Applied Mechanics and Materials Vols. 809-810

Abstract: Surface quality is very important for the finished components. One of the most important parameters that define surface quality in milling is surface roughness . Depending on the cutting conditions chosen, different milling strategies can be applied. One of the ways to reduce the production costs is to optimize the number of inserts that are involved in machining. The aim of present paper is to investigate the behavior of surface roughness under the influence of the number of inserts used in an operation.

Abstract: The current paper deals with the orthogonal cutting of Ti6Al4V alloy. Initially, the cutting process is simulated using the Finite Element Method (FEM). Various cutting conditions including cutting speed and feed rate are considered. Based on this computational analysis the chip creation mechanism is studied. The simulation results describe adequately the chip generation and flow, delivering quantitative data concerning temperature and stress distribution, as well as chip geometry. In addition, orthogonal cutting experiments are conducted on a CNC lathe machine with the same cutting conditions. The experimental results are compared with the analytical ones and useful conclusions regarding the chip formation can be drawn.

Abstract: The paper presents the contribution in methodology of production processes of difficulty to cut materials particularly in optimization method of Duplex Stainless Steels (DSS). In this work, Design of Experiment (DOE) is used to examine turning experimental data. The DOE, based on the Taguchi method with orthogonal array L₉ and signal-to-noise ratio are used. The optimal values of the technological cutting parameters with coated carbide tool point are searched. ANOVA analysis was performed to determine the signification of machining parameters. The significance of various cutting parameters on tool life have been proven. The results at optimum cutting condition are predicted using estimated values. The study was performed within a production facility during the machining of electric motor parts and deep-well pumps.

Abstract: In this paper we analyze the influence of cutting parameters on the surface quality, surface roughness respectively, processed by turning when heat treated bearing steel, also called hard turning, and processing by turning of bearing steel without heat treatment. We set parameters of the cutting regime influencing the achievement of roughness surfaces which must be within the predetermined requirements if bearing rings exceeding 500 mm in diameter. This analysis will be done by statistical methods using the software Minitab 14.

Abstract: Abrasive water jet machining is frequently used in industry. It is one of the most versatile processes in the world. The basic advantages of abrasive water jet machining is that no heat affected zones or mechanical stresses are left on an abrasive water jet cut surface, high flexibility and small cutting forces. Although this cutting technology includes many advantages, there are some drawbacks. For instance, abrasive water jet cutting can produce tapered edges on the kerf of workpiece being cut. This can limit the potential applications of abrasive water jet cutting, if further machining of the edges is needed to achieve the engineering tolerance required for the part. The machining parameters have a great influence on these phenomena. The aim of this paper is to investigate the cut quality of EN AW-6060 aluminium alloy sheets under abrasive water jets. The experimental results indicate that the feed rate (nozzle traverse speed) of the jet is a significant parameter on the surface morphology.

Abstract: Water jet cutting is one of the newest techniques in non-conventional machining processes. It is a flexible technology since the same equipment can be used to cut virtually any material, such as steel stainless steel, high-nickel alloys and polymer composites (usually, for these materials, the water jet is mixed with an abrasive material, the process being known as abrasive water jet cutting - AWJC) . Compared with the classical technologies, water jet cutting presents the following advantages: very low side forces during machining, it is rapid, it is silent, no thermal distortion, a good cutting accuracy and minimal burrs. To optimize the process, it is necessary to analyze the influence of process parameters on the quality of cut. The aim of this paper is to analyze the influence of distance between the cutting head and the working sample on the quality of cut, quantified by the following parameters: width of the processed surface at the jet inlet, jet outlet, deviation from perpendicularity, inclination angle and roughness.

Abstract: For this study with high originality, a teflon bushing with outer diameter of 58 mm and 32 mm internal diameter has been turned. After inner turning with various cutting feeds, the part has been cut in half to measure roughness. The roughness parameters Ra, Rz and Rq have beeen measured with an electronic roughness tester Mitutoyo, Japan, SJ-201 P. The micro-asperity images for each of the 6 samples performed are presented in the paper. Diagrams with the variations of roughness parameters are also given in this study. The trend is the increasing of roughness values with feed increasing, but some abnormalities also appear in samples 3 and 4 for Ra and Rz. At sample 5 for Rz parameter and sample 6 for Rq parameter a decreasing of values occurs, although geometrically there should be with ascending tendencies. It follows that in teflon turning the cutting process is not uniform, although there are no marks on the blade. However, because this material is not metallic, it does not have a uniform structure, which influences the resulted roughness. This is the cause of the anomalies established by these experiments.

Abstract: The paper presents the analysis of plastic indentations resulting after the impact between a steel ball and a disc made of mild steel, rotating about a vertical axis. The imprints are analysed using a laser scanner, the profiles of the mark, in normal and tangent section about the impact point radius, being relevant. It is shown that the use of parabolas is sufficient to approximate the profiles of the imprint. The profiles from the two sections are interpolated and then brought for comparison into the same coordinate system. Finally, the curvature radii of the profiles from the two sections are found and the remark that increasing the angular speed of the disc presents opposite effects to the curvature radius in the two sections.

Abstract: Being able to predict potential defects is a very important aspect of the manufacturing process. The simulation of the injection molding process enables mold and part designers to perform tests during design and development stage and therefore results in a more cost effective and efficient production cycle. This study examines the injection molding simulation of a polystyrene plastic part. The simulation analyzes how melted plastic flows through a mold in order to identify manufacturing defects, while it offers a wide range of simulation parameters and optimizations. Injection molding of the plastic part with the processing guidelines given from the simulation procedure proved successful in the actual manufacturing process. In particular, a significant number of simulations were conducted so that their effect to the final product could be identified. Applying different parameters and optimizations led to several defective parts and identified problems into the process. Common injection molding issues like the short shot occurrence, determining the best injection location or studying the pressure at end of packing had to be addressed by adjusting the simulation parameters and analyzing the results produced. After the procedure's completion it became obvious that the initial processing parameters had to be optimized as otherwise would result in extra manufacturing costs and in delays of production.

Abstract: Roller leveling is a forming process which used to minimize flatness imperfection and residual stresses by repeated forming process of a sheet metal. The determination of the machine settings must be very accurate and ask a precise mechanical study. In order to determine an algorithm which can predict the leveling quality according to the machine settings we start by a theoretical model of stress evolution during the process. The plastification ratio is deducted from this one and the values obtained by this approach are compared whit experimental values. The finite element analysis is performed, in second step in order to assure a good accuracy of the prediction algorithm. Theoretical study determines a minimum of the plastification ratio according to the machine settings. The finite element analysis gives more accurate results due to the consideration of different characteristics of the process, neglected by the theoretical model: cumulative effect of bending/unbending with stretching of the sheet during the passing between each couple of rolls, boundary conditions at the limit of the material deformed by two adjoining couples of rolls, friction force.