Values Of Roughness Parameters Research Articles

Effect of mechanical vibration on Ra, Rq, Rz, and Rt roughness parameters

The effect of mechanical vibration on the roughness parameters (Ra, Rq, Rz and Rt) obtained by an electromechanical surface roughness tester in two samples, a stainless steel with Ra equal to 0.369 μm and a carbon steel with Ra of 5.342 μm, is discussed in this article. The tests were performed by introducing vibration with different values of frequency and amplitude. The measurement uncertainty associated with all roughness parameters was estimated by applying the GUM method proposed in the JCGM 101. The analysis of variance (ANOVA) technique was applied, and it was observed that the variables frequency and acceleration plus interaction between them were statistically significant with a 95% confidence level for all parameters evaluated. In the stainless steel sample, frequency produced the greatest effects on the values of roughness parameters, except for Ra value, which was more influenced by the acceleration. It was also found that the effect of the interaction between frequency and acceleration produced significant effects on the values of Rq and Rz. In the carbon steel sample, the interaction between frequency and acceleration was the main generator of changes in the average values of all parameters evaluated. For Ra, Rq, and Rz, the frequency was also a statistically significant variable.

The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon

The paper concerns the wind influence on bottom shear stress and salinity levels in a Mediterranean semi-enclosed coastal lagoon (Etang de Berre), with respect to a replanting program of Zostera noltii. The MARS3D numerical model is used to analyze the 3D current, salinity and temperature distribution induced by three meteorological, oceanic and anthropogenic forcings in this lagoon. The numerical model has been carefully validated by comparison with daily observations of the vertical salinity and temperature profiles at three mooring stations, for one year. Then, two modelling scenarios are considered. The first scenario (scen.#1), starting with a homogeneous salinity of S = 20 PSU and without wind forcing, studies a stratification process under the influence of a periodic seawater inflow and a strong freshwater inflow from a hydropower plant (250 m3/s). Then, in the second scenario (scen.#2), we study how a strong wind of 80 km/h can mix the haline stratification obtained at the end of scen.#1. The most interesting results concern four nearshore replanting areas; two are situated on the eastern side of EB and two on the western side. The results of scen.#2 show that all these areas are subject to a downwind coastal jet. Concerning bottom salinity, the destratification process is very beneficial; it always remains greater than 12 PSU for a N-NW wind of 80 km/h and an hydropower runoff of 250 m3/s.Special attention is devoted to the bottom shear stress (BSS) for different values of the bottom roughness parameter (for gravels, sands and silts), and to the bottom salinity. Concerning BSS, it presents a maximum near the shoreline and decreases along transects perpendicular to the shoreline. There exists a zone, parallel to the shoreline, where BSS presents a minimum (close to zero). When comparing the BSS value at the four replanting areas with the critical value, BSScr, at which the sediment mobility would occur, we see that for the smaller roughness values (ranging from z0 = 3.5 × 10−4 mm, to 3.5 × 10−2 mm) BSS largely surpasses this critical value. For a N-NW wind speed of 40 km/h (which is blowing for around 100 days per year), BSS still largely surpasses BSScr - at least for the silt sediments (ranging from z0 = 3.5 × 10−4 mm, to 3.5 × 10−3 mm). This confirms the possibility that the coastal jet could generate sediment mobility which could have a negative impact for SAV replanting.

Surface integrity of Mg-based nanocomposite produced by Abrasive Water Jet Machining (AWJM)

ABSTRACTThis paper investigates the influence of jet traverse speed on the surface integrity of 0.66 wt% Al2O3 nanoparticle reinforced metal matrix composite (MMC) generated by Abrasive Water Jet Machining (AWJM). Surface morphology, surface topography, and surface roughness (SR) of the AWJ surface were analyzed. The machined surfaces of the nanocomposites were examined by laser confocal microscope and field emission scanning electron microscope (FESEM). Microhardness and elasticity modulus measurement by nanoindentation testing were also performed across thickness of the samples to see depth of the zone, affected by AWJ cutting. The result reveals that extent of grooving by abrasive particle and irregularity in AWJ machined surface increases as the traverse speed increased. Similarly, the rise in value of surface roughness parameters with traverse speed was also seen. In addition, nanoindentation testing represents the lower hardness and elastic modulus due to softening occurs in AWJ surface.

Behavior of some steels at vibrorolling

The vibrorolling could be sometimes applied as a finishing method to diminish the height of the surface asperities. It is expected that the mechanical characteristics of the workpiece material affect in a certain extent the generation of the new profiles corresponding to the surface roughness and distinct values of the surface roughness parameters could be obtained. An experimental research was designed and achieved taking into consideration some vibrorolling process input factors and distinct steels as materials for the test samples. The experimental results were mathematically processed and empirical models were determined. These mathematical empirical models highlight the distinct behavior of the studied steels evaluated by means of the Ra surface roughness parameter.

The analysis of surface topography during turning of Waspaloy with the application of response surface method

This paper presents the analysis of surface topography during longitudinal turning of Waspaloy. The primary objective of the work was to determine the optimal machining conditions enabling the minimization of surface roughness parameters. Experimental studies were performed with the application of fractional plan (with 1 block and 9 systems). The carried out experiment included the measurements of surface topographies formed after turning with variable cutting conditions (cutting speed vc, cutting depth ap and feed f). Subsequently the measured quantities have been applied to the optimization procedure based on the application of response surface method (RSM). In order to obtain the optimal cutting parameters, the maximization of total utility function was carried out. Results revealed that the minimal surface roughness parameters values during turning of Waspaloy with the cubic boron nitride (CBN) inserts can be obtained for the: f=0.05 mm/rev, ap =0.23 mm and vc =452 m/min.

Ellipsometric and reflectometric characterization of thin films exhibiting thickness non-uniformity and boundary roughness

In this paper epitaxial ZnSe thin films prepared by molecular beam epitaxy onto GaAs single crystal substrates exhibiting two defects, i.e. boundary roughness and thickness non-uniformity, are optically characterized using a combination of spectroscopic ellipsometry and near-normal spectroscopic reflectometry. The influence of boundary roughness is included into optical quantity formulae by the combination of the scalar diffraction theory and Rayleigh–Rice theory. Very thin overalyers modelled by rough thin films with identically rough boundaries are taken into account on the upper boundaries of the ZnSe thin films. Two approximations are used to express the local reflection coefficient of the rough ZnSe thin films covered with the overlayers within combination of both the theories. Thickness non-uniformity is incorporated by means of averaging the elements of the unnormalized Mueller matrices. The universal dispersion model of the optical constants of the ZnSe thin films based on parametrization of the joint density of electronic states is used. The spectral dependencies of the optical constants of the ZnSe thin films are determined within the wide spectral range (0.12–8.7eV). Moreover, the mean thickness of the ZnSe thin films and thickness of overlayers are determined together with the other structural parameters characterizing the defects. The values of roughness parameters, determined by the optical method, are verified by a comparison with results achieved by atomic force microscopy. It is also shown that the approximations of the local reflection coefficient presented are usable for processing the experimental data.

Effect of Grinding Parameters on the Surface Quality of Cutting Tools Made of High-Speed Low-Alloy Steels

The occurrence of defects caused by sharpening leads to the considerable variation of lifetime of cutting tools under identical processing conditions. The loss of cutting ability of cutting tools or the change of the blade original geometry influences the quality of the surface finish as well as both dimensional and shape accuracy of workpieces. The effect of the grinding parameters on the surface finish of selected high-speed steels has been investigated. The influence of the grinding parameters has been defined especially for surface roughness, grinding forces and grinding ratio with a wide range of grinding parameters. It is found that the value of average roughness (Ra ) parameter decreases together with an increase in the grinding depth and the feed length. Furthermore, the value of Ra increases proportionally to the grinding depth. To improve the efficiency of sharpening, it is required to increase the feed length other than the grinding depth.

Polished surface roughness of optoelectronic components made of monocrystalline materials

A study of the mechanism of formation of monocrystal planes of different crystallographic orientations has revealed that in polishing of sapphire the surface roughness parameters Ra, Rq, Rmax decrease in the series c > r > m > a with decreasing dielectric permittivity and thermal conductivity coefficient of the workpiece material, debris particle height, and Lifshitz constant that represents the energy of interaction between the polishing powder grains and the workpiece surface. The minimum allowable values of surface roughness parameters for atomically smooth surfaces have been defined, which linearly depend on interplanar spacings and decrease in the series r > a > c > m.

Determination of the Wenzel roughness parameter by the Power Spectral Density of functional Alumina surfaces

The Wenzel roughness parameter of isotropic Gaussian surfaces is analytically described in terms of the Power Spectral Density function without the smooth surface approximation. This Wenzel roughness parameter — Power Spectral Density link was examined for distinct roughnesses of Aluminum-oxide thin films. The Power Spectral Density functions of the surfaces were determined in a wide spatial frequency range by combining different scan areas of Atomic Force Microscopy measurements. The calculated results presented a good agreement with the Wenzel roughness parameter values obtained directly from the topography measured by Atomic Force Microscopy. Finally, wetting behavior was ascertained through determination of water contact angles, including superhydrophobic behavior. This approach, together with an empirical procedure based on a structural parameter, can predict the wetting properties of a surface by taking all its relevant roughness components into account.

Friction analysis at elastic-plastic contact of rough surfaces using n-point asperity model

The paper describes a theoretical study of friction at elastic-plastic contact of rough surfaces in n-point asperity model framework and based on accurate finite element analysis of elastic-plastic deformation of single asperity contact. Plasticity index, a well-defined nondimensional parameter is used to study the prospective situations arising out of variation in material properties and surface roughness. Using practical values of material properties and surface roughness parameters, results are obtained for the behavior of applied load, friction force, and coefficient of friction as a function plasticity index and mean separation of surfaces. It is observed that with increase in amount of plastic deformation, the load required to be applied for maintaining a particular level of separation between contacting surfaces increases while the frictional force decreases. Coefficient of friction is independent of applied load in predominantly plastic domain of deformation but varies nonlinearly in other domains of deformation. Also, for the same applied load the coefficient of friction increases with increase in elastic deformation.

Comparative Evaluation of Microroughness created on Titanium Alloy for use in Dental Implants subjected to Two Different Acid Etching Techniques: An in vitro Study

ABSTRACTAimThe aim of this study was to comparatively evaluate the microroughness created on titanium alloy for use in dental implants subjected to two different acid etching techniques.Materials and MethodsCommercially available grade 5 pure titanium plates were machine prepared into 26 plates measuring 3 × 1 cm × 5 mm for acid etching with hydrofluoric acid (HF) and dual acid etching technique using sulfuric acid (H2SO4) followed by hydrochloric acid (HCl). Twenty-five plates were divided into four groups based on the duration and sequence of acid etching. Upon completion of the acid etching procedure, the titanium plates were assessed for their surface characteristics by a surface profilometer. The average roughness parameters values Ra, Rq, Rz obtained for each titanium plate were compared against each other and with unetched titanium plate.ResultsThe average roughness value Ra obtained was 0.480 μm for untreated surface and 3.65 μm maximum for the titanium plate etched for 72 hours in H2SO4and 48 hours in HCl, which is about seven times the value of surface roughness on the unetched plates. The roughness values obtained after acid etching with HF for any duration were nonsignificant compared with the unetched plates.ConclusionThe dual acid etching technique seems to be a simple method to develop a titanium implant surface, though evaluation of the biological response to this surface is necessary.Clinical significanceThe present study showed that by optimizing the parameters of acid etching, a rough titanium surface can be obtained similar to the various implant surfaces available commercially.How to cite this articleMadaan VU, Mapara M, Padhye AM. Comparative Evaluation of Microroughness created on Titanium Alloy for use in Dental Implants subjected to Two Different Acid Etching Techniques: An in vitro Study. J Contemp Dent 2016;6(1):1-8.

Surface Texture Parameters of Perpendicular Magnetic Recording Disks

This paper presents the measured values of the surface texture parameters of commercially available perpendicular magnetic disks produced by five different vendors. In addition to the ordinary roughness parameter values, the asperity parameter values necessary for evaluating the mechanical characteristics of a head–disk interface with a clearance of less than 1 nm are evaluated. The mean asperity height is found to be 0.49 nm and the asperity density is 5044 $\mu \text{m}^{-2}$ . The asperity radius of curvature has an anisotropic nature, but its average value is approximately 20 nm. However, the peak radius of the highest asperity group associated with the asperity contact is close to 10 nm.

Investigation of the Effect of Cutting Speed on Surface Quality in Abrasive Water Jet Cutting of 316L Stainless Steel

This study presents the effect of cutting speed on surface roughness in abrasive water jet cutting of 10mm thick stainless steel samples. Photographs of cut surfaces were taken and roughness parameters were measured in different locations across depth of cut. Differences between obtained surface geometric structures and measured roughness parameter values were presented and discussed. The research has shown a considerable effect of cutting speed on surface roughness, surface quality and presence of machining marks. This effect was especially noticeable in lower parts of examined cut surfaces.

Considerations Regarding Some Surface State Parameters Characterized by a more Restricted Use

Frequently, on the drawings of mechanical parts, only indications concerning the surface roughness parameter Ra and, relatively rarely, the surface roughness parameter Rz are included. However, the study of the machined surface roughness highlights the necessity to use yet other surface roughness parameters, in order to have a clearer image on the state of the machined surface. Some other surface roughness parameters possible to be used and presenting importance, without the parameters Ra and Rz, were highlighted. One took into consideration the possibility of measuring parameters Rsk and Rmr by means of the available surface roughness testers. Experimental researches of turning by applying the method of full factorial experiment were developed. As input factors in turning process, the cutting speed, the feed rate and the tool nose radius were used. The experimental results were mathematically processed, being determined empirical mathematical models that highlight the influence of certain input factors of turning process on the values of some surface roughness parameters characterized by a more restricted use

Experimental studies of the cutting force and surface morphology of explosively clad Ti–steel plates

The present work pertains to the study of clad material such as titanium plated steel in drilling process. The study was conducted for two types of indexable insert drills with different configuration of the tool coatings (TiAlN/AlTiN+TiN and TiAlN/TiN), the same geometry of insert and fixed machining conditions. Drilling process was assessed by the analysis of thrust force, torque and signal fluctuations of PSD function. In this context, surface morphology of the drilled holes and contact area was analysed. It has been observed that the use of the PSD function allows assessment of the drilling process in different layers of clad materials. Also was found that the parameters of the surface morphology are dependent upon the type of layers of the clad and the type of drill. Furthermore the reduction in torque results in obtaining smaller values of surface roughness parameter especially in the area of volume parameters of the bearing area curve.

Influence of Temperature and Acid Etching Time on the Superficial Characteristics of Ti

We evaluated the influence of the etching time and temperature of an acid solution (HCl/H2SO4) on the chemical and topographical superficial characteristics of cpTi grade IV. Samples were analyzed by electron microscopy, interferometry, and grazing incidence XRD. The surfaces kept the irregularity aspect when submitted to the same etching temperature. On the other hand, the irregularities increased in size and depth with increasing etching time. The etching treatments that produced higher values for roughness parameters showed a combination of high temperature for a longer etching time. Some treatments produced very large irregularities, with a brittle surface in some regions. According to statistical correlation, the temperature made the strongest contribution in the variance of the mean values of the surface roughness parameters when compared to the etching time. Titanium and oxygen were the only elements on the surface in all groups. All test group samples showed the presence of titanium hydride.

Influence of cooling conditions on the machining process under MQCL and MQL conditions

Original scientific paper The paper presents the results of investigation of the influence of conditions of forming emulsion and oil mist on the chip shape and surface roughness of X10CrNi18-8 stainless steel during turning. In the tests, the following machining operations have been compared: dry machining, cooling by the MQCL (Minimal Quantity Cooling Lubricat) method, cooling by the MQL (Minimum Quantity Lubricat) method. The tests have been performed in two stages. In the first stage, the influence of the mass flow of the active medium on the chip shape and on the Ra and Rq roughness parameters of the machined surface have been determined. The purpose of stage two was to determine the influence of the MQL and MQCL method on the selected indices of the machining process as compared to dry machining as a function of variable cutting speed. It has been found that, under MQCL and MQL conditions, the area of formation of elemental chips and ones with the shape of short spirals is wider as compared to dry turning. With increased mass flow of emulsion and oil, tangled chip is formed. Cooling by the MQCL and MQL method results in reduction of the selected roughness parameter values by 2 % to 42 % as compared to dry machining.

Morphology of Co-Cr-Mo dental alloy surfaces polished by three different mechanical procedures

The present study aims at characterizing the three-dimensional (3-D) morphology of a Co-Cr-Mo dental alloy surface as a result of three different procedures used for polishing it. The sample surface morphology of the sampled surface was examined employing atomic force microscopy (AFM), statistical surface roughness parameters, and fractal analysis. An extra-hard dental alloy of cobalt-chromium-molybdenum (Co-Cr-Mo) (Wironit(®) , from BEGO, Bremen, Germany) was prepared and moulded. Different polishing treatments were carried out on three groups of six samples each--a total of 18 samples. The first group contained six electropolished (EP) samples. The second group containing six samples went through a mechanical polishing process employing green rubber discs and a high shine polishing paste applied by a rotating black brush (BB). The third group comprising six samples as well went through a mechanical polishing process by means of green rubber discs, high shine polishing paste, and a rotating deer leather brush (DL). Fractal analysis on the basis of a computational algorithm applied to the AFM data was employed for the 3-D quantitative characterization of the morphology of the sampled surfaces. The fractal dimension D (average ± standard deviation) of 3-D surfaces for BB samples (2.19 ± 0.07) is lower than that of the DL samples (2.24 ± 0.08), which is still lower than that of the EP samples (2.27 ± 0.09). The results indicated the BB samples as presenting the lowest values of statistical surface roughness parameters, thus the best surface finish, while the EP samples yielded the highest values.

Effect of Roughness and Residual Compression Stresses on the Ultrasonic Fatigue Endurance of Aluminum Alloy AISI 6061-T6

Abstract Ultrasonic fatigue tests were carried out on the aluminum alloy AISI 6061-T6, presenting different values for the principal surface roughness parameters: Ra, Rq, and Rz. For fatigue life comprised between 3 × 105 ∼ 6 × 106 cycles, crack initiates at the specimen surface induced by stress-concentration and micro-plastic deformation (micro-void coalescence); whereas for the very high cycle fatigue (>107 cycles), the mechanism of crack initiation moves to subsurface or inside the specimen and is associated with internal imperfections such as micro-porosities or nonmetallic inclusions. For the first fatigue life regime, compression residual stresses induced by the work-hardening machining process and the associated micro-plastic deformation are the principal factors controlling the fatigue endurance on this aluminum alloy. Experimental results show that fatigue endurance is higher for the high surface roughness in the 3 × 105 ∼ 6 × 106 cycles of fatigue life, whereas this behavior is inversed in the very high-cycle fatigue regime. These results are analyzed in terms of residual compression stresses induced by the work-hardening machining process, the surface roughness, and the reverse yielding or Bauschinger effect.

Impact of model structure and parameterization on Penman–Monteith type evaporation models

Summary The impact of model structure and parameterization on the estimation of evaporation is investigated across a range of Penman–Monteith type models. To examine the role of model structure on flux retrievals, three different retrieval schemes are compared. The schemes include a traditional single-source Penman–Monteith model (Monteith, 1965), a two-layer model based on Shuttleworth and Wallace (1985) and a three-source model based on Mu et al. (2011). To assess the impact of parameterization choice on model performance, a number of commonly used formulations for aerodynamic and surface resistances were substituted into the different formulations. Model response to these changes was evaluated against data from twenty globally distributed FLUXNET towers, representing a cross-section of biomes that include grassland, cropland, shrubland, evergreen needleleaf forest and deciduous broadleaf forest. Scenarios based on 14 different combinations of model structure and parameterization were ranked based on their mean value of Nash–Sutcliffe Efficiency. Results illustrated considerable variability in model performance both within and between biome types. Indeed, no single model consistently outperformed any other when considered across all biomes. For instance, in grassland and shrubland sites, the single-source Penman–Monteith model performed the best. In croplands it was the three-source Mu model, while for evergreen needleleaf and deciduous broadleaf forests, the Shuttleworth–Wallace model rated highest. Interestingly, these top ranked scenarios all shared the simple lookup-table based surface resistance parameterization of Mu et al. (2011), while a more complex Jarvis multiplicative method for surface resistance produced lower ranked simulations. The highly ranked scenarios mostly employed a version of the Thom (1975) formulation for aerodynamic resistance that incorporated dynamic values of roughness parameters. This was true for all cases except over deciduous broadleaf sites, where the simpler aerodynamic resistance approach of Mu et al. (2011) showed improved performance. Overall, the results illustrate the sensitivity of Penman–Monteith type models to model structure, parameterization choice and biome type. A particular challenge in flux estimation relates to developing robust and broadly applicable model formulations. With many choices available for use, providing guidance on the most appropriate scheme to employ is required to advance approaches for routine global scale flux estimates, undertake hydrometeorological assessments or develop hydrological forecasting tools, among many other applications. In such cases, a multi-model ensemble or biome-specific tiled evaporation product may be an appropriate solution, given the inherent variability in model and parameterization choice that is observed within single product estimates.