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,
Analysis of Wire Wear in WEDM
Objective: This paper emphasizes the effect of cutting parameter on the size of crater and wire wear ratio because wire breakage is most common problem in WEDM and wire crater is very much responsible for wire breakage. Methods/statistical Analysis: Many researchers had adopted various methods for the evaluation of the dominating parameters on wire EDM process. In this study Response Surface Methodology (RSM) was used as a statistical analytical tool for the evaluation of the parametric effect on wire creator of wire EDM process. OLYAMPUS BX51M optical microscope was used for the observation of wire creator. For experiment MAXICUT WEDM machine was used and experiment were conducted on INCONEL 625 work piece and zinc coated brass wire of 0.25mm diameter was used. Finding: The experiments were conducted under different cutting parameters, which are open circuit voltage, pulse duration, wire speed and flushing pressure. As a result it was found that crater size increases with increase in pulse duration because increased pulse duration contributes to large energy content of spark discharge further it was also found that the creator size also increases with open circuit voltage and feed wire speed whereas decrease with increase in flushing pressure. Applications/Improvements: This analysis can become the basis for industries where the manufacturing is done by the wire EDM process and wire breakage is the common problem.
Properties of a monopivot centrifugal blood pump manufactured by 3D printing
An impeller the same geometry as the impeller of a commercial monopivot cardiopulmonary bypass pump was manufactured using 3D printing. The 3D-printed impeller was integrated into the pump casing of the commercially available pump to form a 3D-printed pump model. The surface roughness of the impeller, the hydraulic performance, the axial displacement of the rotating impeller, and the hemolytic properties of the 3D-printed model were measured and compared with those of the commercially available model. Although the surface roughness of the 3D-printed model was significantly larger than that of the commercially available model, the hydraulic performance of the two models almost coincided. The hemolysis level of the 3D-printed model roughly coincided with that of the commercially available model under low-pressure head conditions, but increased greatly under high-pressure head conditions, as a result of the narrow gap between the rotating impeller and the pump casing. The gap became narrow under high-pressure head conditions, because the axial thrust applied to the impeller increased with increasing impeller rotational speed. Moreover, the axial displacement of the rotating impeller was twice that of the commercially available model, confirming that the elastic deformation of the 3D-printed impeller was larger than that of the commercially available impeller. These results suggest that trial models manufactured by 3D printing can reproduce the hydraulic performance of the commercial product. However, both the surface roughness and the deformation of the trial models must be considered to precisely evaluate the hemolytic properties of the model.