper presents the importance of the establishment of traceability to international standards as a key role for the reliability of 3D CMM measurement results.

Abstract: This paper mainly make a theoretical research and exploration on software quality assurance quality assurance improvement based on CMM process, with the educational software quality assurance model as an example. It elucidates the relationship between educational software process improvement and quality assurance, and explicits the importance of educational software development process improvement to the quality of educational software. Additionally, it discussed the establishment of educational software development model on the basis of the waterfall model of traditional software development, and construction of process quality management models and platforms based on CMM educational software process improvement.

Abstract: Element geometry can be restored with basic measurement techniques. However if the element geometry is too complex (free form surfaces), it is not possible to take all measurements in that way. Example presented in the paper is a drop forged element (car suspension link). In situation when spare element is out of reach (product withdraw from market, producer technological process tooling redesign), the element can be reproduced (singularly or in series, what depends on producer). Reconstructed element is slightly different from a master element (impossible existence of reliably identically designed and manufactured parts), because of measurement uncertainty. Another problem is that original element is usually worn out or during disassembly process can be damaged, so it has different geometry,(when worn out is not fitting to tolerances) than newly manufactured one. The practical approach for reverse engineering is based on: measurement uncertainty extrapolation, 3D part scanning, transformation of point cloud to solid model, composition examination of an alloy. The method is a complex solution that brings: geometrical description and material assignment and heat treatment. Important part of the method is typical measurement techniques. In cases when tolerances have to be preserved, additional tolerance assignment is needed according to linkage between redesigned part of element and parts of other elements in assembly. The insurance of measurement was checked according to typical tolerance of the drop forged element. The retrieved 3D model was compared with virtual mass to real master element mass. The technological tooling reconstructed prototype and element reconstructed prototype have been made. Finally the alloy material is assigned according to measurement result analysis (electron spectroscopy EDS). Proposed example shows many important clues that can be used in order to provide properly redesigned element.

Abstract: The Material Loss Detection Method for Cylindrical Shape parts (MLDMCS) was presented in the previous article. The verification of the method was executed on two different samples, manufactured from different materials and with different geometries. The main goal of research was to set the diameter tolerance for a detection process. The first sample was examined nine times with a modification of one parameter diameter tolerance. The results interpretation gives a possibility to check the proper set of data for future cylindrical shape examinations according to accuracy class of manufacturing. Preparation of the first sample was done in order to check: centricity of compared models, uniform material los detection mechanical friction worn, various distribution and shape of material loss, various depth of material loss. Second sample was prepared in order to check correct detection of material loss in case when element have a feature (like key slot), that is in a part but simultaneously it exist according to design. The main target is to recognize with the algorithm: what is, what is not and properly classify material loss. Furthermore second examination sample was damaged in a border area of the mentioned feature. The presented verification proves that is possible to apply the proposed MLDMCS in industry to support overhaul process of technical means. The important part of examination preparation is a set of a technological base that is used to fit together sample model (from 3D scanning) and the design pattern model (from CAD design). The main result is a material loss digital presentation, 3D and 2D simplified distribution. Groups of material loss can be assigned to specific areas in order to prepare refurbishing process turning surface layer before laser cladding is applied. The distribution map (2D and 3D) fully corresponds to material loss distribution on samples. Time of element examination with MLDMCS is strictly related to accuracy in angle division and axial division in distribution of singular volume. The verification proves that the 3^rd generation of refurbishing process operation preparation is possible to put in to practice. However it has to be prepared with proper methods and equipment. The method should be applied especially in situation when an element is: refurbished in series, elements that are refurbished have similar design, elements characterizes with same accuracy class of manufacturing and similar diameters, but with various designs.

Abstract: In order to prepare a refurbishing process of an element that characterize with a material loss which is a result of worn process or damage could be 3D scanned. Then it 3D model is gained after triangularization process and surface fitting. This model is compared with a CAD model which is an element design representation. In order to provide such comparison, the proper implementation of the MLDMCS (Material Loss Detection Method for Cylindrical Shape parts) in to the software is needed. The software is prepared in Visual Studio environment (.NET) with C# programing language (the algorithm code and the interface), SQL server (database) and Siemens NX software (PARASOLID internal libraries). MLDMCS is implemented as the one of the author Computer Aided Overhaul software modules (CAO). The implementation is a complex task, according to: interface preparation, data collecting, data presentation an input data form, proper set of input data configuration, preparation of 3D graphics processing an analysis algorithms, preparation of output data form and interpretation. The result of software algorithm should be an easy to interpret set of data with a possibility of automatic rapport generation. Furthermore the data should be collected in a data base for future analysis of element worn and damage repeatable progression. Data collected each time from a element during it technical state examination gives also an answer to future proceeding according critical quantity of refurbishing processes in recirculation of technical mean. Additionally collected data gives suggestion of it repeatability in worn or damage after various technologies of refurbishing. Future systems probably will be set on such solution and MLDMCS will be one of typical method used in industry oriented to overhaul of machines parts. Previously presented article, shows only pure method with it foundations. Nowadays solutions are mainly based on a metrology, also supported with CMM (Coordinate Measuring Machines) and offline measuring paths generating systems. The accuracy of proposed solution (3D scanning and transformation of point clouds to solid model) is less accurate than typical measuring methods; however foresights of application are promising. The demand accuracy is sufficient in order to prepare a cladding process by turning worn-out or damaged surface layer.

Abstract: A coordinate measuring machine (CMM) is a measuring system with the means to move probing system and capability to determine spatial coordinates on working surface. CMM is used in many industry fields from few micrometers of work pieces to a 5-meter truck. The verification method of CMM is done following international standard. The artifacts for calibrated reference length are the end standards, such as gauge block and step gauge, or laser interferometer for large size CMM. The current laser interferometer is operated by continuous laser and interference fringe counting. One constraint of continuous laser is an incremental measurement. The measurement path cannot be interrupted during the measurement period. We developed a new absolute interferometer system from a short-pulse mode-locked fiber laser. A Fabry–Pérot etalon (FPE) is used to select high-frequency parts of repetition-frequency modes of the mode-locked comb laser at the wavelength of 1.55 μm. The 5-GHz repetition-modified laser beam, which is realized by a new fiber-type FPE, is transmitted to a fiber-type Michelson interferometer. The interference fringes exhibit a temporal coherence interference and can be used for measuring spatial positioning. The temporal coherence between different pairs of modified pulse trains is referred to as absolute length standards. The performance of CMM was determined directly from different positions of two interference fringe patterns.

Abstract: Connecting rod is often in high speed movement as one of the main parts of automobile engine. It’s shape error and accuracy of the hole or the plane will directly influence the working performance and the service life of engine. So the production has very strict requirements on the shape error. Connecting rod standard gauge block, as a standard part of manufacturing connecting rod, it’s manufacturing accuracy is higher, and the measurement and calibration of error directly affects the machining efficiency and the precision of the connecting rod. CMM develops so fast that constantly pounding all kinds of special measuring equipment. In the contact, a digital measurement is carried out for the key dimension and the space shape error of connecting rod standard gauge block. so data processing of the measuring results has been obtained, then reconstructed geometry elements of the plane and round hole ,etc., and got the required shape error by the contact CMM, it provides the basis for improving machining precision of the connecting rod.