Measurement of various properties of Southern pine and aspen as function of heat treatment

The objective of this study was to investigate the influence of heat treatment parameters, namely temperature and exposure time on surface roughness, shear strength, hardness and density of Southern pine (Pinus echinata) and aspen (Populus grandidentata) samples. The specimens were exposed to two different temperature levels of 120–200 °C for time spans of 2–8 h. A stylus type portable profilometer was employed to evaluate the surface characteristics of the samples by taking measurements across the grain orientation. Average roughness (R_a), mean peak-to-valley height (R_z) and maximum roughness (R_max) were used to evaluate surface roughness of the samples exposed to various heat treatment schedules. Comten testing unit was also used to determine shear strength and Janka hardness of the control and heat treated specimens. Based on the results of this study Southern pine samples had more enhanced surface quality but lower hardness values than those of aspen specimens with increased temperature and time of heat treatment schedules. It was found that heat treatment adversely affected hardness and shear strength properties of all types of samples. Reduction in shear strength values of Southern pine and aspen samples ranged from 23.31% to 68.59% and from 4.67% to 48.55%, respectively as compared to those of control samples. It appears that influence of heat treatment on all properties of the samples was more pronounced with increasing temperature and exposure time.     

Effects of Surface Roughness and Wood Grain on the Friction Coefficient of Wooden Materials for Wood–Wood Frictional Pair

In order to investigate the effects of the surface roughness and wood grain on the friction coefficient of wooden materials, the friction coefficients of solid wood, medium-density fiberboard (MDF), and particle board (PB) with varying surface roughness were tested by a friction coefficient tester. The friction coefficients of solid wood for a wood–wood frictional pair were measured under varying wood grain (the orientation of fibrils). The results showed that the friction coefficients of the solid wood increased linearly with the arithmetic mean deviation of the surface profile (R_a). The friction coefficients of MDF and PB increased sharply at first and then stabilized with increasing R_a. The friction coefficient of solid wood was respectively maximized and minimized when the grain directions of two wood specimens were both perpendicular to the sliding direction and perpendicular to each other.     

In-process surface roughness measurement of bulk metallic glass using an adaptive optics system for aberration correction

Bulk metallic glasses (BMGs) have received extensive attention recently due to amorphous-related extraordinary properties such as high strength, elasticity, and excellent corrosion resistance. In particular, Zr-based BMGs are recognized as a biocompatible material and surface roughness may affect many aspects of cell attachment, proliferation and differentiation. Therefore, this study presents an in-process measurement of surface roughness by combining an optical probe of laser-scattering phenomena and adaptive optics (AO) for aberration correction. Measurement results of six Zr-based BMGs samples with a roughness ranging from 0.06 to 0.98 μm demonstrate excellent correlation between the peak power and average roughness with a determination coefficient (R²) of 0.9974. The proposed adaptive-optics-assisted (AO-assisted) system is in good agreement with the stylus method, and less than 8.42% error values are obtained for average sample roughness in the range of 0.05–0.58 μm. The proposed system can be used as a rapid in-process roughness monitor/estimator to further increase the precision and stability of manufacturing processes for all classes of BMGs materials in situ.     

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.     

Measurement of bonding strength of pine,kapur and meranti wood species as function of their surface quality

The objective of this experimental study was to evaluate bonding strength of specimens from widely used three species, pine (Pinus strobus), kapur (Dryobalanops spp.) and meranti (Shorea spp.) as they were sanded with different grits of sandpapers. Surface quality of control samples and those sanded with 80, 100 and 240 grit sandpapers was determined using a stylus type equipment. Control samples of both hardwood species resulted in less smoother surface values when they were sanded with 80 grit sandpaper. Rougher surface quality of the samples had higher bonding values as compared to those of control specimens as well as those sanded with 100 and 240 grits. Based on the findings in this work, the stylus method can have a potential to evaluate surface roughness of these specimens to have a better understanding of overall bonding quality of such species so that they can be used more effectively for different applications.     

Investigations on machined metal surfaces through the stylus type and optical 3D instruments and their mathematical modeling with the help of statistical techniques

The measurement of roughness on machined metal surfaces is of considerable importance to manufacturing industries as the roughness of a surface has a significant influence on its quality and function of products. In this paper, an experimental approach for surface roughness measurement has been based on the comparison of roughness values taken from the stylus and optical type instruments on the machined metal surfaces (turning, grinding and milling) is presented.Following this experimental study, all measured surface roughness parameters have been analyzed by using Statistical Package for Social Science (SPSS 15.0) statistically and mathematical models for the two most important and commonly used roughness parameters R_a and R_z have been developed so that R_a = R_a (F, P, C) and R_z = R_z (F, P, C, M), whereas F expresses feed, P periodicity, C contrast and M the type of material. The statistical results from numerous tests showed that there has been a correlation between the surface roughness and the properties of the surface topography and there have been slight differences among three measurement instruments on machined metal surfaces in this experimental study.     

Assessment of surface finish on bulk scattering materials: A comparison between optical laser stylus and mechanical stylus profilometers

The accuracy of autofocusing laser stylus measurement systems based on the compact disk pick-up technique has been discussed in recent years, in particular for surface roughness measurement in the submicron-micron range. In this article we present a thorough comparison between an optical laser stylus measurement system and a Talystep mechanical stylus profilometer. Sixteen surfaces having root mean square roughnesses from 0.002 μm to 3 μm for cut-off lengths <0.8 mm have been used in the study. Both bulk scattering (paper, white ceramic) and surface scattering (metal sheet) types of samples were included. Our study shows that the laser stylus exaggerates the surface profile, in particular on surfaces having laterally small but steep local slopes. For the paper surfaces the laser stylus data were on average off by a factor of two for a cut-off length of 0.68 mm.     

Photoetching of narrow deep slots for stylus wear standards

The performance of surface texture instruments needs to be assessed periodically. Although a step height standard checks vertical magnification and an R_a standard checks mathematical integration, no stylus wear standard was available for checking resolution.Such a standard has now been produced with vertical-walled slots of widths 2.5, 5, 10 and 20μm, and a minimum depth of 42.4μm, made by anisotropic photoetching of polished silicon slices.During exposure of photoresist the slots were aligned with a crystal cleavage plane to control line width and this was achieved using a circular table to orientate the slice with a chrome-on-glass mask.These stylus wear standards are now commercially available     

光针式三维表面形貌测量仪的研制

研制了一种基于动态聚焦探测法的新型光针式三维表面形貌测量仪,该仪器可实现表面三维形貌的快速、无损、非接触测量。介绍了该仪器的测量原理、仪器结构、伺服机构的设计并给出了实测结果。仪器垂直测量范围为500μm;垂直方向测量精度可达0·5μm,分辨率为0·01μm。     

Noncontact roughness measurement of turned parts using machine vision

The surface roughness of turned parts is usually measured using the conventional stylus type instruments. These instruments, although widely accepted, have several limitations such as low speed measurement, contacting in nature, requiring vibration-free environment, etc. Machine vision methods of roughness measurement are being developed worldwide due to their inherent advantages, including noncontact measurement, high information content, rapid measurement, and surface measurement capability. In past research, area-based light scattering method and gray scale line intensity measurement have been developed for roughness assessment using machine vision. Such methods, however, produced redundant data when applied to measure roughness of turned parts. In this paper, an alternative method of roughness measurement using the 2-D profile extracted from an edge image of the workpiece surface is proposed. Comparison with a stylus type instrument shows a maximum difference of 10% in the measurement of average roughness R _a using the vision method.     

Experimental analysis of applicability of a picosecond laser for micro-polishing of micromilled Inconel 718 superalloy

An increasing number of recent technological advancement is linked to the widespread adoptions of ultra-short picosecond (ps) pulsed laser in various applications of material processing. The superior capability of this laser is associated with the precise control of laser–material interaction as an outcome of extremely short interaction times resulting in almost-negligible heat affected zones. In this context, the present study explores the applicability of a picosecond laser in laser micro-polishing (LμP) of Ni-based superalloy Inconel 718 (IN718). The specific research goals of the present study constitute determination of melting regime—a mandatory phase for LμP, establishing the concept of polishability of the spatial contents of the initial surface topography and experimental demonstration of the process capability of a ps laser for potential micro-polishing applications. The initial surface topography was prepared by micromilling operation with a step-over of 50 μm and scallop height of 2 μm. The LμP experiments were performed at five different levels of fluence associated with the melting regime by changing the focal offset, a parameter denoting the working distance between workpiece surface and focusing lens focal plane. The LμP performance was evaluated based on the line profiling average surface roughness (R _a) spectrum distributed at different spatial wavelength intervals along the laser path trajectory. Furthermore, additional statistical metrics such as material ratio and power spectral density functions were analyzed in order to establish the process parameters associated with best achievable surface finish. The applicability of ps LμP was demonstrated in two regimes—1D (line) and 2D (area) polishing. During 1D LμP, significant (～52 %) improvement of the surface quality was achieved by reducing an R _a value from 0.50 μm before polishing to an R _a value of 0.24 μm across the laser path trajectory on initially ground surface. In addition, an initially micromilled area of 4.5?×?4.5 mm was LμPed resulting in the reduction of an areal topography surface roughness (S _a) value from 0.435 to 0.127 μm (70.8 % surface quality improvement).     

PEEK不同表面粗糙度与分形维数关系研究

为探究PEEK不同表面粗糙度与分形维数之间的关系,在触针式表面轮廓仪上测量PEEK不同表面的粗糙度并采集了其轮廓曲线和数据。运用分形理论随机过程的结构函数方法,分析轮廓曲线的分形特征,并计算出不同表面粗糙度的分形维数。利用SPSS统计软件对粗糙度和分形维数关系进行拟合并得到最佳的拟合模型。结果表明:分维可以作为一个独立的表征参量来表征粗糙表面的复杂程度和粗糙度水平;PEEK的分形维数与粗糙度存在单调递减的关系,粗糙度数值越大,分形维数值越小;通过分形维数值与粗糙度之间的关系式,在一定范围内,可以通过粗糙度值计算得出分形维数值。     

Surface finish of bulk metallic glass using sequential abrasive jet polishing and annealing processes

Surface finish plays an important role in product quality due to its direct effects on product appearance. Hence, improvement of the surface finish is an essential requirement in industrial products. In an attempt to improve the surface finish of bulk metallic glass (BMG) material, several common methods have been used, such as milling, grinding, and lapping. However, the BMG surface finish has not yet been significantly improved by using these methods. Therefore, this paper proposes sequential abrasive jet polishing (AJP) and annealing processes that can considerably improve the BMG surface finish. In addition, this paper also takes into account optimal parameters for the AJP and annealing processes based on the Taguchi’s L ₁₈ and L ₈ orthogonal array experimental results, respectively. The experimental results show that using optimal AJP parameters, the surface roughness (R _a) of the ground specimens can be significantly improved from 0.675 to 0.016 μm. After the AJP process, the surface roughness (R _a) of the polished specimens can be further improved from 5.7 to 2 nm within an area of 5?×?5 μm by using optimal annealing parameters.     

Surface roughness aspects in milling MDF (medium density fibreboard)

Medium density fibreboard (MDF) is an industrial wood product. It is made out of wood waste fibres glued together with resin by heat and pressure. Nowadays MDF products are preferred over solid wood in many applications due to certain comparative advantages. Milling is the machining operation frequently used in manufacturing parts of MDF. The aim of this article is to study the influence of cutting parameters (cutting speed and feed rate) on surface roughness in MDF milling. A plan of MDF milling experiments was performed with prefixed cutting parameters. The objective was to establish correlation between cutting speed and feed rate with the surface roughness in MDF panels after milling. The surface roughness decreases with an increase of spindle speed and increases with the feed rate. The milling tests showed the important role spindle speed plays on the evolution of the surface roughness as a function of material removal rate (MRR). The advantage of using a high cutting speed in MDF milling is evident.     

Comparative assessment of wiper and conventional ceramic tools on surface roughness in hard turning AISI 4140 steel

This study considers the comparison between the surface roughness criteria (Ra, Rz and Rt) of the wiper inserts with conventional inserts during hard turning of AISI 4140 hardened steel (60 HRC).The planning of experiments was based on Taguchi’s L₂₇ orthogonal array. The response surface methodology (RSM) and analysis of variance (ANOVA) were used to check the validity of quadratic regression model and to determine the significant parameter affecting the surface roughness. The statistical analysis reveals that the feed rate and depth of cut have significant effects in reducing the surface roughness. The optimum machining conditions to produce the best possible surface roughness in the range of this experiment under these experimental conditions searched using desirability function approach for multiple response factors optimization. The results indicate that the surface quality obtained with the wiper ceramic insert significantly improved when compared with conventional ceramic insert is 2.5. Roughness measurements reveal a dependence on CC6050WH tool wear. However, although the wear rises up to the allowable flank wear of value 0.3 mm, roughness Ra did not exceeded 0.9 μm.     

On the tribological behavior of retrieved hip femoral heads affected by metallic debris. A comparative investigation by stylus and optical profilometer for a new roughness measurement protocol

In this study, 35 retrieved ceramics femoral heads with evidence of metallic dark lines on the surface were analyzed. The surface roughness of these femoral heads was acquired using both a stylus contact profiler and an optical non-contact profilometer. The metallic deposition on hip ball surface, also known as Metal Transfer (MT), appeared as dark metallic and can occur during the surgery or during the reduction of a dislocated prosthesis. In this study, we validate a new protocol to measure surface roughness on retrieved femoral heads, by using the aforementioned two different acquisition techniques and also to investigate the hypothesis that such metal transfer retrieved ceramic femoral head is associated with increased surface roughness.All femoral components of this investigation showed remarkable differences in roughness values between MT-affected and MT-unaffected areas. The two acquisition procedures – conventional stylus and 3D confocal profilometer – confirmed a satisfying agreement, even considering the obvious resolution difference.     

Sinusoidal profile precision roughness specimens

The design, specifications, fabrication, testing and potential use of a series of sinusoidal profile precision roughness specimens are described. These specimens were designed primarily to provide a means for optimum transfer of an accurate roughness average R_a value from primary to secondary laboratories. However, properties of the specimens also make them very useful for evaluating instrumentation and computational algorithms designed to measure the statistical parameters and functions now being investigated in many laboratories. Specimens with an R_a value of 1.0 μm and spatial wavelengths of 40, 100 and 800 μm are being fabricated. For the wavelength of 100 μm, specimens are also being fabricated with R_a values of 3.0 and 0.3 μm. Fabrication using numerically controlled diamond lathes has produced specimens with very high quality sinusoidal profile waveforms with uniform R_a values across the surfaces and with very low amounts of waviness over a test area of about 2 cm².     

磨合阶段的机械密封端面形貌特征研究

表面粗糙度对机械密封性能有着显著影响。利用MMU-2摩擦磨损试验机和表面轮廓仪,对3个不同粗糙程度的密封端面进行了摩擦磨损试验。引入特征粗糙度,研究了3个不同粗糙程度的密封端面在摩擦磨损过程中的特征粗糙度变化规律,并与表面的轮廓算术平均偏差粗糙度变化规律进行了比较。研究表明,不同初始粗糙程度的端面在跑合过程结束后,粗糙度趋于一致。这一结果为利用特征粗糙度正确设计机械密封端面,合理选择端面加工方法提供了依据。     

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.     

Process investigation on meso-scale hard milling of ZrO2 by diamond coated tools

This paper investigates the feasible machining of zirconium oxide (ZrO₂) ceramics, in the hard state, via milling by diamond coated miniature tools (from here on briefly indicated as meso-scale hard milling). The workpiece material is a fully sintered yttria stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP). Diamond coated WC mills, 2 mm in diameter, four flutes and large corner radius (0.5 mm) are chosen as cutting tools, and experiments are conducted on a state-of-the-art micro milling machine centre. The influence of cutting parameters, including axial depth of cut (a_p) and feed per tooth (f_z), on the achievable surface quality is studied by means of a one-factor variation experimental design. Further tests are also conducted to monitor the process performance, including surface roughness, tool wear and machining accuracy, over the machining time. Mirror quality surfaces, with average surface roughness Ra below 80 nm, are obtained on the machined samples; the SEM observations of the surface topography reveal a prevailing ductile cutting appearance. Tool wear initiates with delamination of the diamond coating and progresses with the wear of the WC substrate, with significant effect on the cutting process and its performance. Main applications of this research include three dimensional surface micro structuring and superior surface finishing.