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In the last decades, we witnessed a continuous global increase in the consumption of plastics, with the packaging sector being a large contributor to this effect. However, while plastic packaging presents positive aspects, and is commercially advantageous, its sustainability is a concern. Associated with this, we have a traditional practice of linear economy use of plastic packaging, designed for single-use and with little planning for end-of-life (EOL) management. Because of these factors, boosted by an irresponsible societal behavior with plastic waste, casually thrown in the street or in nature, a global environmental pollution crisis ensued. It is thus imperative and urgent that plastic packaging evolves past its current unsustainable state. To dissociate the use of plastics from direct environmental pollution, preserve and optimize existing resources, and maintain the economic value of polymeric materials, it is vital to increase circularity in the packaging sector. This change can be achieved through circular economy strategies. To evaluate their effect, many assessments and monitoring tools exist, including circularity indicators. However, the plethora of such tools in the literature have mismatched calculation methodologies, take considerable engineering expertise, and focus only on some aspects of the product life cycle. This paper provides an analysis of relevant circularity micro-indicators specifically for the packaging sector, while identifying guidelines and good practices for packaging. This study aims to contribute to the packaging sector transition to a more circular economy.&nbsp

Purpose. In the present work DMAIC methodology is implemented in a Portuguese enterprise. The main goal is to reduce the percentage of non-conformities in an injection molded part for the automotive industry, through the elimination of defects that appear after painting. Design/methodology/approach. The DMAIC method was adopted to find an optimal set of factors that reduce the existing non-conformities. Along the five DMAIC phases, different quality tools were implemented to identify the root causes of the problem and to develop an action plan to reduce defects and minimize the process variability. Findings. In the application of this method, teamwork and brainstorming were essential for satisfactory results in a short period of time. A key finding is that the analysis of the possible causes that gave rise to the problem must be carried out separately, in order to easily identify the changes that created a significant improvement in the process. Research limitations/implications. The project is not fully completed since some of the improvement actions are being implemented. Originality/value. This paper describes a practical application of DMAIC methodology that contributed to reduce part defects and improve the production process of a Portuguese company., The authors would like to acknowledge Fehst Componentes, Lda. for providing physical, technical and human resources and to be strongly involved on the development of this study; to the founds provide by National Funds through FCT - Portuguese Foundation for Science and Technology, References UIDB/05256/2020 and UIDP/05256/2020.

The coloring of plastics is essential in parts design and in the promotion of new products. As such, metallic pigments are used to color plastics aiming to replace the appearance of metals. However, the metallic look in plastics by the addition of metallic pigments prone the visual appearance of weld lines and flow lines. These defects are caused by the anisotropic character of flake like metallic pigments when there is the meeting of two flow fronts or there are melt flow disturbances caused when holes or castles are present in the part. There are some solutions to overcome this problem, but there are also numerous variables that constrain the elimination of these defects. Therefore, the coloration of plastics should be taken into account in part design. The number of gates, its position and type, abrupt changes in wall thickness and improper wall angles influence the melt flow, which in turn allows these defects. The effect of the amount, size and shape of the metallic particles in the appearance of weld lines and flow lines has been studied. Larger size of metallic particle and spherical/rounded particles attenuate these defects. However, the solution may consist in optimizing the injection process and in the appropriate selection of metallic particles or otherwise can even be necessary changing the mold design. This work aims at studying the influence of the physical characteristics of the metallic pigments (size and shape of the particles) on the aesthetic appearance of defects and on the optimization of the processing conditions to minimize the defects caused by the use of metallic particles. The part geometry used is a two gated box. Morphological analysis and optical characteristics of the part are analyzed in this work.

A substituição do metal pelo plástico em várias aplicações de engenharia ou de uso quotidiano deve-se, fundamentalmente, à melhoria das propriedades dos plásticos, à facilidade em processar os mesmos, à necessidade de reduzir o peso dos produtos e finalmente, à redução do seu custo. No entanto, os plásticos não conseguem substitui-los integralmente, no que toca à sua aparência ou ao seu toque. A produção de peças plásticas com efeito metálico é um desafio para a indústria. Estas podem ser obtidas por moldação por injeção com a incorporação de partículas metálicas, por pintura ou por metalização. As vantagens do primeiro processo são a eliminação de técnicas de pós processamento, redução de custos e tempo de produção, pelo que se reveste de um grande interesse industrial. Contudo, a utilização de partículas metálicas na moldação por injeção resulta em defeitos indesejáveis nas peças, como por exemplo, tornando visivel as linhas de fluxo e de soldadura, caso estas existam. O controlo das condições de processamento e a seleção adequada das particulas metálicas utilizadas para conferir o aspeto metálico ao produto são duas das soluções possiveis para o sucesso e otimização da estética do produto final. Outras soluções passam pela utilização de processos de moldação não convencional, como o SCORIM ou o uso de sistemas de controlo da temperatura do molde, como os sistemas Variotherm. O presente estudo aborda a produção de peças injetadas por moldação por injeção convencional, utilizando pigmentos metálicos com caracteristicas destintas, que confiram a cor metálica ao produto., QREN: Projeto ToolingEdge

O presente trabalho visa estudar a processabilidade de materiais biodegradáveis para embalagens rígidas de paredes finas e demostrar a sua viabilidade económica e técnica. Este enquadra-se num estudo mais alargado que está a ser conduzido no âmbito do projeto ToolingEdge e que pretende estudar a degradabilidade de biopolímeros com potencial aplicação em embalagens rígidas, encontrar soluções adequadas ao seu processamento, conceber moldes capazes para as referidas embalagens e prever o seu desempenho. Dentro do referido projeto, este refere-se ao caso de estudo sobre “Moldes de paredes finas e embalagens com materiais biodegradáveis”. Os parceiros envolvidos são o DEP/IPC - Universidade do Minho, a AHA, a 3DTech e a LN Moldes. Estes têm competências específicas no desenvolvimento do produto, no projeto e fabrico de moldes complexos, no processamento e na caracterização de materiais e produtos., Projeto QREN: ToolingEdge.

Publicado em "ANTEC 2013 - Proceedings of the 71st Annual Technical Conference & Exhibition", Innovation, design freedom, cost and weight reduction are some factors for the replacement of metals by plastics. Plastics continue to offer attractive solutions for design engineers. The metallic effect obtained by incorporation of metal particles in polymers by injection molding has the advantage of eliminating post-processing techniques such as painting or metallization. Moreover, it reduces production costs and time to get a superior part quality. Nevertheless, undesired defects in the final appearance of parts are common, such as flow lines and weld lines. These defects occur due to inhomogeneous orientation and anisotropy of the metal particles. Very few studies are reporting the influence of metallic particles on the morphology development of PP parts. Therefore, this study is focused on the production of parts made of PP/metallic pigments (aluminum, bronze and copper) by injection molding in order to understand the influence of metallic particles on the aesthetic and morphological properties of the parts., ADI -American Dysautonomia Institute

The main function of packaging in the context of the food industry is to store, to promote an increase in the lifetime of products and to facilitate their transport. In recent years there has been a growing demand for plastic packaging for food applications, leading to the optimization of existing packagings. In order to keep products with the desired quality they need to display good barrier properties to gases, vapors and smells. Currently, the barrier in plastic packaging is achieved by the combination of several materials, so called multi-layer packaging or by the use of rigid packaging with preserves (examples brine and oil solutions). This work aims at developing a rigid plastic packaging for food industry, with the following requirements: extend the lifetime of the product, enable the sterilization process, impermeable to oxygen, and avoid the use of preserve solutions which often display high salt and pH levels., ADi - Agencia de Inovação

Plastic parts with metallic effect are a challenge for the industry if it is considered to be done by injection moulding with the incorporation of metallic particles and not by painting or metallization. The advantages of this process are the elimination of post-processing techniques, reducing costs and production time and to get superior part quality. Nonetheless, several defects arise from the use of metallic particles in injection moulding due to their anisotropic nature, with undesired consequences on the appearance of the final part i.e. flow lines and weld lines. It is known that the materials nature, particle size, percentage of particles used, roughness of the cavity surface will affect the final appearance of the part. This work aims at using composite materials made of PP/metallic fillers (aluminium and cooper) on the preparation of injection moulded parts and study the influence of the metallic particles content and type on the aesthetic properties of weld lines in injection moulding parts. The morphological and mechanical characterization of the parts is also studied.

The production of large plastic parts, in small series and at low cost, requires the development of alternative tools and materials. Structural foams (SF) are a good solution, when the production of thicker parts with good properties is the specification. They allow obtaining lightweight parts with high stiffness and good dimensional stability, due to their sandwich-like structure constituted by a cellular core and two solid skins. The porous core results from the addition of a blowing agent in the polymeric matrix. These materials are applied in urban furniture, automotive, nautical and aerospace industries. The most used process to produce SF is the low pressure foam moulding, which is a short shot process, with impression pressures ranging from 1.4 to 4 MPa. Thus, the use of hybrid moulds with moulding blocks obtained by rapid prototyping routes is seen as a viable alternative for SF injection moulding. This work reports on a study of the influence of processing conditions on the aesthetical, morphological, and mechanical properties of SF mouldings of high-impact polystyrene (HIPS-SF). The results compare the effect of the use of hybrid moulds to conventional moulds on the surface aspect of the circular centre gated mouldings. Furthermore the influence of the moulding temperature is ascertained in terms of the resulting cellular morphology, the flexural stiffness of the plate mouldings, and the impact resistance in the instrumented drop weight test., QREN - contract 2010/013307 - project ‘Hybridmould 21’

Polyvinyl chloride, PVC, is one of the most widely produced and used plastic, being commonly used in civil industry due to its wide range of mechanical properties (from rigid to flexible), low cost, durability, and easy to assemble. Due to its good mechanical and thermal properties, PVC can be used to produce window and door frames, protecting the interior from the external actions, such as noise and temperature gradients. In order to achieve the final dimensions and geometry, previously extruded profiles must be cut and assembled, being the butt welding one of the most efficient techniques. This plastic welding method involves three main steps: i) pressing the parts to be joined against either side of a heated plate; ii) removing the plate when the parts are sufficiently molten and iii) pressing the components together and holding them until they are cooled. The amount of molten material, generated during the heating stage at an adequate heating time and the plate temperature, as well as the amount of material forced out from the joint during the pressing stage (joining displacement), have major influence in the final welding properties. Although the lack of information about the butt welding of PVC, previous studies with for others materials [1-3] showed that the welding strength can be optimized changing the plate temperature and/or joining displacement. The aim of this work was to study the influence of the plate temperature and the heating time in the welding strength of PVC profiles used in windows frames. The profiles were welded in an industrial butt welder machine, setting the plate temperature at 245ºC, 260ºC and 275ºC and the heating time at 15 and 20s. The mechanical properties were evaluated by mechanical bending tests, according to UNE-EN 514 standard and the welding strength was correlated with the morphology of the welded parts observed by optical microscopy. The results are showing that the increase of plate temperature and heating time increase the welding strength. However, the presence of impurities in the joint, such as trapped air or degraded material, as well as the joint alignment, can have a detrimental effect on the welding strength, as observed by the morphological analyses.

This work reports an investigation on the solid state uniaxial deformation of neat poly(ethylene terephthalate), PET, and its nanocomposites with montmorillonite, MMT, and nanosilica, SiO2, followed by in situ WAXS/SAXS (under X-ray synchrotron source radiation). The nanocomposites were produced via direct melt blending with addition of 0.3wt% of nanoparticles. Structural characterization by TEM revealed relatively good dispersion of both types nanofillers, namely intercalated morphology for the PET/MMT nanocomposite and agglomerate sizes (c.a. 80 nm) for the PET/ SiO2 nanocomposites. Despite the type of nanoreinforcements, three common stages of multiscale structure evolution were indentified: - Stage I, before necking, is characterized by a small amount of amorphous phase evolving into mesophase at almost constant molecular orientation level; - Stage II, at neck propagation, where a rapid increase of polymer molecular orientation is accompanied by a sharp increase of the mesophase and by the formation of a periodical mesophase; it is also observed the appearance of crazes in the polymer matrix, and voids within the nanoparticles agglomerates 1-4. - Stage III, during necking, corresponds to the transformation of crazes and voids into micro-voids, at a plateau of average molecular orientation. The highest periodical mesophase content is achieved together with a slight increment of mesophase1-4. In comparison to the neat PET structure evolution, all kind of nanocomposites showed: i) improved amount of mesophase and maximum periodical mesophase formed at earlier deformations; ii) retarded crazes widening/growing within the polymer bulk, and iii) similar maximum orientation level are achieved. Multiscale structures modelling are suggested based on the results obtained.

The work reports the preparation of polypropylene (PP)/carbon nanofibre (CNF) composites with different compositions, a PP/CNF/carbon nanotube (CNT) composite, and the production of bi-component injection moulded plaques using these materials. The plaques were formed with a composite inner core and a surface layer of PP, and inversely, with a PP core and a composite surface layer. Samples were also prepared with plain PP and plain composite for comparison. The dispersion of CNF and CNT, the distribution of the polymer/composite layers along the plates formed, and the interaction between the layers, were studied by optical and electron microscopy (OM and SEM). Mechanical properties and electrical resistivity of samples cut from the plaques were measured, and compared with those of standard injection moulded dog-bone specimens with the same composition. OM and SEM showed good dispersion of the CNF and CNT in the polymer matrix, and the presence of some agglomerates, mostly of CNT. An increase in CNF content (max. 8 wt%) on PP composites improved the tensile strength and reduced its volume electrical resistivity to about 107 ım. However, a reduction on the maximum CNF content and the incorporation of a small amount of CNT in the composite (4,5wt% of total nanofiller content, distributed approximately as 3,5% CNF + 1% CNT) have maintained the mechanical performance of the composite and reduced its electrical resistivity to about 104 ım. All bi-component systems studied showed improved mechanical properties relative to PP itself. For the PP/4,5wt% of (CNF+CNT)/PP, the mechanical and electrical properties were equivalent to those of the model plain composite.

Structural foams (SF) are a material solution for injection moulding, in short productions series, of large size parts. They are a composite material constituted by two skins without cells and a cellular core. Injection of SF is a low pressure process, ideal for producing large parts. For this reason they are a viable alternative for light moulding tools. The right formulation of structural foam and the use of adequate processing conditions are important to optimize the performance of the plastics part. In this paper are presented several formulations of polypropylene and blowing agent for injection moulding using hybrid moulds. The rheological, morphological and mechanical characterization is made to evaluate structural foam performance., Program QREN ‘Concessão de Incentivos Financeiros no âmbito do Sistema de Incentivos à Investigação e Desenvolvimento Tecnológico’ - contract 2010/013307 - project Hybridmould 21

For conventional injection moulding of semi-crystalline plastic parts it is common to obtain a skin/core type of structure through the wall thickness. The cause of this structure is the thermo-mechanical environment during the process. The size of the skin and also its degree of orientation strongly influences the mechanical properties of the plastics part. They can be controlled by many technological variables such as injection rate, mould temperature, melt temperature, wall thickness, mould material, etc. Hybrid moulds may use different materials in the moulding blocks which affects the skin thickness symmetry on both sides of the parts. This work aims at understanding the influence of different materials used for the moulding blocks of hybrid moulds on the structural properties of polypropylene parts. The material combination of steel/steel, steel/(epoxy+aluminium), steel/(epoxy+short steel fibres) for the moulding blocks is used to induce asymmetric structure development in the part. Simultaneously the influence of the injection rate is analysed as it is one of the more relevant variables in the skin formation. The morphology structure of the mouldings determined by the various conditions is characterized by polarised light optical microscopy. Moldflow simulations are used to predict the skin/core ratio in the mouldings.

Inorganic particles have been incorporated into poly(ethylene terephthalate), PET, matrix with the aim of offering some aesthetic effects to the standard transparent beverage packaging. To assess to the effect of different type of inorganic particles (with different interaction with the polymeric matrix) in the deformation behaviour of PET composites, particles such as aluminium, bronze, nanoclay, graphite and mica, were used. Two types of processing methods, ensuring a good mixing, were adopted for the composite preparation: i) melt-blending in an asymmetric batch mini-mixer followed by compression and ii) melt-blending in a twin screw extruder followed by injection moulding. The structural and mechanical behaviours of neat PET and its composites were evaluated during uniaxial stretching at temperatures above the glass transition temperature, Tg, namely at 85, 90, 95, 100 ºC, using a standard tensile stretching machine equipped with an environmental chamber. This study aims at understanding the deformation behaviour of the materials at temperatures found in conventional transformation methods used for packaging. To interpret the structural evolution occurring in the samples, off-line techniques such as DSC, WAXD and SEM were used. A detailed structural evolution was accomplished by applying different stretching ratios to the samples up to a maximum of 5x. Injection moulded samples were also characterized for their mechanical properties at room temperature in order to assess the materials behaviour in service. From all particles studied the PET/Aluminium and PET/Bronze composites are the ones showing the best combination of aesthetic effects, deformation behaviour and final mechanical properties. Comparing to neat PET, their general properties are the same during the deformation process making the new materials suitable for conventional processing techniques. It was found that both particles offer superior molecular mobility to PET at room temperature. In other words, these composites present a higher deformation capacity, however its elastic modulus and tensile strength at yield are slightly reduced.

Polypropylene (PP) is a low cost commodity thermoplastic, easy to process and suitable for general applications. However, for structural and electrical applications, its properties are inadequate, demanding the use of reinforcing materials that may provide mechanical strength and/or electrical conductivity. Carbon-based nanoreinforcements are known for their ability to provide good electrical and mechanical properties to polymer matrix composites. However, the improvement depends essentially on the dispersion and adhesion of the reinforcement in the matrix. In this work PP composites with carbon nanofibres (CNF) were prepared and composite samples were produced; the morphology of the nanocomposite parts was studied and correlated with its mechanical and electrical performance, aiming at understanding the ability of the nanomaterial to be applied in multi-functional parts. The approach followed in this work consisted on the preparation of nanocomposites of PP with varying concentrations of CNF (PP + 2.7 % CNF, PP + 8 % CNF and PP + 4.8% (CNF +CNT)) by blending in a twin-screw extruder. These materials were then processed by co-injection moulding to obtain bi-material parts, producing two types of nanocomposite parts: (i) with an inner core of nanocomposite and an outer layer of PP, and (ii) with an inner core of PP and outer surface layer of nanocomposite. All materials/parts obtained were characterized in terms of their morphological, mechanical, thermal and electrical properties. The morphological results showed a preferential alignment of the nanoreinforcement along the flow direction, and a good dispersion in the polymer matrix; however, CNF adhesion to PP was weak. The mechanical and electrical properties varied with the composition of the bi-material part. Thus, the parts with an inner core of PP presented similar mechanical behavior to PP, with surface antistatic characteristics. The parts with an inner core of CNF nanocomposite presented similar mechanical properties to those of plain CNF nanocomposite parts, presenting semi-conducting characteristics for volume resistivity. It was observed that the incorporation of 1 wt% CNT in a composite with approximately 3% wt CNF lead to similar mechanical and electrical properties to composites with 8% wt CNF content.

Dissertação de mestrado integrado em Engenharia de Polímeros, Na indústria transformadora de plásticos, aquando da produção de peças, existe também a produção de resíduos que devem ser devidamente encaminhados. Perante o conceito de economia circular, as empresas têm a necessidade de abandonar o conceito de economia linear. As poliolefinas, particularmente o polietileno (PE) e o polipropileno (PP), são bastante utilizadas na indústria das embalagens. Estes dois materiais possuem massas volúmicas muito semelhantes, tornando difícil a sua separação. Assim sendo, as misturas de PE e PP, são do interesse industrial para combater a dificuldade anteriormente mencionada. No âmbito do projeto Better Plastics com o objetivo de criar soluções para recuperar os resíduos industriais, foi efetuado um estudo sobre a processabilidade e características de misturas de poliolefinas, nomeadamente as misturas de HDPE adequado ao processo de extrusão sopro (HDPE-s) com HDPE adequado para o processo de moldação por injeção (HDPE-i) e as misturas de HDPE-s com um PP de moldação por injeção (PP-i). Foram preparadas misturas com diferentes composições dos materiais (20/80, 40/60, 60/40 e 80/20) virgens e recicladas, sendo posteriormente produzidas peças por moldação por injeção. Os materiais e as peças foram caracterizados reologicamente (índice de fluidez (MFI)), termicamente (calorimetria diferencial de varrimento (DSC)), morfologicamente (microscopia ótica de luz polarizada e microscopia eletrónica de varrimento (SEM)) e mecanicamente (tração e tração-impacto). As misturas de HDPE/ HDPE são compatíveis, enquanto as misturas de HDPE/ PP são incompatíveis, como era esperado. Evidencia-se que as propriedades das misturas são dependentes da composição e que o material virgem tem sempre melhores propriedades que os matérias reciclados, contudo não é uma diferença significativa para grande parte das composições analisadas. O uso destes materiais em processos de fabrico distintos daqueles para o qual foram concebidos é possível, mas recomenda-se a análise das propriedades requeridas para o produto final., In the plastics manufacturing industry, during the production of parts, there is also the production of waste that must be properly routed. Faced with the concept of circular economy, companies need to abandon the concept of linear economy. Polyolefins, particularly polyethylene (PE) and polypropylene (PP), are widely used in the packaging industry. These two materials have very similar density, making their separation difficult. Therefore, blends of PE and PP are of industrial interest to combat the previous mentioned difficulty. As part of the Better Plastics project, with the objective of creating solutions to recover industrial waste, a study was carried out on the processability and characteristics of polyolefin mixtures, namely HDPE mixtures suitable for the blow extrusion process (HDPE s) with HDPE suitable for injection moulding process (HDPE-i) and blends of HDPE-s with an injection moulding PP (PP-i). Mixtures with different compositions of materials (20/80, 40/60, 60/40 and 80/20) were prepared, virgin and recycled, and parts were later produced by injection moulding. The materials and parts were characterized rheologically (flow index (MFI)), thermally (differential scanning calorimetry (DSC)), morphologically (optical polarized light microscopy and scanning electron microscopy (SEM)) and mechanically (traction and traction-impact). HDPE/HDPE blends are compatible, while HDPE/PP blends are incompatible, as expected. It is evident that the properties of the mixtures are dependent on the composition and that the virgin material always has better properties than the recycled materials, however it is not a significant difference for most of the analysed compositions. The use of these materials in manufacturing processes other than those for which they were designed is possible, but it is recommended to analyse the properties required for the final product., Ao projeto Better Plastics – Plastics in a Circular Economy (POCI-01-0247-FEDER-046091), por permitir participar e colaborar nos trabalhos desenvolvidos na PPS2 Linha 2.

Dissertação de mestrado integrado em Engenharia de Polímeros, As indústrias automóvel são marcadas pela elevada competitividade e exigência na qualidade dos produtos, o que obriga as mesmas a recorrer a métodos de melhoria contínua que lhes permitam reduzir custos e antecipar falhas e defeitos, de forma a garantir a satisfação do cliente. O trabalho que conduziu a esta dissertação foi realizado na empresa InovePlastika – Inovação e Tecnologia em Plásticos, S.A., uma empresa que se dedica à injeção de componentes plásticos, principalmente para a indústria automóvel. O presente estudo foca-se na fase de industrialização de dois projetos, em que a empresa enfrenta grandes desafios no cumprimento dos requisitos especificados pelo cliente. O primeiro projeto incide numa peça com uma geometria propicia a empenos e que, por consequência, afeta uma dimensão que inviabiliza a sua montagem e utilização. O segundo projeto, recai sobre um molde multicavidade em que não existe consistência no peso das peças de cavidade para cavidade e de ciclo para ciclo. Assim, pretende-se com este estudo impulsionar a aprovação de ambas as peças para produção, de uma forma mais rápida e minimizando os custos envolvidos, através da utilização de metodologias de melhoria contínua como o método DMAIC (Define, Measure, Analyze, Improve, Control), suportado na filosofia Seis Sigma e o método Taguchi, baseado no Planeamento de Experiências. Através da aplicação da metodologia DMAIC, em conjunto com ferramentas da qualidade, como brainstorming, diagrama de Ishikawa, 5 Porquês, fluxograma, cartas de controlo, entre outos, pretende-se identificar as causas-raiz para o problema mencionado e implementar medidas que reduzam a variabilidade do processo. Com recurso ao método Taguchi, foi possível estudar a influência das variáveis operatórias na qualidade do produto final, de forma a encontrar a combinação paramétrica que leve à otimização do processo e das características críticas de qualidade. A aplicação destas metodologias foi uma mais valia, pois conseguiu-se alcançar processos robustos e estáveis, dentro dos limites especificados pelo cliente, o que permitiu aumentar a sua satisfação e a qualidade dos produtos e processos., The automotive industries are marked by high competitiveness and demand for high product quality, which forces them to use methods of continuous improvement that allow them to reduce costs and anticipate failures and defects, in order to ensure customer satisfaction. The work that let to this dissertation was carried out at the company InovePlastika – Inovação e Tecnologia em Plásticos S.A., a company dedicated to the injection of plastic components, mainly for the automotive industry. The present study focuses on the industrialization phase of two projects, in which the company faces major challenges in meeting the requirements specified by the customer. The first project focuses on a part with a geometry that is prone to warping and, consequently, it affects a dimension that makes its assembly and use unfeasible. The second project concerns a multi-cavity tool where there is no consistency in part weight from cavity to cavity and cycle to cycle. Thus, it is intended with this study to boost the approval of both parts for production, in a faster way and minimizing the costs involved, through the use of continuous improvement methodologies such as the DMAIC method (Define, Measure, Analyze, Improve, Control), supported by the Six Sigma philosophy and the Taguchi method, based on Design of Experiments (DoE). The application of the DMAIC methodology, in conjunction with quality tools, such as brainstorming, Ishikawa diagram, 5 Whys, flowchart, control charts, and others, is intended to identify the root causes for the mentioned problem and implement measures that reduce process variability. Using the Taguchi method, it was possible to study the influence of the operational variables on the quality of the final product, in order to find the parametric combination that leads to the optimization of the process and the critical quality characteristics. The application of these methodologies was an asset, because it was possible to achieve robust and stable processes, within the limits specified by the customer, which has increased customer satisfaction and product and process quality.

Dissertação de mestrado integrado em Engenharia de Polímeros, A indústria automóvel encontra-se em desenvolvimento constante a todos os níveis, desde os materiais utilizados, às técnicas de fabrico, ao design e aos requisitos e exigências necessárias. No entanto, a preocupação crescente com o planeta tem redirecionado as estratégias da indústria, ajustando o seu desenvolvimento para a diminuição ou mesmo a anulação do impacto ambiental negativo gerado. Embora os compósitos utilizados no automóvel sejam maioritariamente com polímeros e fibras sintéticas, têm vindo a ser desenvolvidos novos materiais para a sua substituição, que recorrem a alternativas mais sustentáveis. Assim, o recurso a materiais naturais, como matriz polimérica ou como fibra é um meio para diminuir o impacto ambiental causado, sendo a cortiça um material com potencial de utilização. Face aos requisitos impostos às OEM pelos governos, as empresas encontram-se numa demanda pela sustentabilidade, o que fomenta a introdução de novos compósitos, como é o caso de compósitos poliméricos com incorporação de cortiça, nos quais a cortiça confere um aspeto estético de luxo e representa um material com pegada de carbono negativa. Portanto, o objetivo da dissertação prende-se ao desenvolvimento e caracterização de compósitos poliméricos com cortiça adequados para utilização na indústria automóvel. O trabalho desenvolvido engloba uma análise de mercado para aferir qual a matriz mais adequada, assim, sendo o Polipropileno um dos quatro polímeros mais utilizados na indústria automóvel, é por isso a matriz polimérica escolhida. De modo, a acomodar as necessidades ambientais, recorre-se à utilização de um Polipropileno reciclado e, para consolidar resultados é também estudado um Polipropileno com agentes de nucleação de forma a inferir sob a contração típica do polímero. Procede-se para o design de formulações por forma a permitir inferir a influência: das matrizes; da adição de cortiça com granulometria e em percentagens diferentes e da incorporação de aditivos. Os ensaios realizados permitem uma caracterização mecânica, física, reológica e morfológica. Os resultados obtidos permitem concluir que a adição de cortiça prejudica as propriedades de resistência à tração e ao impacto de todas as matrizes, a cortiça afeta a fluidez do polímero diminuindo a e a microscopia revela alguns defeitos no interior das amostras que estão associadas à presença de cortiça. Um resultado que favorece estes compósitos é o facto da adição de cortiça permitir reduzir o peso do compósito. Em suma, os resultados obtidos apesar de algumas propriedades serem prejudicadas permitem concluir que o trabalho efetuado apresenta potencial para se afirmar na indústria., The automotive industry faces a continuous development at all levels. Since the materials that it is used, the fabrication technique, the design or the requisites and demands require that development. However, the evolving worry for the planet preservation has been redirecting the strategies used by the industry it is necessary to adjust the development to include the decreasing or to vanish at all the negative environment impact caused. Even though most composites are made from synthetic polymers and fibers, the development of composites more sustainable have been done. So, the use of natural materials, matrix or fiber, are a way to reduce the negative impact with cork being a material with great potential. According to the demands made by the governments, the OEM’s must become more sustainable. So, this drives the industry to welcoming new composites, like cork composites. The presence of cork gives an extravagant aesthetics and is a material with negative footprint. Therefore, the objective of this dissertation is the development and characterization of polymer and cork composites suited to be used in the automotive industry. The work done requires an analysis of the market to able the choice of the polymer matrix, which is the Polypropylene since it is one of the four main polymers used at this industry. In a way that is possible to accommodate the environment needs it is studied the use of a recycled polypropylene and, for the consolidation of some results it is also studied the use of a nucleated polypropylene to analyze the typical contraction that occur. The following phase requires the definition of the formulations to allow the study of the influence of the different matrixes used, the effect of adding cork at different percentages and sizes and the incorporation of additives. The data collected allows a mechanical, physical, rheological, and morphological characterization. The results obtained allows some conclusionslike the tensile strength, modulus and impact resistance decrease with the addition of cork for all matrixes. Cork difficult the ability of the composite to flow. Microscopy reveals the presence of some defects associated with the presence of cork. A positive result is that the cork allows the reduction of the composite weight. In conclusion, the results obtained allows to conclude that the work developed contain potential to enter the industry despite the fact some properties are negatively affected by the presence of cork.

Dissertação de mestrado em Engenharia de Polímeros, Num momento em que o mundo atravessa uma grave crise social e económica devido à pandemia COVID 19, seguida por diversas tensões sociopolíticas que bloqueiam as cadeias de fornecimento, aumentam os custos de transporte internacionais e atrasam os prazos de entrega, causando o aumento exponencial do custo de obtenção de matérias-primas, torna-se fulcral que as empresas dinamizem as suas atividades e se adaptem a uma nova dinâmica de mercado, para conseguir reduzir custos e manter a qualidade nos seus produtos. Neste contexto, surgiu o tema da presente dissertação que consiste na substituição de terminais sobreinjetados em Zamak por um material polimérico, para componentes da indústria automóvel. O trabalho é realizado na empresa Fico Cables, onde se produzem cabos de acionamento mecânico aplicados no interior de veículos automóveis de inúmeros produtores mundiais. Estas peças possuem pequenos componentes sobreinjetados num cabo metálico, fabricados em Zamak e sobreinjetados em plástico. O Zamak é uma liga metálica constituída por elementos como zinco, alumínio, magnésio e cobre, tendo como principal característica a elevada resistência mecânica. Este material possui um custo de produção muito elevado, com elevadas taxas de desperdício de matéria-prima na sua moldação e também alguns riscos associados à sua produção devido às elevadas temperaturas de fusão, na ordem dos 400ºC. A substituição por materiais termoplásticos permite taxas produtivas mais elevadas, a redução de etapas do processo e redução de custos produtivos. Tendo em vista a identificação e caracterização de um material termoplástico capaz de substituir as ligas de Zamak nos terminais de bloqueio de cabos metálicos, foram selecionados e testados diferentes materiais, através da realização de ensaios que pretenderam verificar diferentes fatores de controlo associados a este produto, como a geometria da peça e a interface plástico/metal. A realização de ensaios mecânicos e morfológicos permitiu aprofundar o conhecimento acerca das características da relação processamento-estrutura da peça que beneficiem a sua resistência mecânica. Por fim realizaramse também ensaios de fadiga aos componentes plásticos com o objetivo de validar a sua aplicabilidade de acordo com as normas da indústria automóvel. A poliamida aromática foi a opção mais viável para a tipologia de produto em estudo, permitindo a redução de etapas do processo e um ganho significativo de custos produtivos., At a time when the world is going through a serious social and economic crisis due to the pandemic COVID 19, followed by various socio-political tensions that block supply chains, increase international transport costs and delay delivery times, causing an exponential increase in the cost of obtaining raw materials, it is crucial that companies streamline their activities and adapt to a new market dynamic, to be able to reduce costs and maintain the quality of their products. In this context, the subject of this dissertation arose, which consists in the replacement of overmolded Zamak terminals with a polymeric material for automotive industry components. The work is carried out at the company Fico Cables, which produces mechanical drive cables used inside automobiles of many world producers. These parts have small components overmolded into a metallic cable, made of Zamak and overmolded into plastic. Zamak is a metal alloy made of elements such as zinc, aluminum, magnesium and copper, and its main characteristic is its high mechanical resistance. This material has a very high production cost, with high rates of raw material waste in its molding and some risks associated with its production due to high melting temperatures, around 400ºC. The substitution by thermoplastic materials allows for higher production rates, the reduction of process steps and reduction of production costs. To identify and characterize a thermoplastic material capable of replacing Zamak alloys in metallic cable locking terminals, different materials were selected and tested, by performing tests that aimed to verify different control factors associated with this product, such as the part geometry and the plastic/metal interface. Mechanical and morphological tests allowed deepening the knowledge about the characteristics of the processing-structure relationship of the part that benefit its mechanical strength. Finally, fatigue tests were also performed on the plastic components to validate their applicability according to the automotive industry standards. The aromatic polyamide was the most viable option for the type of product under study, allowing the reduction of process steps and a significant gain in production costs.

Dissertação de mestrado integrado em Engenharia de Polímeros, A indústria automóvel é marcada pela elevada competitividade e exigência na qualidade dos produtos. A aplicação de métodos de melhoria contínua torna-se um trunfo imprescindível para que as empresas produtoras de peças para esta indústria alcancem a liderança no seu setor. Estas empresas procuram métodos que lhes permitam reduzir custos, melhorar a qualidade dos produtos e a satisfação do cliente. As empresas especializadas na produção de peças decorativas do interior do automóvel permanecem sempre a par das últimas tendências do mercado, sendo que a estética dos componentes assume um papel preponderante na valorização dos mesmos. As técnicas de acabamento superficial são um forte aliado deste setor, nomeadamente a pintura. O presente estudo centra-se na análise do processo de produção de componentes decorativos com acabamento de alto brilho existente na Fehst Componentes, Lda. Estes componentes, após serem injetados, são pintados com tintas monocura por radiação ultravioleta, de modo a valorizar o seu aspeto estético. No fim do processo de pintura ocorre uma inspeção visual à qualidade superficial dos componentes, onde peças com defeitos, como inclusões, covas, riscos, casca de laranja, entre outros, são rejeitadas. A elevada percentagem de rejeição que ocorre em alguns componentes conduz à aplicação de metodologias e ferramentas da qualidade que visem a melhoria do processo produtivo. Através da aplicação da metodologia DMAIC (Definir, Medir, Analisar, Melhorar e Controlar), e de ferramentas da qualidade como brainstorming, diagramas de Ishikawa, 5Why’s, 5W2H, entre outros, pretende-se implementar medidas que reduzam e estabilizem o valor da percentagem de peças não conformes dos componentes decorativos com acabamento de alto brilho. O estudo realizado permitiu concluir que o defeito inclusões é o defeito que apresenta maior incidência, tendo como origem operações secundárias na cadeia produtiva dos componentes. A alteração de alguns procedimentos e operações, permitiu melhorar significativamente a percentagem de defeitos ocorridos. A implementação da metodologia DMAIC foi uma mais valia na melhoria de todo o processo produtivo e na obtenção das metas definidas anualmente pela empresa, relativamente à percentagem de rejeição de peças com acabamento de alto brilho., The automotive industry is marked by competitiveness and demand for product quality. The application of continuous improvement methods becomes an essential asset for companies that produce parts for this industry to reach the leadership in their sector. These companies are looking for methods that will allow them to reduce costs, improve product quality and customer satisfaction. Companies specializing in the production of decorative parts for the interior of the car always keep up with the latest market trends, being that, the aesthetics of the components play a major role in their improvement. Surface finishing techniques are a strong ally of this sector, namely painting. The present study focuses on the analysis of the production process of decorative components with high gloss finish existing at Fehst Componentes, Lda. These components, after being injected, are painted with monocure paints by ultraviolet radiation, in order to improve their aesthetic appearance. At the end of the painting process, there is a visual inspection of the surface quality of the components, where parts with defects, such as inclusions, pits, scratches, orange peel, among others, are rejected. The high rejection rate that occurs in some components has led to the application of quality methodologies and tools aimed at improving the production process. Through the application of the DMAIC methodology (Define, Measure, Analyse, Improve and Control), and with quality tools such as brainstorming, Ishikawa diagrams, 5Why's, 5W2H, among others, we intend to implement measures that stabilize and reduce the percentage value of non-compliant parts of the decorative components with high gloss finish. The study made it possible to conclude that the inclusions defect is the defect that has the highest incidence, originating from secondary operations in the component production chain. The alteration of some procedures and operations, allowed to significantly improve the percentage of defects that occurred. The implementation of the DMAIC methodology was an asset in improving the entire production process and in achieving the goals set annually by the company regarding its percentage of rejection of parts with high gloss finish.

Dissertação de mestrado integrado em Engenharia de Polímeros, A constante evolução e reinvenção do setor médico hospitalar reflete-se cada vez mais nos processos produtivos das empresas, não sendo a Muroplás uma exceção. No sentido de acompanhar este progresso e aumentar a sua capacidade de resposta, surge a necessidade de ampliar o catálogo da Muroplás através do desenvolvimento de um produto de valor acrescentado para a empresa, isto é, uma check valve para linhas de terapia intravenosa (IV), umas das principais áreas de atuação da Muroplás. A IV check valve é uma válvula antirretorno constituída por três peças distintas, sendo que uma das peças que a constitui é um diafragma interno usualmente produzido em silicone e o principal objetivo deste projeto passa por encontrar um material alternativo que o possa substituir e ser processado internamente sem comprometer o desempenho da válvula. Inicialmente, analisa-se a área e o contexto de aplicação do produto, assim como os tipos de mecanismos e versões que este pode apresentar. De seguida, definem-se as caraterísticas mais importantes do silicone e investigam-se materiais alternativos que as possam substituir, realizando-se também um estudo de mercado dos concorrentes, patentes, custos e consumos anuais da check valve, sendo assim possível a definição do funcionamento, requisitos e especificações técnicas da mesma e do material de cada peça. Posteriormente, realiza-se o design e otimização tecnológica de cada componente da check valve, a definição das suas cotas críticas e condições de processamento, a sua simulação de enchimento e simulação do desempenho mecânico do diafragma, o projeto dos moldes protótipos e de uma ferramenta de montagem do produto, a definição das injetoras adequadas e o controlo do produto e ferramentas maquinadas. Por fim, descrevem-se os testes de validação iniciais, para otimização do processo de montagem e preparação de amostras, e dos testes de validação normativos e adaptação dos mesmos em função da área de aplicação do produto, sendo que depois da sua concretização é realizada uma análise e discussão de resultados, da qual se conclui que o projeto dos componentes de ligação é bem conseguida e que dos três materiais testados no diafragma se verifica, no geral, bons resultados num deles, concluindo-se assim que o principal objetivo deste projeto, o desenvolvimento de uma IV check valve com materiais alternativos ao silicone, é cumprido., The constant evolution and reinvention of medical-hospital sector is increasingly reflected in the productive processes of companies, with Muroplás not being an exception. To accompany this progress and increase its response capacity, there is a need to expand Muroplás catalog through the development of a product with added value for the company, a check valve for intravenous therapy (IV) lines, one of the main areas of occupation of Muroplás. The IV check valve is a non-return valve made up of three distinct parts, one of which is an internal diaphragm usually produced in silicone and the main objective of this project is to find an alternative material that can replace it and be processed internally without compromising valve performance. Initially, the product application area and context are analyzed, as well as the types of mechanisms and versions that it can present. Next, the most important characteristics of silicone are defined and alternative materials that can replace them are investigated, also carrying out a market study of competitors, patents, costs, and annual consumption of check valve, thus making it possible to define the operation, requirements and technical specifications of the same and the material of each part. Subsequently, the technological projection and optimization of each check valve component is carried out, the definition of its critical dimensions and processing conditions, its filling simulation and mechanical performance of the diaphragm, the projection of prototype molds, the projection of a product assembly tool, the definition of the appropriate injection molding machines and the control of the product and machine tools. Finally, the initial validation tests are described, to optimize the assembly and sample preparation process, and the normative validation tests and their adaptation according to the product's area of application, and after their implementation, it is performed an analysis and discussion of results, from which it is concluded that the projection of the connection components is well achieved and that of the three materials tested in the diaphragm, it is verified, in general, good results in one of them, thus concluding that the main objective of this project , the development of an IV check valve with alternative materials to silicone, was accomplished.

Dissertação de mestrado em Polymer Engineering, When industries need to make components with two or more materials using just one mould and one machine, they use multi-material injection moulding techniques. One of these techniques is the core back moulding that allows the subsequent injection of two different materials without opening the mould, commonly used for parts with simple geometry, normally a rigid part involved with an elastomer. These moulds are very complex in its structure, therefore the design of the mould, its construction and assembly need to be carefully done to avoid part defects. Moreover, multi-material injection moulding may be a challenge regarding the adhesion between materials, being dependent on materials compatibility, materials rheological characteristics and injection moulding conditions used. The present dissertation addresses the development of a core back mould for the production of a complex bi-material part for the automotive industry and the study of the processing conditions that best promote the adhesion between the materials used. For that different tools where used such as Solidworks for the mould design, and DOE for the design of experiments. The mould development went through several steps such as the design of the injection, cooling, ejection and gas trap systems. Then the mould components were machined and assembled. Finally, the mould was tested and the parts were analysed. A study about the adhesion of the materials in this type of moulds and how the processing conditions influence the interface quality was realised. To simplify that study, a Design of Experiments was performed. This method is used to reduce the number of tests, assuring the reliability of the results. Finally, to analyse the adhesion of the parts, tensile tests were performed. It was concluded that the mould had a good performance. Parts were successfully made and the strength of the joints evaluate. It was concluded that the adhesion between materials was more efficient in the part extremities comparing with the middle zones. These results are attributed to the location of the gate and also the complex geometry of the part. Furthermore, the processing conditions influence the strength of the joint region. The set of values that would optimise PP/EPDM joints are the injection temperature of the second material of 200ºC, the mould temperature of 40ºC and the injection pressure of 80bar., Quando as indústrias necessitam de fazer componentes com dois ou mais materiais utilizando apenas um molde e uma máquina, utilizam técnicas de moldação por injeção multi-material. Uma destas técnicas é a moldação core back que permite a subsequente injeção de dois materiais diferentes sem abertura do molde, normalmente utilizada para peças com geometria simples, como uma peça rígida envolvida com um elastómero. Estes moldes são muito complexos, pelo que a conceção do molde, a sua construção e montagem precisam de ser realizadas cuidadosamente para evitar defeitos nas peças. Além disso, a moldação multi-material pode ser um desafio no que respeita à adesão entre os materiais, dependendo da compatibilidade dos materiais, características reológicas e condições de processamento. A presente dissertação aborda o desenvolvimento de um molde core back para a produção de uma peça bi-material para a indústria automóvel e o estudo das condições de processamento que melhor promovem a adesão entre os materiais utilizados. Para isso são utilizadas diferentes ferramentas, tais como Solidworks para o desenho do molde, e DOE. O desenvolvimento do molde passou por várias etapas, tais como a conceção dos sistemas de injeção, arrefecimento, ejeção e escape de gás. Em seguida, os componentes do molde foram maquinados e montados. Finalmente, o molde foi testado e as peças foram analisadas. Foi realizado um estudo sobre a adesão dos materiais neste tipo de moldes e como as condições de processamento influenciam a qualidade da interface. Para simplificar esse estudo, foi realizado um Design of Experiments. Este método é utilizado para reduzir o número de ensaios, assegurando a fiabilidade dos resultados. Finalmente, para analisar a adesão das peças, foram realizados ensaios de tração. Concluiu-se que o molde tinha um bom desempenho. As peças foram produzidas com sucesso e a resistência da zona de união foi avaliada. Concluiu-se que a adesão entre os materiais era mais eficiente nas extremidades das peças, em comparação com as zonas médias. Estes resultados devem-se à localização do ponto de injeção e também à complexa geometria da peça. Além disso, as condições de processamento influenciam a resistência da zona de união. O conjunto de valores que otimizariam a adesão da peça PP/EPDM são a temperatura de injeção do segundo material de 200ºC, a temperatura do molde de 40ºC e a pressão de injeção de 80bar.

Dissertação de mestrado integrado em Engenharia de Polímeros, A finalidade em alcançar soluções inovadoras e sustentáveis e a busca de materiais diferenciadores é fundamental nos dias de hoje para a conceção de novos produtos. Os compósitos de polímero-madeira são um desses exemplos. A madeira, sendo um material natural, é totalmente renovável, reciclável e biodegradável, e possui uma vasta gama de propriedades essenciais à espécie humana. No entanto, são geradas grandes quantidades de resíduos de madeira neste setor, que quando aplicados em materiais plásticos, formam materiais compósitos de plástico-madeira com características muito interessantes. Permitem a substituição parcial do uso de plástico em aplicações com aspeto de madeira, em peças com geometrias distintas das convencionais, e podem ser transformados com técnicas de processamento de materiais plásticos. A presente dissertação foi efetuada no âmbito do projeto ROTMI – Inovação em materiais e tecnologias de rotomoldação. O objetivo da dissertação é o estudo da processabilidade de compostos de polietileno/resíduos de madeira pela técnica de moldação rotacional, tendo em vista a viabilidade de novos materiais para a criação de produtos sustentáveis, esteticamente apelativos e funcionais. Foram avaliadas diferentes composições PE/resíduos de madeira e usados resíduos de madeira com características distintas. A técnica de moldação rotacional revelou ser adequada para o processamento de peças em compostos de polímero/madeira, com uma elevada percentagem de incorporação de resíduos de madeira na sua constituição. Dependendo do tipo de resíduo pode ser incorporada entre 45% a 60% em massa de resíduos de madeira. As peças obtidas apresentam cor e efeito estético diferente mediante a composição utilizada, as características do resíduo de madeira e as condições de processamento, nomeadamente o tempo de ciclo do processo. Verifica-se que o aumento da percentagem de resíduo de madeira incorporado na peça aumenta o tempo de ciclo de processamento, conduz ao aumento da espessura da parede, devido à falta de compactação dos materiais durante a sinterização, criando elevada porosidade na peça e a detioração das propriedades mecânicas, comparativamente ao PE virgem. A moldação rotacional é uma técnica viável à produção de peças em compósitos de polímeros-madeira, à promoção de uma economia circular e à criação de novos produtos diferenciadores em termos estético-funcionais., Nowadays, the aim of achieving innovative and sustainable solutions and the search for different materials is fundamental for the design of new products. Wood polymer composites are one such example. Wood, being a natural material, is fully renewable, recyclable and biodegradable, and has a wide range of properties essential to the human species. However, large quantities of wood residues are generated in this sector, which when applied to plastic materials, form plastic-wood composite materials with very interesting characteristics. They allow partial replacement of the use of plastic in applications with a wood aspect, in parts with different geometries than conventional ones, and can be transformed with plastic material processing techniques. This dissertation was carried out within the scope of the ROTMI project - Innovation in rotational molding materials and technologies. The objective of the dissertation is the study of the processability of polyethylene compounds / wood residues using the rotational molding technique, in view of the viability of new materials for the creation of sustainable, aesthetically appealing and functional products. Different PE compositions / wood residues were evaluated and wood residues with different characteristics were used. The rotational molding technique proved to be suitable for the processing of parts in polymer/wood compounds, with a high percentage of incorporation of wood residues in its constitution. Depending on the type of waste, between 45% and 60% in weight of wood waste can be incorporated. The parts obtained have a different color and aesthetic effect due to the composition used, the characteristics of the wood residue and the processing conditions, namely the cycle time of the process. It appears that the increase in the percentage of wood residue incorporated in the part increases the processing cycle time, leads to an increase in the thickness of the wall, due to the lack of a compact structure during sintering, creating high porosity in the part and the deterioration of the mechanical properties, compared to virgin PE. Rotational molding is a viable technique for the production of wood-polymer composite parts, the promotion of a circular economy and the creation of new aesthetic and functional differentiating products., Integração no grupo de trabalho do projeto RoTMI, que permitiu a realização desta dissertação. O agradecimento vai para o projeto RoTMI – Rotomolding Technology and Materials Innovations (Inovação em materiais e tecnologias de rotomoldação), código da operação POCI-01-0247-FEDER-33095, cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do Programa Operacional Competitividade e Internacionalização no âmbito do Programa “Portugal 2020”, nos termos do aviso da candidatura n.º 03/SI/2017.