Generation Of Burrs Research Articles

Cutting Performance of a Longitudinal and Torsional Ultrasonic Vibration Tool in Milling of Inconel 718

Inconel 718 has excellent thermal and chemical properties and is widely used in the manufacture of aerospace parts; however, there are some problems in the machining of Inconel 718, such as a large milling force, serious tool wear, and poor surface quality. In this research, a type of longitudinal–torsional ultrasonic milling (LTUM) tool is designed based on theoretical computations and FEM simulation analysis. To verify the design rationality of the developed LTUM tool, milling experiments are performed. It is verified that the LTUM tool can realize an elliptical vibration path at the tool tip. The resonance frequency of the tool is 21.32 kHz, the longitudinal amplitude is 6.8 µm, and the torsional amplitude is 1.4 µm. In the milling of Inconel 718, the experimental data of LTUM are compared with those of conventional milling (CM). The comparative experiments show that the LTUM tool can effectively lessen the milling force and tool wear in the milling of Inconel 718, improve the surface quality, inhibit the generation of burrs, and improve the chip breaking ability. The application potential of the LTUM tool in high-performance milling of Inconel 718 parts is proven.

Quality enhancement of micro-milled channels with automated laser assistance

AbstractMicrochannels are utilised on material surfaces of a body, allowing coolant to pass through them and enabling heat dissipation by increased contact area. Fabrication of metal surface microchannels is primarily achieved by employing a micro-milling process, which has drawbacks such as excessive cutting forces, top burrs, tool wear, and lower tool life. Alternatively, it is also realised by using Laser micro milling, which has problems associated with lower quality of surface finish, un-desired taper, heat-affected zone, and spatters. The existing literature, after due review of the current state of the art, has brought out gaps needing attention. These gaps are limited capability to reduce surface roughness, unaddressed burr width, and irregular bottom surface morphology, which affect microchannel quality. These gaps motivate this research work to improve and sustain the microchannel quality. To achieve the goals, this research work performs the fabrication of microchannels by micro-milling with automated laser assistance being achieved in two ways (a) sequentially, (b) non-sequentially, termed as LASMM and LPCMM, which are novel for the scientific community. The effects of micro milling parameters, spindle speed and feed on the quality were analysed while machining commercially pure titanium (cp-Ti). Results show that laser assistance to micro-milling provides a lower generation of undesired forces and lesser top burrs compared to micro-milling alone. In sequential laser assistance, the channels have a mean down burr width ~ 58% lower and a maximum down burr width ~ 38% lower than the channels done non-sequentially. In the case of up-burr width, a mean value ~ 60% lower and a maximum value ~ 73% lower is achieved in channels done non-sequentially as compared to those done sequentially. In the case of surface roughness, channels done sequentially have a maximum Sa value of 1.508 µm, a maximum Sq value of 1.912 µm whereas non-sequentially, they show a maximum Sa value of 3.495 µm, maximum Sq value of 4.59 µm. Steady tool wear is observed sequentially, whereas in non-sequential, rapid tool wear occurs after 500 mm of cutting length.

Influence of Cutting Process on the Flanging Formability of the Cut Edge for DP980 Steel

Flanging is a key process in the forming of automobile parts and is influenced by the cutting process before it. In this paper, a set of self-designed tools is adopted. The flanging height and flanging radius are specified as the indexes to investigate the influence of the cutting process on the flanging formability of DP980 steel. Microstructure, microhardness, and tensile properties are tested to evaluate the formability of cut edges. The results show that the flanging formability is positively correlated with an increase in flanging height and a decrease in flanging radius. The flanging formability of six cut edges can be ranked as: LC-L > LC-H > WEDM-HS > WEDM-LS > CNC milling > WJC. In the LC process, acicular martensite is formed and the microhardness of the cut edge significantly increases, with a heat-affected zone of about 150 μm. More and larger microvoids are found on the edge of WEDM-LS than WEDM-HS, which reduces the formability to a certain extent. Plastic deformation of the edges is the reason for the decrease in the formability of CNC milling. For WJC, the formation of irregular edge damage and the generation of burrs are the main reasons for the unstable performance. This research is helpful in guiding the selection of the cutting process, and it may contribute to a high part formability for DP980 steel.

Improving the grindability of Inconel 718 by hydrogen embrittlement in ultrasonic-assisted grinding

Inconel 718 has been widely investigated due to its machining properties. The purpose of this work was to investigate a novel proposed grinding technique for Inconel 718 with a combination of ultrasonic-assisted grinding and hydrogen embrittlement (HE) treatment. The technique was hence named hydrogen embrittlement-enhanced ultrasonic-assisted grinding (HEUAG). Before grinding, a thin stress layer was formed on the surface of the workpiece. To reveal its fundamental performance in the grinding of Inconel 718, experiments were conducted to investigate the effect of ultrasonic vibration on the grinding forces and the surface roughness in the presence of hydrogen embrittlement. To investigate the material removal process for HEUAG, single-grit grinding tests were also conducted with hydrogenated samples. Furthermore, the subsurfaces for HEUAG samples were obtained with the transmission electron microscope (TEM) micrographs. The HE treatment reduced the generation of burrs around the scratches and improved the surface quality after grinding.

Numerical Simulation and Experimental Study on the Drilling Process of 7075-t6 Aerospace Aluminum Alloy.

A finite element model for setting drilling conditions is established. The effect of feed speed and spindle speed on the drilling process was studied. In the test phase, drilling tests were conducted using three different feed speeds (60, 100, and 140 mm/min) and three different spindle speeds (800, 1000, and 1200 rpm). The correctness of the finite element model was verified by comparing the experimental and numerical simulation data. The results show that the axial force and torque increase significantly with the increase of feed speed, while the axial force and torque increase less as the spindle speed increases. The numerical simulation results show that the temperature of the cutting edge increases as the feed speed increases. Increasing the rotating speed increases the formation of chip curl. When the working conditions are high rotating speed and low feed, the tool wear is reduced, and the machining quality is better. The numerical simulation results obtained for the chip forming effect are similar to the experimental data. In addition, the simulation results show the generation of burrs. A comparison of the finite element simulation and experimental data leads to an in-depth understanding of the drilling process and ability to optimize subsequent drilling parameters, which provide reliable process parameters and technical guarantees for the successful implementation of drilling technology for space suspended ball structures.

Simulation and experiment study of burrs in micro-milling Zr-based metallic glass

Metallic glass has been widely used in making micro parts and equipment due to its excellent physical and chemical performance. A large quantity of burrs is produced in the micro-milling process that is hard to remove and seriously affects the quality and precision of the parts. Burrs should be effectively restrained; however, the burrs’ type, position and the effect of milling parameters on burrs’ generation in micro-milling metallic glass have not been systematically studied. In this paper, by using 3-D FEM simulation and taking micro-milling experiments of Zr-based metallic glass (Vit1), the burrs in flat-end milling and ball-end milling micro grooves were investigated. The burrs’ type and position were observed and summarized, the formation process of various burrs was analyzed in detail, and the influence of cutting parameters on burrs was clarified. Comparing the simulation and experiment result, we could confirm that the top burr and the entrance burr were produced during the processing of the flat-end milling cutter, and ball-end milling cutter effectively inhibits the production of the top burr but takes no actions on burrs’ generation at the entrance and the bottom of the groove. The main cause of the top burr is the extrusion of the tool, and the extrusion of the cutting layer metal and chip accumulation were the main reason for entrance and exit burrs. Reducing the axial cutting depth could effectively restrain the generation of burrs for both two kinds of milling tools.

Deburring drilled holes in CFRP composites with large pulsed electron beam (LPEB) irradiation

The generation of burrs is one of the most common problems affecting carbon fiber reinforced plastic (CFRP) machining processes. However, it is difficult to develop machining processes that generate no burrs. To overcome the limitations of conventional CFRP composite deburring methods, we propose a new process for deburring drilled holes in CFRP composites based on large pulsed electron beam (LPEB) irradiation. We evaluated the deburring performance as we independently varied the three major controllable parameters that affect energy transfer during LPEB irradiation, namely the acceleration voltage, solenoid voltage, and number of pulses. We optimized the irradiation process to improve the accuracy of the shapes of the holes, and reduced the sizes of the burrs by 97%. We evaluated deviations in the shapes of the holes from perfect circles by measuring their diameters. As our deburring process reduced these deviations by 93%, it significantly improved the dimensional accuracy of the holes. We hypothesize that the deburring mechanism starts with evaporation of the resin that coats the carbon fibers evaporates. This leaves the uncut carbon fibers exposed so that they can be detached by the LPEB irradiation. We obtained high quality, burr-free drilled holes by applying the proposed LPEB deburring method.

Investigation of chip formation and burr control in PCB fixture hole

Purpose – This paper aims to analyze their generation mechanism and factors influencing burr generation. The final goal is to use appropriate drill design and drilling process to control the generation of burrs. Design/methodology/approach – The mechanism of burr generation was studied through finite element method (FEM) simulation and drilling experiments. High-speed photography technology and scanning electron microscope (SEM) were used in this study. Findings – High-speed drilling burr is a printed circuit board (PCB) copper foil burr. Within a certain range, the feed speed and burr height is in positive correlation, and decrease in the feeding speed will favor the exit burr. Drill angle influences burr and chisel edge affect significantly, followed by the point angle, and helical angle has little effect. From the perspective of reducing the burr, a smaller chisel edge and smaller point angle should be chosen. Grinding chisel edge is another choice to decrease the burr but also ensures the blade strength. Originality/value – This paper investigates the mechanism of burr generation of PCB fixture hole drilling. The process of burr generation was captured by high-speed camera. The controlling methods of burr generation were illustrated at the end.

Study and Analysis the Facture Mechanism for Fine-Blanking with Negative Clearance on 60Mn

In order to improve the punching process, further enhance the blanking section quality. This paper studied the common blanking of 60Mn and the fine blanking with negative clearance of 60Mn blanking work piece metallographic structure by using scanning electron microscope. The results show that the fine blanking with negative clearance process can increase the work-hardening degree and further thin the punching surface tissue, inhibit the crack, and make the blanking surface smooth. The tensile and tear result in the generation of cracks and burrs, and the extrusion forming of fine blanking with negative clearance inhibit the generation of cracks, and eliminate the conditions of the burrs. As the extrusion process, the degree of work hardening in fine blanking with negative clearance is higher than the common blanking, the organizations are more closed.

Edge finishing and deburring of back surfaces of microholes using micro-cutting tools

► The edge finishing and deburring of the back surfaces of micro-through holes from the front surfaces are carried out. ► Micro-cutting tools are fabricated by EDM and used for processing holes. ► Helical tool feeding is employed and workpieces are ultrasonically oscillated. ► A hole drilled using a 0.15-mm-diameter drill in a 0.2-mm-thick plate is successfully deburred and edge-finished. The edge finishing and deburring of the back surfaces of micro-through holes, such as those with a diameter smaller than 1 mm, from the front surfaces by cutting are difficult and in some cases impossible with currently available tools. We have therefore fabricated micro-cutting tools by electrical discharge machining and used them for processing the back surfaces of microholes using helical tool feeding with the assistance of ultrasonic oscillation. As a result, a hole drilled using a 0.15-mm-diameter drill in a 0.2-mm-thick plate was successfully deburred and edge-finished. This is the hole with the smallest diameter whose back surface was processed from the front surface by cutting, to the best of our knowledge. The effects of ultrasonic oscillation, namely, cutting force is reduced and the generation of secondary burrs is restrained, were also observed in this study. Moreover, cutting force was further reduced with an improved geometry of the tool's cutting part.

Experimental Study on Tilted Planetary Motion Drilling for CFRP

The study deals with a proposal and experimental study on the tilted planetary motion drilling for CFRP. The authors have modified cutting mechanism principle of the orbital drilling, which named as the tilted planetary motion drilling. Its axis of tool rotation spindle is not parallel to the axis of planetary revolution. The tilted angle is adjustable from 0 to 2 degrees. Because of tool rotation axis is tilted, penetration is not caused by outermost cutting edges but inner cutting edges. If penetration could be occurred, the inner cutting edges penetrate firstly, then the outermost edges enlarge drilled hole and these sequence can avoid generation of delaminations and burrs. The tilted planetary motion drilling has been demonstrated by the practical fundamental drilling experiment by use of a high-speed spindle unit and a lathe as imitating tilted planetary motion. From the experimental result, capability of tilted planetary motion drilling has been realized and no burrs and delaminations are observed on the workpiece.

Controlling burr formation when drilling intersecting holes

The increasing power density in modern engines and the complexity of parts in automotive production demand complete control of burr formation, especially with regard to intersecting holes. The Institute of Manufacturing Technology and Production Systems (FBK) in Kaiserslautern has developed an approach to control burr formation in terms of the reproducible generation of burrs depending on intersecting geometry and process parameters.

Quality of Trimming and its Effect on Stretch Flanging of Automotive Panels

Traditional trimming requires accurate alignment of the die shearing edges, typically 5–10% of the blank thickness. Increasing the clearance above the recommended value often leads to generation of burrs on the trimmed surface. These burrs may create difficulties for flanging and hemming operations. Details of trimming technology for panels made out of aluminum sheet AA6111-T4 with elastic offal support will be discussed, including such factors as die radii of the tooling, effect of tooling wear, and trimming angle on the quality of trimmed surface. Also, imperfections on the trimmed edge of the panel may result in reduced formability in stretched flanging and hemming operations. Experimental results quantifying the behavior of trimmed surface in stretching will be provided for both a conventional trimming process and a newly developed process.

硬質膜被覆工具による軽金属板のせん断加工

In shearing process, such as blanking or piercing on the sheets of both aluminum and magnesium alloys, there are problems that large burrs generate and the accuracy of cut surface is worse after a few repetitions of these processes. Therefore, in this study, we investigated the cause and solution of these problems. We found that the cause was not the deterioration of the tool edge due to wear or chipping, but that materials of the sheared sheets which adhered to the side of the tool shaved the cut surfaces of the sheets during shearing or adhered to the cut surfaces and induced partial plastic deformation. We also found that a hard-carbon-film-coated tool is effective in preventing the generation of adhesive materials, thereby preventing both the generation of large burrs and the decrease in the accuracy of cut surfaces.