Polishing Machine Research Articles

Application of Response Surface Methodology and Central Composite Inscribed Design for Modeling and Optimization of Marble Surface Quality

Factors affecting the final surface quality of polished marble are not yet fully understood. Clarifying these factors for optimization of multivariate polishing process by trial and error method is difficult, time-consuming, and costly task. In this study, the empirical practices were carried out using an experimental design, specifically, a central composite inscribed (CCI) design. The factors considered in CCI design were belt speed, rotational speed, and pressure of the polishing head, and the responses were surface glossiness and roughness. Mathematical models describing responses were produced using experimental datasets, and analysis of variance (ANOVA) was used to assess the fit of the models generated with the experimental data. For process optimization, desirability function analysis (DFA) was used. This study has shown that the CCI could efficiently be applied for the modelling of polishing machine for surface quality of marble strips. Better surface quality generally resulted from lower belt speeds, which increased contact time between the abrasives and strips. Optimized surface quality for marble specimen was established.

Parameters influencing the polished stone value (PSV) of road surface aggregates

Results of a European round-robin aiming to identify and quantify scattering sources impacting the polished stone value (PSV) of aggregates, and to assess the reference PSV of Herrnholzer granite, are presented and discussed. This reference value corrected against quartz dolerite control stone is calculated as PSVrefHE=56.1±0.5. According to variance analysis calculations, PSV scattering sources breakdown into three main components which have been assessed, a random friction tester term and two biases caused by test specimen preparation and polishing machine. Further investigation carried out on machine parameters using principal component analysis (PCA) reveals that narrowing the tolerance on flour emery flow rate should mitigate the machine bias. The results also evidence a higher scattering for low PSV aggregates, and PCA shows that this relates to their higher sensitivity to wheel speed variability not accounted for by the PSV control stone correcting factor. Besides, the results suggest enlarging the validity range of residual friction measured on PSV control stone prescribed by European standard EN 1097-8:2009, and they raise issues relating to test specimen preparation. Eventually, results and suggestions of the present study will be implemented in the ongoing revision of EN 1097-8:2009.

Process Automation in Computer Controlled Polishing

We report on an ambitious project in the field of automation, applied to bound and free abrasive processing of precision and ultra-precision surfaces, with potentially far-reaching consequences. This involves two main aspects:- directly processing surfaces using industrial robots, and combining robots with Zeeko CNC polishing machines to automate operations that are currently manual. These form steps towards our ultimate vision of the Integrated Manufacturing Cell for bespoke optics rather than mass-produced, and manufacture of other precision surfaces including prosthetic joint implants. Projects such as the European Extremely Large Telescope provide a relevant case study, where significant numbers of high-value bespoke optics are required.

다물체 동역학 해석을 이용한 커버글라스 Edge 연마용 Abrasive Film Polishing 시스템 개발

In recently, the demand of cover-glass is increased because smart phone, tablet pc, and electrical device has become widely used. The display of mobile device is enlarged, so it is necessary to have a high strength against the external force such as contact or falling. In fabrication process of cover-glass, a grinding process is very important process to obtain high strength of glass. Conventional grinding process using a grinding wheel is caused such as a scratch, chipping, notch, and micro-crack on a surface. In this paper, polishing system using a abrasive film was developed for a grinding of mobile cover-glass. To evaluate structural stability of the designed system, finite element model of the polishing system is generated, and multi-body dynamic analysis of abrasive film polishing machine is proposed. As a result of the analysis, stress and displacement analysis of abrasive film polishing system are performed, and using laser displacement sensor, structural stability of abrasive film polishing system is confirmed by measuring displacement.

Identification and evaluation of post-depositional mechanical traces on quartz assemblages: An experimental investigation

The evaluation of the state of preservation of archaeological lithic artefacts is the first step before starting a functional analysis. If lithic artefacts show a variety of damage from many contact materials, they are also subject to modifications from “natural” causes, such as water transport, soil abrasion, trampling etc. Studying alteration features gives us information to reconstruct the life story of lithic tools after their abandonment and helps us to better understand formation processes of archaeological sites.Prolonged movements under soil could be responsible for post depositional surface modifications that sometimes look like wear traces due to use. These alterations could have chemical and/or mechanical origin. Recognizing them is of paramount importance especially on quartz assemblages where usewear analysis requires a long and complex methodology that differs to a certain extent from the protocol applied to other artefacts produced with different raw materials such as flint, obsidian etc … For this reason, the use wear and post-depositional surface modification analysis on quartz and quartzite tools have been undertaken by very few researchers until now. The aim of this paper is to increase the experimental quartz field through the attempt to recreate mechanical contact between quartz flakes and sediments such as in archaeological contexts.Through the use of a Polishing Machine MECAPOL P320 equipped with two counter-rotating platens, it was possible to wear out two experimental flakes in a sandy quartzite sediment coming from Sai Island (Sudan) for 240 h.After the experimentation, the two flakes showed no edge damage or other visible modifications, but some micro traces on the crystal surface were present. Although long and demanding, this step sharply reduces possible errors in the recognition of use-wear during the experimental stage. The micro traces definable as abrasions on some parts of the crystal surface, have been analysed by a metallographic microscope and compared with the same crystal portion taken before the experiment. Even if it is difficult to reconstruct post depositional processes in a laboratory, this attempt shows that the contact between sediment and stone tools in a continuous movement can randomly abrade the crystal surface.

Path planning and parameter optimization of uniform removal in active feed polishing

A high-quality ultrasmooth surface is demanded in short-wave optical systems. However, the existing polishing methods have difficulties meeting the requirement on spherical or aspheric surfaces. As a new kind of small tool polishing method, active feed polishing (AFP) could attain a surface roughness of less than 0.3 nm (RMS) on spherical elements, although AFP may magnify the residual figure error or mid-frequency error. The purpose of this work is to propose an effective algorithm to realize uniform removal of the surface in the processing. At first, the principle of the AFP and the mechanism of the polishing machine are introduced. In order to maintain the processed figure error, a variable pitch spiral path planning algorithm and the dwell time-solving model are proposed. For suppressing the possible mid-frequency error, the uniformity of the synthesis tool path, which is generated by an arbitrary point at the polishing tool bottom, is analyzed and evaluated, and the angular velocity ratio of the tool spinning motion to the revolution motion is optimized. Finally, an experiment is conducted on a convex spherical surface and an ultrasmooth surface is finally acquired. In conclusion, a high-quality ultrasmooth surface can be successfully obtained with little degradation of the figure and mid-frequency errors by the algorithm.

Precision Machining of Mechanical Seals on the Machine "Rastr 220"

Here we present the raster method of final abrasive treatment of surfaces. Here we describe the theoretical foundations and patterns of raster processing method. We also describe the kinematics of lapping and polishing machine Rastr 220. For pieces of brittle composite material based on graphite, we have designed and manufactured a universal multipiece arrangement. The number of simultaneously machined pieces and their location in the device shall provide an even lapping wear. For this purpose, the axis of rotation of the tool shall be offset about its axis of symmetry to 5-15 mm. The device of larger diameter at the lapping should provide for periodic lapping bleed of the pieces by a certain amount. However, from the viewpoint of surface grit, a high lapping bleed of the pieces is not desired. In the process of lapping, the device shall be fully loaded with pieces. In case of impossibility to meet these requirements, it is necessary to periodically change the position of pieces in it. The device allows to compensate for different height of processable workpieces, to provide for their self-aligning on the tool surface, and to place the pieces evenly over the surface of lapping. The experimental testing of the treatment process on the machines with raster kinematics of the tool working movement was carried out. The comprehensive studies of precision treatment process for high-precision pieces made of composite materials based on siliconized graphite of grade (GAKK 55/40) were conducted. The requirements for working planes of the pieces are the following: Ra not more than 0.1 µm, flatness deviation not more than 0.6 µm. An estimation method for surface indulation was offered, and common technological advice on the implementation of raster lapping process for siliconized graphite pieces on the machine Rastr 220 was developed.

A study of the laboratory polishing behavior of granite as road surfacing aggregate

Four sources of granite aggregates with different mineralogical properties were investigated. They were formed into test plates with a flat surface and polished with the Aachen Polishing Machine using quartz powder and quartz sand as the polishing agent respectively. Changes of the texture were studied on the basis of both texture measurements and skid resistance measurements measured by the Pendulum Test and the Wehner/Schulze device. By comparison of the four granites, the influence of mineral composition and crystal size on micro-texture and skid resistance changes of the aggregates is determined. The polishing and wearing resistance can be described with functions of the mineralogical parameters.

Calibration of a parallel mechanism in a serial-parallel polishing machine tool based on genetic algorithm

The calibration is very important to improve the accuracy of the parallel mechanism. This paper proposed a new calibration approach for the parallel mechanism based on the direct kinematics model and the genetic algorithm. The proposed calibration approach avoids the measurement of the absolute position/posture of the moving platform in the calibration. Firstly, the ideal kinematics model, as well as the kinematics model with errors, of the parallel mechanism in the hybrid machine tool is established. Due to the absence of an analytical solution to the direct kinematics, the Newton iterative method is used to provide a solution. Since the calibration of the parallel mechanism can be regarded as a discrete optimization problem of multiple designed variables, the genetic algorithm is specifically used to identify the parameters in the kinematics model. Finally, the calibration experiment is carried out to verify the effectiveness of the proposed method. According to the experimental results, the positioning error of the parallel mechanism is largely reduced from 0.083 to 0.018 mm.

Comparative evaluation of different types of turmeric polisher

Polishing of turmeric in the Sangli (M.S.) district was practiced with different types of polishing machine (polisher). Most of these were operated by different engine such as diesel engine, tractor and electric motor. The majority of them have been developed by the farmers themselves and being used for polishing on custom hiring. The charging and discharging time, rate of polishing and machine output of tractor operated polishing machine was higher than diesel engine operated polishing machine and electric motor operated polishing machine, respectively. The diesel engine operated polishing machine required more energy than tractor operated and electric motor operated polishing machine, respectively. The cost of polishing by diesel engine operated machine was higher than tractor operated and electric motor operated polishing machine, respectively. Overall the performances of tractor operated polishing machine were satisfactory and accepted for application of polishing.

Thermal Effects of Mechanical Polishing and Conditioning on Polishing Pads

Polishing process is a primary technique for planarization of material surface in manufacture fabrication. The pad structure and its material properties are important to determine the polish rate and planarity that can be achieved by the polishing process. Besides, the pad conditioning is used to regenerate the surface of the polishing pad surface by breaking up the glazed areas. Because the polishing and pad conditioning mechanism is inadequately understood and because higher levels of pad polishing performance are desired, the investigation of experiment becomes more important.In this paper, a high precision polishing machine has established. With an improved design, a test rig can be easily used to simulate the polishing, pad conditioning process and acquire the signals of temperature. The temperature of test pads (i.e. Rodel IC1000A, Rodel IC 1000B and Opetech SB 660) is measured during polishing and pad conditioning process. For the self-design test rig, its surface temperature is measured by T-type thermocouples screwed behind the polishing (or conditioning) interface of the carrier. The experimental results provide a temperature index to end-point-detection and contribute to understanding of the mechanism on polishing pads.

Do the mechanical and chemical properties of InvisalignTM appliances change after use? A retrieval analysis.

To investigate the mechanical and chemical alterations of Invisalign appliances after intraoral aging. Samples of Invisalign appliances (Align Technology, San Jose, California, USA) were collected following routine treatment for a mean period of 44±15 days (group INV), whereas unused aligners of the same brand were used as reference (group REF). A small sample from the central incisors region was cut from each appliance and the buccal surface was analysed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy (n = 5). Then the appliances were cut (n = 25) and embedded in acrylic resin, ground/polished in a grinding polishing machine, and the prepared surfaces were subjected to Instrumented Indentation Testing under 4.9 N load. Force-indentation depth curves were recorded for each group and the following parameters were calculated according to ISO 14577-1; 2002 specification: indentation modulus (E IT), elastic to total work ratio also known as elastic index (ηIT), Martens Hardness (HM), and indentation creep (C IT) The mean values of the mechanical properties were statistically analysed by unpaired t-test (a = 0.05). ATR-FTIR analysis confirmed the urethane based structure of the appliances, without important chemical differences attributed to the aging process. INV group showed significantly lower E IT (REF: 2466±20, INV: 2216±168MPa), HM (REF: 119±1, INV: 110±6 N mm-2) and higher ηIT (REF: 40.0±0.3, INV: 41.5±1.2%), and C IT (REF: 3.7±0.2 INV: 4.0±0.1%). The increase in ηIT indicates that INV is a more brittle than REF, whereas the increase in C IT, a decrease in creep resistance. Despite the lack of detectable chemical changes, intraoral aging adversely affected the mechanical properties of the Invisalign appliance.

Corrosion Resistance of Ti6Al7Nb Alloy after Various Surface Modifications

The influence of surface pretreatment prior to the anode oxidation of Ti6Al7Nb alloy samples on corrosion resistance was presented in the work. The preliminary surface treatments were: grinding, vibration machining, sandblasting and electrochemical polishing. Anodic oxidation process was carried out at different voltages. The final procedure of the surface modification was steam sterilization. The scope of the work included: corrosion resistance study (pitting and crevice) of both non-sterilized and sterilized samples, and samples after 28 days exposure to the Ringer’s solution, concentration evaluation of metal ions releasing from the sterilized surface as well as observations of surface topography. The research revealed a significant influence of surface pretreatment of Ti6Al7Nb alloy, prior to the anode oxidation and steam sterilization, on corrosion resistance.

Mold Manufacturing Optimization: A Global Approach of Milling and Polishing Processes

Within the context of molds and dies production, frequent changes in design and increased competitiveness require an overall optimized manu- facturing process. The finishing process is typically composed of an accurate milling stage to manage shape deviations, followed by polishing operations to reach required surface roughness. Local improvements of milling and polishing set independently do not necessarily lead to an op- timal manufacturing process planning. This study aims to propose a method to improve the whole sequence of milling and polishing considering constraints from polishing process and machine tool. The turning point between milling and polishing operations consists in linking them by the evaluation of the surface topography obtained after milling. From there, thanks to a predictive model of surface roughness, the design of polishing operations can be performed, and polishing time evaluated. On the other hand, for a given machine tool and a desired intermediate surface topog- raphy, milling parameters for finishing can also be modified and actual machining time predicted. Thus the whole process is evaluated balancing the milling and polishing times to reduce the total manufacturing time. Experiments are carried out on an aluminum mold for blowing process of plastic bottles.

光学自由曲面研抛机床的综合误差建模与补偿

To improve the machining accuracy of an optical free-form surface,an integrated error model for five-axis polishing machine tool was established based on multi-body system theory.The movement error and rotation error of every axis were measured and analyzed by direct and repetitive measurement model,and it shows that the feed speed and measurement spacing have no significant influence on the movement and rotation errors.By taking the error data into the integrated error model,the variation rule of movement and rotation errors which are the components in the three axes of x,yand zfrom the integrated error of polishing machine tool was obtained.According to the above analysis,the main influence factor of integrated error is linear displacement errors.The compensation experiment was conducted based on integrated error model.The linear displacement errors of the three axes of x,yand z have been compensated obviously and they are decreased by 88%,89% and84%respectively.The experiment results indicate that the integrated error model and compensationmethod have high accuracy and excellent robustness.

WeC-2-3 Development of innovative dilatancy pad and high-speed / high-pressure polishing machine aimed for high-efficient and high-quality processing of next generation semiconductor substrates

WeC-2-3 Development of innovative dilatancy pad and high-speed / high-pressure polishing machine aimed for high-efficient and high-quality processing of next generation semiconductor substrates

Effect of different polishing systems on the surface roughness of full-contour zirconia

Adjustment of any premature occlusal contact of any zirconia restoration requires its polishing or glazing in order to restore the smoothness of the restoration. The objective of this in vitro study was to evaluate the effects of different polishing systems and glazing on the surface roughness of full-contour zirconia. Material and methods: Forty disks (diameter: 8 mm, thickness: 6.4 mm) were prepared from pre-sintered full- contoured zirconia block; they were colored and sintered in a high-temperature furnace at 1500˚C for 8 hours. The specimens were then leveled and finished using grinding and polishing machine and adjusted using diamond disk. The specimens were then randomly divided into four groups (n=10), group I involves samples that were polished using (karat diamond polishing set, Vita zahnfabrik, Germany), group II involves samples that were polished with (zirconia polishing kit, SMEdent, Shanghai, China), group III involves samples that were polished with (OptraFine® diamond polishing system, Ivoclar Vivadent, Germany), while group IV involves samples that were glazed using glazing medium (VITA Akzent Glaze AKZ 25, Vita zahnfabrik, Germany). Surface roughness values (Ra) (in µm) of all the specimens were recorded at each stage of surface treatment of zirconia disks (leveling and finishing, adjustment of the samples and polishing / glazing) using surface roughness tester. Statistical analysis was carried out using one-way ANOVA and LSD tests. Results: The results showed that the glazing group recorded the lowest surface roughness mean value, followed by (OptraFine® polishing system), then (zirconia polishing kit) and finally (karat polishing set) which showed the highest mean of surface roughness. For all groups, there was a statistically very high significant difference of (Ra) value before and after adjustment of the samples. Moreover, there was a statistically very high significant difference in (Ra) value when comparing the adjusted samples with the polished and glazed ones. Karat polishing set group showed a statistically highly significant difference with zirconia polishing kit group (P 0.05). Conclusions: Adjusting full-contour zirconia with diamond bur or disk resulted in a significant increase in (Ra) that necessitates its polishing or glazing to restore the surface smoothness. Furthermore, both glazing and OptraFine®

Path planning of mechanical polishing process for freeform surface with a small polishing tool

Products with freeform surface are widely applied in industries, and the surface quality plays an important role in order to fulfill the targeted functions. As polishing path of small polishing tool affects the polishing removal function considerably, it is highly necessary to study the polishing path of freeform surface for obtaining good polishing efficiency and well-proportioned surface quality. By combining the Preston polishing removal function, the material removal model of small polishing tool under the control of constant polishing force and pressure is established. Based on this model, the material removal functions of scan line, Archimedean spiral, and Hilbert fractal polishing path are derived. The simulation results show that the Hilbert fractal polishing path has the best comprehensive performance. By using the projection relation of differential geometry, the optimal path generation algorithm of the Bezier surface based on Hilbert fractal polishing path is established. The polishing experiments are conducted on a self-developed polishing machine which is based on a parallel manipulator. The experimental results demonstrate that the surface roughness is improved from level 9 to level 11.

Development of new laboratory equipment for measuring the accelerated polishing of asphalt mixes

The skid resistance of pavements tends to decrease over time, resulting in greater risks for drivers. Currently, skid resistance and macrotexture values can only be determined for existing pavements. It would be of interest to be able to predict the evolution of the skid resistance of an asphalt mixture before its installation as a highway wearing course. This paper summarizes the experience gained and the results obtained during the development of a test procedure which has been applied in the laboratory to measure the evolution of the skid resistance of hot mix asphalts through a modified version of an accelerated polishing machine which is normally used to determine the polished stone value of aggregates.

Effect of pad’s surface deformation and oscillation on monocrystalline silicon wafer surface quality

The silicon wafer polishing process has sensitive machining requirements owing to the interaction between various complex process factors, which can include the pad, slurry, applied pressure, polishing speed, polishing time, dressing condition, and the machining temperature. Among these important machining factors, applied pressure, polishing speed, and polishing time were examined. The optimum condition of wafer final polishing was investigated using the Taguchi approach. Moreover, variations in oscillation speed were added to the experiment and it was found that changing the surface contact velocity helped to improve the surface quality of the wafer. Furthermore, the pad surface characteristics which influences wafer surface quality after wafer final polishing with and without oscillation were studied and adding an oscillation speed in wafer final polishing has the dual benefit of improving wafer surface quality and reducing consumable costs. Finally, by selecting the optimum condition, it could achieve an ultra-precision wafer surface with almost no defects.