Jorge Lino Alves

Development of low-cost customised hand prostheses by additive manufacturing

ABSTRACT The absence of hands makes human life very difficult. The development of prostheses becomes fundamental to improve living conditions. There are many types of prostheses ranging from the simplest ones, with only aesthetic function, to bionic, which have functionality closer to the human hand. Despite all actual technological progress, prices are still very high, making them inaccessible for a wide range of population. Therefore, the development of a low-cost prosthesis will allow simple actions like holding a cup, promoting a better quality of life of people without economic capacity to buy an expensive one. The e-NABLE project that aims to design and manufacture prosthetic hands in polymeric materials through additive manufacturing, tailored to meet user’s specific needs. These prostheses work by flexion and extension of the wrist that produces finger movements. Currently, the prostheses provided have some limitations and conceptual problems. This work contributes to overcome these problems.

Post-process Influence of Infiltration on Binder Jetting Technology

Despite the fast and ongoing advances of Additive Manufacturing processes (AM) in last years, including three-dimensional printing (3DP), models produced by the latter are not as strong as the ones made by other AM technologies. This challenge raises the concern to improve post-processing to create competitive mechanical strengths, which in turn requires specific knowledge that has not focused on applied studies of current plaster-based materials. The aim of this study is to characterize the base material, and to measure the influence of infiltration post processing on flexural and tensile strengths of 3D printed parts. VisiJet® PXL Core was characterized in terms of grain size and chemical composition. Green printed specimens were infiltrated with epoxy resin, cyanoacrylate, magnesium sulphate and water, as recommended by the supplier of equipment and materials for 3DP, and their influence on flexural and tensile strengths was analysed. The increase in flexural strength, up to 450%, in the specimens infiltrated with epoxy resin, relatively to the ones without infiltration (green body), suggests the importance of this post-process. The data obtained by mechanical test were lower regarding the data stipulated by the materials producers. Large standard deviations on mechanical strength, compared with the standard deviation of the green body, are characteristic of the manual processes (brush and drip), suggesting the necessity to establish methodologies to allow homogeneous infiltration and controlled dosages, as well as the use of alternative infiltrates.

Transformimg waste in industrial design products for social vulnerable groups: Teaching industrial design based on real projects, a project based learning experience in Faculty of Engineering of University of Porto

The University of Porto, Portugal, started in the academic year 2013/2014 a Master Program in Product and Industrial Design, which is a partnership between the Faculty of Engineering and Faculty of Fine Arts. This new program that replaced a previous Master Program in Industrial Design from Faculty of Engineering, was conceived with a different philosophy, seeking to join designers and engineers in a multi-disciplinar y methodology. The syllabus was sought to “transfer” know-how between those two backgrounds and develop projects, supported in project-based learning principles, in the two main courses; Project Design and Project in Industrial Design. This work explains the main operation principles of the course and presents the results of a project settled in partnership with the Municipality of Matosinhos, in Porto, Portugal, which was developed to design artifacts based on recycling the waste produced by activities of that city. The goal was also to create low cost products in an attempt to generate profit for the poorest communities in the region.

The influence of face coat material on reactivity and fluidity of the Ti6Al4V and TiAl alloys during investment casting

Ti6Al4V alloy belongs to the most significant alloys within the conventional titanium alloys, namely for producing turbochargers impellers and human prostheses. TiAl alloys, because of its attractive properties, such as half density of any nickel-based alloys and excellent high temperature properties, exhibit excellent potential for aerospace turbines and turbocharger turbines application. Investment casting is a near net shape process with great interest for these kind of complex parts, but the processing of these alloys using this technique is still a challenge. In spite of these advantages, these alloys are highly reactive in their molten state, reacting with the ceramic shells used in investment casting, forming a hardened and brittle layer called alpha case on the cast alloy surface, rich in interstitial elements such as oxygen. It is commonly accepted that yttria-based face coats are the best solution for minimizing metal mold reaction, but this ceramic oxide is very expensive. So, the aim of this work is to test alternative materials to produce ceramic shells face coats. A test sample simulating both compressor wheels and turbines was developed and assembled in a wax tree for alpha case and fluidity evaluation. Reactivity studies were conducted based on microhardness measurements and microstructural analysis of γ-TiAl and Ti6Al4V standard test samples, casted in shells with different face coat materials: fused Y2O3, ZrSiO4, Al2O3, yttria (6%) stabilized ZrO2 and yttria stabilized ZrO2 with 10% fine Y2O3 (3–7 µm). The results obtained showed that fused Y2O3 face coat eliminates the alpha case, although affecting the fluidity, and γ-TiAl castings have more misruns blades than Ti6Al4V castings.

Coffee Powder Reused as a Composite Material

With the technological and industrial development, many products have toxicity problems and the rate at which people consume new raw materials has become unsustainable. The markets have been undergoing changes and manufacturing materials tend to be more affordable, but they still have problems related with pollution and other ecological concerns. We know the impact that mankind’s the hunger for consumption, has upon in nature and how that contributes to the slow end of natural resources. For this reason, alternative processes concentrate upon the reuse of waste. This theme has emerged as a way of combating the problem of great environmental impact through design. This research aims to present a production method for reuse ground coffee leftovers. Because at the moment it is treated mostly as junk, obtaining it does not entail any significant costs, and may therefore be an innovative material for use in the production of a variety of objects. From the point of view of sustainability the idea is to extend the life cycle of coffee, eliminating the waste phase that usually follows consumption. The main goal to be achieved, within this research is to obtain a mouldable material, formed by the coffee grounds and a suitable binder found through testing and research. It is also intended that the material created is both durable and washable, with prospects of extending the number of ways in which it can be used. The second objective is the development of a tool for the production of this material, not only by moulding, but eventually by means of 3D printing. To validate these goals it is intended that we should create a set of products made from the developed material. In this paper the results of laboratory experiments are presented as well as some design solutions that were achieved.

Development of Plaster Mixtures Formulations for Additive Manufacturing

Currently world abundancy and production of gypsum exceeds the threshold of 150 million tons per year, resulting in a low cost material. This reality leads to a massive use of plaster in construction, in mould casting, in agriculture as a way of land plaster or manufacture of models and moulds for processing of sanitary ceramics in long series. However, the industry is increasingly demanded to produce short or unit series and more complex components, where the use of conventional processes for this type of series leads to higher manufacturing time and production costs, in addition to significant waste of material. To meet the market demand, companies resort to means of production with models in thermoset resins, making this an expensive process due to the high cost of these materials. To fight these costs, the use of plaster combined with additive manufacturing processes (AM) and subsequent subtractive manufacturing (SM) would thus seem to be an economically viable solution. Despite the low cost of gypsum, the α-hemihydrate and β-hemihydrate without any additives have a very high setting time for the AM purposes, poor mechanical properties and weak resistance to sharp edges fragmentation, leading to a mismatch with machining processes. This work aims to create a family of gypsum plasters compatible with the processes described above, adding setting time accelerators and binders to the mixtures. Additivated plaster formulations were produced and tested with setting time accelerators such as K2SO4, CaCO3 or Zn2SO4 and binders based on vinyl or acrylic. Thus, it was possible to produce gypsum plasters with a reduction in the setting time up to 60% and an increase in flexural strength by 80%, compared to formulations without additives and depending on the selected hemihydrate and mixtures.

Experimental classes of metallic materials challenges in identifying steel components

Todays common accessibility to You Tube videos, Power Point presentations, slide shares, reports, social networks and all kind of information freely available on the internet, leaves teaching staff under a continuous pressure to innovate in their experimental classes. Keep students motivated and strongly enrolled in classes is a very demanding task, pushing professors for continuous creativity in terms of experimental works. In the course of Metallic Materials, of the Integrated Masters Course in Mechanical Engineering of Faculty of Engineering of University of Porto, practical classes are structured around an experimental work where students have the opportunity to design heat treatments of a given steel or identifying a steel component, and use all the necessary equipment to predict and characterize the effect of the heat treatment on the microstructure and mechanical properties of the steel. This experimental work, although very demanding, is extremely appreciated by the students, leading to great motivation for learning and an uncommon enrolment that is reflected on the excellent practical final grades. This paper presents the methodology adopted and the final grades obtained in the last five years, and finally presents a case study of identification of a steel rod used on the manufacture of a bicycle seatpost.