This paper addresses the potential of polypropylene (PP) as a candidate for fused deposition modeling (FDM)-based 3D printing technique. The entire filament production chain is evaluated, starting with the PP pellets, filament production by extrusion and test samples printing. This strategy enables a true comparison between parts printed with parts manufactured by compression molding, using the same grade of raw material. Printed samples were mechanically characterized and the influence of filament orientation, layer thickness, infill degree and material was assessed. Regarding the latter, two grades of PP were evaluated: a glass-fiber reinforced and a neat, non-reinforced, one. The results showed the potential of the FDM to compete with conventional techniques, especially for the production of small series of parts/components; also, it was showed that this technique allows the production of parts with adequate mechanical performance and, therefore, does not need to be restricted to the production of mockups and prototypes.
Silva, M., Mateus, A., Bártolo, Paulo Jorge, Pouzada, A. S., and Pontes, A. J.
RIM process, mechanical properties, rapid prototyping and manufacturing, and polyurethane
The growth of global competition, forces the companies to opt for new technologies, aiming at obtaining competitive, higher quality and precision products with reduced lead time to market. Rapid Prototyping and Tooling (RPT) are important technologies used for short series of products with tight specifications. Simultaneously with these techniques, it is possible to use Reaction Injection Moulding (RIM). In RIM, the mixture and the chemical reaction of the liquid isocyanate and polyol components originate the polyurethane. Since the process handles materials of low viscosity, low processing temperatures and low pressure, it is possible to use moulds with lower structural rigidity and thermal conductivity. The combined use of RIM and RPT allows for the production of high quality and complex prototypes at even lower cost. In this study the characterization of the performance of products produced by RIM is done, using moulds in several materials (aluminum, silicone and resin with graphite) and polyurethane (PUR) reactants in various percentages. The use of materials with different thermal properties affects the PUR curing process, which inﬂuence the morphology and mechanical properties of the mouldings.