Advanced Materials Research Vols. 622-623

Abstract: This research aims to study the effect of cutting speeds on wear behaviors of TiAlN coated insert during the machining process of AISI 316L steel. Experimental investigation and finite element method were employed. The two-dimensional (2D) plane strain orthogonal cutting model was focused at the initial continuous chip formation. The effect of cutting speeds, i.e. 50, 75,120 and 150 m/min, was studied. The tool wear behavior was then further investigated based on computational results which are temperature, von-mises equivalent stress, equivalent plastic strain and contact pressure. High temperature developed at rake face during high cutting speed, i.e. the cutting speed above 120 m/min, suggesting crater wear or diffusion wear. High equivalent plastic strain, i.e. greater than the fracture strain at failure of AISI 316L steel, were observed all along the tool edge around the contact area suggesting the built up edge (BUE) wear at all cutting speed investigated. The adhesive wear was expected on the edge radius at low cutting speed (50 to 75 m/min) based on the von-mises equivalent stress distributions. The overall severity of sliding wear was found to be around the tool nose due to high contact pressure in all cases. The experiments were also conducted with the tail stock constrained in all experiments to reduce the effect of vibration. The insert tool wear was examined by Scanning Electron Microscope. Wear was observed on flank face and rake face of the insert tools with different wear behavior at different cutting speed which agreed well with computational predictions.

Abstract: NAS (National Aerospace Standard) 979 is the only standard well known in industry describing a five-axis machining test for measuring kinematic errors of five-axis machine tools. As it cannot reflect the tool path characteristics of typical ruled surface machining, five-axis machine tools which passed the NAS test may not have the ability to satisfy the requirement of the real industrial applications. To fill this gap between the NAS test and the real industrial applications, an “S” machining test is proposed in this paper. The case study shows that the proposed machining test is feasible and practicable.

Abstract: Ceramic coatings based on sol-gel method have increasingly gained much attention in recent times. In order to ascertain important experimental factors (variables) influencing surface properties, such as adhesion, pencil hardness and advancing contact angle (non-stick) of sol coatings, a 2_6-1-factorial screening design with six experimental variables, precursor mole ratio, low surface energy polymer concentration, silane coupling agent (SCA) concentration, silica nanoparticles concentration (SNP’s),curing temperature and three responses ( surface properties) were investigated. The results indicate that silane coupling agent concentration, SNP’s concentration and their interaction were the most significant experimental factors influencing advancing contact angle. None of the experimental factors studied were statistically significant with respect to hardness and adhesion.

Abstract: This study investigates the effects of injection temperature and pressure on green part density. The high density of the green parts for the ceramic injection molding (CIM) process improves the material properties of the final product. In this study, the feedstock used was a combination of alumina and zirconia powders with a binder consisting of high density polyethylene, paraffin wax, and stearic acid. Powder loading was fixed at 57% volume. A standard screw-type injection molding machine was used to produce the green parts. The density of the green parts was measured using the Archimedes method. Experimental results show that a 160 °C injection temperature and a 110 MP_a injection pressure were the optimum parameters to achieve high density of the green parts. In addition, defect-free green parts were obtained.

Abstract: The paper intends to identify and suggest improvements in two areas crucial for implementing lean principles in an aluminum semi-permanent casting small to medium enterprise (SME). This paper builds an analytical model to measure production performance and presents a case study of an aluminum foundry. The case study reveals the use of two lean principles of bottleneck identification and lean buffering could allow for timely response to customer requirements. This paper helps in identifying areas for lean manufacturing tailored to the needs to foundry SMEs, in which the number of published studies is very limited.

Abstract: Tube bending is a complex process with multi-factor coupling effect and multiple defects occurring. The wall thinning, as one of the important defects in tube bending, determines the bending quality. In this study, taking thin-walled 6061-T4 Al-alloy tube with Φ50.8×t0.889×R101.6mm (outer diameter D × wall thickness t × bending radius R) as the objective, the significance of processing parameters on the wall thinning degree is studied using the orthogonal test under ABAQUS/Explicit platform. The results show that: 1) the bending radius, the clearance between the tube and the pressure die, the friction between the tube and the pressure die, the clearance between the tube and the pressure die, the clearance between the tube and the mandrel and the friction between the tube and the mandrel affect the wall thinning significantly, while the coefficient of boost velocity, the number of mandrel balls, the friction between the tube and the wiper die, the mandrel extension length and the friction between the tube and the bending die have little effect on the wall thinning degree.

Abstract: Superplastic behavior of certain metals and alloys having very fine grains, very large tensile elongations are obtained within certain temperature ranges at low strain rates. These alloys can be formed into complex shapes by superplastic forming, a process that employs common metalworking techniques. This paper aims to study the formability characteristic for aluminium material (Al 7075) by considering variable parameters such as sheet thickness of 1.75 and 1.5 mm and the temperature of 520°C and 530°C.

Abstract: The short description of the new approach to the pneumatic powder injection process analysis was presented in the article. The experiments with the high speed camera recording of the two-phase jet in pneumatic powder injection process were carried out in the Department of Foundry, Silesian University of Technology, Poland. The results were briefly analyzed and some interesting conclusions appeared, especially that the real velocity of the injected particles is far less than it is normally calculated with use of the well-known formulas. They were compared with existing literature data as well as with some experimentspreviously made by authors. Powder particles velocity and two-phase jet mass concentration were analyzed as the most important parameters for powder injection process. The results described are part of the complex experimental plan and the next step is computer modeling (just launched) of the jet introducing liquid.

Abstract: Material flow pattern in extrusion is an important part of the forming process. Understanding and formulating the material flow helps to determine the optimum shape of the die and important details of the process. In this paper, physical modelling of forward extrusion of non-symmetric L-shape section has been carried out to obtain an experimental understanding of the material flow pattern. A theoretical formulation using the conformal mapping theory has also been presented to predict the material flow pattern. The conformal mapping function was set up to translate the non-circular cross-section region of special-shaped products into unit dish. The results for the material flow pattern for the forward extrusion of L shaped profile from circular billets are presented here. In the physical modelling tests plasticine was used as the model material and different coloured layers of plasticine were used to build up the billet. Experimental and theoretical results were compared and good agreements were observed.

Abstract: Friction factor varies with respect to change in size of specimen. To identify suitable methodology for finding friction factor, extrusion process was selected. In this research work, three dies were used with diameter size reduction of 12:2, 8:4 and 4:2. Al6061/sic composite were produced by stir casting process. Specimens were extruded at 3000c and constant strain rate of 1 s^-1. Friction values were obtained in three dies and size effect were studied. Extruded specimens, hardness, surface roughness and microstructures were compared with the machined specimens.