Wyniki wyszukiwania - Biblioteka Nauki

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Influence of Recast Layer on the Fatigue Life of Ti6Al4V Processed by Electric Discharge Machining

100%

Eakambaram A. , Xavior M. A.

Archives of Metallurgy and Materials

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2019

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tom Vol. 64, iss. 4

1541--1548

EN

In this research work, Ti6Al4V alloy material was subjected to electric discharge machining (EDM) and its fatigue life was investigated at low cycle fatigue mode. In order to evaluate the influence of recast layer generated during the machining process on the fatigue life, samples prepared using end milling process were also subjected to similar tests and a comparative analysisis presented. Data were observed in the fully reversed fatigue mode at room temperature using samples fabricated as per ASTM standard E606. The specimen were machined on a spark electric discharge die sink machine which were subjected to fatigue, and the recorded fatigue lives were compared with the fatigue life of end milled specimen. The machined surfaces were examined through optical and scanning electron microscopes, and the roughness was measured with a standard profilometer. It was observed that when the discharge current is augmented, the recast layer formed was in the range of 20 to 70 μm thick. From the results, it is being concluded that fatigue life of the samples fabricated by EDM is less for various load conditions when compared with that of the end milled sample. The milled sample at 160 MPa load exhibited 2.71×105 cycles, which is 64% more when compared to EDM sample.

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On micromachining with a focus on miniature gears by non conventional processes: a status report

81%

Chaudhary T. , Siddiquee A. N. , Chanda A. K. , Khan Z. A. , Chaudhary T. , Siddiquee A. N. , Chanda A. K. , Khan Z. A.

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3

Experimental investigation of recast layer formation on the surface of Ti-6Al-4V titanium alloy during EDM process (machining carried out at lower range of machining parameters)

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Thesiya D. , Patel S.

Advances in Manufacturing Science and Technology

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2014

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tom Vol. 38, nr 4

53--59

EN

The recast layer forms during the machining of Ti-6Al-4V titanium alloy carried out with a use of electrical discharge machining (EDM). The paper presents the description of EDM process carried out at lower range of machining parameters also the formation process of recast layer. The recast layer was analyzed using scanning electron microscopy and 3D viewer image. The performed experiments involved application of copper and graphite electrode with positive polarity. In order to analyze the results, the authors used design of experiment (DOE) method – Taguchi technique (L18) with mixedlevel design. The influence of peak current (A), servo voltage (V), pulse on time (Ton) and pulse off time (Toff) on the recast layer was described in the article.

PL

W artykule przedstawiono wyniki badań mikrostruktury warstwy przetopionej stopu tytanu Ti-6Al-4V w wyniku cięcia elektroerozyjnego (EDM), w zakresie małych wartości wyładowań elektrycznych z zastosowaniem miedzianej i grafitowej elektrody spolaryzowanej dodatnio. Dokonano analizy badań mikroskopowych przeprowadzonych z użyciem skaningowego mikroskopu elektronowego SEM, stosując zaawansowaną metodę DOE (ang. DOE – Design Of Experiments) wyznaczania wpływu zmiennych wejściowych na wynik analizowanego procesu. Wyznaczono wpływ parametrów prądowych – napięcia, czasu włączenia i wyłączenia układu na jakość warstwy przetopionej stopu tytanu.

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On wire spark erosion machining induced surface integrity of Ni55.8Ti shape memory alloys

72%

Sharma N. , Gupta K. , Davim J. P.

Archives of Civil and Mechanical Engineering

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2019

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tom Vol. 19, no. 3

680--693

EN

Ni55.8Ti shape memory alloys (SMAs) find applications in different fields of medical and engineering. In every field, surface integrity greatly affects the functional performance of shape memory alloy parts. In the present work, wire spark erosion machining of Ni55.8Ti shape memory alloys has been conducted and surface integrity parameters of the machined specimens have been evaluated. Experiments are designed using Taguchi L16 robust design of experiment technique. Effect of important process parameters, i.e. voltage, pulse-on time and pulse-off time on maximum surface roughness has been studied. Deterioration in surface integrity at various combinations of pulse-on and pulse-of time which produced high discharge energy has been observed. Scanned electron microscopic investigation, energy dispersive spectroscopy and XRD analyses, roughness measurement, and micro-hardness testing results are presented, analyzed and discussed. Optimization of process parameters resulted in surface integrity enhancement with low roughness (Rt – 7.78 mm and Ra – 1.45 mm) and very thin recast layer (4–6 mm) along with minimum subsurface defects.

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Optimization of wire EDM process parameters on Al6061/Al₂O₃ composite and its surface integrity studies

58%

Mythili T. , Thanigaivelan R.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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tom Vol. 68, nr 6

1403--1412

EN

Metal matrix composites (MMC) are finding application in many fields such as aerospace and automobile industries. This is due to their advantages such as light weight and low cost. Among all the available non-traditional machining processes, wire electric discharge machining (WEDM) is found to be a suitable method for producing complex or intricate shapes in composite materials. In this study, an aluminum metal matrix composite (AMMC) with 6% and 8% weight (wt) fraction of Al2O3 is prepared through the stir casting process. The fabricated AMMC specimen is machined using WEDM, considering various process parameters such as wt % of reinforcement, gap voltage (Vg), peak current (IP) wire tension (WT) and dielectric pressure (Pd). Output responses such as the machining rate (MR) and surface roughness (Ra) of the slots are analyzed by conducting L18 mixed orthogonal array (OA) experiments. The experiments are analyzed using techniques for order preference by similarity to ideal solution (TOPSIS) and analysis of variance (ANOVA). Based on the analyses, the optimum combination of process parameters for better MR and Ra is as follows: wt % = 6 gm, Vg = 53 V, Ip = 8 A, WT = 11 g, Pd = 13 bar. The optimum level of process parameters for MR and Ra are 1.5 mm/min and 3.648 µm, respectively. Based on ANOVA, the peak current is found to have a significant influence on MR and Ra. Moreover, based on a scanning electron microscope (SEM) image, the presence of micro-ridges, reinforcement, micro-craters, micro-cracks, recast layers and oxide formation are all analyzed on the surface being machined.