Study On Precision Of FDM And Rapid Tooling Based On FDM & LOM

In increasingly stinging market competition, the lead-time to market of new product has become crucial. Therefore, development and fabrication period of new product must be shortened as possible, in order to adapt modern manufacturing mode characterized by low volume, many types and swift change. Rapid Prototyping Manufacturing (RPM) and Rapid Tooling (RT) can rapidly fabricate complicated prototypes and various mould & dies of higher dimensional precision and better surface roughness respectively. With those technologies, the objective of Rapid Product Development (RPD) can be achieved consequently.Fused Deposition Modeling (FDM) has successfully been applied in rapid fabrication of prototype. Combined with traditional mould & die manufacturing technologies, when FDM is used to rapidly fabricate plastic injection mould and EDM electrode, the dimensional, geometrical precision and surface roughnesses of FDM prototype have decisive effects on quality of final product. It is necessary that the precision of FDM process be studied.Firstly, the structures and properties of ABS resin, a kind of material for FDM process, are introduced, and Theological properties of melted ABS filament during extrusion from FDM's nozzle are studied in viscosity and elasticity, the research results can provide theoretical guidance for establishing the compensation model of ideal contour line.After systemically analyzing the precision of FDM process, the research contents of FDM precision are given, which include material shrinkage during prototyping and its compensation, the compensation of ideal contour line induced by nozzle, and FDM process parameter optimization.The effects of ABS resin shrinkage during prototyping on dimensional precision of workpiece and the method of control and compensation over shrinkage have been studied theoretically and experimentally.According to the rheological properties of melted ABS filament during extrusion from FDM's nozzle, on the basis of research on extruded filament section shape, the compensation model of ideal contour line is established, and a new technique for compensating inner or outer contour line of workpiece is put forward, which should depend on the real width of extruded filament (instead of nozzle radius) and the real dimensional shrinkage of workpiece. The experimentally validated results prove that the compensation model of ideal contour line and the compensation technique forinABSTRACTcontour line of workpiece are correct and feasible.The main process parameters influencing FDM prototype quality are determined. By Taguchi experiment, various features data of the 27 prototyped standard test part are measured and treated, the effects of FDM process parameters on the quality of prototype are investigated, and FDM process parameters are optimized, thus, a set of FDM prototyping process rules based on parameter optimization is presented.After studying the precision of FDM process, a rapid EDM electrode fabrication technology based on FDM is developed, The technology, which combined pulse-reverse electroforming with strengthening of copper wire-arc spraying, can obtained compact crystal electrode's working part, and strengthened filling part which has big adhesion strength, better electricity and heat conductivity, The EDM performance of the obtained electrode reaches that of electrolysis copper electrode. At the same time, the technology effectively shortens the manufacturing period and reduces the cost.Finally, aimed at Laminated Object Manufacturing (LOM) machine which is widely applied in domestic market, a new technique for covering LOM prototype with special coating spraying is put forward, the problem on metallization of LOM prototype is resolved by means of rapid electroless plating copper, a rapid EDM electrode fabrication technology based on LOM is established. The technology not only reduces working procedure but avoids conversion errors caused by making transition model, and can ensure EDM performance of the obtained electrode using the comb...