Papers by Keyword: Burr Formation

Abstract: Additively manufactured titanium alloys such as Ti-6Al-4V have been used as functional components in industry due to their excellent mechanical properties. However, the machining of these alloys is a challenge due to their enhanced tensile/yield strength, low elastic modulus, poor thermal conductivity, and microstructural anisotropy. Thermal assisted machining (TAM), as a hybrid manufacturing technology, can improve the machinability of additively manufactured alloys. The main aim of this paper is to investigate the effect of temperature buildup on the machinability of additively manufactured Ti alloy with different build directions in the TAM process. It was found that the surface integrity was notably enhanced by preheating, and it was the best at 90° build orientation. Serrated chips were generated at room temperature, and curlier chips were formed in high-preheating machining environment. By analyzing the surface quality, the influence of the build-up orientation on the surface quality at different temperatures was evaluated.

Abstract: Micromachining technology is a challenge in industrial production to meet the demand for components for machinery. In this research, a study of the best parameters was required to produce the best hole accuracy and the lowest burr formation in the inlet and exit holes using micro-drilling. The work-piece material and cutting tool used respectively was a brass plate with a thickness of 0.5 mm and a micro drill with a diameter of 0.2 mm commonly used for electronic PCBs. The quality of holes was measured and observed by using a stereomicroscope (optical equipment). This microscope can zoom up to 50x objects to facilitate measurement. The microscope was attached by using a digital camera type YW-200 so that the object of observation could be measured using a computer. The result shows that the largest deviation of hole diameter (0.217 mm) occurred at a spindle speed of 14,000 rpm with the lowest feed rate (5 mm/min). Meanwhile, the smallest deviation of hole diameter (0.202 mm) occurred at a spindle speed of 20,000 rpm with a maximum feed rate of 10 mm/min. The maximum burr height (0.050 mm) occurred at a spindle speed of 17,000 rpm and a feed rate of 10 mm/min. In addition, the minimum burr height (0.038 mm) occurred at a spindle speed of 14,000 rpm and a feed rate of 5 mm/min. Therefore, it can be concluded that the deviation of hole diameter was inversely proportional to the spindle speed, and the height of the burr formation was directly proportional to the feed rate.

Abstract: First investigations focus on the usage, processing and material properties of polycarbonate (PC) based materials used in cable duct production. Test coupons were taken from in-situ cable ducts including further additives generally used in industry. Different mechanical and optical analytical methods were performed. Significant differences in tensile properties of polycarbonate/ acrylonitrile butadiene styrene (PC/ABS) compared to mineral reinforced PC were observed. The hardness of mineral reinforced PC is significantly dependent on the geometry of the cable ducts. The fracture behavior and morphology of the PC/ABS fracture surface is directly related to the coupon temperature during Charpy impact testing. The process temperature influences the failure behavior during high impact processing such as high speed punching. Due to the lower impact strength of mineral reinforced PC less film and burr formation compared to PC/ABS are likely. However, the mineral distribution is not homogeneous and therefore subject to further investigation. This study aims at a better understanding of process properties of PC/ABS products, parameter selection, quality improvement and general understanding of underlying microstructural and surface properties.

Abstract: The energy consumption and machinability index of metallic alloys are very important in determining the economic and environmental value of manufacturing process. Various machinability problems with Nitronic 33 steel alloy have been reported in literature. These problems have been attributed to the work hardening of the material during machining operation and hence greatly influences and contributes to the green house gas emission. In this work, the chip and burr formation during the machining of Nitronic 33 steel alloy was investigated in other to optimize the cutting parameters and provide a knowledge base for machinists when machining austenitic stainless steels. The result shows that although continuous chips were formed throughout the machining tests, an evidence of continuous chip with built-up edges was also observed. This phenomenon tends to initiate the formation of discontinuous chips especially at high pressure coolant flow of 7 and 9.7 MPa. It is concluded that conventional cutting environment at 90 m/min cutting velocity is the optimum process parameter most suitable for machining Nitronic 33 steel alloy. The research outcome will address some of the problems encountered during high speed machining of Nitronic 33 steel alloy and the general understanding of the machinability of this alloy.

Abstract: In ultrasonic vibration the cutting edge of a tool is vibrated in the principal or cutting direction, generally at a constant ultrasonic frequency. The main characteristic of this cutting method is its intermittent nature involving repeated cutting and pausing. In this paper, ultrasonic elliptical vibration cutting is used to assist micro-groove turning of cylindrical surfaces. The elliptical locus during the cutting process is generated by a newly designed 2D resonant ultrasonic vibrator. A series of experiments were performed to verify the effects of the ultrasonic elliptical vibrations. The generated cutting forces and burr formation were compared for the ordinary and the elliptical vibration-assisted cases. Comparison results show the effectiveness of the elliptical vibration cutting method in reducing cutting forces and alleviating burr formation.

Abstract: Burrs generated in micro-milling operation have a significant impact on the surface quality and operational performance of the finished microstructures. In order to gain a better recognition of burr generation process, 3-dimensional double-edged micro-flat end milling operation FEM models on Ti6Al4V have been established. Burrs occurred in simulation can be classified into three types: entrance burr, exit burr, top burr. Their formation processes and causes are well investigated and analyzed, moreover, a series of experiments are conducted to validate the burr morphologies which are received in simulation. At last, the effect of cutting parameters on top burr size is studied through orthogonal experiment on Ti6Al4V, it can be concluded that the axial depth of cut has the greatest effect on top burr size, and the effect of spindle speed on top burr size is the least.

Abstract: Remained burrs on edges of the parts after metal cutting operations may cause many problems in the production process and in the quality of products, therefore the burrs must be completely removed. In the paper, the authors give an outline of the elements and the technical and economical influences of the burr formation, and the characteristics of the burrs and the burr formation mechanisms. The authors present some special processes that are suitable for deburring of small pieces (e.g. Magnetic Abrasive Deburring), and a frequently applied mechanical process: power brushing. The authors have carried out many investigations regarding the magnetic abrasive deburring of small, blanked sheet metal parts, furthermore the machine deburring of large-sized metal workpieces by carbide-reinforced cylindrical brushes. The detailed conditions, data, results and conclusions of these deburring experiments are treated in the paper too.

Abstract: The milling characteristics experiments with typical micro three dimensional parts are done by the developed 3-axis micro-milling machine tool, and the micro burr formed in micro-milling process is observed and analyzed. Burr formation and its influence factors in micro-milling process are studied and general influencing rule of each factor to burr formation is summarized. Based on the results, the purpose to reduce the burr is achieved through choosing proper machining parameters and tool material.

Abstract: In recent years, with the development of machinery industry, micro-cutting technologies have been gradually moving into engineering realization. The paper carries out a series of works on simulation modeling of micro-cutting of Ti-5Al-5V-5Mo-3Cr considering tool edge radius. Unlike conventional cutting, in micro-cutting the effect of tool edge radius which has a marked impact on cutting force, specific cutting energy, burr formation and burr size can no longer be neglected.

Abstract: In this study, machinability of Zr-based bulk metallic glass (Zr52.5Ti5Cu17.9Ni14.6Al10) (BMG) material was investigated by conducting a set of milling and drilling experiments. In milling, two different tool paths, spiral and slot milling, were used. To investigate the behavior of BMG in drilling by two different tools at different feed rates, two sets of drilling experiments are conducted. Crown shaped exit burr formation are observed in drilling of BMG. Best results on thrust force, exit burr formation and hole surface roughness is obtained while using micrograin WC tool on BMG drilling. No chip light emission was observed during all tests. This study concludes that BMG can be achieved machining with good surface roughness, (Ra=0.113 µm), using conventional cutting tools.