Inorganic composition and filler particles morphology of conventional and self-adhesive resin cements by SEM/EDX

The purpose of this study was to characterize the inorganic components and morphology of filler particles of conventional and self‐adhesive, dual‐curing, resin luting cements. The main components were identified by energy dispersive X‐ray spectroscopy microanalysis (EDX), and filler particles were morphologically analyzed by scanning electron microscopy (SEM). Four resin cements were used in this study: two conventional resin cements (RelyX ARC/3M ESPE and Clearfil Esthetic Cement/Kuraray Medical) and two self‐adhesive resin cements (RelyX Unicem/3M ESPE and Clearfil SA Luting/Kuraray Medical). The materials (n = 5) were manipulated according to manufacturers' instructions, immersed in organic solvents to eliminate the organic phase and observed under SEM/EDX. Although EDX measurements showed high amount of silicon for all cements, differences in elemental composition of materials tested were identified. RelyX ARC showed spherical and irregular particles, whereas other cements presented only irregular filler shape. In general, self‐adhesive cements contained higher filler size than conventional resin luting cements. The differences in inorganic components and filler particles were observed between categories of luting material and among them. All resin cements contain silicon, however, other components varied among them. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

模具失效形式判定依据与技术应用性研究

阐述模具一般表面失效形式和失效机理,并且依据失效形式总结了模具失效判据以及给出描述性失效判据,为进一步研究模具失效提供了基本思考路线.     

A study of the Taguchi optimization method for surface roughness in finish milling of mold surfaces

The objective of this paper is to develop a Taguchi optimization method for low surface roughness in terms of process parameters when milling the mold surfaces of 7075-T6 aluminum material. Considering the process parameters of feed, cutting speed, axial-radial depth of cut, and machining tolerance, a series of milling experiments were performed to measure the roughness data. A regression analysis was applied to determine the fitness of data used in the Taguchi optimization method using milling experiments based on a full factorial design. Taguchi orthogonal arrays, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) are used to find the optimal levels and the effect of the process parameters on surface roughness. A confirmation experiment with the optimal levels of process parameters was carried out in order to demonstrate the effectiveness of the Taguchi method. It can be concluded that Taguchi method is very suitable in solving the surface quality problem of mold surfaces.     

Determination of paper filler Z-distribution by low-vacuum SEM and EDX

Paper, mainly constituted of cellulose fibres, often contains mineral fillers. These fillers increase some of the properties of the paper (whiteness, printability, etc.) and are cheaper than the cellulose fibres. Nevertheless, the fillers reduce the mechanical properties of the sheet. Paper presents an anisotropy corresponding to three main directions. This anisotropy characterises the sheet mechanical properties, structure and filler distribution. Analyses of the cross section of the paper sheet with a low‐vacuum scanning electron microscope with an energy dispersive spectrometer analysis module can show this distribution. The procedure developed consists in analysing discrete profiles to build the mean profile known as filler Z‐distribution for each of the fillers. To develop this method, problems such as determination of the surface points, the number of points to analyse to define a cross section profile and the time required for the test, have been solved. Paper is sensitive to electron irradiation. In order to avoid deterioration of the material and to obtain satisfactory results, the time span for analyses is restricted to 40 s with a 12 kV electron beam accelerating voltage. Monte Carlo simulations are used to determine the diffusion cloud size and thus to determine the number of points that constitute a profile. The samples are gold sputtered and, with the aid of backscattered imaging, the coated surface allows determination of the sample surface points.     

基于RE的复杂曲面零件模具的快速设计与制造

随着现代计算机技术和测试技术的发展,利用逆向工程技术对产品进行建模、仿真、优化及新产品开发成为现代设计的一大热点,并已成为CAD/CAM领域特别是模具设计和制造的重要技术之一。以油壶切边模为例,采用逆向工程技术通过实物原型获取了油壶的三维轮廓数据,然后利用Pro/E等软件将得到的轮廓数据三维重构,得到了实物原型的三维数字模型,实现了油壶切边模具的设计与制造。采用逆向工程技术可以快速实现模具的设计与制造,大大缩短产品设计周期,提高产品竞争力。     

Measurement of in-plane deformation by surface inclusion (proposed measuring method and some experimental results)

A new measuring technique is proposed for measuring the in-plane deformation of soft metal surfaces when indented by a hard indenter, using the displacement of inclusions on the soft metal surface as sensors. In in-plane deformation, the soft metal surface flows along the hard indenter surface. In this paper, the principle of this new measuring technique is explained and some example measurements obtained from the experiments with aluminum and copper beryllium alloy plates, are presented.     

The factors affecting surface roughness measurements of the machined flat and spherical surface structures – The geometry and the precision of the surface

The quantitative determination of surface roughness is of vital importance in the field of precision engineering. This paper presents an experimental study of the roughness analyses for the flat and spherical surfaces of machined metal in order to compare the roughness data taken from the cloud data produced by the stylus type profilometer and two optical-based measurement instruments, namely the infinite focus microscope and the confocal laser scanning microscope.In this experimental study, the roughness measurements for fifteen flat and six spherical surfaces were repeated six times using three different measurement instruments. Great care was paid to measure the same location for each measurement. For the comparison of the measurement techniques, the same measurement process was applied to the flat and spherical surfaces individually, and the configurations of the measurement instruments (filter type, cut-off, resolution etc.) were synchronized. R_a, two-dimensional (2D) roughness parameter and S_a, three-dimensional (3D) roughness parameter were also compared. The measurement results for the samples having spherical surfaces indicated a considerably high difference in values taken from the stylus profilometer and two optical-based measurement instruments in contrast to those for flat surfaces.     

Theoretical and experimental analysis of the effect of error motions on surface generation in fast tool servo machining

The fast tool servo (FTS) machining process provides an indispensable solution for machining optical microstructures with sub-micrometer form accuracy and a nanometric surface finish without the need for any subsequent post processing. The error motions in the FTS machining play an important role in the material removal process and surface generation. However, these issues have received relatively little attention. This paper presents a theoretical and experimental analysis of the effect of error motions on surface generation in FTS machining. This is accomplished by the establishment of a model-based simulation system for FTS machining, which is composed of a surface generation model, a tool path generator, and an error model. The major components of the error model include the stroke error of the FTS, the error motion of the machine slide in the feed direction, and the axial motion error of the main spindle. The form error due to the stroke error can be extracted empirically by regional analysis, the slide motion error and the axial motion error of the spindle are obtained by a kinematic model and the analysis of the profile in the circumferential direction in single point diamond turning (SPDT) of a flat surface, respectively. After incorporating the error model in the surface generation model, the model-based simulation system is capable of predicting the surface generation in FTS machining. A series of cutting tests were conducted. The predicted results were compared with the measured results, and hence the performance of the model-based simulation system was verified. The proposed research is helpful for the analysis and diagnosis of motion errors on the surface generation in the FTS machining process, and throws some light on the corresponding compensation and optimization solutions to improve the machining quality.     

Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processes

This study investigates the possibilities of automated spherical grinding and ball burnishing surface finishing processes in a freeform surface plastic injection mold steel PDS5 on a CNC machining center. The design and manufacture of a grinding tool holder has been accomplished in this study. The optimal surface grinding parameters were determined using Taguchi’s orthogonal array method for plastic injection molding steel PDS5 on a machining center. The optimal surface grinding parameters for the plastic injection mold steel PDS5 were the combination of an abrasive material of PA Al₂O₃, a grinding speed of 18000 rpm, a grinding depth of 20 μm, and a feed of 50 mm/min. The surface roughness R_a of the specimen can be improved from about 1.60 μm to 0.35 μm by using the optimal parameters for surface grinding. Surface roughness R_a can be further improved from about 0.343 μm to 0.06 μm by using the ball burnishing process with the optimal burnishing parameters. Applying the optimal surface grinding and burnishing parameters sequentially to a fine-milled freeform surface mold insert, the surface roughness R_a of freeform surface region on the tested part can be improved from about 2.15 μm to 0.07 μm.     

3D surface parameters (ISO 25178-2): Actual meaning of Spk and its relationship to Vmp

3D parameters are important in tribological studies and many of them show strong correlation with surface operational performance. Characterization of cylinder liner surfaces is a good example of the use of 3D roughness parameters. Standard ISO 25178-2:2012 defines new parameters retaining some of the old ones, even though presented as their equivalent 3D successors. That is the case for instance of the “k” series: S_pk, S_vk and S_k. This paper covers an analysis of the relationship between S_pk and the new volume parameter V_mp where it is shown that it is not correct to designate S_pk as the average height of the protruding peaks above the core surface as stated in the standard. It is also suggested that S_k should be maintained but that the new volume parameters, through their relationship to the “k series”, make it possible to discard S_pk and S_vk.     

Characterization of surface defects in fast tool servo machining of microlens array using a pattern recognition and analysis method

Microlens array (MLA) is a type of structured freeform surfaces which are widely used in advanced optical products. Fast tool servo (FTS) machining provides an indispensible solution for machining MLA with superior surface quality than traditional fabrication process for MLA. However, there are a lot of challenges in the characterization of the surface defects in FTS machining of MLA. This paper presents a pattern recognition and analysis method (PRAM) for the characterization of surface defects in FTS machining of MLA. The PRAM makes use of the Gabor filters to extract the features from the MLA. These features are used to train a Support Vector Machine (SVM) classifier for defects detection and analysis. To verify the method, a series of experiments have been conducted and the results show that the PRAM produces good accuracy of defects detection using different features and different classifiers. The successful development of PRAM throws some light on further study of surface characterization of other types of structure freeform surfaces.     

Increasing nanohardness and reducing friction of nitride steel by laser surface texturing

Laser surface texturing is often employed to improve tribological performances of mating surfaces. The principal aim of the present work is to study local modifications induced by laser beam during the texturing process (microdimpling), on the mechanical properties of a 30NiCrMo12 nitride steel.A brief tribological characterization was initially made in order to verify the improvement of tribological behaviour ensured by microdimpling. Friction measurements were carried out in lubricated flat-on-flat and round-on-flat configurations.A sub-surface characterization was performed by focused ion beam cross-section and imaging. Modified material layers were discovered in correspondence of laser-affected zones around dimples, where grain dimensions were observed to be reduced. To quantify this phenomenon, a new theoretical energetic model was developed.Hardness measurements were performed by atomic force microscope nanoindentation. This approach allowed to observe an hardening effect moving from bulk material to dimple edges. Therefore, the theoretical model was integrated with the Hall-Petch's law in order to quantify the observed hardening behaviour.     

在线紫外/过硫酸盐消解流动分析法测定地表水中总氮

应用FS Ⅳ型流动分析仪,采用在线紫外/过硫酸盐消解测定地表水中总氮。通过试验,确定最佳测定参数,对该方法的灵敏度、准确度和精密度等进行试验。测得的检出限0.019mg/L、相对标准偏差? 5.0%及回收率在95%～100%范围内。     

Nanoscopic surface texture formed by indentation and sliding of a smooth wedge tool

To achieve reliable replication of a flat tool surface through a metalforming process with nanometer-scale surface roughness, a wedge tool was indented and slid under a constant normal load. In a workpiece finished with abrasive paper, some of the initial valleys remain on the tested surface, though at the boundary contact area the surface roughness is as small as that of the tool. The final surface roughness of the workpiece was much reduced by starting with a smoother surface of the workpiece and by unlubricated short sliding. A nanoscopically smooth surface of 0.8 nm sRa was obtained with a gold-coated copper workpiece after unlubricated indentation and sliding. This suggests the beneficial effect of a soft surface film coated over a hard substrate, causing complete filling of the interfacial vacancies.     

Thickness characteristics and improved surface adhesion of a polypyrrole actuator by analysis of polymerization process

Characterizing electrochemical polymerization of polypyrrole film on a substrate depends on many parameters. Among them, potential difference and cumulative charges play important role. The level of potential difference affects the quality of the polypyrrole. On the contrary, cumulative charge affects the thickness of the polypyrrole. The substrate surface is adjusted physically and chemically by treating with sandblasting and the addition of thiol for surface adhesion improvement. Experimental results show that the sandblasted and thiol treated substrate provides better adhesion than non-sandblasted and non-thiol treated substrate.     

Application of Taguchi and response surface methodologies for surface roughness in machining glass fiber reinforced plastics by PCD tooling

This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in machining glass fiber reinforced (GFRP) plastics with a polycrystalline diamond (PCD) tool. The experiments have been conducted using Taguchi’s experimental design technique. The cutting parameters used are cutting speed, feed and depth of cut. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is feed followed by cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of GFRP composites. The predicted values are confirmed by using validation experiments.     

3-D measurement and evaluation of surface texture produced by scraping process

The scraping process involves traditional manual work and is an important technique for producing flat bearing surfaces with lubricating grooves on a sliding surface. In order to meet the requirements of precision engineering, the scraped surface should have an equally distributed pattern with a required number of high points per unit area while retaining good flatness. In the machine tool manufacturer’s workshop, however, the quality inspection of scraped surfaces still depends on human eyes. In this study, a 2-D evaluation system is first developed using image processing so that the peak points per area of square inch (PPI) and the percentage of points (POP) can be quantified as parameters. A vision-assisted laser focus probe system is then developed to measure the 3-D form of the scraped profiles. The laser probe is made of a DVD pickup head based on the astigmatic principle. Driven by an XY stage, the entire scraped profile can rapidly be scanned. The quality of the scraped surface can thus be interpreted in a more scientific manner. Based on the measured 3-D data, new evaluation methods are proposed for five parameters, namely the PPI, POP, height of points (HOP) or depth of surroundings (DOS), flatness, and oil retention volume. Experiments show that the 3-D system is consistent with the 2-D system. It not only reveals more surface quality parameters but also uncovers more characteristic surface phenomena than the 2-D image system.     

KDP晶体卧式飞刀切削加工表面质量影响因素及其规律的实验研究

研究了KDP晶体卧式飞刀切削加工时刀具前角、进给量及背吃刀量对晶体表面粗糙度和表面波纹度的影响规律;比较分析了KDP晶体卧式与立式两种飞刀切削加工方法的各自优势和两种切削加工方式下切削参数对工件表面质量影响规律的异同.