Percorrer por autor "Pouzada, A. S."
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- Characterization of polymer behaviour in microchannelsPublication . Costa, M.; Vasco, J.; Pouzada, A. S.; Pontes, A. J.Microinjection moulding can be used to process monitoring and rheological characterization can help to understand the behavior of polymer melt flows during the filing of micro cavities. The system used allows a study on characterization of polymer behavior in microchannels. This approach is appropriate since rheological phenomena such as wall slip, surface tension, melt pressure drop and polymer flow length can be studied. In this system, the data acquisition has made by incorporation of two sensors inside the mould.
- A study on microinjection moulding using moulding blocks by additive micromanufacturingPublication . J C Vasco; Pouzada, A. S.Microinjection moulding is one of the most efficient replication methods for polymeric components in microsystems. The manufacturing of moulding blocks for complex geometries is resorting increasingly to the techniques of rapid prototyping. This development on the use of additive microtechnologies can promote the massification of microsystems within a shorter tooling development cycle time. However, the microinjection moulding process itself has mechanical and thermal demands that must be addressed and require specific consideration of the selection of the tool material. This constrains the selection of the best-suited additive manufacturing process. The current state of the art of additive manufacturing technologies at the micrometric scale favours laser sources to process layer by layer the media contained in a vat. The media type, the laser power and the laser spot size are parameters that can influence the replication tool tolerances and physical properties. This work explores the possibilities of two additive technology tooling approaches for microinjection moulding, using different materials. The research parameters included replication detailing onto the plastic part, surface roughness, microtool integrity and wear. The evaluation of these parameters was carried out using both optical and hybrid microscopy, a laser perthometer as a non-contact solution for surface roughness evaluation, scanning electron microscopy and X-ray spec-troscopy. The results of this research work showed that the processed material and technology play an important role both on surface quality and tool life, enabling criteria definition for technology selection.
- A study on the mouldability of technical parts using hybrid moulds and structural foamsPublication . Nogueira, A. A.; Martinho, P. G.; Brito, A. M.; Pouzada, A. S.The production of large plastics parts in small series by injection moulding requires the devel-opment of a new concept of moulds that allows an economic production. This type of products is applied in urban furniture, automotive, nautical and aerospace industries. The use of alternative methodologies for de-sign and manufacturing in a current stage in Portugal gave rise to the concept of hybrid mould. The control and monitoring of the injection moulding process is essential to evaluate the reproducibility of the mouldings and to obtain a product with good quality. Thus the injection mould, which has a significant influence on the final part, must be carefully designed.