Browsing by Author "Leite, M."
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- Development of a large size 3D delta printer for advanced polymersPublication . Pereira, D.; Leite, M.; Ferreira, M.; Machado, D.; V. Dionísio, R.; Cláudio, R. A.Additive Manufacturing has been extensively used in the last years for prototyping and small series production of functional parts. One of the most popular processes is material extrusion, where a material is extruded through a nozzle, being the part created layer by layer. In this work, an advanced 3D printer is presented, build by the authors, based in a Delta Robot configuration, able to produce parts with 400 mm diameter and up to 850 mm height. The chosen concept provides a very stiff structure with ease of access to all components. A high temperature water-cooled print head (that can reach 500 °C) and a closed heated chamber makes this printer able to produce large size parts with some advanced thermoplastic materials. To improve accuracy, a new sensor based in a load cell with specific signal conditioning is proposed for z-probe and to accurately determine some characteristics of the Delta mechanism. The principal features of this new sensor are compared with a previous assembled sensor (IR). A careful assembly and non-clearance mechanisms with the new sensor proposed are expected to improve print quality.
- Effect of Fused Filament Fabrication Processing Parameters on The Mechanical Properties of PLA ComponentsPublication . Marat- Mendes, Rosa; Guedes, M.; Leite, M.; Baptista, R.
- Effect of Fused Filament Fabrication Processing Parameters on The Mechanical Properties of PLA ComponentsPublication . Marat-Mendes, R.; Guedes, M.; Leite, M.; Baptista, R.This paper studies the influence of Fused Filament Fabrication processing parameters upon mechanical properties and microstructural features of processed PLA parts. The effect of extrusion temperature and raster angle were tested upon two PLA filaments of different trademarks, DoWire and BQ, using a commercial fused deposition extruder. The filling density, layer thickness and velocity were kept constant at 60 %, 0.2 mm and 40 mm/s, respectively. Results allowed to determine fused filament fabrication parameters resulting in increased mechanical performance of manufactured parts. Mechanical performance is higher when material is stored under controlled atmosphere before use, and when material deposition direction is aligned with applied load. Increasing the extrusion temperature also increases performance, by increasing deformation ability of PLA molecules. Obtained results contribute to accumulation of a property database and provide design guidance to the procurement of additive manufacturing products with enhanced mechanical strength.