Papers by Keyword: Microcutting

Abstract: The manufacture and repair of mechanical engineering products and other industries is associated with the qualitative preparation of their surfaces for the application of protective non-metallic coatings on them, which ensures an increase in their durability and reliability. Among the methods of cleaning metal surfaces, the environmentally friendly and energy-saving crushing process occupies a priority place. Therefore, it is important to substantiate aspects of the destruction process of the metal products’ surface layer of mechanical engineering during shot blasting, depending on the process parameters, which allows more rational planning and a balanced technology for high-quality surface preparation of products. The results of experimental and analytical studies of the mechanism of destruction of the surface layer of steel specimens attacked by a shot, as well as a shot torch, depending on the specified parameters: angle and speed of attack, shot diameter and mechanical properties of the material are presented. The destruction coefficient is related to the ratio of the trace volume left by the pellet on the attacked surface to the pellet volume, which integrates the result of dynamic contact. The results obtained indicate that the degree of destruction intensity does not depend on the diameter of the shot and reaches a maximum at angles of attack at a given speed. The analytical setting of the destruction coefficient allows, without unnecessary technological samples, to balance the process parameters to achieve the required quality of surface cleaning at the lowest possible cost.

Abstract: There have been few reports on the drilling of microholes on rod end faces by cutting, which can be employed for fabricating micronozzles or microneedles. Such drilling was therefore attempted in the present study using a micro turn-milling machine with the tool and workpiece axes being parallel. The drilling was performed on the end faces of brass rods with cemented tungsten carbide micro-cutting tools processed by electrical discharge machining (EDM). As a result, a microhole 12‍ μm in diameter was successfully drilled using a 10-μm-diameter tool at a feed speed of 0.5‍ μm/s. The feed speed could be increased to 25 μm/s for a tool with a diameter of 20 μm and body length of 50 μm.

Abstract: Given that the grain geometry has an important impact on grinding process, it’s necessary to investigate the influence of grain shapes on grinding mechanism. In this paper, a 3D FEM model is developed to study the effects of CBN grain geometry on its microcutting performance under various speed levels, which is effective to understand the microcutting process qualitatively and quantitatively. The simulation results indicate that the single grain microcutting force ratio and material removal ratio are both sensitive to the grain shape and those grains with truncated tetrahedron shape of large cross-sectional area and negative rake angle would improve the cutting performance.

Abstract: The turning of straight micropins with a diameter smaller than 10 µm, which has not been reported so far, was carried out using micro turning tools made of cemented tungsten carbide. Tools of 50 µm diameter were fabricated by electrical discharge machining, which is suitable for fabricating micro cutting tools because it can deal with hard materials and carry out micromachining. A turning machine designed especially for micro turning tools was used in the experiments. A brass workpiece was turned using a tool with a length of cut of 100 µm at a feed speed of 3.0 µm/s, feed per revolution of 0.06 µm and depth of cut of 10–11 µm. As a result, a straight micropin of 7.5 µm diameter and 80 µm length was successfully turned. Furthermore, turning was also performed using a tool with a length of cut of 50 µm at a feed speed of 3.0 µm/s, feed per revolution of 0.06 µm and depth of cut of 8.5–20 µm to fabricate a straight micropin of 3 µm diameter and 30 µm length. This micropin is the pin with the smallest ever diameter fabricated by turning, to the best of our knowledge, indicating the possibility of further minimization of the machinable size in turning. Turning properties were also investigated to determine the maximum depth of cut and feed speed that can be employed without tool breakage.

Abstract: Microburrs have great influence on printed circuit board’s quality. PCB is composed of glass fiber plastic reinforcement material and copper foil. The PCB microburrs are generated in copper foil drilling process. These burrs are generated by copper extrusion and accumulation around the micro-hole. Enter burr and exit burr is quite different. Enter burrs are lower than exit burrs. The burr formation experienced three stages: First, Copper foil extrudes with the feed of microdrill; Second, Most of the Materials are cut off by drill tip and the rest of material; At last, rollover burrs appear when drill enters or exits uncut chip rolls.