The machining of Titanium alloy, Ti-6Al-4V has got an extensive attention from industries like aerospace, medical, and biomedical plants due its unique properties like high strength at elevated temperature and better strength to weight ratio. Still, properties like reduced thermal conductivity, affinity to react with the tool and work hardening make difficult to cut it by conventional turning process. Ultrasonic vibration-assisted turning (UVAT) is one of the advanced turning method in which tool is allowed to vibrate with ultrasonic frequency (~ 20 kHz) with small amplitude and hence converting the continuous cutting to an intermittent cutting process. In the present work a horn (acts as an amplifier as well as a tool holder) with inserted tool tip is designed and FEM analysis has been done for its suitability for the process. The dynamic analysis has also been performed to find out the stress distribution in both parts under cyclic loading conditions. It enables to locate the highly stressed nodal regions. Experimental investigation has been carried out for both conventional turning (CT) and UVAT processes to demonstrate effects of various inputs on the output responses like cutting forces, surface roughness, tool wear and temperature rise in UVAT. Additionally, a 3D finite element model for UVAT and CT has been prepared. The simulation results like force and steady state tool tip temperature have also been validated with the experimental results and found to be in good agreement. The advantages of UVAT process have been discovered in terms of reduction in the cutting forces and surface roughness for the used Ti-6Al-4V workpiece.
Recent trends in additive manufacturing (AM) are to produce geometrically complex structures at minimal wastage of material, time and cost, without sacri cing part quality, mechanical performance and to introduce ease in processing and part removal. Here a non-transferred arc (NTA) based wire arc additive manufacturing (WAAM) system has been developed to achieve the above objectives, where arc is only generated between tungsten electrode and consumable ller wire. No electrical contact with substrate facilitates deposits even on non-conductive substrate surface that helps in easy removal of nal deposits. In uence of deposition parameters (welding current, voltage, wire feed speed (WFS), and travel speed) on response characteristics (bead uniformity, height deviation, droplet diameter, droplet transfer frequency) is studied on multi-performance level using grey relational analysis (GRA). Then single and multi-bead layer is fabricated over SiO 2 substrate for ease in part removal after complete fabrication. WFS is referred as a key deposition parameter which have in uence on all deposition characteristics. It has been observed that NTA based WAAM results high bead uniformity with minimal spatter and bead height difference between start and exit arc point. Complete ferrite microstructure with few pearlites is observed on the deposits with similar elemental composition on top, bottom and interface surface. X-ray diffraction (XRD) study reveals ferrite diffraction planes ({110}, {200}, {211}, and {220}) with no intermetallic formations on deposits. Also, compressive residual stress with less variation in crystallite size, stress, strain and microhardness among top, bottom, and lateral surface of deposit indicates isotropic nature of the fabricated part.
Ultrasonic welding is one of the promising solid state welding methods which have been widely used to join highly conductive materials like aluminum and copper. Despite these applications in the automotive field, other industries also have a strong interest to adopt this process for joining of various advanced alloys. In some of its applications, poor weld strength and sticking of the workpiece to the tool are issues. Thus, an attempt has been taken in the present study to overcome these issues by performing experiments with a suitable range of weld parameters. The major objectives of this study are to obtain a good joint strength with a reduced sticking phenomenon and microstructure of Al-Cu weld coupons. The results uncovered the mechanical strength of the joint increased up to 0.34 sec of weld time and afterward, it gradually decreased. Meantime, the plastic deformation in the weld zone enhanced the formation of an intermetallic layer of 1.5 μm thick, and it is composed of mainly Al2Cu compound. The temperature evolved during the welding process is also measured by thermocouples to show its relationship with the plastic deformation. The present work exemplifies a finer understanding of the failure behavior of joints and provides an insight of ultrasonic welding towards the improvement in the quality of weld.
Recent developments in manufacturing require holes on composite materials, especially on the carbon fiber reinforced polymer (CFRP) with smooth hole periphery, low delamination, burr formation, taper, better circularity, and a high processing speed. Its non-conductive surface (epoxy layering) limits its machining through electrical discharge machining (EDM). To overcome this limitation, an aluminum fixture has been designed to guide the copper electrode of EDM for producing holes on a CFRP sheet of 1 mm thickness at low machining complexity, cost, time, delamination, burr in hole periphery and without affecting the material’s surface quality and performance. Even components with high geometrical complexity can also be drilled through this approach. Here, a multi-quality analysis called grey relational analysis is developed for examining the hole quality attributes, considering peak current, pulse on and off time, and flushing pressure as input parameters. This approach points out the optimum factor level setting and critical parameters (pulse-on time and peak current) that regulate the hole attributes (entrance and exit diameter, circularity, taper, material removal, and tool wear rate). An artificial neural network model has been designed and trained through experimental data sets. This model can also be adopted during the determination of hole quality attributes when the parameter settings are beyond a defined boundary, as the regression analysis value is very close to 1, and model performance is 4.99e-10. Peak current = 4 A, pulse-on time = 25 µs, pulse-off time=25 µs, and flushing pressure = 0.6 MPa were the optimum drilling parameters. In the initial hole, average burr length is 391.75 μm, and delamination of 539.3 μm is noticed. But burr formation is very negligible with delamination of 350.7 μm being observed with uniform circularity (0.979), low taper angle (−0.81354°), and TWR (0.000069 g/min) under optimum drilling conditions through this drilling approach.
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