Polishing Operations Research Articles

Flexible Tools with Diamond Blades for Polishing Granite Surfaces

Polishing is an operation of treating the surface of the stone that gives it final useful features, giving the surface shine, which in the final stage of stone surface treatment give it important usable features, which include: aesthetics, i.e. surface property of the stone, characterized by the glassiness of the surface in some case has a mirror effect, which is characterized by a high degree of reflection of light, allowing it to observe the structure of the stone well in the aspect of its decorative elements placed on its surface. The physical features of polished surfaces are, above all, a shorter time to maintain moisture on its surface, which is the basic factor of material destruction. The quality of the polished surface of natural stone determines the degree of its longevity, this principle is particularly important for polished marble and concrete surfaces. An important value of the quality of polished products is the assessment of this parameter in a commercial assessment. The property of achieving a high degree of polishing can only be achieved with the help of highly effective diamond tools for polishing operations, where the quality of their work is evaluated by instrumental methods using tools measuring the amount of reflected light from the polished surface (gloss meter). Flexible diamond tools for dry and wet polishing operations are a set of 8 discs with a diameter of 100 mm mounted on a fast link formed in the friction surface on a synthetic binder of diamond abrasive with a grain size of 50 ÷ 3000 #. In order to increase the efficiency of surface treatment technology in polishing operations, it is necessary for granite processing for a given polishing operation with grain size 800 #, to select the appropriate hardness resulting from the synthetic binder formulation.

Z historii „operacji narodowościowych” NKWD lat 1937–1938 w Kirgizji. Represje wobec mniejszości etnicznych (na przykładzie narodowości polskiej)

Przełomem w rozpętaniu masowego terroru w ZSRR stało się lutowo-marcowe plenum KC WKP(b) (1937), które zainicjowało działania NKWD na rzecz likwidacji „kontrrewolucyjnych elementów”. Równolegle do tych działań prowadzone były od lipca 1937 r. do listopada 1938 r. operacje przeciwko „wrogim narodowościom” – potencjalną „piątą kolumną”, „bazą powstańczą” na wypadek wojny. Obejmowały one wszystkie warstwy ludności. Skazano wtedy ponad 335 tys. osób, spośród których rozstrzelano prawie 74%. Głównym celem było zniszczenie resztek „nacjonalistycznych elementów” – bazy dla zagranicznych wywiadów. Na przykładzie tej operacji w Kirgizji zostały przedstawione jej etapy (przygotowania, aresztowanie, śledztwo, wyrok) oraz „technologia” represji. Nawiązując do „operacji polskiej” NKWD, przytoczono bliższe informacje archiwalne o sprawie Ludwika Krynickiego. Dokonano analizy pochodzenia narodowościowego 137 ofiar, których szczątki wydobyto w Czon-Tasz, a także składu narodowego prawie 21 tys. represjonowanych w Kirgizji w latach 1918–1953 (m.in. 180 Polaków).

Parameters of the machining tool and quality of quartz glass elements

Рассматриваются методы обработки стекла, в том числе кварцевого. Исследования направлены на улучшение качества поверхности при физическом и химическом методах воздействия на изделие, обеспечение высокой точности обработки и качества поверхности без микротрещин и царапин. Обработка применялась к телам вращения. В качестве полирующего инструмента применялись полиуретаны с твердыми включениями. Исследованы параметры твердых включений и оценено их влияние на качество получаемой поверхности. Жесткость станка, оснастки значительно превышала жесткость обрабатываемой детали и полирующего инструмента, подпружиненного в осевом направлении.Получены результаты исследования для операций шлифования, полирования и травления образцов кварцевого стекла с разными режимами обработки. Проведена оценка влияния этих процессов на значение параметра шероховатости поверхности кварцевого стекла. Установлено, что существует ряд факторов, влияющих на качество поверхности стекла при обработке: геометрия и шероховатость поверхности перед обработкой; качество инструмента для полирования, механизм процесса травления; время и режимы при полировании, а также влияние полирующей суспензии. При обработке происходит изменение параметра шероховатости, зависящее от формирования макрогеометрии обрабатываемой поверхности в процессе полирования и травления; как следствие, происходит разделение на условные границы зон обработки. Формирование макрогеометрии обусловлено схемой полирования, размерами и геометрией инструмента, а также точностью юстировки станка. Наглядно представлены результаты исследования, проанализированы полученные данные экспериментов по полированию и травлению, сделаны выводы по данной работе.

Machine learning for in-process end-point detection in robot-assisted polishing using multiple sensor monitoring

The decision on polishing operation stopping time when employing a robot-assisted polishing machine is a critical issue for the full automation of the polishing process. In this paper, a machining learning approach based on artificial neural networks was developed using multiple sensor monitoring data to realize an intelligent system capable to determine the state of the polishing process in terms of target surface roughness achievement. During the experimental tests, surface roughness measurements were performed on each polished workpiece and the acquired sensor signals were analyzed and processed by applying two kinds of feature extraction procedures: statistical features extraction and principal component analysis. By feeding diverse types of feature pattern vectors to artificial neural networks, a highly accurate classification of the polishing process state was obtained using the principal component feature pattern vectors.

Lynx x-ray optics based on thin monolithic shells: design and development

Lynx is the future x-ray observatory with superb imaging capabilities (<1 arc sec half-energy width) and large throughput (2 m2 effective area @ 1 keV), which is being considered in the U.S. to take over Chandra. The implementation of the x-ray mirror module represents a very challenging aspect, and different approaches are being considered. Thin and low-weight substrates, working in grazing incidence configuration, are necessary to meet the severe mass constraints, but they have to also preserve the requirement of an excellent angular resolution. The use of monolithic glass (fused silica) shells is an attractive solution, provided that their thickness is kept very small [<4 mm for mirror shells up of 3-m diameter]. We present the optomechanical design of the Lynx mirror assembly based on this approach, together with the ongoing technological development process. In particular, we discuss the figuring process, which is based on direct polishing followed by an ion-beam figuring correction. A temporary structure is specifically devoted to support the shell during the figuring and polishing operations and to manage the handling of the shell through all phases up to integration into the final telescope supporting spoke wheel. The results achieved so far on a prototype shell will be discussed.

Precision Machining of Silicon Substrates

Brittle nonmetallic structural materials, such as quartz, glass, silicon, ceramics, ferrites and glass ceramics, are widely used in mechanical engineering, instrument making and radio electronics, as well as in optical, clock and jewelry industries. These materials have high hardness, strength, wear resistance and brittleness; therefore, their machining is a complicated problem. For production of piezoelectric resonators and filters, semiconductor devices, solid-state lasers, optoelectronic devices and other parts of electronics, plates made from monocrystals of quartz, lithium tantalate and niobate, silicon, germanium, sapphire, etc. are used. Semiconductor plates, which were obtained after cutting of a boule, have a number of defects, such as presence of a mechanically affected layer, nonflateness of sides, twisting and large variation of thickness. Therefore, after cutting it is necessary to carry out grinding and polishing. Grinding (abrasive finishing) is machining of semiconductor plates by means of hard finishing grinding discs (lapping tools) using abrasive flour grains. Finishing discs (lapping tools) are usually made from cast iron, glass, steel, copper or tin. The grain size of flour grains for grinding of semiconductor plates is selected from M14 to M5. Finishing machining of silicon substrates is complicated by a number of factors, such as provision of stable sizes, and, which is more important, the required microrelief of a machined surface, and unacceptability of machining marks and micro fissure on a surface. In Perm National Research Polytechnic University, the method of abrasive finishing and polishing of surfaces of silicon substrates by means of “Rast-350” flat-finishing machine was developed. The feature of the machines is in sliding movement of a tool (lap) along a nonrecurring trajectory, which has a form of a grid of complicated configuration. At that, the speeds of movement of all points of the working face of the lapping tool are the same. The studied and proposed technological recommendations for operations of finishing and polishing of silicon substrates allowed determining the main technological regimes (time, specific pressure, and density of the grid of tool marks), as well as the required abrasive material of corresponding grain size, which allowed providing the required microrelief of substrates (Rz 25 nm, Ra 5 nm) and eliminating machining marks and micro fissures on a polished surface.

Human-robot collaborative reconfigurable platform for surface finishing processes

Surface polishing can be counted among the most challenging manufacturing operations, especially when high qualitative levels in terms of surface texture characteristics are requested, such as in the case of polishing operations for plastic injection moulds. Robot-based solutions for surface polishing and quality assessment operations have been proposed at the state of the art, but it still is required the involvement of skilled workers for process supervision and final tuning operations. The introduction of human-machine collaborative solutions opens new opportunities, as the use of symbiotic polishing approaches, where both the humans and the machines capabilities can be shared to improve process effectiveness. The current work proposes a human-robot collaborative approach for surface polishing processes that integrates state of the art robot-based polishing and surface quality assessment technologies in a human-safe shared working environment. As a proof of approach feasibility, the paper presents the prototype of a reconfigurable platform designed to implement a flexible human-robot collaborative scenario for execution of polishing and quality assessment operations. Preliminary demonstrative polishing sessions on simple and complex components validate the system effectiveness with respect to manufacturing efficiency and reconfigurability capabilities. The results obtained provide a first positive response that symbiotic approach can objectively improve the polishing processes.

Analysis of the results of the finishing process for manufacturing low-hardness products from non-metallic structural materials

Abstract The methods and results of glass processing, including quartz glass, are considered. Research is aimed at improving the quality of the surface in the physical and chemical methods of exposure to the product, to ensure high precision machining and surface quality without cracks and scratches. Processing was applied to rotation bodies. Polyurethanes with solid inclusions were used as a polishing tool. The parameters of solid inclusions are investigated and their influence on the quality of the surface obtained is evaluated. The results of the study were obtained for the operations of grinding, polishing and etching quartz glass samples with different processing modes. The influence of these processes on the value of the surface roughness parameter of silica glass is estimated. It has been established that the quality of the glass surface during processing is affected by geometry and surface roughness before processing; the quality of the polishing tool, the etching mechanism; time and modes during polishing, as well as the effect of the polishing slurry. In the process of polishing and etching, the division into conditional boundaries of the treatment zones occurs. The formation of roughness and macro geometry is due to the polishing scheme, the size, and geometry of the tool, as well as the accuracy of the alignment of the machine. The results of the study are clearly presented, the obtained data of experiments on polishing and pickling are analyzed, conclusions are made in this work.

Effect of surface treatment by sandblasting on the quality and electrochemical corrosion properties of a C-1020 carbon steel used by an Algerian oil company

The purpose of the different operations under the term surface preparation is to get a clean surface able to be coated. It is essential to adapt this preparation in terms of the metallurgical nature of the substrate, cleanliness, its shape and roughness. Surface preparations especially the operations of sandblasting, polishing, or grinding prove of capital importance. It allows to modify the superficial properties of these materials, after these treatments the surface becomes very active. This paper evaluates the mechanical surface treatments effect by sandblasting (Sa 1.5 and Sa 2.5) on the electrochemical corrosion characteristics of C-1020 carbon steel in 3% NaCl solution electrolyte simulating aggressive sea atmosphere. Investigations are conducted using stationary (free potential "E-t, polarization curves "E-i", the Tafel rights and the Rp) and nonstationary electrochemical tools such as electrochemical impedance. The results obtained allowed us to highlight that sandblasted carbon steel degrades with immersion time because of the roughness of the surface. These results were confirmed by the plot of the electrochemical impedance diagrams, confirming that the process governing kinetics is under charge transfer control. Good protection against corrosion cannot be obtained only with a good surface preparation of the adapted steel.

Theoretical-Probability Model of Metal Removal During Magnetic-Abrasive Treatment

The work is devoted to the issue of calculating material removal during magnetic abrasive processing. Cutting grains have random dimensional characteristics, are randomly located on the surface of the tool, the workpiece has an irregular profile. The cutting parts of the grain tops partially remove the chips, and partially elastically-plastic deform the metal. Part of the vertices falls into the risks on the surface of the workpiece formed by the previous machining, and part -into the risks from passing through the previous vertices. This process is determined by the probability of the contact of the top of the grain with the metal. The developed stochastic models make it possible to predict the removal of metal from the treated surface depending on the time and parameters of the operation, which creates the prerequisites for their use in the design of polishing operations.

On the development of an haptic tool based autonomous polishing system

Automated polishing often relies on the toolpath generation based on a CAD model. This task is time-consuming, human skilled dependent and struggles to deal with the inaccuracy of parts to be finished. Manual labour is still very used for being capable of adapting to said inaccuracy, but also very dependent on individual polishers’ ability, thus not granting consistent results. In addition, this task is associated with health issues and also quite tedious.Automated finishing can be accomplished using robots or dedicated automation systems. Research has shown that force control based systems can be used to perform finishing operations. Hence, automated finishing often requires expensive hardware, generally using 6 axis force sensors or requiring custom-built equipment depending on the part geometry. Moreover, most automated polishing solutions struggle to adapt to radical changes in part geometry.The research work focuses on the use of simple force monitoring solutions to guide the automatic generation of a polishing toolpath without resorting to CAM techniques. The work is oriented toward industrial applications. A force monitoring device is conceptualized, simulated, and developed using off the shelf components and a rotational spindle is used on an industrial robot. The research is performed based on simulations in ABB’s RobotStudio and other in-house developed software. Results are tested using an ABB IRB1600 industrial robot to verify their feasibility for polishing operations for the tooling industry.

Electrochemical polishing of selected stainless steels

The AISI 316Ti (EN 1.4571) austenitic stainless steel sample (50 × 30 × 1,5 mm) was used for the study. The main elements forming the steel are: chromium (16-18%), molybdenum (2.0-3.0%), nickel (10.0-14.0%), titanium (max 0.7%), and iron as the rest of the steel composition. The electrolytic polishing operations were performed at the current density of 50 A/dm2. The main elements of the electropolishing setup were a processing cell, a DC power supply RNG-3010, the electrodes and connecting wiring. The studies were carried out in the electrolyte of initial temperature of 50±5 °C. For the studies, as the electrolyte a mixture of two acids, i.e. H3PO4:H2SO4 equal to 60%:40%, was used. For surface characterization the 3D roughness parameters(Sa=0.744 μm, Sq=0.984; Sp=2.32, Sv=3.5, St=5.88; Ssk=–0.898; Sku=2.97) regarding ISO25178 were used.

Ultrasound in the manufacture of medical instruments

AnnotationThe article contains information on the properties and possibilities of ultrasonic oscillations of high intensity, the features of the application of ultrasonic vibrations for the intensification of processes occurring in liquid, solid, gaseous media, polymeric materials, as applied to solving problems in the chemical, biotechnological, food industries and related industries. The methods of using ultrasound for cleaning parts on grinding and polishing operations, which are primarily intended for use in the manufacture of medical instruments, are described in more details.

Recurrent feature-incorporated convolutional neural network for virtual metrology of the chemical mechanical planarization process

In semiconductor manufacturing, the chemical mechanical planarization (CMP) process produces higher thickness variability in the edge area of the wafer than that in the center area due to the characteristics of the polishing operation. To address this problem, advanced CMP equipment includes a function that controls the removal rate of each area. However, to take full advantage of this capability, effective advanced process control systems must be implemented with a virtual metrology (VM) model. However, the prediction performance of the VM model often deteriorates due to process drift. Here, we present a deep learning-based VM model that demonstrates high performance in the presence of nonlinear process drift. The proposed model combines a recurrent neural network and a convolutional neural network to extract time-dependent and time-independent features. A two-stage model training method is proposed that alternately updates the weights of each network to improve prediction performance. In the experiments using on-site CMP process data, the performance of the deep learning models exceeded that of standard machine learning models. The proposed model showed an 8.48% decrease in process variability relative to the best-performing machine learning model, which was elastic nets.

A model-based residual approach for human-robot collaboration during manual polishing operations

A fully robotized polishing of metallic surfaces may be insufficient in case of parts with complex geometric shapes, where a manual intervention is still preferable. Within the EU SYMPLEXITY project, we are considering tasks where manual polishing operations are performed in strict physical Human-Robot Collaboration (HRC) between a robot holding the part and a human operator equipped with an abrasive tool. During the polishing task, the robot should firmly keep the workpiece in a prescribed sequence of poses, by monitoring and resisting to the external forces applied by the operator. However, the user may also wish to change the orientation of the part mounted on the robot, simply by pushing or pulling the robot body and changing thus its configuration. We propose a control algorithm that is able to distinguish the external torques acting at the robot joints in two components, one due to the polishing forces being applied at the end-effector level, the other due to the intentional physical interaction engaged by the human. The latter component is used to reconfigure the manipulator arm and, accordingly, its end-effector orientation. The workpiece position is kept instead fixed, by exploiting the intrinsic redundancy of this subtask. The controller uses a F/T sensor mounted at the robot wrist, together with our recently developed model-based technique (the residual method) that is able to estimate online the joint torques due to contact forces/torques applied at any place along the robot structure. In order to obtain a reliable residual, which is necessary to implement the control algorithm, an accurate robot dynamic model (including also friction effects at the joints and drive gains) needs to be identified first. The complete dynamic identification and the proposed control method for the human-robot collaborative polishing task are illustrated on a 6R UR10 lightweight manipulator mounting an ATI 6D sensor.

Construction of the new gas meter high pressure calibration facility – Technical and metrological problems

The necessity of the gas flowmeters calibration with the use of gas at expected working pressure is now beyond dispute. Most of gas meters types show the sensitivity to the parameters of the measured gas. The calibration factor, usually expressed as number of pulses per unit of volume, shifts when there is a change of an operating pressure. Change of operating pressure causes shift of calibration curve - so gas meters should be calibrated as close to operating conditions as possible. Polish Gas Transmission System Operator GAZ-SYSTEM SA decided to build the High Pressure Gas Meters Calibration Facility (HPCF) where natural gas is used as a working medium. The paper presents measures taken to overcome technical and metrological problems encountered during design and construction of the facility.

Design and Evaluation of Global Freight Transportation Solutions (Corridors). Analysis of a Real World Case Study

Abstract The paper presents the design and evaluation of the global freight transportation solutions (corridors) between China and Europe (Poland in particular). The authors of this paper develop a universal, generic methodology of designing and evaluating the global transportation corridors. They claim that this problem has a multiple criteria character, and thus produce the proposed approach based on the principles of the methodology of Multiple Criteria Decision Making/ Aiding. The developed paradigm allows for intuitive, heuristic construction of alternative global transportation corridors and their multi-aspect, multi-dimensional evaluation. In the proposed approach the designed transportation solutions can be assessed from different perspectives, including: economic, technical, social, environmental and other aspects. The final output of the analysis is the ranking of the designed transportation corridors resulting in the selection of the most desired solution. The proposed methodology has been tested on a real world case study of a Polish company operating in the clothing industry and being one of the leading business entities in retail clothing market in Central and Eastern Europe.

Employees Motivation and Openness for Continuous Improvement: Comparative Study in Polish and Japanese Companies

AbstractCurrently, companies must change and evolve to keep pace with the changing environment, customers’ requirements and to be better than their competitors. The changes result from the need to adapt the products to new customers’ requirements as well as to maintain competitive prices of their products. Therefore, companies should be flexible to guarantee short lead time and minimalize their costs to offer a good price for the customers. At the same time, companies should create good work environment for their employees in order to get them involved in improvement processes. In order to survive and develop companies should motivate and involve their employees into a continuous improvement process in different areas of the company. Unfortunately, as based on the companies’ practice and previous research, in many cases employees are not willing to engage in the company development. Continuous improvement is the basis of the philosophy of Quality Management and Lean Manufacturing, which come from Toyota Production System (TPS). The TPS eventually spread throughout the world, and it is held up as an example of the proper management of a production system. The assumptions of TPS system were used to build systems in other companies, but not always with the same success as it was in Toyota. For this reason, the authors of this paper seek to answer the question of whether there are differences in engagement in a continuous improvement process between employees in a Japanese company and a Polish company operating in the same industry and realizing the similar manufacturing. In order to verify this, the research was conducted in two manufacturing companies which operate in the automotive industry. The results of the study and their analysis are presented in the work.

Upgrading of natural gas ultra-rich in carbon dioxide: Optimal arrangement of membrane skids and polishing with chemical absorption

Water depths in oil and gas offshore production are moving from shallow to deep and ultra-deepwaters. Floating Production Storage and Offloading platforms are preferred in such frontier offshore enterprises. However, ultra-deepwaters natural gas processing imposes challenges in the design of floating units, limited in area and weight of processing equipment. Oil reserves with high gas/oil ratio (>250 sm3/m3) and high carbon dioxide content create additional challenges due to the impacts in the deck area of the gas plant. Among other natural gas processing operations, removal of carbon dioxide is required to meet sales gas specification, being skid-mounted membrane modules well suited for this purpose. To avoid emissions and to increase oil production, the separated acid gas is injected for enhanced oil recovery, creating a changing scenario due to increasing carbon dioxide content in the reservoir along production lifetime. In this context, this work optimizes arrangements of membranes modules and operational conditions via nonlinear programming formulations to optimize total membrane area for minimum footprint of membrane skids, with either carbon dioxide content in the treated natural gas less than 3%mol (Type 1 Constraint) or methane losses in the injection gas limited by imposing carbon dioxide content in the injection gas greater than 75%mol (Type 2 Constraint). To reduce computational effort, surface response models are employed, regressed from data simulated with a rigorous phenomenological model of spiral-wound membrane modules. Optimization results – total and stage area, carbon dioxide contents in retentates and permeates and natural gas production – are obtained for three feed scenarios: 10%mol, 30%mol and 50%mol carbon dioxide in raw natural gas. Type 1 Constraint leads to higher methane losses while Type 2 Constraint demands a polishing Chemical Absorption to comply with carbon dioxide specification of sales gas, configuring a hybrid process. Life cycle costs and total footprint area point to superiority of carbon dioxide separation design resulting from Type 2 Constraint, with optimal service distribution between bulk removal in Membrane Permeation and polishing operation in Chemical Absorption, considering time-varying composition of the raw natural gas.

A wheel-type in-pipe robot for grinding weld beads

To improve the safety and efficiency of polishing operations in circular boiler headers, a new type of wheel-drive polishing robot was developed in this study. The robot was designed to grind weld beads on the inner walls of pipes in diameter between 550 mm and 714 mm. The robot consists of a moving structure, a positioning structure, and a polishing structure. Charge coupled device (CCD) cameras and line lasers are used in the robot's vision system, thus the robot can be manually controlled to move, locate, and grind quickly and accurately. The experimental results showed that the robot performed well in practical applications.