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Performance evaluation of mechanical micro-drilling, electrical discharge machining and laser beam machining on Nimonic 80A alloy

Sat, 01 Dec 2018 00:00:00 GMT

Title: Performance evaluation of mechanical micro-drilling, electrical discharge machining and laser beam machining on Nimonic 80A alloy Authors: Sudhakar, Sake; Kumar, Praveen; Srinivas, G; Ravishankar, S; Chakradhar, D; Barshilia, Harish C Abstract: Micromachining techniques such as mechanical micro-drilling, electrical discharge machining (EDM) and laser beam machining (LBM) play an important role in the manufacturing of micro-devices used in mechanical, electronics, aerospace and medical applications. In this paper, an effort has been made to compare the performance of these micromachining techniques with regard to tool wear, burr formation and surface integrity. This is done by producing 20 micro-holes of approximately 800 μm diameter on a rectangular block (90×30×3 mm³) of Nimonic 80A superalloy. TiAlN coated WC micro-drills, Cu electrodes and CO₂ laser beam are used to produce these holes in conventional micro-drilling, EDM and LBM, respectively. The quality of the drilled hole (diameter, surface roughness and micro-burr formation), tool diameter analysis, taper angle and material removal rate (MRR) are compared and reported. A comprehensive analysis is also carried out on overcut, which leads to hole inaccuracy. Results show that mechanical micro-drilling produces better results in the above mentioned characteristics in comparison to LBM and EDM techniques. The relatively better performance of mechanical micro-drilling is attributed to the usage of TiAlN coating on WC tool. Page(s): 437-444

Influence of LBW parameters on properties of Ti6Al4V/AA2024 dissimilar alloy joint

Sat, 01 Dec 2018 00:00:00 GMT

Title: Influence of LBW parameters on properties of Ti6Al4V/AA2024 dissimilar alloy joint Authors: Kalaiselvan, K; Elango, A; Nagarajan, N M; Sekar, K Abstract: Light weight dissimilar metal joints are very much needed for aerospace, automobile and similar such industries. While assessing the feasibility of joining dissimilar metals to produce sound weldment, numerous factors are to be considered. In the present investigation an attempt is made to join Ti6Al4V and AA2024 dissimilar metals using laser beam welding (LBW) under different weld speeds. For evaluating microstructure, scanning electron microscope (SEM) analysis has been adopted. Experimental investigations reveal that weld speed is found to be a significant variable to enhance strength of weld joint. Finer grains with homogeneous distribution at higher speeds as seen using SEM support this finding. Page(s): 445-449

Impact response and damage resistance behavior of GFRP/aluminium fiber metal laminates during low velocity impact test

Sat, 01 Dec 2018 00:00:00 GMT

Title: Impact response and damage resistance behavior of GFRP/aluminium fiber metal laminates during low velocity impact test Authors: Melba, V Asha; Kumar, A Senthil Abstract: Fiber metal laminates (FMLs) are widely used for aerospace applications. Impact response and damage resistance are the two important parameters to be considered for the effective use of FMLs. Glass fiber/epoxy-aluminium metal laminate (GEAML) is a class of FML prepared as a laminate with glass fiber mats and aluminium metal sheets staked in alternate layers with epoxy adhesive bonding. In this experimental work, woven fiber mats and chopped strand mats (CSM) of glass fiber were used along with aluminium sheets to prepare Woven based GEAML and CSM based GEAML respectively. Low velocity impact test was conducted as per ASTM standards using an instrumented falling weight impact testing machine on woven based GEAML and CSM based GEAML. For comparison, aluminum sheets of the same thickness were also subjected to low velocity impact test. The woven based GEAML withstood higher impact load and its absorbed energy is 3.4% higher than that of CSM based GEAML. The damage area and the depth of penetration of Woven based GEAML are much lower than that of CSM based GEAML and aluminum sheets. The woven based GEAML exhibited better impact response and damage resistance than CSM based GEAML and aluminum sheets. Page(s): 450-458

Effect of alkali treatment and nano filler addition on properties of palm/glass fiber reinforced polymer composite

Sat, 01 Dec 2018 00:00:00 GMT

Title: Effect of alkali treatment and nano filler addition on properties of palm/glass fiber reinforced polymer composite Authors: Pradeep, P; Dhas, J Edwin Raja Abstract: Usage of natural fiber as reinforcements with polymer resins increases the physical, chemical and mechanical properties of the fabricated composites. Composites developed from natural hybrid fiber have more advantage than composites developed from individual fibers. This may be due to the limitation of one fiber which is replaced by the advantage of other. In the proposed work hybrid palm/glass fibers with coconut shell nano filer have been used as reinforcements and its effects on mechanical properties were studied. The mechanical properties (hardness, tensile, flexural, impact strengths), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) analyses are investigated. Composites containing hybrid fibers found to posses better mechanical properties when compared to pure palm fibers. The morphological analysis namely scanning electron microscope (SEM) is also performed. All the results indicate that introduction of natural filler added hybrid palm/glass fiber reduces the overall cost of the composites with no compromise in strength enabling green technologies. Page(s): 459-464