Analyses of Burr and Exit Thrust Force of Ultrasonic-Assisted Micro-Drilling

Abstract Nickel-based superalloys have been extensively used in the aerospace industry due to their excellent mechanical properties at elevated temperatures. The mechanical properties of the Inconel-718 majorly depend on its microstructure which can be controlled using thermomechanical treatments. Machining of the heat-treated Inconel-718 component is very difficult due to very high hardness. This paper investigates the relationship between the material microstructure developed through a thermomechanical process and the machinability through micro-drilling of Inconel-718. In this study, a wide range of microstructures with hardness ranging from 179 HV to 461 HV was achieved by different thermomechanical and heat-treatment processes. Flank wear, thrust force, and burr height analysis were carried out to understand the machining behavior after micro-drilling. Electron back scattered diffraction (EBSD) technique was used to characterize the microstructure. No correlation between grain size and thrust force was observed. However, a clear trend between thrust force and hardness was established. It was also observed through misorientation analysis that the machined surface deforms significantly with material hardness.

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Influence of Drill Geometry Parameters on Helical Point Micro Drilling Performance

Materials Science Forum ◽

10.4028/www.scientific.net/msf.836-837.198 ◽

2016 ◽

Vol 836-837 ◽

pp. 198-204

Author(s):

Su Yan Zhang ◽

Zhi Qiang Liang ◽

Xi Bin Wang ◽

Tian Feng Zhou ◽

Pei Yan ◽

...

Keyword(s):

Thrust Force ◽

Helix Angle ◽

Contributory Factor ◽

Drilling Performance ◽

Micro Drilling ◽

Moderate Effect ◽

Drill Point ◽

Micro Drill ◽

Selection Of ◽

Small Point

Helical point micro-drill is characterized by a continuous helical flank instead of the piecewise planar flank, and its improved drilling performance is validated compared with planar drill point by some researchers. In this study, to analyze the effect of geometry parameters of helical point drill on the drilling performance, the micro-drills with different point angles, web thicknesses and helix angles of the flute are fabricated on a 6-axis CNC tool grinder, and a serial of micro-drilling experiments involving these drills on 1Cr18Ni9Ti austenitic stainless steel are carried out. In experiments, the drilling forces are measured and exit burrs are observed. Within a certain range of geometry parameters, thrust force increases with the increase of point angle and web thickness, and the decrease of the helix angle of the flute. The point angle is the main contributory factor for the thrust force followed by web thickness, while helix angle has a moderate effect on the force. Furthermore, poisson burr and rollover burr are generated with different point angles. Based on the results, a good selection of the helical point drill geometry parameters with small point angle, big helix angle and small web thickness are proposed to improve the micro-drilling performance.

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Performance evaluation of different variants of jet electrochemical micro-drilling process

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405416646689 ◽

2016 ◽

Vol 232 (3) ◽

pp. 451-464 ◽

Cited By ~ 9

Author(s):

Harsha Goel ◽

Pulak M Pandey

Keyword(s):

Material Removal Rate ◽

Direct Current ◽

Material Removal ◽

Removal Rate ◽

Ultrasonic Vibrations ◽

Current Voltage ◽

Ultrasonic Assisted ◽

Micro Drilling ◽

Direct Current Voltage ◽

Pulsed Direct Current

The article describes fabrication of an experimental setup which could be used for electrochemical drilling process to produce micro-holes in a copper workpiece with its different variants, namely, jet electrochemical micro-drilling, air-assisted jet electrochemical micro-drilling, ultrasonic-assisted jet electrochemical micro-drilling, and pulsed direct current–jet electrochemical micro-drilling process. Process parameters like voltage, electrolyte concentration, interelectrode gap, and electrolyte pressure have been selected to find out their effects on the process responses, namely, hole taper and material removal rate in all the above process. Attachments for air assistance and ultrasonic vibration application have been fabricated and incorporated in the setup. The effects of ultrasonic vibrations and the pulsed direct current voltage on the process responses like material removal rate and hole taper have been investigated. The effect of application of ultrasonic vibrations on the electrolyte jet has been studied. The experimental findings of ultrasonic-assisted jet electrochemical micro-drilling were compared with the findings of jet electrochemical micro-drilling. Similarly, the findings of pulsed direct current–jet electrochemical micro-drilling were also compared with the results of pulsed direct current ultrasonic-assisted jet electrochemical micro-drilling experiments. It has been found that the ultrasonic vibrations have significant effect on the two process responses. From the results, it was observed that with the use of ultrasonic vibrations, the material removal rate has increased to significant level and the hole taper has been decreased than in jet electrochemical micro-drilling. Effects of the pulsed direct current voltage supply on jet electrochemical micro-drilling and (ultrasonic-assisted jet electrochemical micro-drilling) were also analyzed. Application of pulsed direct current voltage has improved the material removal rate and reduced the hole taper in jet electrochemical micro-drilling as well as in ultrasonic-assisted jet electrochemical micro-drilling. The experimental results concluded that ultrasonic assistance have generated the holes with greater material removal rate and lower hole taper and with continuous direct current and pulsed direct current voltage.

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Modelling and simulation of ultrasonic-assisted jet electrochemical micro drilling process

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406219834328 ◽

2019 ◽

Vol 233 (12) ◽

pp. 4199-4212

Author(s):

Harsha Goel ◽

Usharani Rath ◽

Pulak M Pandey

Keyword(s):

Material Removal ◽

Removal Rate ◽

Electrochemical Machining ◽

Modelling And Simulation ◽

Drilling Process ◽

Ultrasonic Assisted ◽

Micro Holes ◽

Micro Drilling ◽

Experimental Findings ◽

Electrolyte Jet

Ultrasonic-assisted jet electrochemical micro drilling is an advanced variant of electrochemical machining to drill micro holes quickly and efficiently. The present article deals with the modelling and simulation of the integration of ultrasonic vibration with the conventional jet electrochemical micro drilling process. Multi-physics-based modelling and simulation approach has been used in the present work. The flow pattern of electrolyte jet was analysed for both jet electrochemical micro drilling and ultrasonic-assisted jet electrochemical micro drilling processes. The simulation results were validated with the previous experimental findings of ultrasonic-assisted jet electrochemical micro drilling process. It was found that the material removal rate (MRR) improved significantly as the ultrasonic wave got superimposed onto the electrolyte jet. In addition to that, voltage and concentration of the electrolyte also played vital roles in improving the MRR.

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Characterization of Thrust Force, Temperature, Chip Morphology and Power in Ultrasonic-assisted Drilling of Aluminium 6061

10.21203/rs.3.rs-441144/v1 ◽

2021 ◽

Author(s):

Amin Moghaddas

Keyword(s):

Feed Rate ◽

Thrust Force ◽

Chip Morphology ◽

High Amplitude ◽

Spindle Speed ◽

Drilling Parameters ◽

Out Of Sample ◽

Ultrasonic Assisted ◽

Turning Center ◽

Chip Size

Abstract In this study, a special resolution V design and Response surface methodology (RSM) were used to characterize the ultrasonic-assisted drilling (UAD) process of Aluminum 6061. This characterization was done through developing mathematical models to study the effect of ultrasonic and drilling parameters including spindle speed, feed rate and amplitude on thrust force, temperature, chip morphology and power. The tests were done using an industrially hardened non-rotating UAD system mounted in a CNC turning center. The analysis of variance (ANOVA) was used to find significant parameters of thrust force, temperature, chip morphology and power. Then, for all responses, the optimum drilling parameters that provide desired solutions for all responses were obtained. This was followed by out-of-sample testing to verify the accuracy of the developed models. The results of this study showed that in UAD of aluminum, the minimum values of thrust force and chip size were obtained at low spindle speed, low feed rate and high amplitude. The results also showed that amplitude was not a significant parameter affecting the tool temperature and cannot be used to analyze the effect of ultrasonic vibrations on generated heat during UAD. Instead, the interaction of amplitude and feed rate was significant and should be considered in the analysis. Finally, minimum consumed power, specially at higher amplitudes, can be obtained using high spindle speed and low feed rate.

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