Papers by Keyword: Machining Performance

Abstract: The Ti₃SiC₂-TiB₂-TiC three-phase ceramics are prepared by Spark Plasma Sintering (SPS) method with Self-propagating High-temperature Synthesis (SHS) using Ti, Si, C andB₄C powders. The characterization of sintering product’s image and structure is analyzed by XRD and SEM. Most of TiB₂’s images are angular cuboid or short bar-shaped and most of TiC phase’s images are irregular spherical particles which are evenly embedded in Ti₃SiC₂ substrate and have a good combination interface with Ti₃SiC₂. In the composite ceramic SPS sintering process, sinter sample’s displacement along Z-axis goes through three stages of falling, balance and rising along with the change of heating temperature, which reflects the sample’s change rule between heated expansion force and pressure. Finally its machining performance is analyzed by wire cutting method and machining method. The Ti₃SiC₂-TiC-TiB₂ block composite ceramic proves to have a good machining performance.

Abstract: In this paper, a detailed comparison between dry, wet and gas-cooled turning has been presented based on experimental study. Machining of super duplex stainless steel is considered. Cutting tool considered in this paper is uncoated carbide tool. It was observed that gas cooled machining provides a better machining performance while compared with the dry and the wet machining. Gas cooled machining is particularly needed in case of high speed machining and hard turning. In this study we investigated the chip morphology for various condition of machining and concludes that gas cooled machining is suitable for machining at higher production rate..

Abstract: An experimental study of the machining process for micro-channels on a brittle quartz crystal material by an abrasive slurry jet (ASJ) is presented. A statistical experiment design considering the major process variables is conducted, and the machined surface morphology and channelling performance are analysed to understand the micro-machining process. It is found that a good channel top edge appearance and bottom surface quality without wavy patterns can be achieved by employing relatively small particles at shallow jet impact angles. The major channel performance measures, i.e. material removal rate (MRR) and channel depth, are then discussed with respect to the process parameters. It shows that with a proper control of the process variables, the abrasive water jet (AWJ) technology can be used for the micro-machining of brittle materials with high quality and productivity.

Abstract: SiC/Cu composite materials were fabricated by powder metallurgy, and microstructure of composite was analyzed by means of metallographic microscope. The high speed steel tool and cemented carbide tool are used as cutters, and machining performance of SiC/Cu Composites were studied by cutting lathe and wire-electro discharge machine. The relationship between wire-electro discharge machining cutting speed and pulse interval were studied by wire-electro discharge machine. The results show that the composite cutting surface roughness increases with increasing of the content of SiC particles when the size of SiC is 40μm, while composite cutting surface roughness decreases with increasing of the content of SiC particles when the size of SiC is 20μm, the cemented carbide tolls have longer life than high-speed steel tools. The surface roughness of composite increases with the increasing of source voltage, but it decreases with increasing of pulse interval in the wire-electro discharge machining cutting conditions.

Abstract: This paper introduces an experimental design and evaluation of two newly developed conformable vices. One conformable vice is sheet metal vice and the other is ball bearing vice, these two conformable vices are designed for holding complex-shaped components. The experimental investigation is performed by comparing the conformable vices against a standard vice in static performance and machining performance. Force signals are monitored during experiments. From the comparison, the performance of the two conformable vices is discussed. The results prove that the two conformable vices can be applied for clamping components with performance comparable with a standard vice.

Abstract: Carbon fiber reinforced plastics (CFRP) have been widely used for manufacturing spacecraft, aircraft and automobile structural parts in aerospace and automotive industries. However, CFRP is a kind of hard machining materials and conventional tungsten carbide drills always experience severe tool wear, and thus short lifetime in the CFRP drilling process. In this paper, the CVD diamond films are deposited on the surface of cobalt cemented tungsten carbide (WC–Co) drills using hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscope (SEM) is adopted to investigate the surface morphology of as-fabricated CVD diamond coated drills, additional analysis using Raman spectrum also indicates the high purity of sp3 phase of as-deposited diamond film. Furthermore, the machining performance of as-fabricated CVD diamond coated drills is examined in drilling the CFRP, comparing with the uncoated WC-Co drills. The chisel edge and primary cutting edge wear of drills are studied using the tool microscope. The results show that as-fabricated CVD diamond coated drills exhibit a much elongated lifetime than that of uncoated WC-Co drills, and also smoother surface finish of machined holes, which is supposed to be attributed to the excellent wear resistance and satisfied adhesive strength between the as-deposited diamond films and drills.

Abstract: Monolayer brazed diamond tools, which are high bonding strength at the interface between brazing alloy and grits, are becoming the active field in which improvements in processing and advanced products can be anticipated. Some researchers proposed brazing diamond methods with Ni-Cr and Ag-Cu-Ti alloy, but there is a shortage of the comparative study of the characteristics of the brazed diamond tools fabricated with the different brazing alloy. In this paper, machining performance experiments have been carried out, including contrast tests about tool life and machining efficiency for thin-walled monolayer brazed diamond core drills fabricated with Ni-Cr and Ag-Cu-Ti alloy. The results show that the Ag-Cu-Ti alloy can improve the machining performance. Wear mechanism of diamond grits was studied in those drilling processes. The results show that the low ratio of grit breakdown of the core drill using Ag-Cu-Ti alloy is the key factor of its longer life. Furthermore, based on the experimental results, the areas of the grits wear flat increase the feed force, and decrease the machining efficiency.

Abstract: The two biggest problems that often experienced in machining cast iron are poor machinability and high hardness. Up to now, many researchers have investigated machining performance and how to find optimum condition in machining ductile cast iron. This study aims to investigate the machining performance of ductile cast iron and carbide cutting tool using FEM. Performances were evaluated by changing the cutting tool geometries on the machining responses of cutting force, stress, strain, and generated temperature on the workpiece. Deform-3D commercial finite element software was used in this study. Ductile cast iron FCD 500 grade was used as the work piece material and carbide insert DNMA432 type with WC (Tungsten) was used for the cutting tool. The effects of rake and clearance angles were investigated by designing various tool geometries. Various combination of carbide insert geometries were designed using Solid Work to produce +15, +20 and +30 deg for rake angle and 5, 7, 8 and 9 deg for clearance angle. Machining condition for the simulations were remained constant at cutting speed of 200 m/min, feed rate of 0.35 mm/rev, and depth of cut of 0.3 mm. The results of effective-stress, strain and generated temperature on both chip and material surface were analysed. The results show that by increasing the rake angle (α), it will improves the machining performance by reducing the cutting force, stress, strain and generated temperature on surface of workpiece. But, by increasing the clearance angle (γ), it will not affect much to the cutting force, stress, strain and generated temperature on chip.

Abstract: An attempt has been made to investigate the new generational manufacturing technology for multi-layer diamond tools by brazing. A kind of new multi-layer brazed diamond core drills with random grains distribution was made by mixing diamond particles with brazing alloy powders. And a preliminary machining performance experiment was carried out through drilling granite. The testing results show the typical topography of the multi-layer brazed diamond core drills after drilling granite, just like that of multi-layer sintered ones, is that diamond grits drag long tails. Different from multi-layer sintered diamond core drills, no grit pull-outs can be seen during the whole drilling process because of chemical metallurgical effect between diamond grit and brazing alloy, the same as monolayer brazed diamond core drills. The main drawback to this kind of multi-layer brazed diamond tools is each individual particle is not subjected to the same drilling force throughout the drilling operation because of random grain distribution. This leads to premature fracture of the leading particles. Similarly, because large gaps between particles exist, the bond is being exposed to the workpiece, which leads to erosion of the bond. The overall performance is lower tool lives and slower drilling speeds. Therefore, ideally, diamond particles should be evenly distributed throughout the bond, which means they are all subject to the same drilling forces and the multi-layer brazed diamond tool is operated at its optimum efficiency.

Abstract: Increasing the performance of the abrasive waterjet (AWJ) cutting technology for engineering materials is the ultimate aim of research in this field. This paper presents a review on the studies using a controlled nozzle oscillation technique to increase the cutting performance of the AWJ cutting technology and the associated mechanisms primarily based on the work in the author’s laboratory. Primary attention is paid to the discussions of the depth of cut, the effect and selection of process parameters and the advantages by using this technique in both single- and multi-pass cutting modes.