Browsing by Subject "SLA process"
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Item Make-up Fabrication of Big or Complex Parts Using the SLA Process(1996) Wang, W. L.; Fuh, J. Y. H.; Wong, Y. S.; Miyazawa, T.Rapid prototyping is a highly flexible manufacturing technology which can produce big or complex parts without any special fixtures and tools. But it is often a costly and time consuming process to produce big and complex parts. To solve this problem, this paper proposes the makeup fabrication process. The process cuts the CAD models of big or complex parts into several small components. optimizes the building orientation and the layout of the multiple objects and then uses theSLA process to build. The paper discusses the basic process, the discretion rules of the CAD models and the optimization of the layout of multiple objects in the simultaneous buildingItem Photopolymerization Reaction Rates By Reflectance Real Time Infrared Spectroscopy: Application To Stereolithography Resins(1995) Chartoff, Richard P.; Du, JinAn advanced real time infrared technique for studying the isothermal in-situ cure of ultra-fast photopolymerization reactions has been developed. The method, referred to as reflectance real time infrared (RRTIR), involves time resolved IR analysis by reflected IR radiation while a resin sample is being exposed to a UV laser beam. The effect of factors such as chemical composition, radiation intensity, and temperature on reaction rate were determined for multifunctional acrylate resins exposed to a HeCd laser (325 nm). Isothermal cure profiles were monitored quantitatively through disappearance of the 810 cm-1 acrylate IR absorbance band. The dark reaction after the UV radiation was turned off also was monitored. The RRTIR method is shown to be highly effective for quantifying photopolymerization reactions in the millisecond time range. The rate data indicate that quantitative comparisons between reactivities and conversions for different stereolithography resins are possible using this method under conditions that simulate the SLA process. Also, the data show conclusively that the reaction continues for long periods of time after initial laser exposure. This is expected to be a significant factor in the development of warpage and curl during the SLA building process.Item Quality of Parts Processed by Fused Deposition(1995) Weeren, R. Van; Agarwala, M.; Jamalabad, V.R.; Bandyopadhyay, A.; Vaidyanathan, R.; Langrana, N.; Safari, A.; Whalen, P.; Danforth, S.C.; Ballard, C.FDMTM (fused deposition modeling) is a SFF technique for the fabrication of polymer parts. Research is being conducted on the fabrication of ceramic parts by fused deposition. In this study polymer and ceramic parts were made using a commercially available FDMTM system, 3D Modeler, and the Quickslice™ software. These parts were evaluated for processing defects. Defects originate from the fused deposition process, from material characteristics, or a combination thereof. Process defects, which are present in all polymer parts, are due to current hardware, software and build strategy limitations. These same defects are seen in ceramic parts fabricated by fused deposition of ceramics (FDC). Another set of defects in ceramic parts is due to materials characteristics, i.e., non-uniformities in the feed stock filaments, their mechanical and/or rheological properties. The presence of defects in polymer or ceramic parts was studied using simple build primitives (single roads) and parts in the green state. Parts were characterized for their quality using SEM and optical microscopy.