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.
Investment casting is synonym with producing precision components and investment casters usually take up the order if the volume is huge enough. This is due to high and unjustifiable tooling cost and long lead times associated with the development of metal moulds for producing wax (sacrificial) patterns for customized single casting or small
quantity production. One of the feasible solutions is opt rapid tooling. In so- called rapid investment casting the most critical process will be building the investment shell and protecting it from thermal crack. This work investigates the shell crack and
counter. In this work pattern are modeled on rapid prototyping machine. During the ceramic shell preparation cracking is reported. Hence a remedy is explored as to control the thermal expansion of the pattern build material-acrylonitrile butadiene styrene (ABS) by using different build styles. Thermal expansion of five distinct styled ABS rapid samples were tested on Dilatometer. The investigation indicates the possibility of 63% reduction in thermal expansion of the pattern, which is very very encouraging.
Investment Castings (IC) is one of the most economical ways to produce intricate metallic parts when forging, forming and other casting processes tend to fail. However, high tooling cost and long lead time associated with the fabrication of metal moulds for producing IC wax (sacrificial) patterns result in cost justification problems for customized single casting or small-lot production. Generating pattern using rapid prototyping (RP) process may be one of the feasible alternatives. For this purpose present study assessed the suitability of the fused deposition modeling (FDM) process for creating sacrificial IC patterns by studying FDM fabricated part thermal response at various temperatures. A series of experiments with RP patterns are conducted and a set of test castings are also made in steel for establishing feasibility. The build material used is acrylonitrile butadiene styrene (ABS). As an annexe to this work a concurrent attempt is also made to quantify the risk in using Selective Laser Sintering patterns for Investment Castings. Authors hope this work might establish applicability of ABS in IC and also lead the investigations to theoretically tone down the shell cracking tendency with Selective Laser Sintering patterns when Proprietary Duraform is used as the build material.
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