ACHIEVING THRESHOLD BARRIER OF 1 nm ROUGHNESS VALUE OF SILICON SURFACE BY DIAMOND TURNING

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Comparison of tribological parameters of surfaces determined by the stylus method and by the immersion method of holographic interferometry

The investigation of surface roughness by the use of the improved immersion method of holographic interferometry is reported in this paper; the results obtained for some engineering surfaces are given.The application of the holographic microscope, specially designed imersion cell and transparent replicas that reproduce details of the differently machined engineering surfaces allows us to obtain contour maps of the surface asperities with intervals between contour lines of about 1 μm.The contour maps were used for determining the tribological parameters of the surface which were compared with those obtained by the use of stylus methods.It is shown with a few examples that the roughness parameters determined from the contour maps have greater values than those obtained by the profilometry.     

Noncontact surface roughness measurement of engineering surfaces by total integrated infrared scattering

As precision engineering surfaces are gaining in importance in industry, so are the surface quality requirements. These surfaces have rms roughness typically ranging from some nanometers up to a few micrometers. Although numerous techniques exist for rough surface characterization, from traditional line-scanning stylus profilometers to modern three-dimensional (3-D) measurement instruments, there is a need for a fast, area-covering technique. An efficient method for the characterization of smooth surfaces is elastic light scattering. At visible wavelengths, the limits on roughness range and spatial frequency range make the method unsuitable for characterizing engineering surfaces. By increasing the wavelength of the incident light from the visible to the infrared, elastic light scattering turns out to be applicable for engineering surfaces. We have used total integrated scattering at 10.6 μm wavelength to measure rms roughness up to two micrometers. In this paper, the instrument design and properties are reviewed. We also present results from measurements on ground steel surfaces. Excellent correspondence with mechanical stylus measurements exists for surfaces with rms roughness in the range from 0.1–1.7 μm. The technique shows potential for rapid quality inspection of engineering surfaces.     

Comparison of optical and stylus methods for measurement of surface texture

Optical methods are increasingly used for measurement of surface texture, particularly for areal measurements where the optical methods are generally faster. A new Working Group under Technical Committee (TC) 213 in the International Organization for Standardization is addressing standardization issues for areal surface texture measurement and characterization and has formed a project team to address issues posed by the optical methods. In this paper, we review the different methods of measuring surface texture and describe a classification scheme for them. We highlight optical methods and describe some of their characteristics as well as compare surface-profiling results obtained from three optical methods with those obtained from stylus profiler instruments. For moderately rough surfaces (Ra?≈?500 nm), roughness measurements obtained with white light interferometric (WLI) microscopy, confocal microscopy, and the stylus method seem to provide close agreement on the same roughness samples. For surface roughness measurements in the 50 to 300 nm range of Ra, discrepancies between WLI and the stylus method are observed. In some cases the discrepancy is as large as about 75% of the value obtained with the stylus method. By contrast, the results for phase shifting interferometry over its expected range of application are in moderately good agreement with those of the stylus method.     

Laser optical roughness measurement

A method for non-contacting profile assessment and roughness measurements of engineering surfaces is presented. The well known effect of focusing a light beam on the surface is used, at the same time compensating for the effect on the measuring results of varying material colours by appropriately processing the measuring signal. The sensor and the transducer are connected with the data-processing unit of a stylus instrument, which provides for a simple procedure of recording the roughness profile and calculating standard roughness parameters from it. The measuring results thus obtained agree well with the results of traditional stylus instruments.     

The influence of stylus flight on change of surface topography parameters

Theoretical and experimental work on stylus flight is described. The paper describes the development of a simulation model for assessing the magnitude of surface topography distortion by stylus flight. Experiments on the surfaces support the theoretical model, which predicts stylus flight. The measurements of different surface topographies (including surfaces after grinding, turning, honing, milling) were done using Talyscan 150 measuring instrument with four traversing speeds (0.5, 1, 2 and 3 mm/s). The results of theoretical considerations and experiments were compared. The effect of stylus flight on surface topography parameters of measured surfaces basing on experimental investigation was assessed. The tendency was found that slope decreased, decrease of amplitude parameters and increase of horizontal parameters took place, but these effects were different for various surface types. The simulation procedure assured good accuracy of surface topography parameters changes.Based on theoretical investigation, the effect of stylus flight and stylus tip radius on parameters of computer-generated profiles was predicted. The choice of traversing speed to different types of surfaces was done. The parameters of biggest changes caused by error in measurement due to stylus kinematics were selected.     

Analysis of the active profile of grinding wheel surfaces

Tests have been carried out on simulated surfaces (produced by a signal generator in conjunction with an analogue computer) and on real surfaces to determine the effect of limited depth of stylus penetration in the characterization and specification of surface texture. This work is directed mainly to the working surface of grinding wheels.     

3-Dimensional profile distortion measured by stylus type surface profilometer

In this paper, the distortion effect in measured profiles caused by stylus tip radius size of stylus-typed surface profilometer was analyzed in terms of 2D and 3D. On the basis of our analysis results, we propose selection criteria for the stylus tip radius to improve the reliability of measurement results. For this purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3-dimensional surface texture used in simulation was obtained using an Atomic Force Microscope (AFM) on an actual machined surface to improve the reliability of simulation results. The simulation results are compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study is confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency components field using a stylus type profilometer is clarified, and the selection criteria of the stylus tip radius for measurement is proposed considering the surface texture characteristics of the specimen. The purpose of this paper is to provide a basis of a simple and effective method which could be an alternative of some engineering standard that specifies selection of stylus tip radius for the measurement using only nominal Rq for machined surface.     

On the Use of Silicon Rubber Replica for Surface Topography Studies

Silicone rubber is often used to obtain replica of surfaces which are hard to study directly. Here we discuss under what conditions engineering stylus measurements can be used to obtain the correct surface roughness from the replica. We also show how thin vertical slices of the silicone rubber can be used to obtain the surface roughness power spectra for the long-wavelength roughness on even very rough surfaces, such as road surfaces, which may be hard to probe directly with standard optical or stylus instruments.     

触针式三维粗糙度测量仪的开发及应用

基于表面微观形貌三维分析的完整性,介绍了一种新开发的触针式三维粗糙度测量仪。该测量仪可对表面各种功能属性、纹理结构、表面重要缺陷等进行量化描述,并通过对气缸套内表面珩磨平台网纹角度、分布、有效沟槽等的检测,验证了三维图像对实现表面个性化功能属性描述的重要意义,给人们认识和研究微观形貌提供了帮助。     

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.     

Quantitative characterization of abrasive surfaces using a new profile measuring system

An on-line computer-controlled profilometer is described for quantitative characterization of extremely rough surfaces such as grinding wheels and coated abrasives. Conventional profilometers offer difficulty in the characterization of such surfaces because of the tendency of the stylus to become stuck in the crevices. In this present system, the stylus oscillates while the surface below moves incrementally so that the surface is stationary when contacted by the stylus. Both stylus and wheel motion are controlled by a digital computer. Measurements of surface elevation are input to the computer for digital processing and various surface characteristics are computed. The use of the system is illustrated by showing the effects of grit size on coated abrasive topography.     

Local slope analysis in the stylus-based assessment of surface integrity

The need for a robust indication of surface integrity is addressed thrcugh the utilization of a traditional stylus instrument. Conventional parameters do not characterize adequately the functionally important, qualitative aspect of the surface. However, with the knowledge of the stylus flank angle and through the analysis of local slopes, a determination of the presence of reentrant features (folds, micro-burrs, etc.) can be made. The development of the methodology is presented along with an example of its application to machined cast iron surfaces. Further considerations are presented in light of the application of this methodology to the general assessment of surface integrity.     

Assessment of surface roughness based on super resolution reconstruction algorithm

In this work, an attempt has been made to use a super resolution image processing algorithm for preprocessing the images over and above existing image quality enhancement techniques. The improved quality images processed using a machine vision system have been used to assess the quality of the surfaces. To ensure the validity of the approach the roughness values quantified using these images are then compared with widely accepted standard mechanical stylus instrument values. Quantification of digital images for surface roughness is performed using two Fourier transform parameters (major peak frequency and principal component magnitude squared value) and the standard deviation of gray level intensity values. Then the group method of data handling (GMDH) technique was used to obtain an analytical relationship of the roughness parameters calculated using the digital surface image and the stylus instrument values. We present in this paper an analysis based on the comparison to make sure that the present approach of estimation of surface finish based on the digital processed image could be implemented in practice.     

Analysis of profile measurement techniques employed to surfaces planed by an active machining system

The importance of a reliable and robust surface profile measurement system in the inspection of surface finish is beyond any doubt. For years, visual inspection has been employed in industries to determine the quality of surface finish. Since, in most cases, it fails to ensure a consistent minimum standard of finish quality, mechanical stylus based measurement systems have successfully taken over from human inspection. However, in recent years, the trend is to explore other techniques for conducting surface profile measurements. Non-contact optical methods have emerged as one of the leading candidates. In this paper, capabilities of two optical profile measurement methods (namely, light-sectioning and two-image photometric stereo) have been explored for surfaces machined using an active machining system. These profile measurement results have been compared to the ones obtained from a conventional mechanical stylus instrument. An industry-standard Talysurf CLI system has been used to provide the benchmark, traceable to NPL standards, for the measurements. Suitability of different measurement techniques have been discussed based on the results obtained.     

Roughness measurement by electronic speckle correlation and mechanical profilometry

A practical optical sensor for rough surface diagnostics has been developed for applications in mechanical engineering. The principle of the sensor is based on digital speckle correlation. First, the measuring principle and the optical system arrangement are described, then optical measurements on different rough surfaces are compared with mechanical stylus measurements and the results are discussed with consideration of the advantages and differences of the two methods.     

Uncertainty analysis of roughness standard calibration using stylus instruments

A stylus instrument was characterized and calibrated, including a dynamic calibration of the probe. This stylus instrument was used to calibrate ten roughness standards for six surface roughness parameters. The sensitivity of each parameter of each standard to such measurement conditions as stylus geometry, measurement force, cut-off wavelength, and so forth was determined experimentally. These results were used for an uncertainty evaluation of each parameter for each roughness standard. It is shown that the manufacturers’ specification for the stylus instrument (2% uncertainty in roughness parameters) is approximately correct for the most commonly used samples and parameters, but the uncertainty may range from 0.03% (for sinusoidal profiles) to 100% (for very fine surfaces), depending upon the standard and parameter to be calibrated.     

触针式表面结构区域法软件系统的开发

在分析触针式表面结构区域法测量系统的基础上,介绍了其软件系统的功能设计、软件构架及软件实现等。并根据ISO/TC25178-7软件测量标准,通过与NIST-Internet based Surface Metrology Algorithm Testing System调用同一组SDF格式数据进行对比,验证了本软件的准确性。     

A new stylus instrument with a wide dynamic range for use in surface metrology

An instrument has been developed which can measure not only radius of curvature but also form deviation and surface texture at the same time. A computer is used to mathematically separate the form from the texture. The technique can be applied to the measurement of cross track curvature of bearing raceways and to other precision components whose form is defined as a circular arc, or a straight line, in which case angle will be measured instead of radius. The measurement of other forms such as parabolic, elliptical, hyperbolic and aspheric are the subject of continuing development. The instrument provides a distinctive and useful advance in measurement by the stylus method, offering possible solutions to many obdurate problems in the field of surface metrology