Fabrication of microfluidic channel using micro end milling and micro electrical discharge milling

This paper discusses the fabrication of microfluidic channels using micro end milling and micro electrical discharge (ED) milling on metals and polymers. The width of the microchannels fabricated by micro end milling was 100-800 µm with 1-2 aspect ratio. The average surface roughness values were 100-200 nm and 80-120 nm on metals and polymers respectively. The end milling was found to form more burrs on metallic surface. Micro ED milling, on the other hand, was capable to produce high aspect ratio microchannels on metallic materials without forming any burrs. Using this micro ED milling process, microchannels of 120 µm width and 8-9 aspect ratio were machined with 40-50 nm average surface roughness. Micro swiss-roll combustor mold cavity was machined by using micro ED milling

Application of Silicon Carbide in Abrasive Water Jet Machining

Silicon carbide (SiC) is a compound consisting of silicon and carbon. It is also known as carborundum. SiC is used as an abrasive material after it was mass produced in 1893. The credit of mass production of SiC goes to Edward Goodrich Acheson. Now SiC is used not only as an abrasive, but it is also extensively used in making cutting tools, structural material, automotive parts, electrical systems, nuclear fuel parts, jewelries, etc. AWJM is a well-established non-traditional machining technique used for cutting difficult-to machine materials. Nowadays, this process is being widely used for machining of hard materials like ceramics, ceramic composites, fiber-reinforced composites and titanium alloys where conventional machining fails to machine economically. The fact is that in AWJM no heat is developed and it has important implications where heat-affected zones are to be avoided. AWJM can cut everything what traditional machining can cut, as well as what traditional machining cannot cut such as too hard material (e.g. carbides), too soft material (e.g. rubber) and brittle material (e.g. glass, ceramics, etc.). The basic cutting tool used in water jet machining is highly pressurized water that is passed through a very small orifice, producing a very powerful tool that can cut almost any material. Depending on the materials, thickness of cut can range up to 25 mm and higher (Kalpakjian & Schmid, 2010). A water jet system consists of three components which are the water preparation system, pressure generation system and the cutting head and motion system

A new approach of applying cryogenic coolant in turning AISI 304 stainless steel

In the present study a special device has been designed to apply liquid nitrogen coolant during turning of AISI 304 stainless steel. The base of the device is a magnet and it can be fixed at any suitable position on the tool or tool post. A long flexible and adjustable copper nozzle is used to apply liquid nitrogen at any angle or from any position. Experiments with three positions of the copper nozzle were performed. The results of the investigations showed that the most effective way to apply liquid nitrogen directly to the machining zone without any interference by the chips. Tool life increased four times compared to dry machining under this condition. The next effective way was to apply liquid nitrogen along the principal cutting edge. It was found that application of liquid nitrogen coolant did not improve job surface finish, but all the three positions of the copper nozzle demonstrated almost similar effectiveness

A study of electrode shape configuration on the performance of die sinking EDM

This paper discusses the performance of die sinking EDM due to the shape configuration of the electrode. The effect of electrode shape on material removal rate (MRR), electrode wear rate (EWR), wear ratio (WR), and average surface roughness (Ra) has been investigated for mild steel work material and copper electrode. The shapes of the electrodes were round, square, triangular, and diamond of constant cross-sectional area of 64 mm2. Experiments were repeated for three current values of 2.5, 3.5, and 6.5 A. The highest MRR was found for round electrodes followed by square, triangular and diamond shaped electrodes. However, the highest EWR and WR were found for the diamond shaped electrodes. The minimum surface roughness was found for the round electrodes followed by square, triangular and diamond shaped electrodes. However, the influence of the shape of the electrodes on surface roughness was found to be insignificant

Fabrication of Micropillar Sheet for Cell Culture Dish

Cell culture is one of the major tools in life sciences. Conventionally, cells are placed in a flat petri dish made of glass or plastic. It is used to monitor cells behavior under controlled conditions. As the cells are strongly adhered to petri dish, an additional process of trypsinization is applied to remove the cells from the dish. Alternatively, by using micropillar sheet, the contact surface between the cells and the pillars is smaller than traditional two dimensional petri dish. Cells were found to grow in a different way on the micropillars because of these differences in adherence to the support materials. The micropillars structure enables the cells to be removed without any additional process where the cultured cells can be collected simply by pipetting. However, it remains a challenge to fabricate high aspect ratio metallic or polymeric micropillar sheets of about 1 μm or less of the micropillar diameters. This research presents the fabrication process using focused ion beam (FIB) a maskless sputtering technique for the fabrication of micropillar sheet to be used in cell culture dish. Micropore sheet on metallic materials is also machined using FIB sputtering which can be used as a master microtool for the mass production of polymer micropillar sheets by micro/nano hot embossing. The typical diameter of the micropillars is 1 μm with 3-10 aspect ratio. This FIB based process is direct, easy to fabricate, and less expensive compared to LIGA (lithography, electroplating and molding) and lithography based techniques as reported

Simulation of micro-injection molding

Two challenges in micro-injection molding process were the modification of conventional injection molding machine and simulation of the molding process. This paper simulates the micro-injection molding process using a conventional software. Successful simulation was performed for the micro-injection molding of polycarbonate micro-components with sub-millimeter dimensions. The micro-cavities, keeping along with a macro-cavity, were filled completely under non-variothermal process conditions. The percentage weight of the melt flow and average flow length were found proportional to the filling time. A sudden drop of melt temperature and a high concentration of shear stress were observed at the entrances of all micro-cavities. The melt flow velocity inside the micro-cavity was much lower than any other places of the cavity. Air traps were identified in each of the micro-cavities

Investigation of recast layer of non-conductive ceramic due to micro-EDM

This paper presents the investigation of minimum recast layer of zirconium oxide (ZrO2) due to micro-EDM using EDM-3 synthetic oil as dielectric fluid and tungsten as the tool electrode with control parameters of rotational speed and gap voltage. The investigation was performed using multi-process micro machine tools DT 110. The recast layer thickness was observed using scanning electron microscope and its hardness was measured using micro-Vickers hardness tester. The hardness data were analyzed and an empirical model was developed. The optimum value for minimum recast layer hardness was 873.46 Hv with rotational speed of 395 rpm and gap voltage of 110 V