Papers by Keyword: Cutting Performance

Abstract: The effects of coarse-grained ring on the mechanical properties and cutting performance of 2011 aluminum alloy extruded bars were studied by metallographic microscope, scanning electron microscope, tensile testing machine and high-speed lathe. The results show that the microstructure of aluminum alloy extruded bar was composed of α-Al phase, Al₇Cu₂Fe phase, CuAl₂ phase and SnBi eutectic phase. There was a coarse-grained ring in the aluminum alloy extruded bar. The coarse-grained ring reduced the mechanical properties and cutting performance of the aluminum alloy extruded bar. The aluminum alloy extruded bar with a diameter of 30 mm had a coarse-grained ring depth of 9 mm and lower mechanical properties, whose the tensile strength was 287.9 MPa, the elongation was 17%, the cutting performance was poor and the chips were long. The aluminum alloy extruded bar with a diameter of 40 mm had a coarse-grained ring depth of 1 mm, higher mechanical properties and better cutting performance, whose the tensile strength was 394.5 MPa, the elongation was 23.5%, the chips were fine and uniform.

Abstract: Diamond particle with tungsten boride (WB) coating was synthesized by the molten salt method. Three different diamond/Fe-Ni composites made from pristine diamond, B4C coated diamond and WB coated diamond with Fe-Ni powders were prepared by powder metallurgy. The composition and microstructure of the tungsten boride coating were investigated. Both bending strength and cutting performance of the composites were investigated. Addition of the WB coating provided an increased bending strength (871.2 MPa) and relative density (93.54%), compared with the composites consist of uncoated diamond and Fe-Ni (746.8 MPa, 92.81%). Three different Fe-Ni-based impregnated diamond drill bits contained 20 vol.% pristine diamond, B4C coated diamond and WB coated diamond were manufactured by powder metallurgy, respectively. Drilling rate of bits was measured by XY-4 geological core drill on granite. The test results show that the drilling rate of bits with WB coated diamond (2.42 m/h) was 40% higher than that with pristine uncoated diamond (1.72 m/h).

Abstract: An experimental study of the effect of the content of the oxygen in the auxiliary process gas on the laser cutting speed and the quality of the cut-off zone surface was made. For the research, the auxiliary technological gases of the brand LAZAL, produced by Air Liquide (99.95% oxygen content) and Energo grade (99.7% oxygen content), were used. For the experiments, a low-carbon steel with a thickness of 8 mm and 3 mm was used. The main objective of the study was to increase the productivity of laser equipment by increasing the cutting speed. It is established that the use of oxygen in laser cutting as an auxiliary gas makes it possible to increase the cutting speed, to decrease the power of the laser installation, or to increase the thickness of the cut metal at the same power.

Abstract: The five stage experiments including without assistance, single and hybrid assisted machining systems on Inconel 718 milling were conducted in this study. First of all, the milling experiment without assistance was performed to investigate the variations of cutting performance and the results were used for a suitable process parameter planning in the subsequent stage experiments. Next, a laser assisted system was introduced in the second stage where the spacing distance between the laser spot and cutting-tool along the cutting direction was modified to test whether laser preheating may effectively reduce the cutting force. A biaxial ultrasonically assisted system with only one-axis oscillation (x or y direction) and with two-axis simultaneous oscillations (x and y directions) were subsequently introduced at the third to fourth stage experiments, respectively. While a biaxial ultrasonically and the laser assisted systems were integrated together to construct a hybrid assisted cutting system at the last stage experiment. Under these assistances, milling experiments of Inconel 718 by cutting-tool of tungsten carbide with nanoSi® coating were conducted. And the full-factorial experiments of process parameter combinations such as spindle speed, radial cutting depth and feed rate were planned. The results indicated that the laser-preheating assisted system could effectively reduce the cutting force as well as enhance the cutting performance. The effect of the biaxial ultrasonic oscillation on tool service life could greatly be promoted. Furthermore, the cutting performance exhibited in the integrated hybrid assisted milling prevails over that in milling without assistance as well as with each single assisted system. Under this hybrid assisted milling, the better surface roughness of 0.216μm was obtained under a combination of spindle speed of 6000 rpm, radial cutting depth of 0.01 mm, and feed rate of 300mm/min, accompanied by a maximum cutting-tool wear of 13.849μm.

Abstract: Cutting performance of reaming alloy gray cast iron HT250 using carbide, cermet and CBN reamers was studied. Experiments were conducted under constant cutting parameters and cooling strategy. Tool life, hole diameter, spindle power, surface roughness and tool wear were analyzed. The hole diameter and spindle power would keep steady when reaming with carbide reamer after 400 holes to the tool life of 1050 holes. But holes diameter reduced and spindle power increased with the number of machined holes increasing during the whole tool life when using cermet or CBN reamer. The surface roughness Rz of the holes reamed by carbide reamer was within the tolerance, although it was worse than that reamed by cermet and CBN reamer. It can be summarized that the carbide was the most suitable material for reaming alloy gray cast iron because of the longest tool life, steady hole diameter and spindle power, qualified surface roughness. After machining, crater wear and clearance wear were produced on the cermet and CBN reamer, which were caused by abrasive wear. In addition, flaking and breakages appeared on the edge of cermet reamer, which were not found on CBN reamer. However, the clearance wear of carbide reamer was smaller than that of CBN reamer, and built up edge was found along the cutting edge.

Abstract: In this paper, cutting mechanism and cutting performance of ball end mill for spherical surface with contour path method is investigated. Ball end mills are used to produce molds, dies and so on. However, the edge shape is complex, so cutting process is not clear. Then, it is not clear effectively using method of the tool based on good cutting performance. Therefore, in this study, the purpose is proposal of high efficient and high accurate cutting method is using 5-axis control machine tool. At first, cutting model assembled by a ball end mill (R8 mm) and a workpiece with convex or concave spherical surface (Workpiece radius 20 mm) is carried out using 3D-CAD (SolidWorks). The pick feed direction which is from bottom to top is defined “Stepped up”, the one which is inverse direction is defined “Stepped down”. In addition, both cutting methods include up milling and down milling, then there are four cutting modes. The radius of tool path for contour path are varied from 14.0 mm to 19.4 mm for convex spherical surface, from 6.5 to 9.2 mm for concave spherical surface. The lead angle of the tool is defined the plus sign when the tool is inclined to the tool feed direction and varied from-45° to 45°. Secondly, the cutting cross-sectional area is calculated by the interference of a rake surface of the tool and an uncut chip volume which can be removed by one cutting operation. Thirdly, cutting experiments are done in order to measure cutting force. Finally, analytical and experimental results are discussed, and then the cutting conditions which are expected good cutting performance are considered.

Abstract: In this work, two kinds of Al₂O₃-TiC-TiN ceramic cutting tools (AC2U and AC2UN2) were developed by hot-pressing sintering techniques. The mechanical properties were measured and the cutting performance was investigated. The workpiece used in the cutting experiment was quenched carbon tool steel T10A, and the tool material for comparison was LT55. The wear resistance and the main wear patterns of the ceramic tools were analyzed at the high speed of 300m/min. The results indicated that the novel Al₂O₃-TiC-TiN ceramic cutting tools showed better cutting performance than LT55, and AC2UN2 was better suitable for machining quenched T10A. When the cutting condition was v=300m/min, f=0.1mm/r and a_p=0.1mm, the adhesion wear and abrasive wear of the novel ceramic tools were slighter than those of LT55, the diffusion wear resistance of AC2U was better and the oxidation resistance of AC2UN2 was better.

Abstract: Related researches of bionic tribology indicate that reasonable bionic micro-texture’s surface has a good effect on tool’s anti-friction property. In order to study bionic micro-texture effects on tools’ cutting performance further, in this paper groove and scallop micro-texture are made out on the surface of carbide tool with laser processing technology. Then orthogonal cutting tests are made to cut steel 45 in dry or wet cutting with different feedings. The results show that cutting forces can be effectively reduced by the cutting tool with micro-texture’s surface. Especially, the micro-texture’s tool has the best effect when the direction of grooves is vertical to the direction of chip’s motion, and the wear degree of its rake face is also slighter. All of those will be helpful to guide the design of cutting tool.

Abstract: The cutting performance, failure mechanisms and reliability of Al₂O₃/TiC micro-nanocomposite ceramic tools with different geometry parameters in continuous machining of austenitic stainless steel were studied. The results showed that the largest metal removal amount was got at the cutting speed of 80 m/min, the feed rate of 0.15 mm/r and the cutting depth of 0.1 mm. The failure modes of the tool with small chamfering width and corner radius were mainly cutting edge fracture and tool materials peeling off, which was due to the subcritical crack growth. The life of the tool with small chamfering width and corner radius well followed the Gamma distribution.

Abstract: A series of research on the interactions among tool wear, cutting force and cutting vibration were conducted through high speed milling experiment in this paper, which objected the titanium alloy as difficult-to-cut materials. The results showed that the increasing of tool wear led to enlarging the cutting force and cutting vibration; and vice versa, the increasing of cutting force and cutting vibration aggravated the tool wear in the process of machining. Besides, the variation trend of tool wear with cutting was similar to the trend of cutting force, while the variation trend between cutting vibration and tool wear was different. Especially in the sharply cutting tool wear stage, the influence of tool wear on cutting vibration became more complicated.