Papers by Keyword: Roughness

Abstract: By analyzing the geometry of craters in a single pulse, the model of surface roughness in EDM was established and the main factors impacting on surface roughness were analyzed. On the base of establishment of the roughness model, the effect of discharge parameters on surface roughness was investigated by the process test method during the process of aluminum alloy 2A12 in EDM. At the same time, surface morphology obtained by different discharge parameters was comparatively analyzed. The results show that the effect of peak current and pulse width on the surface roughness is more significant, the crater on the machined surface has larger size while using higher peak current and pulse width, but the number of discharge craters is reduced.

Abstract: The investigated brush-plated silver and gold coatings are used for refining the surface properties of electric apparatuses. Tensile residual stresses generated in the plated coatings were determined with a thin-walled ring substrate using the curvature and instrumented indentation techniques. These stresses relax over time; the dependence of relaxation time was approximated by a linear-fractional function. The modulus of elasticity and the nanohardness of the coatings were determined by nanoindentation. The surface morphology and structure in cross-section of the coated substrates are presented.

Abstract: The problem of evaluating the life period of different mechanisms is of great importance nowadays. This could be explained by the fact that the wear process is very complex and very many factors take place simultaneously. During the history a variety of theories that offered different methods of wear calculation models were developed. However still there is no exact wear calculation model that could be applied to all cases of wear processes. The offered method is dealing with the calculation of rough surface peaks that make the contact between two surfaces. Taking into account the number of these peaks and applying fatigue wear model based on 3D surface micro-topography, assessing the materials physical and mechanical characteristic quantities and considering definite service conditions of sliding friction pair it is possible to make the wear calculation of friction pair under definite working conditions.

Abstract: Theobservation of cracks in mechanical parts shows that cracks often initiate oncutting edges. A lot of effort has been done to developing theories to predictfatigue behaviour of welds. However for the cut-edges available data is veryscarce on the fatigue behaviour. Thispaper presents theresults obtained in fatigue tests on DP600 dual-phase steel sheet specimens, underthree types of cutting edges processes: milling with two cutting parameters andabrasive waterjet cutting. The tests were carried out using smooth specimens (K_t=1)and with a fatigue constant amplitude loading with R=0.1. Surface roughness andresidual stresses induced by these different cutting conditions were measuredand analysed. It was found that the fatigue strength of the abrasive waterjetcutting specimens was smaller than the predicted fatigue strength of themilling specimens and these may be attributed to the surface roughness inducedby the cutting process. Finally failure mechanisms were studied with the scanningelectron microscope (SEM) at fracture surfaces, including the identification ofthe fatigue crack initiation region. It was also observed that fatigue crackinitiation takes place on the cut-edges.

Abstract: The paper deals with the problematic of contact comfort as a part of body conscious design/ human-centred design. Contact comfort consist of a combination of balanced surface temperature, heat transmission, surface roughness, surface elasticity/hardness, sorption activity of the surface in terms of vapour/fluids absorbance, sorption activity of the surface in terms of absorbing the external moisture (e.g. sweat or humidity of air/its condensates), having control over body position, possibilities of maintenance and visual comfort connected with cultural background of users, individual mental and physical setting that is creating overall feeling of comfort. All these parameters are measurable and it is possible to optimize them with an aim to get good solutions that are providing higher contact comfort.Roughness is extremely important for overall feeling of contact comfort it has direct relation also to the other features. The current paper presents also the methodology and results of the pilot study of contact comfort. .Different wood based materials and wood species with different types of surface finishing in comparison with other materials were investigated by using a test chair.

Abstract: Aluminum alloy have been used for machine components in many functions and sizes. Every part need to be strong and long life, but when wear should be considered, then one have to hardened the surface, usually the harder the surface, the longer the life. One of the components that mention above is speed boat impeller. The sea water may cause the surface of the impeller eroded. Base on that reason the impeller should be hardened to extend its life. The anodizing process was chosen to improve the surface quality of the aluminum to reduce abrasion/erosion. Aluminum is a special material, other metal will be damaged or being worse when corroded, but Aluminum oxide is harder then the pure aluminum. In this process we use H₂SO₄ solution and the range of the anodizing temperature were changed gradually. This process was using single electrical force 20 Volt, to serve the anodizing for several minutes. All specimens finally were tested in Vickers micro hardness tester, also in Ogoshi High Speed Universal Wear Testing Machine. The last but not least, we cuts the specimens to see the thickness of the oxide layer by SEM. The result shows that for both hardness and wear, the quality of the surface increase with the increase of the solution of H₂SO₄, and also better for longer anodizing time. The thickness of the oxide layer was measured using SEM, at five places, and the average of the thickness is 2.662 mm.

Abstract: The purpose of the paper is to investigate the dependency of various parameters on metal forming process using mathematical models. The incremental sheet metal forming process was studied using Box–Behnken design of experiments along with response from surface methodology analysis. In the study process factors namely feed rate, speed and coolant were analysed to understand the effect on the surface roughness, percentage (%) of thickness reduction, grain size and hardness of the Aluminium (Al) sheet metal, were examined after forming. The surface model analysis predicts that all four responses of the incremental forms show very strong correlation with the experimental results. The optimized process of incremental forming that runs on maintained levels of predicted factors, yield responses very close to that predicted from the model.

Abstract: The performance of high strength steels is sensitive to the surface quality of machined surfaces. The effect of cutting condition on the variation of surface roughness in turning of 30CrMnSiA steel has been investigated through a serial of dry and oil-lubricant cutting tests. The characters of an amplitude characteristics set, Ra, Ry and tp, which are associated with the general shape of the machined surface profiles, are investigated in this study. It is concluded that, in the aspect of Ra and Ry values, dry cutting condition provides a similar surface roughness as in wet cutting condition under the experimental conditions of the present research; the bearing capacity of both kinds of machined surfaces, characterized by the bearing length rate tp, could be different according to the cutting parameters combinations.

Abstract: The contribution describes complex solution of stamping punch production from the view manufacturability and quality of stamping punch active surfaces. The application of proposed procedure is shown as an example of manufacturability experimental and production stamping punch designed for complex parts production. There is also proposal of both, the production process and strategies for stamping punch manufacturing. The quality of manufactured parts was reviewed according to its manufactured surfaces by optical evaluation and the roughness measurement on selected areas as well.

Abstract: Passive microwave remote sensing is one of the most effective methods for inversing soil moisture. Under the condition of laboratory, firstly, C band microwave radiation was used to achieve the trial of ground-based remote sensing soil moisture, and then regression analysis was carried out according to the data measured, finally, got the C band experience regression model of soil moisture inversion. The results showed that: in the level-off state of soil surface, soil humidity and soil microwave emission rate is linear negative correlation, in the other words, soil microwave emission rate decreased while the soil moisture increased. Besides, with the increasing of soil surface roughness, both the value of microwave polarization index (MPDI) and microwave emission rate polarization difference Δe have the same trend of quick drop, stabilization and slow raise, and it presented the relationship of quadratic curve with the change of roughness.