A Wear Investigation of Repeatedly Used Wire in Wire Cut Electrical Discharge Machine
Wire electro-discharge machining (WEDM) is a fully extended and competitive machining process widely used for hard and difficult to machine materials. In the present research, experimental investigation have been conducted to find out the wire wear rate at different machining parameter Such as peak current, pulse on time, pulse off time, based on full factorial design of experiment. Molybdenum wire of 0.18 mm and EN-8 material were used as tool and work piece material for the experiment, ANOVA analysis were done to find out the effect of peak current, pulse on time, pulse off time on wire wear and found that the increasing in peak current slowly increase the wire wear but increasing in pulse on time increase the wire wear rapidly and pulse off time not much affects the wire wear. Keywords— WEDM, WWR, ANOVA, Full factorial,
“Research Work for Optimization and Effect of WEDM Cutting Process Parameters on Performance Measures- a Literature Review”
: Use of traditional machining methods to machine intentionally developed new hard, tough and reinforcement materials is no longer efficient due to greater tool wear, which causes serious surface damage. Thesekinds of materials can be machined with the help of non-traditional machining methods. WEDM is one of the non-traditional methods which provide greater degree of surface finish with high MRR while cutting electrical conductive materials. WEDM performance estimation is based on MRR (Material Removal Rate), WWR (Wire Wear Rate), Kerf width and SR (Surface Roughness). Lots of work has been done by various researchers on WEDM process parameter optimization for various materials.This paper presents a literature review of work done on optimization of various cutting process parameters like: Pulse on time (Ton), Pulse off time (Toff), Wire feed rate, Peak current, Servo voltage, Spark gap set voltage etc.) and the effect of these cutting parameters on performance measures like (MRR, WWR, kerf width and SR etc.) on WEDM. important parameters [15].L. Li. Et. al. checked on the evolution of surface integrity and machining efficiency of WEDM when machining Nickel-based Alloy (IN718). One rough cut (RC) mode and three trim cut (TC) modes were used for this study. Studied machining parameters were material removal efficiency, surface roughness, surface topography, surface alloying and micro hardness. Results explained that Surface roughness in RC mode was different than TC modes. In TC modes micro cracks absent, high toughness of IN 718 would have been the reason for this absence. Micro-cracks exists in white layer of 6-8 µm thickness in RC mode and thin white layers of 0-2 µm free from micro-cracks was observed in TC2 mode. In TC3 mode white layer was invisible [16].A. Goswamiet. al. in his research surface integrity, material removal rate (MRR) and wire wear ratio was investigated for WEDM process using Nimonic 80A as work piece material. ELECTRONICA SPRINTCUT (Electra- Elplus 40A DLX) CNC WEDM was used to perform experiments using soft brass wire of diameter 0.25 mm as tool electrode. Experiments were designed based on Taguchi’s design of experiments (DOE). Input process parameters taken was peak current, pulse ON time, pulse OFF time, wire speed, wire tension, wire offset, spark gap and pulse peak voltage, servo voltage, flushing pressure as constant process parameters. After machining, Scanned Electron Microscopy (SEM) was performed on machined work piece samples to study microstructure. It was concluded that thicker recast layer results through higher pulse ON time setting. The wire deposition on machined surface was lower when using lower pulse ON time and higher pulse OFF time settings [17]. S. Ramesh et. al. contributed an effort to obtain maximum surface finish in WEDM dealing with multi cutting passes while machining Metal Matrix Composite (MMC) obtained through past researchers work. Gap voltage, Pulse on time, Pulse off time and Wire feed were selected as Input parameters. TOPSIS was used for Optimization of Multi performance characteristics like MRR and kerf width. The suggested methodology can be employed for any type of selection problem involving any number of selection criterions [23].J.R. Mevadaet. al. investigated the wire wear rate with relation to separate machining parameters such as peak current, pulse ON/OFF time through factorial design of experiment. EN-8 material was used as work piece and molybdenum wire of 0.18 mm was selected as tool material for the experiments. The effect of peak current, pulse ON/OFF time on wire wear was analyzed through ANOVA. It was concluded that wire wear increases with increase peak current and pulse ON time. Also, it was found that wire wear was not much affected with pulse OFF time D.S. Kumar et.al. evaluated performance of WEDM parameter (Surface Roughness) while using Al6063/Sicp composite as work piece. Experiments suggested selection of 4 process parameters (Pulse on time, Pulse off time, gap voltage, wire feed) as input parameters. Sic was mixed in 5%, 10% & 15% different proportions in Aluminum through stir casting method and then machining of pure Al 6063 and Al MMC was done. It was found that Surface Roughness (Ra) increases on provided increment in percentage fraction of Sic particles in MMC. Another result so found was relative importance of process parameters which were Pulse off time, Wire feed, Pulse on time and Voltage for surface roughness in WEDM process [25]. V. Parasharet.al. investigated kerf width for WEDM with Stainless Steel grade 304L as workpiece material & CNC Ezeecut WEDM machine was used for execution of experiments. Tool electrode is selected of Brass wire of 0.25 mm diameter. The variables affecting the kerf width were determined through
Correlation between Fluoride Release, Microhardness and Solubility of High viscosity Glass Ionomers
This study was to measure and compare the amount of fluoride, microhardness and solubility of high viscosity glass ionomer and resin-reinforced glass ionomer during 84 days. Fuji IX GP EXTRA, Fuji IX GP, Fuji II LC and FiltekTM Z350XT stored in deionized water for 84 days to measure fluoride release, microhardness and solubility. As a result of measurement of fluoride release, all the glass ionomers showed the highest amount of fluoride release on day 1 and gradually decreased. Fuji IX GP EXTRA showed the highest amount of fluoride release and cumulative release. And Fuji IX GP and Fuji II LC showed no significant difference. Microhardness measurements showed that all experimental groups decreased 1 day after exposure to water. After 84 days, microhardness showed no significant difference between Fuji IX GP EXTRA and Fuji IX GP, and Fuji II LC was the lowest. In the solubility measurement, Fuji IX GP EXTRA, Fuji IX GP, and Fuji II LC increased rapidly to 21 days. After 21 days, there was no significant difference in the three groups. As a result, short term fluoride release affects solubility and microhardness, but long term fluoride release has no correlation. Through this study, the amount of fluoride, microhardness, and solubility of various glass ionomers were evaluated, and these properties could be applied clinically.