Papers by Keyword: Surface Topography

Abstract: AA6xxx alloys are known to suffer from a phenomenon called roping, which is a ridge and valley pattern appearing after stamping is treated as a fatal surface defect for the automotive skin panels. Although the roping is the important factor to determine the exterior quality, it is commonly evaluated by visual check done by inspecting staff, which is very subjective and difficult to measure quantitatively. In this study, to quantify the roping level in detail and easily, a new calculation method based on Fourier transform and using simple device to measure topography is proposed. As a result of analyses for several different AA6022 alloy sheets, it is found that the strong roping surface has the intensive directional pattern along the rolling direction with a specific wavelength. The roping level can be expressed numerically as the ratio between the amplitude of the rolling directional pattern and the average amplitude of each directional pattern. This value shows good agreement with the roping level determined by human observation. Moreover, it is found that the proposed method can be applied to the surface appearance obtained by digital camera without a 3D profiler.

Abstract: The essential purpose of the work was to determine the phenomena that occur in multipass wire drawing process of high carbon steel wires with high speed in hydrodynamic dies and to assess their influence on moulding the wire properties after the drawing process. The multiparameter analysis of the issues has involved the theoretical dissection of the phenomena arising in high speed wire drawing process in hydrodynamic dies with the usage of the finite element method supported by the experimental multipass drawing process in industrial conditions. On the basis of numerical analysis the influence of drawing speed on wire temperature was estimated. For final wires the investigation of mechanical properties, topogrhaphy of wire surface, the amount of lubricant on the wire surface, the pressure of lubricant in hydrodynamic dies were determined.

Abstract: Biomedical materials are materials that can be implanted in an organism or combined with biological tissue. They are used for the diagnosis, treatment, and replacement of tissues or organs, and enhance their functions. With high strength, good toughness and bending fatigue strength, excellent processing performance which can not be replaced by other medical materials, biological medical metallic materials, such as stainless steel, cobalt based alloy, titanium and titanium alloys and noble metal are widely used in medical field. The surface topography has a great influence on the function of the parts, especially for the wear, vibration, noise, corrosion resistance of the friction surface. And the surface morphology of medical metal is very important in the influence of its corrosion resistance.

Abstract: WC-Co composite materials possess a vast range of industrial applications owing to their excellent properties such as superior hardness, toughness and dimensional stability. Present article has been targeted at investigating the impact of different experimental conditions (power rating, cobalt content, tool material, thickness of work piece, tool geometry, and abrasive grit size) on penetration rate in ultrasonic drilling of WC-Co composite material. Taguchi’s L-36 orthogonal array has been employed for conducting the experiments. Significant factors have been identified using analysis of variance (ANOVA) test. The experimental results revealed that power rating, abrasive grit size, and tool profile is most significant factor for penetration rate. From the microstructure analysis, the modes of material deformation have been observed and the parameters (i.e. work material properties, grit size, and power rating) were observed as the most crucial for the deformation mode.

Abstract: Poly-crystalline cubic boron nitride (PCBN) is one of the hardest known material. Therefore only advanced methods are able to treat such material. Advanced machining methods, proper for machining of hard and brittle materials (such as glass and ceramics) include rotary ultrasonic machining (RUM). This method should achieve high precision and low surface roughness (at least during machining of materials such as ceramics). Achievable roughness is affected by machined material and machining parameters. This contribution investigates influence of machining parameters, such as cutting speed and feed rate, on resultant surface roughness during machining of PCBN by rotary ultrasonic machining.

Abstract: Ultra-precision fly cutting machines have long been the hardest one to compliant and induce great focus of researchers. In this paper, a surface topography model is proposed to predict the surface generation in an ultra-precision fly cutting machine. The building of surface topography model is based on the trace of the tool tip. With the 3D surface profile simulations of workpieces, several influencing factors of surface topography, especially the factors related to micro waviness error, are studied.

Abstract: Ultra-precision grinding is widely used in machining of the hard and brittle materials due to its high surface accuracy and machining efficiency. However, grinding inevitably brings about surface and subsurface damage that needs to be removed by the polishing processes. This study investigated the surface and subsurface integrity of glass-ceramics induced by ultra-precision grinding. The characteristics of surface roughness, surface topography and subsurface damage depth of ground glass-ceramics with diamond grinding wheels with different grain sizes were presented and compared. Discussion was also provided to explore corresponding reasons of surface and subsurface integrity induced by diamond grinding wheels with different grain sizes.

Abstract: A series of wet braking tests has been performed using two different pad materials. Brake tests were conducted in different operating conditions i.e. dry, humid air and wet environment in which both pad samples were tested against grey cast iron disc at certain sliding speed and contact pressure. Wear analysis was performed to find correlation between presence of water and changes in brake pad wear characteristics. The results revealed that regardless of the frictional behaviour, wear rate for both pad materials tested at humid air and wet braking is significantly lower than in dry results.

Abstract: Silicon carbide particles reinforced aluminum matrix composite (abbreviated as SiCp/Al) offers excellent performance such as high specific strength and stiffness, which make it widely used in aerospace, automobile and other fields, but it is hard to be manufactured. An aluminum matrix composite reinforced with 45% volume fraction of 5μm silicon carbide particles in an A12 aluminum matrix was experimental studied by ultrasonic vibration-assisted scratch (UVAS) and traditional scratch. Cutting forces and surface topography were measured by Kistler dynamometer and SEM. The experimental results showed that the cutting forces fluctuated obviously and the axial force was larger than the tangential force during both UVAS process and traditional scratch process. Average cutting forces of UVAS process were less than those of traditional scratch process. At the same time, small chips of SiC and high surface quality were observed in the scratch surface of UVAS. These indicate that ultrasonic vibration-assisted method plays an important and effective role in reducing cutting forces and improving surface quality.

Abstract: The paper reports experimental results from tests carried out at room temperature on servo-hydraulic system dedicated for examination of the exploitation properties of rocker arms. The ball joint of this element was modified by an application of composite coating such as the tungsten carbide (WC). To apply cyclic loading to rocker arms the griping system was designed and elaborated. Results from tests performed on the composite coated ball joints were compared with data obtained for typical elements. Variations of the following parameters versus time i.e. force, temperature and surface topography of balls were analysed with respect to exploitation properties of the modified ball joints. An increase of the wear coefficient was achieved for sliding joints of the steel ball-steel cups coated by the WC.