Spectral and 3D motifs identification of anisotropic topographical components. Analysis and filtering of anisotropic patterns by morphological rose approach

In this paper we show two new developments in the three-dimensional characterisation of rough surfaces. The basic idea is to consider roughness as a combination of components defined by the roughness amplitude, wave length, local and overall direction of various components. The anisotropic topography is dealt with in two ways:

• - the anisotropy between form, waviness and roughness;

• - the local anisotropy of three-dimensional motifs.

The directional parameter is used both to identify and separate the anisotropic components by appropriate anisotopic filtering and by a complete characterisation of surface motifs. This allows the decomposition of the topography into local motifs with a representation similar to the two-dimensional Fourier transform, where the direction represents the topographic phase in the form of a morphological rose.     

Modelling of specific energy requirement during high-efficiency deep grinding

Grinding is a multi-point cutting operation. The specific energy or the energy expended for unit material removal in grinding is very high, typically one or two orders higher than the machining specific energy. Such high specific energy required in grinding can be attributed to the irregular and random geometry of the abrasive grits, which induce a lot of rubbing and ploughing actions along with the chip formation by shearing process. Also the effective angle in grinding is highly negative which is again responsible for such high-specific energy requirement in grinding. In grinding, a number of notable phenomena occur during the chip formation process, which actually consumes a significant percentage of energy. Such main energy consumers in grinding are:

• Chip formation due to shearing

• Primary rubbing

• Secondary rubbing

• Ploughing

• Wear flat rubbing

• Friction between the loaded chip and workpiece

• Friction between bond and workpiece, etc.

The present paper tries to analytically predict the specific energy consumed during high-efficiency deep grinding (HEDG) of bearing steel by monolayer cBN wheel. During the HEDG process, energy is spent mostly for shearing, rubbing and ploughing processes. The other energy consumers have insignificant role in such high-speed grinding process. So, models which take into account the processes of shearing, primary rubbing, secondary rubbing and ploughing process can reasonably be used to predict the energy requirement in such HEDG process. The total specific energy value obtained from the model has been validated with those experimentally observed values. A good trend matching of the modelled and experimental values have been observed and the root mean square error values have been found to vary between 7% and 11%.     

3D fractal-based characterisation for engineered surface topography

We investigate the concept of surface roughness by assuming that z(x) verifies a Lipschitz condition in terms of variance var(z(x+Δ)−z(x))∝Δ^2H with 0<H<1 and Δ→0. Such surfaces are only locally self-affine at scale where the prev relation is verified. The Lipshitz Hölder exponent H, which is directly connected to the surface fractal dimension D, is determined from the log-log plot of σ²-(L) versus the characteristic size L of the sampling area. Different results are presented. The first, which concerns simulated profiles derived from the Weierstrass function, gives some indication on the accuracy of the method. The other concerns 3D analysis of real sandblasted surfaces parallel to a simulated fractal surface. An extension of the theoretical analysis to certain non isotropic surfaces is also presented and applied to a real ground surface.     

Corrosion resistance without hexavalent chromium—new zinc plating systems

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•|Automotive OEMs are moving rapidly to eliminate hexavalent chromium to meet the new requirements.

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•|Substitution of hexavalent chromium by alternatives requires more attention to be paid to mechanical handling since alternatives have inferior “self healing” properties.

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•|Enthone has developed technology to meet these needs for many areas of application.

     

Geometrical modification of coated carbide inserts for improved performance in high production face milling

The role of some geometrical modifications of coated carbide inserts on the improvement of their performance in high production face milling has been investigated.

The principal geometrical features investigated were:

1. (i) edge-bevelling for controlled contact cutting effects, higher edge-strength and better heat dissipation;

2. (ii) intermediate cutting edge for higher tip-strength and better heat dissipation;

3. (iii) wide planishing edge for good surface finish.

The role of these different geometrical parameters of the inserts on cutting forces, wear and surface finish in machining low carbon steel has been studied. Some benefits of edge-bevelling have been observed. Mathematical relationships for the cutting forces have also been developed.     

Suppression of chatter vibration of boring tools using impact dampers

In this study, improvement of the damping capability of boring tools and suppression of chatter vibration were attempted using impact dampers. Bending tests, impact tests and cutting tests were carried out, whilst widely varying the method of applying an impact damper to a boring tool. The effects of the amount of free mass and clearance, the overhang length of boring tools and their cutting condition were investigated. As a result, the following points were clarified.

(i)

The damping capability of boring tools is considerably improved using impact dampers.

(ii)

All three types of impact dampers used in the experiment can considerably suppress the vibration of boring tools in the vertical direction (principal force direction), but hardly suppress it in the horizontal direction (thrust force direction) where the amplitude is extremely small.

(iii)

In practical use, the method of equipping an impact damper on the flank face of a boring tool is desirable.

(iv)

Using an impact damper, it is possible to bore deeper holes in comparison with boring tools now on the market and to improve the efficiency of boring operations.

Surface and geometry error modeling in brittle mode grinding of ophthalmic lenses moulds

The selection of modeling and machining parameters for glass mould fabrication in ophthalmic lenses production, has required the definition of a theoretical–empirical model of the ground surface in order to predict the overall geometry errors of the surface. The accurate control of the geometrical errors and of the surface texture for the mould functional surface is crucial for the subsequent polishing operation, which is responsible for the final geometry, surface finish and cost. The basic hypotheses validation has been accomplished by measuring the micro-geometric parameters P, W and R and by characterizing the macro-geometry comparing the nominal profile and the measured profile. The correspondence among theoretical hypotheses and experimental results allows realistic predictions of the attainable surface texture during a contour grinding operation and the adoption of preventive actions in order to compensate the geometrical errors due to modeling and tool path generation parameters.     

3D surface characterisation of electropolished EDMed surface and quantitative assessment of process variables using Taguchi Methodology

The electro discharge machining (EDM) process produces surfaces that require some form of finishing operation. This is done in order to improve the surface texture and appearance of the component’s surface. However, it is also desirable to remove the white uppermost recast layer (produced by the EDM process) so as to improve the functional performance of the surface. Electropolishing or electrochemical polishing (ECP) is one technique that is used mainly to improve the appearance of steels as well as for passivation of stainless steels. However, this process is very complex in nature, and it is not well understood how the different process parameters influence the surface integrity of the component in salt solutions. The aim of this paper is to present the results of a preliminary design of experiment of an EDM+ECP process sequence using Taguchi methodology. 3D characterisation of the surfaces has been done and ANOVA technique has been used to assess the quantitative influence of the different process factors of ECP. The results have shown that the direct current is the most dominant factor in modifying the surface texture, especially the S_q and S_m 3D parameters. The interaction effect between current and distance between electrodes is relatively important as compared to the individual effect of the latter variable.     

Servo scanning 3D micro-EDM based on macro/micro-dual-feed spindle

Using the end discharge of micro-rod-shaped electrode to scan layer by layer, micro-electrical discharge machining (EDM) can fabricate complex 3D micro-structures. During the machining process, the discharge state is broken frequently due to the wear of the tool electrode and the relative scanning motion. To keep a favorable discharge gap, the feed spindle of the tool electrode needs the characteristics of high-frequency response and high resolution. In this study, an experimental system with a macro/micro-dual-feed spindle was designed to improve the machining performance of servo scanning 3D micro-EDM (3D SSMEDM), which integrates an ultrasonic linear motor as the macro-drive and a piezoelectric (PZT) actuator as micro-feeding mechanism. Based on LabVIEW and Visual C++ software platform, a real-time control system was developed to control coordinately the dual-feed spindle to drive the tool electrode. The micro-feed motor controls the tool electrode to keep the favorable discharge gap, and the macro-drive motor realizes long working range by a macro/micro-feed conversion. The emphasis is paid on the process control of the 3D SSMEDM based on macro/micro-dual-feed spindle for higher machining accuracy and efficiency. A number of experiments were carried out to study the machining performance. According to the numerical control (NC) code, several typical 3D micro-structures have been machined on the P-doped silicon chips. Our study results show that the machining process is stable and the regular discharge ratio is higher. Based on our fundamental machining experiments, some better-machined effects have been gained as follows. By machining a micro-rectangle cavity (960 μm×660 μm), the machined depth error can be controlled within 2%, the XY dimensional error is within 1%, the surface roughness R_a reaches 0.37 μm, and the material removal rate is about 1.58×10⁴ μm³/s by using a tool electrode of Φ=100 μm in diameter. By machining multi-micro-triangle cavities (side length 700 μm), it is known that the machining repeatability error is <0.7%.     

Developments in Australia's surface roughness measurement system

Roughness standards in Australia are established, maintained and disseminated by the Melbourne Branch of the National Measurement Laboratory (NML), Commonwealth Scientific and Industrial Research Organisation (CSIRO).A Taylor Hobson Talysurf 3 stylus instrument has been upgraded by replacement of the original valve amplification with solid-state electronics and the implementation of Windows 95 based software for profile analysis. The amplification is calibrated using gauge blocks wrung onto an optical flat or with master groove standards, calibrated using an interference microscope with a helium–neon laser light source. Measurements of step height or peak-to-valley roughness height in the range 0.1–50 μm are possible.The stylus instrument interfaces directly with a PC via a high speed analogue-to-digital card. Software has been developed to analyse grooves and steps and to characterise surfaces by calculation of various parameters such as arithmetic mean deviation (R_a). Typical uncertainties are better than 4% at a confidence level of 95% and are calculated automatically by the software according to the ISO “Guide to the Expression of Uncertainty in Measurement”.Technical and administrative procedures are discussed in the context of accreditation within the National Association of Testing Authorities, the Australian laboratory accreditation organisation.The facility has participated informally in a regional Asia–Pacific Metrology Programme intercomparison in which three surface roughness and two groove standards were circulated and the results are discussed.Using historical data, alternate traceability routes, and various artefact chains, the integrity of surface texture measurement at the new facility has been evaluated and verified.     

A brief review: acoustic emission method for tool wear monitoring during turning

Research during the past several years has established the effectiveness of acoustic emission (AE)-based sensing methodologies for machine condition analysis and process monitoring. AE has been proposed and evaluated for a variety of sensing tasks as well as for use as a technique for quantitative studies of manufacturing processes. This paper reviews briefly the research on AE sensing of tool wear condition in turning. The main contents included are:

1. The AE generation in metal cutting processes, AE signal classification, and AE signal correction.

2. AE signal processing with various methodologies, including time series analysis, FFT, wavelet transform, etc.

3. Estimation of tool wear condition, including pattern classification, GMDH methodology, fuzzy classifier, neural network, and sensor and data fusion.

A review of AE-based tool wear monitoring in turning is an important step for improving and developing new tool wear monitoring methodology.     

Evolution of hot rolling textures in a two-phase (α2+β) Ti3Al base alloy

Texture development during thermomechanical processing of two-phase (α₂+β) Ti–24Al–11Nb alloy was studied as a function of variables like initial microstructure, rolling temperature, cooling conditions, etc. The evolution of texture in different conditions has been critically analysed. It has been found that unrestricted rolling of primary α₂ at lower temperature leads to a good basal {0001}uvtw texture, while at higher temperatures, the α₂→β→α₂ phase transformation leads to weakening of the basal texture. Texture of secondary α₂ derived from rolled β is generally non-basal. However, the texture of secondary α₂ derived from recrystallized β has a basal character.     

Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

AA5182 aluminium alloy cold rolled samples were coated by thin films of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very effective for corrosion protection of aluminium alloys in neutral environment. This study underlines the prominent role of surface cathodic intermetallic particles in pit initiation and coating break down in enhanced corrosion conditions and suggest that, beside the EB barrier properties, the enhanced corrosion resistance observed on the EB coated samples could partly arise from two other mains factors:

•

a weak redox activity of the polymer which passivate the metal,

•

a proton involving self-healing process taking place at the polymer-metal interface, which contributes to delay local acidification in first steps of corrosion on EB coated aluminium surfaces.

     

基于3D打印与三维图像处理的服装信息提取方法研究

在形状基不定情况下,对三维服装信息提取过程存在特征关联较弱,分割区域扩大等问题.为此,提出一种基于3D打印与三维图像处理的服装信息提取方法.首先对采集的服装三维图像进行纹理特征分割,图像序列自适应块匹配方法进行信息增强处理,然后采用桌面型3D打印技术进行服装设计中的图像三维重构,进行服装三维图像表面渲染,实现服装信息提取.最后通过仿真实验进行性能测试,结果表明:采用该方法进行服装信息提取,能准确反映服装的纹理信息和三维渲染信息,服装设计的色彩均衡性较好,有效指导服装设计优化.     

基于GRNN的珩磨缸套表面3D粗糙度图像检测方法

活塞-缸套系统是内燃机重要的摩擦副之一，活塞-缸套的表面质量影响着活塞-缸套系统的摩擦学性能，进而直接影响整机的服役性能。针对珩磨缸套表面 2D 粗糙度参数的局限性与表面粗糙度非接触检测方法研究，提出一种基于广义回归神经网络(GRNN)的珩磨缸套表面 3D 粗糙度图像检测方法。通过运用灰度共生矩阵(GLCM)提取缸套表面图像的纹理特征参数，并分析纹理特征参数与 3D 粗糙度间的相关性。以图像纹理特征参数作为输入，分别采用 GRNN 和多元回归分析 (MRA)建立 3D 粗糙度检测模型，通过与试验检测结果对比验证了模型的准确性。GRNN 检测模型获得的可决系数 R2均值 (0.962)优于 MRA 检测模型，且均方误差 MSE 均值(0.07)更小，与试验检测结果对比可知，采用 GRNN 建立的珩磨缸套 3D 粗糙度检测模型具有更高的精度，与实测 3D 粗糙度的相对误差均值为 7.9%。所建立的 3D 粗糙度检测模型具有较高的检测精度。     

Degradation of space exposed surfaces by hypervelocity dust bombardment, and refractory materials for space

Dust particles with diameters below 100 μm represent an important part of the space environment. Objects like satellites or spacecrafts, are constantly bombarded with particles of cosmic velocities of 10 km/s and more. These hypervelocity impacts lead to evaporation of a large fraction of these particles and to the formation of craters on the material surfaces which exhibit diameters which are up to one order of magnitude larger than the impinging particles. This results in a remarkable materials degradation of space exposed surfaces which can considerably reduce the life time e.g. of semiconductor panels for the generation of energy, due to the cumulative effect of a multitude of such particles which hit a surface during a certain time.The particle population in space near to earth consists of two distinct groups:

(a) Natural particles, micrometeorites: These particles are a natural part of the space environment and cannot be avoided. Most of them have so-called “chondritic” compositions and consist of Si, Al, Mg, Fe, Ca and O, an elemental makeup resembling the bulk composition of the original solar nebula from which our solar system and the planets formed 4.5 billion years ago.

(b) Man made debris particles: These stem from various sources, e.g. exhausts from solid rocket fuels, paint chips, fragments from space crafts etc. These particles pose an increasing danger to space flight and their future production must be reduced by strict debris policies.

The important question was now:What percentage of impact particles is man-made?Cosmic and man-made particles exhibit different chemical compositions. Hence, a micro-chemical analysis of particle impacts on satellite surfaces can be used to determine the particle ratio. For this purpose, the LDEF-experiment (Long Duration Exposure Facility) was launched by NASA in 1984 to study erosion phenomena on material surfaces (of more than 10,000 test samples) in a Low Earth Orbit (LEO)-environment. LDEF was retrieved only in 1990 because of the Challenger disaster which essentially delayed the retrieval up to the last moment before the experimental setup would have been destroyed upon entrance into the earth atmosphere.The demonstration of pronounced material degradation of space exposed materials logically leads to the question which materials are used in space technology. Plansee SE in Reutte/Tyrol has quite a tradition in the production of smaller rocket nozzles, e.g. satellite propulsion nozzles and general propulsion components made of Mo, W, Nb or Ta-based alloys. The W–Ag evaporation cooled alloy was among the earliest materials for rocket combustion chambers enduring ultra high temperatures due to partial evaporation of the silver which thereby cooled the chamber. Ni- and Fe-based ODS superalloys find application in durable TPS/hot structures of hypersonic vehicles, e.g. as honeycomb panels and fasteners of PM 1000/2000. These are PM-ferritic and nickel based oxide dispersion strengthened alloys. We have studied the significance of Yttrium depletion within the oxide scales of these alloys.     

3D Reconstruction and Visualization of Microstructure Surfaces from 2D Images

This paper describes a stereophotogrammetry method that reconstructs 3D microstructure surfaces from Scanning Electron Microscope (SEM) images. The microstructure surfaces are represented as 3D meshes with texture. The method's algorithm is based on the following stages: a) computing 3D points from 2D matched points; b) triangulating the 3D points into a 3D mesh; and c) mapping a 2D image as a texture on the surface. The textured 3D surface exhibits very realistic 3D microstructure surfaces for 3D visualization and engineering analysis. The performance of the proposed method has been analyzed and demonstrated on a variety of materials and complex geometries.     

3D graphical evaluation of micron-scale protrusion topography of diamond grinding wheel

A new graphical evaluation of micron-scale wheel protrusion topography is proposed by using 3D coordinate data derived from contact measuring of 180 diamond grinding wheel. The objective is to quantify 3D distribution of grain protrusion height, gain rake angle and grain relief angle on wheel working surface in dressing. First adaptive measuring was conducted on the base of topographical curvature to identify grain cutting edge in 3D space, second grain protrusion mode was established by polar coordinate transfer so as to ascertain datum plane of grain protrusion, then linear approximation graphics was conducted to display wheel protrusion topography, finally distributions of gain rake angle and grain relief angle were investigated with reference to grain protrusion height. Analytical results show that higher outer grains have more and shaper cutting edges, but lower layer grains retain approximately original crystal forms. In wheel protrusion topography, grain protrusion heights, grain rake angles and grain relief angles are dispersedly distributed in the range 0–28 μm, −45.0° to −89.1° and 1.2–73.1°, respectively, which can be increased by dressing. It is concluded that 3D grain protrusion attitudes distributed on wheel working surface can be quantified by 3D graphical evaluation method.     

Separation of form from orientation in 3D measurements of aspheric surfaces with no datum

Measurement and characterisation of 3D form to maintain manufacturing quality has particular problems in cases such as lenses which do not generally have a clear measurement datum. A 3D-form measurement includes information about the form, the orientation and the position of the surface under test. Orientation and position can be design parameters or may result from misalignment of the test specimen on a measurement table. In either case, it is necessary to separate form from orientation and position if the data-set is to be fitted and compared with an “ideal” surface. In this paper two pre-processing algorithms are presented and examples given of the separation of form from orientation and position. The algorithm is applied to simulated data-sets consisting of up to 26,000 discrete points on a square grid, simulating the measurement of an aspheric lens in 3D. The rotationally symmetric data-set is translated for a distance x₀, y₀ and z₀ and rotated about two axes, x and y, to simulate misalignment. To simulate inaccuracies from a manufacturing process, normally distributed random noise is superimposed on the ideal surface. An application of pre-processing using a real data-set is also shown. Furthermore, form fitting is addressed and the interpretation of form by decomposition of the data into error types is discussed.