End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the < cos2θ > for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting < cos2θ >. The breakage prediction improves if measured FLD of the extrudate is input into the model.

Made available in DSpace on 2016-12-08T17:19:16Z (GMT). No. of bitstreams: 1 Carlos Mauricio Sacchelli .pdf: 64226 bytes, checksum: 73274c8d6f55e4c10fb6577ed6dcd062 (MD5) Previous issue date: 2000-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo é uma comparação entre os resultados obtidos pelo processo de injeção do copolímero poli (óxido de Metila) POM M90, produzido pelo Hoechst com os de simulação de injeção através do aplicativo Moldflow. Os experimentos foram realizados em dois moldes, um com três cavidades e outro com duas cavidades. A pressão de injeção, para ambos foi ajustada em um valor máximo e as válvulas de vazão totalmente abertas, assim, foi determinado o tempo mínimo de injeção (tm) para completar as cavidades. As pressões de injeção foram reduzidas e o processo de injeção foi interrompido no tempo tm. Como resultado, as cavidades não foram completamente preenchidas, sendo as massas dos corpos de prova injetados determinadas. Na simulação, as cavidades foram modeladas, e simuladas segundo normas do aplicativo, sendo os parâmetros de simulação utilizados iguais ao da injeção. As vazões de injeção na simulação foram determinadas em função da massa do injetado, de sua especifica e do tempo tm. A massa especifica foi obtida experimentalmente através do plastômetro de extrusão (aparelho utilizado para a determinação do índice de fluidez). Após as simulações, foram analisados os seguintes parâmetros de comparação: preenchimento das cavidades no tempo de referencia tm, massas do injetado e do simulado, as vazões simuladas e injetadas e a massa especifica do material. Como parâmetro simples de comparação entre estas técnicas foi utilizado a massa especifica do POM M90. Os resultados encontrados no método de obtenção da massa especifica foram coerentes indicando que o plastômetro de extrusão pode ser utilizado para este fim, os dados obtidos pela simulação de injeção indicaram que a mesma pode descrever com boa aproximação o processo de injeção do POM M90.

The thesis work is to show that the use of SLM (Additive Manufacturing) compared with the traditional process to make injection molds will have advantages in design, especially in waterways.  This thesis work gives seven different versions of design applied to the SLM method to analyze and compare them in Solidworks® and Moldflow® to figure out what design is suitable for the SLM method. Through analysis of different versions, the finding of this thesis work is that the conformal waterway of design and lighter but stead structure in the SLM method causes the SLM molds' cooling performance to be almost 15% better than the conventional way and shorten the production time by 18% per product. Based on the advantages of the SLM method in cooling system design and structure optimization, the company can use the SLM method in the production process to improve economic and environmental benefits.

Die Produktqualität und Kosten sind ein eindeutiger Indikator für die Wettbewerbsfähigkeit innovativer Produkte. Toleranzen steuern hier nicht nur die Prozesskosten in der Fertigung und Montage, sondern auch die endgültige Produktqualität. Mit der statistischen Toleranzanalyse werden diese Indikatoren vorhersagbar. Eine fertigungsprozessorientierte Toleranzvergabe ist heute unabdingbar, um Produkte schon frühzeitig in der Produktentwicklung mit den Mitteln der CAD-Umgebung robust nach den Grundsätzen von Design for Six Sigma auszulegen (DfSS=kein Ausschuss bei hoher Funktionalität). Viele innovative Produkte und Funktionsprinzipien würden ohne diese Vorgehensweise am Markt nicht bestehen können. Einige Beispiele aus der Praxis werden das im Rahmen dieses Vortrages aufzeigen.

The heat transfer in the filling phase of injection moulding is studied, based on Gunnar Aronsson’s distance model for flow expansion ([Aronsson], 1996). The choice of a thermoplastic materials model is motivated by general physical properties, admitting temperature and pressure dependence. Two-phase, per-phase-incompressible, power-law fluids are considered. The shear rate expression takes into account pseudo-radial flow from a point inlet. Instead of using a finite element (FEM) solver for the momentum equations a general analytical viscosity expression is used, adjusted to current axial temperature profiles and yielding expressions for axial velocity profile, pressure distribution, frozen layer expansion and special front convection. The nonlinear energy partial differential equation is transformed into its conservative form, expressed by the internal energy, and is solved differently in the regions of streaming and stagnant flow, respectively. A finite difference (FD) scheme is chosen using control volume discretization to keep truncation errors small in the presence of non-uniform axial node spacing. Time and pseudo-radial marching is used. A local system of nonlinear FD equations is solved. In an outer iterative procedure the position of the boundary between the “solid” and “liquid” fluid cavity parts is determined. The uniqueness of the solution is claimed. In an inner iterative procedure the axial node temperatures are found. For all physically realistic material properties the convergence is proved. In particular the assumptions needed for the Newton-Mysovskii theorem are secured. The metal mould PDE is locally solved by a series expansion. For particular material properties the same technique can be applied to the “solid” fluid. In the circular plate application, comparisons with the commercial FEM-FD program Moldflow (Mfl) are made, on two Mfl-database materials, for which model parameters are estimated/adjusted. The resulting time evolutions of pressures and temperatures are analysed, as well as the radial and axial profiles of temperature and frozen layer. The greatest differences occur at the flow front, where Mfl neglects axial heat convection. The effects of using more and more complex material models are also investigated. Our method performance is reported. In the polygonal star-shaped plate application a geometric cavity model is developed. Comparison runs with the commercial FEM-FD program Cadmould (Cmd) are performed, on two Cmd-database materials, in an equilateral triangular mould cavity, and materials model parameters are estimated/adjusted. The resulting average temperatures at the end of filling are compared, on rays of different angular deviation from the closest corner ray and on different concentric circles, using angular and axial (cavity-halves) symmetry. The greatest differences occur in narrow flow sectors, fatal for our 2D model for a material with non-realistic viscosity model. We present some colour plots, e.g. for the residence time. The classical square-root increase by time of the frozen layer is used for extrapolation. It may also be part of the front model in the initial collision with the cold metal mould. An extension of the model is found which describes the radial profile of the frozen layer in the circular plate application accurately also close to the inlet. The well-posedness of the corresponding linearized problem is studied, as well as the stability of the linearized FD-scheme. / <p>Report code: LiU-TEK-LIC-2002:66.</p>

End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the <cos2θ> for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting <cos2θ>. The breakage prediction improves if measured FLD of the extrudate is input into the model. / Autodesk Ltd.

A new material system was developed for fabricating the combustion engine of an unmanned aerial vehicle. The material system consisted of a mixture of nanoscale and microscale particles of silicon nitride. Magnesia and yttria were used as sintering additives. The powders were mixed with a paraffin binder system. The binder-powder was analyzed for its properties and molding attributes. The study involved several steps of the development and processing. These steps include torque rheometery analysis, mixing scale-up, property measurements of binder-powder, injection molding, binder removal, sintering, scanning electron microscopy analysis and mechanical properties measurements. Simulations of the injection molding process were conducted to assess the feasibility of manufacturing a ceramic engine and to determine its optimal process parameters. The model building required for the simulation was based on flow and solidification behavior data compiled for the binder-powder mixture. The simulations were performed using the Moldfow software package. A design of experiments approach was set up in order to gain an understanding of critical process parameters as well as identifying a feasible process window. Quality criteria were then analyzed in order to determine the optimal production parameters. The study resulted in the successful development of design parameters that will enable fabrication of silicon nitride engine components by powder injection molding. / Graduation date: 2012

Integrally moulded hinges and tension bands are important features in packaging components for plastic closures and their function is critically dependent on the flow induced micromorphology in the hinge section. Polymer characteristics and processing of the hinge also have an influence on the hinge properties obtained. This study is aimed at obtaining interrelationships between polymer characteristics, in-cavity flow, microstructure development and hinge properties, to produce hinges with enhanced functional properties. Three different virgin polypropylene (PP) grades were investigated (homopolymer PP-H, random copolymer PP-RC and impact copolymer PP-IC) and injection moulding simulation was carried out using Moldflow software. In-cavity data acquisition has been carried out for different sets of injection moulding conditions, using high performance transducers and a data acquisition system. A comparison between Moldflow simulation and practical injection moulding data suggests that, for thin wall injection moulded components the real time pressure data are in close agreement during the injection stage. During the packing stage there is some disagreement between these data, since the thickness of hinge and tension band sections are 0.4 mm and 0.5 mm respectively, suggesting that these dimensions are extending the capability of the software. An extensive study using a design of experiments (DoE) approach was carried out on both practical and predictive data. Injection velocity and melt temperature were the most influential factors on the component mechanical properties. From the optical micrographs it is observed that PP-RC has a finer micro-structure compared to PP-H and PP-IC and some micrographs confirm Moldflow simulation results in which hesitation effects are evident, as the flow converges into the thin hinge and tension band sections. PP-clay nanocomposites (PP-CN) were prepared using a twin screw compounder. Transmission electron microscopy (TEM) has shown some evidence of dispersion and exfoliation of the clay particles in the PP matrix. However, X-ray diffraction (XRD) results show a reduction in inter-layer spacing of PPCN s possibly due to clay compaction. The addition of nano-clay however has not resulted in any significant improvements in the mechanical properties of hinges and tension bands. The high degree of molecular orientation induced in the hinge and tension-band sections appears to mask any improvements attributed to the addition of nano-clay. From the reprocessed and post consumer recyclate (PCR) study conducted on hinges and tension bands, it is seen that with an increase in both the re-processing and PCR content there is a decrease in the component strength of around 14%, giving scope to potentially use PCR in future packaging applications. Investigations conducted on colour pigments (violet and green) reveal that the onset of crystallisation for green pigmented mouldings is considerably higher (16°C) than for natural and violet mouldings. Optical micrographs also reveal a finer microstructural texture for green components, indicating a high nucleating capability of the green pigment. Irrespective of the colour, both for hinges and tension bands, the yield stress values were around twice as high as the values quoted in the manufacturer s data sheet for isotropic PP, due to the high levels of molecular orientation in the hinge and tension band sections. In order to industrially validate the findings from the DoE study, commercial closures were produced in industry on a production tool then characterised. In the case of tension bands, there was a good agreement between the results obtained from lab scale and industrial study due to the relatively simple geometry. For hinges this agreement is not so clear. Finally a comparison of mechanical properties of the 3 PP grades shows that PP-H has a higher yield stress compared to PP-IC and PP-RC and yield stress is significantly higher (yield strain values are lower) than values quoted by the manufacturer. The PhD study has confirmed the process conditions that are able to optimise all the interactive effects to improve functional properties in high volume parts in the packaging industry.

Formsprutning är en tillverkningsmetod somställer krav på produkters utformning. För att göra en lämplig ingötsplacering räcker inte alltid riktlinjer utan en produktspecifik analys kan vara nödvändig. Materialval kräver en tydlig kravspecifikation och kan med fördel göras i samråd med en materialexpert. Riktlinjer för Design for manufacturing and assembly inkluderar bland annat rekommendationer för formgivning. Detta kandidatarbete strävar efter att hjälpa produktutvecklare att tidigt i produktutvecklingsprocessen ta hänsyn till tillverkningsaspekter. Baserat på litteraturstudier, intervjuer och fallstudier har riktlinjer tagits fram för materialval, design for manufacturing and assembly och formgivning för formsprutning. Arbetet är avgränsat till att endast titta på formsprutningsbara termoplaster. Arbetet, som genomförts vid Linköpings universitet, är en del av projektet Säkra monteringsverktyg som resulterade i ett portabelt dödmansgrepp. Defallstudier som genomfördes inom projektetbehandlar värdering av koncept utifrån produktionsperspektiv, materialval och formsprutningsanalyser i programmet Moldflow. Arbetet resulterade i riktlinjer för applicering av metoden design for manufacturing and assembly, formsprutningsanpassning samt materialval. Fallstudien i Säkra monteringsverktyg utmynnade ien värdering av koncept utifrån produktionsaspekter, ett materialval baserat på projektets kravspecifikation och rekommendationer för produktens utformning med syfte att optimera dess tillverkning. En slutsats av arbetet är att produktionsanpassning av produktens utformning bör ske tidigt i utvecklingsprocessen. En annan slutsats är att besök i industrin, hos exempelvis ett formsprutningsföretag, leder till bättre förståelse av vilka krav som behöver uppfyllas för att en produkt ska vara möjlig att producera. Om simuleringsprogram för formsprutning finns bör det användas i kombination med riktlinjer för produktutformning. Ytterligare en slutsats som gjorts är att materialval underlättas genom tidig kontakt med materialleverantörer. Materialvalet baseras på kravspecifikationen och därför bör kraven tydliggöras och dess rimlighet kontrolleras innan materialvalet sker. / Injection molding is a manufacturing method that requires specific features to attain manufacturability. Gating suitability requires analysis and mere guidelines do not always provide the correct gate placement. Material selection requires a pronounced specification and is preferably supervised by an expert. Guidelines concerning design for manufacturing and assembly include, among other things, recommendations directly affecting the shape of the product. The aim for this bachelor thesis is to aid product developers and designers in taking manufacturing aspects into account early in the product development process. This is achieved by providing them with guidelines regarding material selection, injection molding, as well as design for manufacturing and assembly. The thesis is limited to thermoplastic materials suitable for injection molding and its results are based off thorough literature research, interviews and case studies. This bachelor thesis project, which is conducted at Linköping University,is a part of a project calledSafe manual assembly tools, and the resulting portable enabling device developed in Safe manual assembly toolsis used as case studies in this thesis. The case studies include: evaluation of concepts concerning manufacturability; material selection; and injection molding analysis through the software Moldflow. The thesis results in guidelines concerning design for manufacturing and assembly, injection molding and material selection. The case study is requited with concept selection suggestions, a selection of material that meets the specification of requirements stated in Safe manual assembly tools and design recommendations that aim to improve the manufacturability of the concept. This bachelor thesis concludes that design alterations striving to meet requirements for manufacturability should be made early in the devolpment process. Visiting the polymer-based product manufacturing industry offers better insight into which requirements that need to be fulfilled to make a product producible. Injection molding simulation software, if such is available, should be used in combination with design guidelines.The thesis also concludes that material selection is simplified through early contact with suppliers of material. Material selection is based off the specification of requirements and therefore requirements specified in the specification should be clarified and have their plausibility confirmed before the selection takes place.