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1
Scholz, Steffen Gerhard. « Micro injection moulding : process monitoring and optimisation ». Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/14054/.
Texte intégralRésumé :
The advances in micro engineering and especially micro products and micro components with functional micro and nano structures / features are directly dependent on the advances in manufacturing technologies for their scale up production. Micro injection moulding is one of the key technologies for cost affective serial production of micro components. In this thesis, the process capabilities and constraints of this technology were studied systematically. More specifically, new tool making process chains and various process factors affecting the micro injection moulding process were investigated. The manufacturing capabilities of this technology were further analysed by investigating the filling behaviour of micro cavities, the influence of air in micro cavities and the forces occurring during the demoulding stage. Chapter 2 of this thesis reviews the slate of the art in micro tooling and micro injection moulding. In Chapter 3 an advanced condition monitoring system was developed to better understand the behaviour of the injection moulding process. In particular, cavity pressure sensors were utilised to analyse interdependences between process conditions and key characteristics of cavity pressure curves. Chapter 4 investigates the influence and effects of air inside micro cavities. A design of experiments’ study was carried out to identify process settings for achieving an optimum filling of micro cavities In particular the flow length inside the cavity was investigated to judge about the process performance. Next, the demoulding stage of the injection moulding cycle was studied in Chapter 5. In particular, ejection forces were analysed to investigate the influence of different process settings on demoulding behaviour of polymer parts. This is especially important in order to avoid any part damage during demoulding. In Chapter 6 micro stereolithography was used to fabricate mould inserts for micro injection moulding. Experiments were carried out with such mould inserts, and the tool life in relation to process settings for both the manufacture of the inserts and their replication performance, was studied systematically. Finally, Chapter 7 summarises the main conclusions and contributions to knowledge of this research. Also, future research directions in the area of micro injection moulding are proposed and briefly discussed The main findings of this research can be summarised as follows: • Indirect measurement methods can be utilised to monitor cavity pressure conditions in micro injection moulding and it was shown that Pmax, Pwork and Prate were dependent on the materials and processing conditions. • The performance of the u-IM process can be improved by understanding the effects of V1 and air evacuation on Qmax, Q, and the part flow length. High u-IM process settings and a limited venting through the primary split line have a significant impact on the filling performance. The u-IM process performance can be improved by incorporating secondary vents and by applying vacuum methods for air evacuation. • Pmax, Pwork and Fe max were dependent on the processing conditions and there is a direct correlation between cavity pressure and demoulding force. The position of the pressure sensors is important, but the readings of both sensors correlate. The holding pressure has the highest impact on the maximum demoulding forces. Rapid tooling can be applied successfully in u-IM and offers a faster, cheaper and highly flexible manufacturing route for producing prototypes in the final material. Only the uSL inserts produced with a layer thickness of 20 um (less undercuts) survived during the demoulding stage. The best results were achieved with PP, followed by PC. ABS polymer parts couldn’t be replicated successfully.
2
Corrigan, N. E. « Development of the reactive rotational moulding process ». Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273426.
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3
Griffiths, Christian Andrew. « Micro injection moulding : tooling and process factors ». Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54854/.
Texte intégralRésumé :
The development of new micro devices is highly dependent on manufacturing systems that can reliably and economically produce micro components in large quantities. Micro injection moulding is one of the key technologies for micro-manufacture and is considered as a cost effective replication method for mass production. The capabilities of this replication technology have to be studied systematically in order to determine the process constraints. The present work concerns the tooling and process factors that influence micro injection moulding. The requirements of this manufacturing process are identified, and a review of the current state of the art in the field, Chapter 2, is used to assess the potential of this technology. To analyse further the manufacturing capabilities of this technology against the requirements, an investigation of the pre-filling, filling and part removal stages of the process cycle is conducted. In particular, in Chapter 3 the pre-filling capabilities of multi cavity micro tools with the use of a runner system is explored. The filling performance of spiral-like micro cavities was studied as a function of runner size in combination with selected process factors. Then, in Chapter 4 the filling of micro mould cavities with controlled tool surface finishes is investigated. Factors affecting the flow behaviour are discussed and a special attention is paid to the interaction between the melt flow and the tool surface roughness. Using the same part design as that of the tool surface finish investigation, in Chapter 5 a Finite Element Analysis (FEA) is used to verify the effects of process parameters, particularly the factors affecting shear rate, pressure and temperature. The results of this investigation were then compared with those reported in the experimental study. Finally, in Chapter 6 the application of micro mould surface treatments is analysed. The effects of different surface treatments on the de-moulding of parts with micro features are investigated to identify the best processing conditions in regards to de-moulding behaviour. To validate the process effects for these three process stages micro injection moulding experimental set-ups were specially designed and implemented. These experiments apply various part designs, tool-making techniques, process factors, part inspection and condition monitoring techniques, and FEA. To further understand the importance of process characteristics at the micro scale, an in depth analysis of the experimental results for each of the selected investigations was carried out. Finally, in Chapter 7 the results from each of the investigations are summarised, and the main research findings identified, in particular the influence of runner size on the process performance, tool surface finish effects on the filling process, the accuracy and sensitivity of the proposed FEA model, and the effects of tool surface treatment on part de-moulding.
4
Correia, Nuno André Curado Mateus. « Analysis of the vacuum infusion moulding process ». Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/12762/.
Texte intégralRésumé :
This thesis focuses on flow through compliant porous media with applications to the manufacturing of composites by vacuum infusion (VI). The context of this work is the need for reliability in environmentally friendly composite processing methods for composite materials. Commercial reality and the prospective application to low cost structures for the transportation industry dictate that appropriate emphasis should be put on obtaining robust simulations, ensuring reliability and progressing toward efficient means of process control. In this context, the open mould manufacturing processes which have been used to produce large composite structures, and are not conducive to quality nor environmental responsibility, must be replaced. Hence, establishing composites as a viable alternative requires closed moulding techniques, of which VI is the most practical for large structures, but where reliability is required for economic survival. This work addresses many aspects of this problem, by making innovative use of fluid mechanics and developing, implementing and proposing new analysis and modelling tools for VI. Main results include a validated analytical model for flow through compliant media, a study of the compliance of textile reinforcements, a finite element model for VI and novel stochastic techniques for the analysis of reliability in liquid composite moulding processes. The work discussed herein stems from a thorough evaluation of published models and leads to novel flow modelling tools for VI including a unique and general formalism for textile compliance. Using these tools it was possible to study, for the first time, the effect of different parameters on VI manufacturing. The reliability issue was addressed by integrating stochastic models for compliance and permeability, and the ability to model complex geometries was demonstrated by adapting a commercial finite element flow code (LIMS).
5
Bon, Abdul Talib. « Process quality improvement on beltline moulding manufacturing ». La Rochelle, 2008. http://www.theses.fr/2008LAROS239.
Texte intégralRésumé :
Le monde industriel de fabrication d'aujourd'hui doit satisfaire la demande des utilisateurs finaux et l'un des facteurs déterminants est la demande des produits de haute précision. Plusieurs stratégies ont été employées par les fabricants pour réduire le nombre des défauts et prédire la précision des processus de fabrication. L'approche de l'amélioration de contrôle de qualité, implémentée dans cette étude, comprend la mise en place des paramètres et l'optimisation pour le processus de la moulure des ceintures de caisse afin de réduire la durée de la prise et le nombre des défauts. Nous avons développé de nouvelles techniques dans la sélection des paramètres et l'optimisation, dans lesquelles nous utilisons deux techniques statistiques qui sont notamment l'optimisation d'essaim de particules et l'algorithme génétique. Les techniques de prévisions ARIMA développées au cours de cette étude pourraient devenir un outil d'interprétation des données plus supérieur que la méthodologie traditionnelle existante. Les résultats de cette étude serviront d'évidences utiles dans l'applicabilité de l'implémentation de la méthodologie de la moulure des ceintures de caisses proposée aux fabricantsThe world of manufacturing industries is forced to meet the demand of the end users and one of the factors is highly quality demand from customer and highly precise products have determined by manufacturing systems. Many strategues from manufacturer already did how to reduce the number of defected and forecast the manufacturing process to more accurate. Process Quality Improvement approach was introduced and implemented in this study. Which is a parameter setting and optimization for beltline moulding process have developed and optimized to both shorten setting time and reduce number of detect procedures. We developed new techniques in parameter selection and optimization which is we apply a statistical techniques, Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) approach in this study. The ARIMA forecasting techniques developed for this study can forecast, and can become superior to traditional methodology where interpretation is needed. The findings from the study will serve as a useful evidence and applicability of the proposed methodology to beltline moulding manufacturer for implementation
6
Vietri, Umberto. « Intelligent monitoring of the injection moulding process ». Doctoral thesis, Universita degli studi di Salerno, 2011. http://hdl.handle.net/10556/1602.
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2009-2010The quality requirements of injection-moulded components have become more stringent because of the growing s applications of plastics and increasing customer demands. The quality of the moulded parts depend on the processing conditions and this creates a continuous demand for developing advanced techniques for monitoring and controlling the process The current practice in industry is to adjust the parameters based on the product defects through trial and error, starting from information from the material supplier, mould designer, and, largely, on the basis of the moulding engineer’s (or setup person’s) own experience. Nevertheless, defects can occur in moulded parts due to, for instance, the variation in material properties (particularly when reground or biodegradable resins are used), the change in environmental conditions (e.g., humidity or temperature in the surroundings), and the machine characteristics (particularly those using hydraulic power). In this case, the process conditions have to be readjusted in order to re-establish the part quality targets. To overcome these difficulties, injection moulding quality control has been the subject of many off-line and on -line quality control studies. The purpose is to achieve automatic and adaptive quality control able to guarantee a stable and repeatable process, from the part quality point of view.[edited by author]
IX n.s.
7
Somnuk, Peerawat. « Experimental study of simultaneous co-injection moulding process ». Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308577.
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De, Kock Willem Johan. « Numerical simulation of the plastics injection moulding process ». Doctoral thesis, University of Cape Town, 1994. http://hdl.handle.net/11427/18307.
Texte intégralRésumé :
The Hele-Shaw formulation is widely used for the simulation of the injection moulding process. The influence of the Hele-Shaw approximations is, however, unknown. A two-dimensional numerical model based on the Hele-Shaw formulation, and a model based on the Navier-Stokes equations without the Hele-Shaw approximations were developed. The solutions obtained with these two approaches were compared to investigate the influence of the Hele-Shaw approximations on the simulation of the injection moulding process. Weakly compressible, non-Newtonian flow of an amorphous polymer melt under non-isothermal conditions were simulated using constitutive equations generalized to non-Newtonian materials. The finite volume method, which is a very powerful method yet easy to use, was used to discretize the governing equations as compared to finite element methods used in most other reported models. The influence of the Hele-Shaw approximations on the solutions of specific flow cases was determined by comparing the solutions obtained with the model based on the Hele-Shaw formulation and the model based on the Navier-Stokes equations. Parametric studies were done to compare the solutions of the two numerical models for a wider range of flow cases. The following conclusions were made as a consequence of this study: Numerical models to simulate the injection moulding process can be simplified and the computer time required to solve these models can be reduced by using the Hele-Shaw formulation instead of solving the full Navier-Stokes equations. Numerical models based on the Hele-Shaw formulation are well suited to simulate the injection moulding process when the geometries and flow conditions fall within certain limits. These limits are determined by the combined effect of the geometry and the flow conditions represented by the Reynolds number. The simplicity of the finite volume method used in the generalized Hele-Shaw model makes it an attractive model to use for injection moulding simulations.
9
Zhiltsova, Tatiana Vladimirovna. « Injection moulding process optimization for microstructured parts production ». Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12059.
Texte intégralRésumé :
Doutoramento em Engenharia MecâncicaAo longo das últimas décadas, a micromoldação (u-moldação) por injeção de termoplásticos ganhou um lugar de destaque no mercado de equipamentos eletrónicos e de uma ampla gama de componentes mecânicos. No entanto, quando o tamanho do componente diminui, os pressupostos geralmente aceites na moldação por injeção convencional deixam de ser válidos para descrever o comportamento reológico e termomecânico do polímero na microimpressão. Por isso, a compreensão do comportamento dinâmico do polímero à escala micro bem como da sua caraterização, análise e previsão das propriedades mecânicas exige uma investigação mais alargada. O objetivo principal deste programa doutoral passa por uma melhor compreensão do fenómeno físico intrínseco ao processo da μ-moldação por injeção. Para cumprir com o objetivo estabelecido, foi efetuado um estudo paramétrico do processo de μ-moldação por injeção, cujos resultados foram comparados com os resultados obtidos por simulação numérica. A caracterização dinâmica mecânica das μ-peças foi efetuada com o objetivo de recolher os dados necessários para a previsão do desempenho mecânico das mesmas, a longo prazo. Finalmente, depois da calibração do modelo matemático do polímero, foram realizadas análises estruturais com o intuito de prever o desempenho mecânico das μ-peças no longo prazo. Verificou-se que o desempenho mecânico das μ-peças pode ser significativamente afetado pelas tensões residuais de origem mecânica e térmica. Estas últimas, resultantes do processo de fabrico e das condições de processamento, por isso, devem ser consideradas na previsão do desempenho mecânico e do tempo de serviço das u-moldações.
Over the last decades, microinjection moulding (uIM) of thermoplastics has gained a pertinent place on the market of electronic equipment and a broad range of the mechanical aids. However, when size of components drop to the micro level, the assumptions of the conventional injection moulding cease to describe the complex rheological and thermo-mechanical behavior of the polymer in the microimpression. Therefore, understanding of the polymer flow dynamics at the micro scale as well as characterization, assessment and prediction of the final mechanical properties require a great deal of additional research. The prime objective of this doctoral thesis is to get an insight into the physical phenomena inherent to μIM process. In order to comply with the established objective, a number of parametrical studies of the μIM process were carried on an instrumented micromould and then their results were compared with the obtained numerical simulation results gathered from process modeling phenomena. Dynamical mechanical characterization of μ-moulded parts was performed in order to collect the data required for prediction of their long-term mechanical performance. Finally, after calibration of polymer material model, a long-term transient structural analysis was carried out. It was found out that the structural performance of microparts was significantly affected by the thermo-mechanical (residual) stresses. The latter is an inherent feature of the injection moulding processing, and therefore has to be accounted for the prediction of the u-moulded parts’ service life.
10
Schiffers, Reinhard, Georg P. Holzinger et Gernot Huster. « Adaptive process control for stabilizing the production process in injection moulding machines ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200201.
Texte intégralRésumé :
Plastic injection moulding machines are a positive example of the possibilities in terms of performance and energy efficiency of modern hydraulic drives technology. In addition to the performance and energy efficiency of the machines, the quality of the plastic mouldings and an easy to use machines control is the focus. To ensure a constant plastics part quality the set process parameters of the injection moulding machines are kept constant by appropriate closed loop control strategies today. Assuming a constant quality of the processed plastic raw material, this strategy is effective. If it comes to a qualitative variation in the processed plastics, which often leads to a change in viscosity of the plastics melt, keeping processing parameters constant will not lead to a constant quality of the moulded parts. The deviations in the plastics viscosity have such a great influence on the moulding process that the relevant process parameters have to be adjusted manually in many cases. Often the stroke of the reciprocating screw system has to be adapted to reach a constant filling volume of the cavity and therefore avoid burr formation or short shots. In this paper an approach for adaptive process control is introduced. This control loop is able to correct the set points of specific machines parameters online within the production cycle and therefore is able to avoid changes in the produced parts quality.
11
Jüttner, Gabor, Tham Nguyen-Chung, Günter Mennig et Michael Gehde. « Simulation of the Filling Process in Micro-Injection Moulding ». Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200801189.
Texte intégralRésumé :
Nowadays, the filling and solidification of macro-scale injection mouldings can be predicted using commercial CAE software. For micro-injection moulding, the conventional tools do not work for all process conditions. The reasons might be the lack of high quality database used in the simulation and the improperly specified boundary conditions which do not reflect the real state in the cavity. Special aspects like surface tension or "size dependent" viscosity might also be responsible for the inaccuracy of the simulations.
In this paper, those aspects related to the boundary conditions were taken into consideration, especially the thermal contact behaviour and the melt compression in the barrel which affects not only the temperature of the melt due to the compression heating, but also reduces the actual volume rate in the cavity. It can be shown that the heat transfer coefficient between the melt and the mould wall has a significant influence on the simulation results. In combination with precise material data and considering the reduction of the volume rate due to the melt compression in the barrel, the heat transfer coefficient may be quantified by means of reverse engineering. In general, it decreases when either the cavity thickness or the injection speed increases. It is believed that a pressure dependent model for the heat transfer coefficient would be more suitable to describe the thermal contact behaviour in micro injection moulding. The melt compression in the barrel affects definitely the filling behaviour and subsequently the heat transfer in the cavity as well, which is especially true for micro parts of high aspect ratio.
12
Khan, Muhammad Imran, et Muhammad Junaid Atta. « Process control and automation of a PU moulding machine ». Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Data- och elektroteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-17588.
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This Thesis Involves the Automation and Control of PU moulding machine. Foam is made by a chemical reaction of ISO and Polyol, when they combined each other by the help of some agitator or with some mixing element, foam starts to grow which can shaped after. Previously there were such companies for foam making moulding machines they designed low pressure machines, because of this foam quality were not good because of low agitation and penetration. This Project is based on the Improvement and enhancement of such moulding machines with high pressure up to 200 Bar.
13
Yin, Kam Hoe. « Dynamic optimisation for energy efficiency of injection moulding process ». Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28837/.
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Low carbon economy has emerged as an important task in China since the energy intensity and carbon intensity reduction targets were clearly prescribed in its recent Twelfth Five-Year Plan during 2011-2015. While the largest enterprises have undertaken initial initiative to reduce their energy consumption, small and medium-sized enterprises (SMEs) will need to share the responsibilities in meeting the nation’s targets. However, there is no established structure for helping SMEs to reduce their efficiency gap and hence the implementation of energy-saving measures in SMEs still remains patchy. Addressing this issue, this thesis seeks to understand the critical barriers faced by SMEs and aims to develop proprietary methodologies that can facilitate manufacturing SMEs to close their efficiency gap. Process parameters optimisation is perceived to be an effective “no-cost” strategy which can be conducted by SMEs to realise energy efficiency improvement. A unique design of experiment (DOE) introduced by Dorian Shainin offers a simplistic framework to study process optimisation, but its application is not widespread and being criticised over its working principles. In order to address the inherent limitations of the Shainin’s method, it was integrated with the multivariate statistical methods and the signal-response system in the empirical study. The nature of the research aim also requires a theoretical approach to evaluate the economic performance of the energy efficiency investment. Hence, a spreadsheet-based decision support system (file SERP.xlsm) was created via dynamic programming (DP) method. The main contributions of this thesis can be subdivided into empirical level and theoretical level. At the empirical level, a technically feasible yet economically viable approach called “multi-response dynamic Shainin DOE” was developed. An empirical study on the injection moulding process was presented to examine the validity of this novel integrated methodology. The emphasis has been on the integration of multivariate techniques and signal-response analysis. The former successfully identified the critical factors to energy consumption and moulded parts’ impact performance regardless of the great fluctuation in the impact response. The latter enables the end-user to achieve different performance output based on the particular intent. At the theoretical level, the “DP-based spreadsheet solution” provides a convenient platform to help the rationally-behaved decision makers evaluate the energy efficiency investments. A simple hypothetical case study on the injection moulding industry was illustrated how the decision-making process for equipment replacement can evolve over time. To sum up, both proprietary methodologies enhance the dynamicity in the optimisation process to support injection moulding industry in closing their efficiency gap. The study at the empirical level was limited by the absence of real industrial case study where it is important to justify the practicality of the proposed methodology. Regarding the theoretical level, the dataset for initial validation on the spreadsheet solution was not available. Finally, it is important to continue the future work on the research limitations in order to increase the cogency of the proprietary methodologies for common use in the industry.
14
Dorf, Tomasz. « Contributions to ultrasonic micro-moulding process of high performance polymers ». Doctoral thesis, Universitat de Girona, 2019. http://hdl.handle.net/10803/667506.
Texte intégralRésumé :
Polymeric materials, which are suitable for high performance applications for example human
implants are one of the most expensive available polymers. Standard injection micromoulding
process, dedicated for mass production, it is often uneconomical for low-series or
single-piece production.
Recently available ultrasonic-micro moulding technology, which can plasticize only amount of
polymers required for one part seems to be a potential alternative to standard injection micromoulding
technology especially by limiting the waste of materials during small production
runs. This thesis focus on increasing knowledge about the ultrasonic micro-moulding process
of polymers, such as polyphenylsulfone PPSU and polyetheretherketone PEEK, establishing
relationship between the process parameters and the key aspect of the high performance
parts such as mechanical propertiesEls materials polimèrics de altes prestacions són considerats apropiats per desenvolupar diferents aplicacions, en especial en el cas dels implants o próstesis mediques. El procés de injecció o en el seu defecte la micro-injecció ve essent utilitzada per la fabricació en grans volums, però resulta inapropiat per la fabricació de petites sèries pel seu cost econòmic. Recentment els avanços realitzats en la tecnología del moldeig per ultrasons ha fet que aquesta sigui una tecnología més apropiada per la fabrició de petites sèries. El moldeig per ultrasons permet fondre, moldejar i solidificar la quantitat necessària per fer una peça petita, evitant així una gran pèrdua de material en les zones de colades. Aquesta tesi doctoral és una contribució al coneixement del procés de micro-injecció per ultrasons amb materials d’altres prestacions com el polifenilsulfona PPSU i el polieteretercetona PEEK, establint relacions entre els paràmetres de processat i les propietats mecàniques del producte, establint un aspecte clau en la producció de futures peces
15
Fronimidis, Dimitris. « On-line monitoring and control of the injection moulding process ». Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436877.
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Whiteside, Benjamin R., Maxims Babenko et Elaine C. Brown. « Micro Molding Process Monitoring and Control ». Carl Hanser Verlag, 2018. http://hdl.handle.net/10454/17075.
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Hopkinson, N. « Investigation into part injection and heat transfer in the direct AIM'T'M process ». Thesis, De Montfort University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391647.
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Sombatsompop, Narongrit. « The characteristics fo flowing polymer melts in the injection moulding process ». Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493734.
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Nixon, James. « Analysis of the stretch blow moulding process and subsequent simulation development ». Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677457.
Texte intégralRésumé :
Injection stretch blow moulding (ISBM) is the most common processing method of producing thin-walled poly (ethylene) terephthalate (PET) containers. With numerous processing parameters and complex deformation, there is still a certain amount of expert knowledge required to successfully convert a PET preform into a useable bottle, capable of passing rigorous post-process testing. The purpose of this work is to develop an accurate simulation of the bottle forming procedure through extensive examination of the input parameters and how they affect the preform deformation and bottle characteristics. By removing the bottle mould, a free-stretch-blow analysis was performed over a large process window. This procedure utilised the digital image correlation (DIC) method with a patterned preform heated using an oil bath. A corresponding simulation was constructed using ABAQUS/Explicit FE solver and a constitutive viscoelastic user material subroutine. A comparison between the experimental and predicted values of internal cavity pressure, stretch-rod force and surface strain was performed resulting in reduced accuracy at low flow rate, sequential-type deformations. Free-stretch-blow trials also highlighted the need for adequate preform storage as increased moisture content affects the deformation behaviour. Reapplying the bottle mould and using the same process parameters revealed that the simulation had difficulties in predicted accurate bottle thickness, particularly at higher flow rate. An insufficient contact friction model was concluded and more insight into the heat transfer and back pressure between the polymer and mould was required. Results from the simulation also demonstrated that the previously assumed incompressible behaviour of PET during bottle formation is incorrect. A novel method of measuring strain levels in all three directions was devised to reveal that deformation mode greatly affects the value of Poisson's ratio. Insight into the ISBM process and development of the simulation has been advanced through this work and key areas of further improvement have been revealed.
20
Statham, Michael J. « Economic manufacture of freeze-cast ceramic substrate shapes for the spray-forming process ». Thesis, University of Bath, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285297.
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Ruano, Bocaletti P. (Pamela). « Process analysis of the forming process during blow moulding of rubbers and the resulting component quality ». Master's thesis, University of Oulu, 2018. http://urn.fi/URN:NBN:fi:oulu-201802281272.
Texte intégralRésumé :
Silicone rubbers are inorganic polymers whose structure contains repeating silicon-oxygen groups. Among their properties are high resistance to temperature, ultraviolet light and oxidation. Silicone rubbers offer little stability against deformation and tears very fast, which makes it, on its uncured state, not suitable for extrusion blow moulding. To improve the blowability of the rubbers, a precuring step is used. A goal of this thesis is to better understand the inflation process of precured silicone rubbers. In addition, it is aimed to produce hollow bodies and examine their part quality. The blow moulding process was studied in free and confined inflation. First, free parison inflation profiles were studied to determine the parameters that have an influence on the inflation process. The blowing pressure, parison temperature, pre-curing degree, die gap of the extrusion head, wall thickness and the shore hardness of the material for the solid silicone rubber Addisil 20XXE were studied on this first stage. Results show that inflating the parison after the extrusion is key for the process. Parison in the studied range also benefit from lower pressures and a smaller die gap.
The study of confined parison inflation profiles show that it is possible to use the extrusion blow moulding process to produce hollow bodies of silicone rubber using the parameters determined on the first stage of the research. First, confined inflation was studied with glass bottles. Afterwards, bottles were produced and cured using a heated tool. The part quality of the bottles formed were studied. Aspects such as surface quality, wall thickness distribution and quality of the weld seams were studied. Results show that the surface quality is highly dependent on the quality of the parison. The study of the wall thickness distribution shows that the centering of the die gap and the position of the parison when inflating have a big influence on the resulting distribution. The weld seams proved to fully seal and cure. These results apply mostly for parisons 32 cm long or shorter. Longer parisons could need higher inflation pressures. An important step for further research is the automation of the blow moulding process, in order to reduce significant sources of error. The results of this thesis allow further research to focus on improving the quality of the hollow bodies and the stability of the process.
22
Yang, Ziqi. « Advanced batch process modelling, control and optimization for injection stretch blow moulding ». Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713464.
Texte intégralRésumé :
The injection stretch blow Moulding (ISBM) process is widely used to manufacture PET bottles for the beverage and consumer goods industry. However, at present the ISBM process, including both the stretch blow moulding and reheating processes, are totally open-loop. The processes are complex and users often have to rely heavily on trial and error method to set up and control it. In this research, with the main purpose to displace this experience-based trial and error method in the ISBM process, the associated modelling and control methods are proposed.
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Dawson, A. J. « Process and production measurements for automatic inspection and control of injection moulding ». Thesis, University of Bradford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535848.
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Lim, Kok Khoon. « Modelling of the rotational moulding process for the manufacture of plastic products ». Thesis, Nottingham Trent University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403085.
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Scott, J. A. « A study of the effect of process variables on the properties of rotationally moulded plastic articles ». Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381175.
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Fu, Tingrui. « PP/clay nanocomposites : compounding and thin-wall injection moulding ». Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24655.
Texte intégralRésumé :
This research investigates formulation, compounding and thin-wall injection moulding of Polypropylene/clay nanocomposites (PPCNs) prepared using conventional melt-state processes. An independent study on single screw extrusion dynamics using Design of Experiments (DoE) was performed first. Then the optimum formulation of PPCNs and compounding conditions were determined using this strategy. The outcomes from the DoE study were then applied to produce PPCN compounds for the subsequent study of thin-wall injection moulding, for which a novel four-cavity injection moulding system was designed using CAD software and a new moulding tool was constructed based upon this design. Subsequently, the effects of moulding conditions, nanoclay concentration and wall thickness on the injection moulded PPCN parts were investigated. Moreover, simulation of the injection moulding process was carried out to compare the predicted performance with that obtained in practice by measurement of real-time data using an in-cavity pressure sensor. For the selected materials, the optimum formulation is 4 wt% organoclay (DK4), 4 wt% compatibiliser (Polybond 3200, PPgMA) and 1.5 wt% co-intercalant (erucamide), as the maximum interlayer spacing of clay can be achieved in the selected experimental range. Furthermore, DoE investigations determined that a screw speed of 159 rpm and a feed rate of 5.4 kg/h are the optimum compounding conditions for the twin screw extruder used to obtain the highest tensile modulus and yield strength from the PPCN compounds. The optimised formulation of PPCNs and compounding conditions were adopted to manufacture PPCN materials for the study of thin-wall injection moulding. In the selected processing window, tensile modulus and yield strength increase significantly with decreasing injection speed, due to shear-induced orientation effects, exemplified by a significantly increased frozen layer thickness observed by optical microscopy (OM) and Moldflow® simulation. Furthermore, the TEM images indicate a strong orientation of clay particles in the flow direction, so the PPCN test pieces cut parallel to the flow direction have 36.4% higher tensile modulus and 13.6 % higher yield strength than those cut perpendicular to the flow direction, demonstrating the effects of shear induced orientation on the tensile properties of thin-wall injection moulded PPCN parts. In comparison to injection speed, mould temperature has very limited effects in the selected range investigated (25-55 °C), in this study. The changes in moulding conditions show no distinctive effects on PP crystallinity and intercalation behaviour of clay. Impact toughness of thin wall injection moulded PPCN parts is not significantly affected by either the changes in moulding conditions or clay concentration (1-5 %). The SEM images show no clear difference between the fracture surfaces of PPCN samples with different clay concentrations. TEM and XRD results suggest that higher intercalation but lower exfoliation is achieved in PPCN parts with higher clay content. The composites in the thin sections (at the end of flow) have 34 % higher tensile modulus and 11 % higher yield strength than in the thicker sections, although the thin sections show reduced d001 values. This is attributed to the significantly enhanced shear-induced particle/molecular orientation and more highly oriented frozen layer, according to TEM, OM and process simulation results. In terms of the reduced d001 values in the thin sections, it is proposed that the extreme shear conditions in the thin sections stretch the PP chains in the clay galleries to a much higher level, compaction of clay stacks occurs as less interspacing is needed to accommodate the stretched chains, but rapid cooling allows no time for the chains to relax and expand the galleries back. Overall, data obtained from both actual moulding and simulation indicate that injection speed is of utmost importance to the thin-wall injection moulding process, development of microstructure, and thus the resulting properties of the moulded PPCN parts, in the selected experimental ranges of this research.
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Gebart, Rikard. « Analysis of heat transfer and fluid flow in the resin transfer moulding process ». Doctoral thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 1992. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26582.
Texte intégralRésumé :
This thesis contains an analysis of fluid flow and heat transfer problems in the resin transfer moulding (RTM) process for manufacturing of polymer based fibre composites and it consists of five separate papers. The permeability of unidirectional fabrics, that are often used in advanced composites, is considered in Paper A and a theory for the permeability dependence on the micro geometry is developed. The theory is based on lubrication theory for narrow gaps which is motivated by the fact that most of the flow resistance comes from a small region where the fibres are closest to each other. Despite this limitation the results agree excellently with numerical results. 'Me best performance of the theory is expected at high fibre volume fractions (Vf) but the dependence on Vf is surprisingly good even at as low values as 0.3. Although the theory is formulated for an idealised geometry it can be used to predict the variation of the anisotropic permeability tensor with fibre volume fraction in real fabrics after fitting of three model parameters. Paper B is a study of the influence from different process parameters on the void content in the laminate. The void content is shown to be reduced strongly by an applied vacuum during mould filling. The main mechanism for void formation appears to be mechanical entrapment at the flow front. The voids are convected by the flow so that their concentration is highest close to the flow front. Microscopy investigation of the bubbles show that they are of two basic types, large spherical bubbles in the interstices between fibre bundles and smaller cylindrical bubbles inside the fibre bundles. The positive influence of vacuum compared to no vacuum can be explained as a combined effect of an increased mobility due to larger volume changes during mould filling and compression by the increased pressure during cure. In Paper C a comparison is made between the mould filling times for different injection strategies. The possible alternatives for a normal laminate are point injection, edge injection and peripheral injection. Theoretical results are derived that can be used to estimate the mould filling time with the different alternatives. In addition, fundamental theoretical results are derived from the governing equations showing the scaling of the mould filling time with the process parameters. This analysis also shows that the flow front motion during mould filling is only a function of the anisotropy of the reinforcement and the location of the gates. Paper D presents an analysis of the non-uniform flow at the flow front during impregnation of a stack of fabrics consisting of layers with different flow resistance. A detailed derivation of the theory and an analytical solution to the equations are presented in an addendum to Paper D. The theoretical model is compared with experimental results and is found to describe the experiment qualitatively well. The resulting permeability of a stack of different fabrics is derived from the basic equations and is found to be a weighted average of the permeability in the individual layers. This result is compared with experiments with different stacking sequences and it is found that the stacking sequence has no influence on the resulting permeability as expected from the theory. Experimental results in excellent agreement with Darcy's law are also presented for the case with radial flow and with unidirectional flow. Finally, Paper E is a theoretical study of the curing behaviour of thick laminates. A general solution independent of the cure kinetic model is derived. The solution is valid for low exothermal peak temperatures and it is characterised by two dimensionless numbers. The first parameter is the ratio between the time scales for the reaction and for heat conduction, the second parameter is the ratio between the processing temperature and the adiabatic temperature rise. The general solution is specialised to a second order autocatalytic cure model so that the results can be compared to numerical results. The agreement between the numerical and the analytical solution is excellent for small exothermal peak temperatures, as expected. The particular model used also serves as an example of the additional dimensionless parameters that are introduced by a specific kinetic model.Godkänd; 1993; 20070426 (ysko)
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Khoun, Karine. « Process-induced stresses and deformations in woven composites manufactured by Resin Transfer Moulding ». Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66887.
Texte intégralRésumé :
This work investigated the factors leading to the generation of process-induced stresses and deformations in woven composites manufactured by Resin Transfer Moulding (RTM). Both intrinsic and extrinsic mechanisms were examined. First, a comprehensive methodology was applied to characterize the thermal, chemorheological and thermomechanical properties of the CYCOM 890RTM epoxy resin. The developed models were essential to establish a clear understanding of the resin behaviour during the processing conditions. Then, the thermomechanical properties of 5-Harness satin woven fabrics were investigated using a micromechanical approach. Different fibre volume fractions between 50% and 62%, corresponding to typical volume fractions used in the RTM process, were examined. These thermomechanical properties were compared to the properties of equivalent unidirectional crossply laminates in order to validate the use of crossply configuration to model the behaviour of woven fabric laminate. The developed resin models and the fibre properties were then implemented in a finite element software, ABAQUS/COMPRO in order to predict the evolution of the laminate properties during the RTM process. Fibre Bragg Grating sensors were then used to characterize experimentally the tool-part interaction occurring during the RTM process. The separation of the composite from the mould during the cool down period was measured by the optical sensors. The maximal shear stress allowed by the laminate before the debonding was estimated to be 140 kPa for a steel mould. The observed tool-part interaction was simulated using frictional contact conditions at the composite/mould interface in a finite element analysis. Finally, using the ABAQUS/COMPRO interface, the manufacturing of a composite structure by RTM was modelled, taking into account simultaneously the intrinsic and extrinsic mechanisms examined. This case study demonstrates the capacity of the process modCe travail étudie les facteurs conduisant au développement de contraintes et déformations résiduelles induites par le procédé d'injection sur renforts dans le cas de composites à renforts tissés. Les mécanismes intrinsèques ainsi qu'extrinsèques ont été pris en considération. Tout d'abord, une méthodologie a été utilisée pour caractériser les propriétés thermo-chimiques et thermo-mécaniques de la résine époxy CYCOM 890RTM. Le développement de modèles mathématiques pour décrire les différentes propriétés est une étape essentielle pour comprendre clairement l'évolution du comportement de la résine lors du procédé de fabrication. Ensuite, les propriétés thermo-mécaniques d'un tissu satin de 5 ont été examinées en utilisant une approche de micromécanique sur un motif élémentaire. Différentes fractions volumiques de fibre entre 50% et 62%, correspondant aux fractions volumiques de fibre typiquement utilisées pour le procédé d'injection sur renfort, ont été étudiées. Les propriétés ont été comparées aux propriétés obtenues pour des laminés unidirectionnels croisés équivalents. En général, les propriétés des deux configurations sont comparables. Ceci justifie l'utilisation des propriétés de fibre unidirectionnelle dans une configuration croisée pour simuler le comportement d'un laminé à renfort tissé satin de 5. Les modèles des propriétés de la résine et des fibres ont été ensuite implémentés dans un logiciel d'éléments finis, ABAQUS/COMPRO, afin de prédire l'évolution des propriétés du laminé pendant le procédé d'injection sur renforts. Des fibres optiques à réseaux de Bragg ont été également utilisées pour caractériser expérimentalement les interactions entre le composite et le moule générées pendant le procédé. Les fibres optiques saisirent la séparation entre le composite et le moule pendant le refroidissement. La contrainte
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Salomeia, Y. M. « Improved understanding of injection stretch blow moulding through instrumentation, process monitoring and modelling ». Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517044.
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Cutri, Francesco Angelo. « Production enhancement in the planing and spindle moulding process utilising a mechatronic approach ». Thesis, De Montfort University, 1991. http://hdl.handle.net/2086/4079.
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Vahlund, C. Fredrik. « Fibre orientation, rheological behaviour and simulation of the compression moulding process for composite materials / ». Luleå, 2001. http://epubl.luth.se/1402-1544/2001/25/index.html.
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Alenezi, Dharay Falah Saleh. « Process Parameters Optimisation of Injection Moulding using SLA Inserts in Conventional & ; CCC Moulds ». Thesis, University of Portsmouth, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523624.
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Al-Ashaab, Ahmed H. S. « A manufacturing model to capture injection moulding process capabilities to support design for manufacture ». Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/10338.
Texte intégralRésumé :
The achievement of "better, faster, cheaper" product designs is heavily dependent on providing appropriate information to design teams. One of the essential parts of the information is the manufacturing process information. The aim of this research has been to explore the representation of the capability of the injection moulding process in a software form. The resulting model termed a Manufacturing Model must provide a common source of information to a range of interacting Design for Manufacture applications. These applications in turn would produce feedback advice as the design evolves, to the users in order to assist in their design decisions. The manufacturing information to support injection moulding process has been categorized as mouldability features, mould elements and injection mould machine elements which represent the main entities of the Manufacturing Model. The EXPRESS language and EXPRESS-G have been used to provide a formal non-software dependent representation of the underlying structure of the Manufacturing Model. To explore the use of the Manufacturing Model information to support Design for Manufacturing (DFM) applications the Object-Oriented methodology of Booch has been used. Three DFM applications have been considered, these being Desigu for Mouldability, Supporting Mould Design and the Selection of Injection Machine. An experimental Manufacturing Model, based on the EXPRESS representation, and related DFM applications have been implemented in Object-Oriented form using LOOPS (Xerox 1988). This has been used to show that the capability of the injection moulding process has been captured in the Manufacturing Model and provides support to a range of interacting Design for Manufacture applications. While the EXPRESS language has provided a good tool to capture the structure of the Manufacturing Model, further work has been required to define the functional interactions between entities within the model. Using the object oriented paradigm to implement the Manufacturing Model has been demonstrated. The Booch methodology in addition to EXPRESS has provided the basis to model the functional interaction between the Manufacturing Model entities. As an implementation tool, LOOPS has proven to provide adequate object oriented capability. However there is requirement for software tools which can readily be integrated with other software tools. The research has provided a contribution to a structured, and extensible, approach which should influence future CAB system structures aiming to provide support to Concurrent Engineering.
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Yan, Shiyong. « Modelling the constitutive behaviour of poly(ethylene terephthalate) for the stretch blow moulding process ». Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677854.
Texte intégralRésumé :
The stretch blow moulding (SBM) process is the main method for the mass production of PET containers. Understanding and modelling the behaviour of PET is critical for design the optimum product and process. However due to its nonlinear viscoelastic behaviour, the behaviour of PET is highly sensitive to its thermomechanical history making the task of modelling its constitutive behaviour very complex. This means that the constitutive model will be useful only if it is known to be valid under the actual conditions of the SBM process of interest. The aim of this work was to develop a material model capable of capturing the deformation behaviour of PET subject to an arbitrary strain history, and to develop a new material characterization method providing new data for the deformation behaviour of PET relevant to the SBM process. In or~er to achieve this goal, a reliable, robust and non-touch characterization method was developed based on the data acquisition system and digital image correlation system to determine the stress-strain relationship of material in deforming preforms during free stretch-blow tests. Considerable experimental work, including conventional biaxial stretching tests and free stretch-blow tests, was carried out to characterize the mechanical properties of the material. These tests revealed the properties of PET under displacement-controlled deformation and load-controlled deformation. The material model was developed based on the original Buckley model in two aspects. One was the development of the 'lock-up' process in the network system, representing the onset of strain-induced crystallization (SIC). Another was the consideration of self-heating effect of PET during the deformation.
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Polynkin, A., L. Bai, J. F. T. Pittman, J. Sienz, Leigh Mulvaney-Johnson, Elaine C. Brown, A. Dawson et al. « Water assisted injection moulding : development of insights and predictive capabilities through experiments on instrumented process in parallel with computer simulations ». Maney Publishing, 2008. http://hdl.handle.net/10454/3511.
Texte intégralRésumé :
YesAn idealised model of core-out in water assisted injection moulding (WAIM) is set up to isolate the effect of cooling by the water on the deposited layer thickness. Based on simulations, this is investigated for a specific case as a function of Pearson number and power law index. It is found that cooling significantly reduces the layer thickness to the extent that a change in the flow regime ahead of the bubble, from bypass to recirculating flow, is possible. For shear thinning melts with high temperature coefficient of viscosity, the simulations show very low layer thickness, which may indicate unfavourable conditions for WAIM. Although in the real moulding situation, other effects will be superimposed on those found here, the results provide new insights into the fundamentals of WAIM. Investigation of other effects characterised by Fourier and Reynolds numbers will be reported subsequently. Some early process measurement results from an experimental WAIM mould are presented. Reductions in residual wall thickness are observed as the water injection set pressure is increased and the duration of water bubble penetration through the melt is determined experimentally. The formation of voids within the residual wall is noted and observed to reduce in severity with increasing water injection pressure. The presence of such voids can be detected by the signature from an infrared temperatures sensor.
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Rawson, Keith William. « Shear controlled orientation effects with injection mouldings produced by the SCORIM process ». Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/6380.
Texte intégralRésumé :
Injection moulding using the process of Shear Controlled Orientation Injection Moulding (SCORIM) to enhance the aesthetic characteristics of plastics was investigated. Unsightly surface weld lines were successfully removed from highly reflective aluminium flake pigmented plastics by the application of a single macroscopic SCORIM shear when used in series with Bright Surface Moulding (BSM). A gonio spectrophotometer (GSP) was used for the quantitative characterisation of the Al flake pigmented mouldings as a measure of surface reflectivity and preferred angle of reflection. The different directional properties of surface reflectivities to either side of a conventional weld line are unacceptable, but were successfully reoriented approximately uniformly with the use of SCORIM and BSM moulding (i. e. SBM) used in series. SBM therefore provided an acceptable quality of surface finish for mouldings originally containing a weld line, without deterioration of mechanical properties. Indeed, some improvements in mechanical properties were observed. Translucent two-colour mouldings were used to successfully demonstrate the flow paths taken by sheared material during the application of macroscopic shears. The use of intermittent shearing to encapsulate shear oriented material in the solidifying layers, manifested original and profound aesthetic effects. This resulted from mixing the two colours and was reproducible and widely variable. The morphology of isotactic polypropylene (iPP) processed in this way and examined by light and electron microscopy revealed how only one or two intermittent shears were required to orient a large volume of the moulding in the shear direction. Moreover, U-shaped flow paths demonstrated that the easiest shear route was close to the mouldings edges, an observation supported by x-ray analysis. The addition of Al flake pigment was found to act as a heterogeneous nucleant for ß-spherulites. This acted as a suitable marker for the clear identification of the displaced weld interface using polarised light microscopy, of filled and unfilled iPP. y-phase was identified with the use of only one or two intermittent shears which reflects an increase in molecular alignment and consequent improved mechanical properties. The intensity of the y-phase increased with the volume of material sheared. Strong evidence was also obtained of a linear relationship between the logarithm of the time lapse between two intermittent shears and the corresponding values of a-phase index, crystallinity index and percentage crystallinity. The values of each increasing proportionally with the length of time used. Microhardness characterisation revealed anisotropy within SCORIM samples consistent with preferred orientation and increased modulus in the shear direction. The skin layers were characterised as the softest region through the thickness of SCORIM mouldings. The results of this work were used to provide the basis of a computer simulation of the SCORIM process under development at the University of Wales Swansea.
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Gruber, Juan-Mario. « Prozessführung beim Thermoplastspritzgießen auf Basis des Werkzeuginnendrucks : process control based in cavity pressure for the injection moulding process of thermoplastics / ». Aachen : Mainz, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014914373&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Nugent, Paul James. « A study of heat transfer and process control in the rotational moulding of polymer powders ». Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317138.
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Buriánková, Alena. « Analýza zmetkovitosti ve výrobním procesu ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402585.
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The master’s thesis is focused on the reduction of rejection rate in production of plastic bowls with the use of statistic methods. The theoretical part of this thesis describes among others Statistical Process Control, Process capability and types regulatory diagrams. The basis for the practical part is data collection over a certain period of production, from which the percentage of the rejection rate is evaluated. Experiments and corrective actions are designed to improve the process and thereby reduce scrap.
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Srivastava, Prashant. « Value stream mapping on foam injection moulding process-- the starting point of a six sigma project ». Menomonie, WI : University of Wisconsin--Stout, 2005. http://www.uwstout.edu/lib/thesis/2005/2005srivastavap.pdf.
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Reiß, Markus [Verfasser], et F. [Akademischer Betreuer] Henning. « Entwicklung eines optimierten Halbzeugherstellungsprozesses für kohlenstofffaserverstärktes Sheet Moulding Compound = Development of an optimized process for the manufacturing of carbon fibre reinforced sheet moulding compound / Markus Reiß ; Betreuer : F. Henning ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1176022555/34.
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Kietzmann, Clinton van Lingen. « Numerical simulation of the plastics moulding process using a thin gap numerical model / Clinton van Lingen Kietzmann ». Thesis, Potchefstroom University for Christian Higher Education, 1995. http://hdl.handle.net/10394/851.
Texte intégralRésumé :
The injection moulding process is one of the most popular means of mass producing components to
very small tolerances. Before the advent of the affordable computer, the methods used in injection
mould design were empirical in nature. Computational fluid dynamics offers the mould designer a tool
to predict and verify the mouldability of a part before any metal is cut on the actual mould. This thesis
describes the development of a thin gap numerical model that can be used by mould designers. The
thin gap assumption enables the Navier-Stokes equations to be simplified by the Hele-Shaw
approximation enabling the flow variables to be solved more efficiently, without a significant loss of
accuracy. Finite element solutions of the thin gap model are well documented and are well suited to
solving problems with complex geometries but in general finite element methods require more
memory and are slower in execution than finite-difference and finite volume methods.
A personal computer based program utilising the finite volume method for solving the Hele-Shaw
flow problem is developed in this thesis, which simulates the filling stage of the plastics injection
moulding process. The basic model was first developed on a two dimensional constant thickness
Cartesian coordinate domain using a constant tiscosity. This Newtonian model was then extended
with the Volume-of-Fluid method to include the moving boundary or free front. A suitable material
model was chosen to predict the viscosities of various grades of plastic at different temperatures and
pressures. Once this model produced accurate results it was extended to include generalised
curvilinear coordinates in order to solve problems on complex three dimensional geometries. The
program is tested and verified extensively with numerical experiments and experimental data from
previous published work and excellent results are obtained.
The final product of this thesis is a computer program which simulates the moving boundary during
the filling stage of the injection moulding process. This work contributes to the development and
understanding of finite volume and finite-difference methods in the simulation of plastic injection
moulding.Thesis (MIng (Meganies))--PU vir CHO, 1995.
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Pereira, M. F. V. T., J. M. Benson, M. Williams et H. Chikwanda. « Component and die design principles and process parameters for the metal injection moulding of a Ti alloy ». Journal for New Generation Sciences, Vol 8, Issue 2 : Central University of Technology, Free State, Bloemfontein, 2010. http://hdl.handle.net/11462/562.
Texte intégralRésumé :
Published ArticleMetal injection moulding (MIM) offers advantages for mass production of components over conventional production methods for parts with complex shapes and large production runs. The MIM process includes mixing a fine metallic powder with a polymeric binder to produce a homogeneous feedstock. This enables the production of metallic components in a similar manner to plastic injection moulding. After undergoing a process of binder removal the components undergo a conventional sintering cycle. As significant shrinkage occurs (as much as 30%) this must be considered when designing the die cavity. This paper describes the design and manufacture of a die to produce tensile specimens. Extensive injection moulding trials to produce acceptable tensile components were undertaken. The complexities and possible implications of the design of a mould on the process are discussed. The outcomes of this research will be used by the CSIR for further development and application of the MIM technology for manufacture of high value components, such as dental implants.
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Gülçür, Mert, J.-M. Romano, P. Penchev, Timothy D. Gough, Elaine C. Brown, S. Dimov et Benjamin R. Whiteside. « A cost-effective process chain for thermoplastic microneedle manufacture combining laser micro-machining and micro-injection moulding ». Elsevier, 2021. http://hdl.handle.net/10454/18446.
Texte intégralRésumé :
YesHigh-throughput manufacturing of transdermal microneedle arrays poses a significant challenge due to the high precision and number of features that need to be produced and the requirement of multi-step processing methods for achieving challenging micro-features. To address this challenge, we report a flexible and cost-effective process chain for transdermal microneedle array manufacture that includes mould production using laser machining and replication of thermoplastic microneedles via micro-injection moulding (micromoulding). The process chain also incorporates an in-line manufacturing data monitoring capability where the variability in the quality of microneedle arrays can be determined in a production run using captured data. Optical imaging and machine vision technologies are also implemented to create a quality inspection system that allows rapid evaluation of key quality indicators. The work presents the capability of laser machining as a cost-effective method for making microneedle moulds and micro-injection moulding of thermoplastic microneedle arrays as a highly-suitable manufacturing technique for large-scale production with low marginal cost.
This research work was undertaken in the context of MICRO-MAN project (“Process Fingerprint for Zero-defect Net-shapeMICROMANufacturing”, http://www.microman.mek.dtu.dk/).MICROMAN is a European Training Network supported byHorizon 2020, the EU Framework Programme for Research andInnovation (Project ID: 674801). This research has also receivedfunding and support from two other Horizon 2020 projects:HIMALAIA (Grant agreement No. 766871) and Laser4Fun (GA no.675063).
The full-text of this article will be released for public view at the end of the publisher embargo on 04 Feb 2022.
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Soyama, Juliano [Verfasser], et Florian [Akademischer Betreuer] Pyczak. « Development of creep resistant titanium aluminide alloys for the Metal Injection Moulding process / Juliano Soyama ; Betreuer : Florian Pyczak ». Cottbus : BTU Cottbus - Senftenberg, 2014. http://d-nb.info/111428310X/34.
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Demirel, Bilal, et bilal demirel@student rmit edu au. « Optimisation of Petaloid Base Dimensions and Process Operating Conditions to Minimize Environmental Stress Cracking in Injection Stretch Blow Moulded PET Bottles ». RMIT University. SAMME, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090305.154433.
Texte intégralRésumé :
ABSTRACT Injection stretch blow moulded PET bottles are the most widely used container type for carbonated soft drinks. PET offers excellent clarity, good mechanical and barrier properties, and ease of processing. Typically, these bottles have a petaloid-shaped base, which gives good stability to the bottle and it is the most appropriate one for beverage storage. However, the base is prone to environmentally induced stress cracking and this a major concern to bottle manufacturers. The object of this study is to explain the occurrence of stress cracking, and to prevent it by optimising both the geometry of the petaloid base and the processing parameters during bottle moulding. A finite element model of the petaloid shape is developed in CATIA V5 R14, and used to predict the von Mises stress in the bottle base for different combinations of three key dimensions of the base: foot length, valley width, and clearance. The combination of dimensions giving the minimum stress is found by a statistical analysis approach using an optimisation and design of experiments software package ECHIP-7. A bottle mould was manufactured according to the optimum base geometry and PET bottles are produced by injection stretch blow moulding (ISBM). In order to minimise the stresses at the bottom of the bottle, the ISBM process parameters were reviewed and the effects of both the stretch rod movement and the temperature profile of the preform were studied by means of the process simulation software package (Blow View version 8.2). Simulated values of the wall thickness, stress, crystallinity, molecular orientation and biaxial ratio in the bottle base were obtained. The process parameters, which result in low stress and uniform material in the bottle base, are regarded as optimum operating conditions. In the evaluation process of the optimum bottle base, bottles with standard (current) and optimized (new) base were produced under the same process conditions via a two-stage ISBM machine. In order to compare both the bottles, environmental stress crack resistance, top load strength, burst pressure strength, thermal stability test as well as crystallinity studies ¬¬¬via modulated differential scanning calorimetry (MDSC) and morphology studies via environmental scanning electron microscopy (ESEM) and optical microscopy were conducted. In this study carried out, the new PET bottle with the optimised base significantly decreased the environmental stress cracking occurrence in the bottom of the bottle. It is found that the bottle with optimised base is stronger than the bottle with standard base against environmental stress cracking. The resistance time against environmental stress cracking are increased by about % 90 under the same operating process conditions used for standard (current) bottles; and by % 170 under the optimised process conditions where the preform re-heating temperature is set to 105 oC.
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Mulvaney-Johnson, Leigh. « Gas assisted injection moulding : experiment and simulation : industrial machine experimental studies of the effect of process variables on gas bubble formation, and with simulation based upon a pseudo-concentration method ». Thesis, University of Bradford, 2001. http://hdl.handle.net/10454/4983.
Texte intégralRésumé :
The gas assisted injection moulding process is an important extension to conventional injection moulding. Gas assist can be applied in a number of ways, but here the penetration of a gas bubble through the polymer melt is of interest. A 3D fi nite element implementation of a pseudo concentration method is employed to simulate the primary penetration of the gas bubble. The wall thickness prediction is an important result since the extent of bubble penetration is sensitive to the remaining melt fraction. A number of methods for experimental measurement are developed to measure characteristics of the gas assisted injection moulding process dynamics and product. Key process variables, on an industrial gas-assist machine, were measured and analysed, leading to an empirical model for wall thickness prediction. Gas delay time and injection velocity are shown to be most influential in controlling residual wall thickness. Simulation results are evaluated against the empirical model. The trends observed, for simulation and experiment, in wall thickness after changes in process variable settings are found to agree qualitatively. The wall thickness prediction is found to be within 10% of the experimentally obtained measurements.
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Raza, Umar. « A service orientated architecture and wireless sensor network approach applied to the measurement and visualisation of a micro injection moulding process : design, development and testing of an ESB based micro injection moulding platform using Google Gadgets and business processes for the integration of disparate hardware systems on the factory shop floor ». Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/13362.
Texte intégralRésumé :
Factory shop floors of the future will see a significant increase in interconnected devices for monitoring and control. However, if a Service Orientated Architecture (SOA) is implemented on all such devices then this will result in a large number of permutations of services and composite services. These services combined with other business level components can pose a huge challenge to manage as it is often difficult to keep an overview of all the devices, equipment and services. This thesis proposes an SOA based novel assimilation architecture for integrating disparate industrial hardware based processes and business processes of an enterprise in particular the plastics machinery environment. The key benefits of the proposed architecture are the reduction of complexity when integrating disparate hardware platforms; managing the associated services as well as allowing the Micro Injection Moulding (µIM) process to be monitored on the web through service and data integration. An Enterprise Service Bus (ESB) based middleware layer integrates the Wireless Sensor Network (WSN) based environmental and simulated machine process systems with frontend Google Gadgets (GGs) based web visualisation applications. A business process framework is proposed to manage and orchestrate the resulting services from the architecture. Results from the analysis of the WSN kits in terms of their usability and reliability showed that the Jennic WSN was easy to setup and had a reliable communication link in the polymer industrial environment with the PER being below 0.5%. The prototype Jennic WSN based µIM process monitoring system had limitations when monitoring high-resolution machine data, therefore a novel hybrid integration architecture was proposed. The assimilation architecture was implemented on a distributed server based test bed. Results from test scenarios showed that the architecture was highly scalable and could potentially allow a large number of disparate sensor based hardware systems and services to be hosted, managed, visualised and linked to form a cohesive business process.
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Cheng, C.-C., Y. Ono, Benjamin R. Whiteside, Elaine C. Brown, C. K. Jen et Philip D. Coates. « Real-time diagnosis of micro powder injection molding using integrated ultrasonic sensors ». Hanser, 2007. http://hdl.handle.net/10454/4068.
Texte intégralRésumé :
noReal-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification, temperature variation and part detachment of the feedstock inside the mold cavity were observed. It has been demonstrated that ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact duration during which the part and mold are in contact, and holding pressure can be used to assist with optimization of injection and cooling parameters to minimize energy consumption and maximize process efficiency.Real-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification, temperature variation and part detachment of the feedstock inside the mold cavity were observed. It has been demonstrated that ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact duration during which the part and mold are in contact, and holding pressure can be used to assist with optimization of injection and cooling parameters to minimize energy consumption and maximize process efficiency.
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Gibson, Millan-John. « Fibre Length Distribution and Dispersion during the Injection Moulding Process : An experimental study evaluating fibre length attrition and dispersion during processing of long glass fibre reinforced polymer composites in injection moulding including an evaluation of long glass fibre measurement techniques ». Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17360.
Texte intégralRésumé :
This project evaluates fibre length dispersion and distribution within the injection moulding process of long glass fibre reinforced polypropylene, sponsored by Autodesk Simulation.
The primary material used in this investigation was a 15 mm long glass fibre reinforced polypropylene consisting of two fibre content levels, 20 wt. % and 40 wt. %.
A review of previous research was compiled in this study to evaluate various glass fibre measurement methods and fibre breakage studies to establish where along the injection moulding process fibre breakage predominantly occurs and which process parameters have the greatest influence on fibre length distribution along the screw.
Based on literature findings, a manual fibre length measurement method was developed and applied in this study and benchmarked against existing commercially available automated software programs and found to be more accurate in obtaining a reliable fibre length distribution within a glass fibre reinforced sample.
Fibre length measurements from the nozzle confirmed that the majority of fibre breakage had already occurred in the screw. Measurements taken along the screw showed a drastic decrease in weighted average glass fibre length from initial pellet form to the end of the metering zone with sudden transitions to lower weighted average values seen at the beginning of the feeding zone and along the compression zone.
Fibre dispersion results from the nozzle and along the screw through the use of a μ-CT scanner showed a complex fibre flow and orientation of fibres with the preservation of fibre clusters being seen all along the injection moulding process but chiefly in the feeding and compression zones of the screw.