Search results for "Surface finish"
showing 10 items of 167 documents
Turbulence structures over irregular rough surfaces
2010
Turbulent flow in a channel with irregular two-dimensional rough surfaces is analysed through wall-resolving large eddy simulation (LES). Both walls of the channel are roughened through the superimposition of sinusoidal functions having random amplitude and four different wavelengths. The downward shift of the velocity profile in the log region due to the roughness, known as roughness function, is well captured in the simulations. The spanwise and wall-normal turbulence intensities are found to increase with the roughness height, while the streamwise component decreases. The analysis of the Reynolds stress anisotropy tensor highlights a tendency towards isotropisation, confirmed by the vort…
Induced roughness in thin films of smectic-C* elastomers
2002
The surface topography of a thin homeotropically oriented film of ferroelectric smectic-C* elastomer is studied by atomic force microscopy. We find that when the film is mechanically stretched, its surface becomes increasingly rough, in proportion to the applied strain. The effect depends strongly on the nature of crosslinks forming the elastomer network. The r.m.s. roughness correlations show a consistent trend [h(x) − h(0)]21/2 ~ (x/ξ)0.5. We introduce a theoretical model assuming that random disorder in the smectic tilt angle is induced by deformations via the coupling of mesogens to the elastic network. The model describes the observed power law and gives a prediction for the correlatio…
Modeling the machined surface quality of an aluminum alloy using the active experiment type
2019
Abstract The surface roughness obtained by the cutting processes has always been a subject of great interest when it is intended to improve the quality of the final product requested by the customer. The objective of this scientific paper involves a comparative study on the tracking of the surface roughness measured both longitudinally and transversely in the direction of the cutting feed movement, following the end-milling process of an aluminum alloy used in the aerospace industry worldwide. Practical experiments have conducted in a prestigious company in the aerospace industry of Romania. Regarding the cutting regime, in terms of milling, a cutting speed was adopted to maintain its const…
Grinding Tungsten Carbide Used for Manufacturing Gun Drills
2015
This paper presents a study of grinding cemented carbide DK460UF (91 % WC and 9 % Co), a material used to produce cutting tools with solid cutting edges. The aim is to establish the manufacturing conditions that lead to high surface quality. A model of the main factors that influence the grinding process is presented first. Following that, grinding wheel wear and surface roughness are analysed. Grinding wheel wear is studied in experimental conditions under which small diameter gun drills were sharpened with two diamond grinding wheels of different grain sizes. Finally, the wear curve can be made. The "G ratio" is used to characterise the performance of the grinding process. Next, the exper…
The influence of roughness geometry and shields parameter on flow resistance in gravel-bed channels
1997
The spatial variability of bed particles of a gravel-bed channel is analysed and treated experimentally in order to simulate the effects of the arrangement of coarse bed elements on the flow resistance law. For the studied bed patterns, characterized by the concentration Γ of coarser elements arranged on the bed layer, a particle arrangement parameter α is proposed. The α parameter is useful for estimating the intercept b0 of the semi-logarithmic flow resistance law deduced by flume measurements carried out for the hydraulic condition of large-scale and transition roughness. The differences between the experimental friction factor parameter values and the ones calculated by the proposed sem…
Surface Integrity
2008
This chapter provides comprehensive knowledge regarding the state and properties of both surface and subsurface layers generated during machining processes, including different associated mechanical and thermal influences. Basic models of the superficial layer and factors effecting surface integrity are presented. Decomposition of surface topography into roughness, waviness and form along with appropriate filtering methods is outlined. The characterization of surface roughness based on 2D and 3D roughness parameters as well as motif, fractal and frequency characteristics are presented. In particular, all standardized areal surface parameters are specified, and practical examples are provide…
Optimisation of TA6V alloy surface laser texturing using an experimental design approach
2008
International audience; Active surfaces of plastic injection moulds are nowadays textured using classical techniques (chemical etching or EDM). Replacement of these technologies by a laser technology introduces a big flexibility: absence of mechanical contact with the tool, decrease of the effluent's volume and a big machining precision, even in the case of the complex forms as injection moulds for example. This paper reports the experimental study of the surface laser texturing of TA6V alloy. The influence of the operating factors on the laser texturing process has been studied using two experimental approaches: Taguchi methodology and response surface methodology (RSM). Empirical models h…
Comparative assessment of surface roughness produced by hard machining with mixed ceramic tools including 2D and 3D analysis
2005
Abstract This paper provides a new comprehensive analysis of part surface finish in continuous dry turning of a hardened construction steel when using mixed alumina cutting tools. Consequently, the surface profiles (2D arragement) and surface microstereometries (3D arragement) generated during different hard part turning operations on a 40H low chromium alloy steel (equivalent to AISI 5140 or DIN 41Cr4), heat treated to the hardness of about 60 HRC, were evaluated. As a result, this paper aggregates the multi-parameters characterization of the surface roughness with the machined surface structure obtained at the three selected feed rates and constant cutting speed of 100 m/min. Results show…
Effect of latex on surface structure and wetting of pigment coatings
2010
Abstract The amount and type of latex binder has a significant effect on both the structure and chemical properties of pigment coatings, which affects critical surface properties, e.g., gloss, ink setting rate via liquid absorption, and spreading properties. Increased knowledge is required for improved optimization in practical applications of pigment coating layers. To this end, the effect of binder amount for two different styrene–butadiene latices in kaolin pigment coatings on a base paper was studied, by measuring the surface topography, surface chemistry, and liquid absorption of these coatings. The topography was thoroughly analyzed from nanometer to millimeter length scales by atomic…
Comparative study of polar perovskite surfaces
2004
A novel model of the ‘‘zig–zag’’ (1 1 0) polar surface termination of ABO3 perovskites is suggested and analyzed. Classical shell model calculations for BaTiO3, SrTiO3 and LaMnO3 show that such the (1 · 2) (1 1 0) surface reconstruction has the lowest energy, comparable to that for the (1 0 0) surfaces. The calculated surface energy reaches the saturation only when 6–8 atomic near-surface planes are allowed to relax. Surface relaxation leads to the formation of considerable dipole moment perpendicular to the surface. The predicted surface polarization of thin perovskite films, even in the cubic phase, could affect their dielectric properties. � 2004 Elsevier B.V. All rights reserved.