Fused Deposition Modeling (FDM), a fast growing rapid prototyping technology, is a process for developing physical objects by adding fused layers of materials according to a three dimensional CAD geometry. FDM can be used to produce parts with complex geometries. Hence it gains distinct advantages in industries. One of the major drawbacks of FDM is the reduced part quality measured in terms of dimensional accuracy, surface finish and mechanical characteristics. The major share of research literature related to the field of FDM process parameter optimization focuses on flat and circular surfaces, while only a few studies are available on helical surfaces. This paper is based on a close study conducted to understand the effect of four parameters, namely, layer thickness, raster width, print speed and support material density on dimensional accuracy, tensile strength and surface finish of FDM processed helical surfaces. The experiments were designed by taking three levels of each process parameter selected. Optimum parameter level for improving dimensional accuracy, tensile strength and surface finish simultaneously were obtained by Grey Relational Analysis. The main effect plots were also analyzed.
To improve the weld quality of AA 5083 plate using AA 5356 filler rod, an automatic TIG welding system is developed, by which welding speed can be controlled and a uniform speed is obtained. Welding of aluminium 5083 plate is carried out for different welding currents and welding speeds. In this work, the effect of welding speed and current on, the tensile strength of the weld, hardness at the three different zones viz. weld metal, HAZ and base metal are investigated. The temperature is measured at the HAZ and base metal. The hardness and temperature on the weld zone and the base metal are greatly influenced by the welding speed and current. It is found that the weld strength is influenced by different values of weld current and speed, but sometimes with high current, welding speed has no specific effect on the tensile strength of the weld. The effect of material deposition rate on the weld strength in uniform welding is studied. The weld thickness to width ratio is an important aspect in the analysis of weld strength. The values obtained for current and speed are taken for optimizing the strength and hardness, using Taguchi method and utility concept.
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