Evaluación del sistema de mantenimiento de la máquina de inyección de plástico mediante el método TOPSIS

The following document talks about the parameters of the maintenance system implemented in plastic injection machines of a maquiladora company located in Ciudad Juarez Chihuahua. The method used in this investigation is essentially ulti-criteria decision making, the technique for the order of preference for similarity to the ideal TOPSIS solution. Therefore, an evaluation of the maintenance system is carried out, using measurable collected in said company. With this evaluation the plastic injection machine is determined in better conditions, as well as the machine in worse conditions, which helps management to make better decisions regarding each machine. The objective of this research is to address the study of decision-making in the industrial field specifically in the maintenance system of plastic injection molding machines.El siguiente documento habla sobre los parámetros del sistema de mantenimiento implementado en las máquinas de inyección de plástico de una empresa maquiladora ubicada en Ciudad Juárez Chihuahua. El método utilizado en esta investigación es esencialmente la toma de decisiones multicriterio,  la  técnica  para  el  orden  de  preferencia  por  la  similitud  con  la  solución  ideal  de  TOPSIS.  Por  lo  tanto,  se  realiza  una  evaluación  del  sistema  de  mantenimiento,  utilizando datos medibles recogidos en dicha empresa. Con esta evaluación se determina la máquina de inyección de plástico en mejores condiciones, así como la máquina en peores condiciones, lo que ayuda a la dirección a tomar mejores decisiones respecto a cada máquina. El objetivo de esta investigación es abordar el estudio de la toma de decisiones en el campo industrial específicamente en  el  sistema  de  mantenimiento  de  las  máquinas  de  moldeo  por  inyección  de  plástic

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

Application of ultrasound in twin-screw extrusion and microinjection molding: improvements of properties of processed materials and nanocomposites : polymers and biopolymers

Pla de Doctorat Industrial, Generalitat de Catalunya, Aplicat embargament fins el dia 22 de novembre de 2022The plastics industry is in constant evolution looking to improve the properties of new materials and performance in different applications. Currently, the environmental impact associated with the use of plastics is one of the main concerns for the society. It was reflected in regulations at European level such as SUP Directive, Green Deal or studies such as Patents for tomorrow's plastics by European Patent Office on the trends reflected in research on alternative materials to conventional plastic. In order to transfer these new and more sustainable alternatives to an industrial and realistic environment, first applied research has to be carried out on both the development and processes of the materials to optimize their performance. In this thesis study, applied research was carried out using ultrasound technology on different nanocomposites and their transformation processes. Advances in the application of ultrasound for different transformation processes have been studied previously to ensure the approach of the practical study. This study focuses on the application of ultrasound in the process of obtaining new formulations by compounding extrusion and in injection molding, specifically in microinjection. The application of nanotechnology in the development of new materials will allow an improvement in performance and will open a range of new possibilities and applications. To explore the potential of ultrasonic molding (USM) technology, a preliminary process stability study was performed with polypropylene. The evaluation was carried out from a mechanical point of view, in which it was shown that, with an optimization of the process parameters and a correct design approach of the components with the nodal point allow a stability close to production was allowed. To deepen into the potential of USM technology in synergy with new nanocomposite formulations, a comparative study with the conventional microinjection process was performed. Two different nanocomposites based on a biopolymer matrix of poly 3-hydroxybutyrate with Cloisite 20 (organic modification), and with Cloisite 116 (unmodified) were studied. This research reveals that the USM technology, is stable obtaining micro-pieces, maintaining the chemical structure of the initial biocomposite without degrading and homogeneously achieving an exfoliation of both nanoclays. Conventional microinjection did show slight changes in the level of degradation and chemical structure, highlighting that it was not possible to micro-mold samples of the material with the unmodified nanoclay. The stabilization of the compounding extrusion assisted by an ultrasound system has been studied, with a design of a single component that allows the new approach to work in continuous condition and on pre-industrial equipment. Due to the success of the new component, it was possible to carry out the study of new formulations of polypropylene loaded with two different nanoclays (Cloisite 20 and Garamite 1958) and glass bubbles. The new nanocomposites reached the mechanical properties of a conventional material used for door panels in the automotive sector, but with a reduced density. The aim was to demonstrate that it is possible to reduce the weight of plastic components used in the automotive industry and reduce CO2 emissions for a standard vehicle. The research carried out in this thesis work has opened a new field of application to nanocomposites for weight reduction with improved mechanical properties when high level of dispersion is reached. In addition, the potential of USM technology for micro-molding applications has been demonstrated, showing high stability without material degradation during the process, and good dispersion of nano-reinforcements.El sector del plástico está en continuo cambio en busca de mejorar sus propiedades y rendimiento en diferentes aplicaciones. Actualmente. el impacto ambiental asociado al uso de los plásticos es una de las principales preocupaciones en el ámbito social. Se puede ver reflejado en regulaciones a nivel europeo como SUP Directive. Green Deal o estudios como el que efectúa la Oficina de Patentes Europeas Patents for tomorrow's plastics sobre las tendencias que reflejan las investigaciones en materiales alternativos al plástico convencional. Para poder llevar a un ambiente industrial y realista estas nuevas alternativas más sostenibles. primero se ha de llevar a cabo una investigación aplicada tanto del desarrollo de los materiales como de los procesos que pueden optimizar su rendimiento. En este estudio de tesis se lleva a cabo una investigación aplicada sobre diferentes nanocompuestos y sus procesos de transformación que pueden ser mejorados con la tecnología de ultrasonidos. Se ha estudiado los avances en la aplicación de ultrasonidos para diferentes procesos de transformación con el objetivo de enfocar correctamente el estudio práctico. Este estudio centra la aplicación de los ultrasonidos en el proceso de obtención de nuevas formulaciones por extrusión compounding y en el moldeo por inyección, concretamente en microinyeccion. La aplicación de nanotecnología en el desarrollo de nuevos materiales permitirá una mejora del rendimiento y abrirá un abanico de nuevas posibilidades y aplicaciones. Para explorar el potencial de la tecnología de microinyección por ultrasonidos (USM}, se realizó un estudio preliminar de estabilidad del proceso con un polipropileno. La evaluación fue llevada a cabo desde un punto de vista mecánico, en el que se demostró que con una optimización de los parámetros de proceso y un enfoque de diseño correcto de los componentes que hacen intervenir el punto nodal, se puede alcanzar un nivel de estabilidad cercano a producción. Para profundizar en el potencial de la tecnología USM en sinergia con nuevas formulaciones de nanocompuestos, se realizó un estudio comparativo con el proceso de microinyección convencional. Dos nanocompuestos basados en una matriz del biopolímero poli 3-hidroxibutirato con Cloisite 20 (modificación orgánica). Y con Cloisite 116 (sin modificar) fueron estudiados. Este estudio revela que la tecnología USM además de ser estable en la obtención de micropiezas, mantiene la estructura química del biocompuesto inicial sin llegar a degradación y alcanzando homogéneamente la exfoliación de ambas nanoarcillas. La microinyección convencional si mostro ligeros cambios a nivel de degradación y estructura química, destacando que no fue posible micromoldear muestras del material con la nanoarcilla sin modificar. La estabilización del proceso de extrusión compounding asistida por ultrasonidos ha sido estudiado, diseñando un componente único que permite al sistema de ultrasonidos trabajar en régimen continuo en equipos preindustriales. Gracias al éxito del nuevo componente, se ha podido llevar a cabo el estudio de nuevas formulaciones de polipropileno argado con dos nanoarcillas diferentes (Cloisite 20 y Garamite 1958) y esferas huecas. Los nuevos nanocompuestos alcanzaron las propiedades mecánicas de un material empleado para paneles de puerta en el sector automoción, pero con una densidad reducida. El objetivo fue demostrar que se puede reducir el peso de los componentes plásticos empleados en automoción y reducir las emisiones de CO2 para un vehículo estándar. La investigación llevada a cabo en este trabajo de tesis ha permitido abrir un nuevo campo de aplicación a los nanocompuestos para reducción de densidad con buenas propiedades mecánicas cuando la dispersión es alta. Además, se ha demostrado el potencial de la tecnología USM para aplicaciones de micromoldeo, mostrando alta estabilidad sin degradación del material durante el proceso, y buena dispersión de los nano-refuerzos.Polímers i biopolímer

Investigation Of The Effects Of Various Types Of Plasticizers On The Properties Of Polyester Polyol Based Thermoplastic Polyurethane

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2016Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2016TPU (termoplastik poliüretan) kırılmayan, aşınma direnci yüksek, esnek ve düzgün kalıp özelliği taşıyan sentetik bir malzemelerdir. Aynı zamanda her türlü şekle uygun özellik göstermesi sebebiyle çok farklı sektörlerde kullanım alanı bulur. Poliüretanın diğer malzemelere kıyasla en büyük avantajı, formülasyonların da değişiklik yapılarak birbirinden çok farklı sertlik, yoğunluk ve elastikiyete sahip ürünler elde edilebilmesidir. Bu da aynı üretim hattında, sadece hammadde değiştirilerek farklı kullanım alanlarına uygun ürün üretilebilmesine olanak vermektedir. TPU, endüstriyel ve kişisel ürünlerin sağlam, ekonomik ve kullanışlı olması yönünden hammadde girdisi olarak en önemli tercih nedenidir. TPU’nun en önemli avantajı aşınma direncinin yüksek olması, geniş sıcaklık aralığında esneklik ile çok sayıda yağ ve greslere karşı iyi direnç göstermesidir. TPU geniş sıcaklık aralığında kullanılabilmektedir, kısa ve uzun süreli uygulamalarda - 40°C ile 80 °C’ye kadar kullanılmakla beraber, tüm mekanik özellikler sıcaklığa bağlı olarak değişmektedir, 120 °C nin üzerindeki sıcaklıklara kısa süreli direnç göstermektedir. Termoplastik poliüretan elastomerlerinin iyi işlenebilmeleri için kurutulmaları gereklidir. Kurutma işlemi, 100 -110 °C de hava sirkülasyonlu fırınlarda veya 1-2 saat kurutma odalarında tutularak yapılmaktadır. Granüllerin içerdiği nem miktarı ağırlıkça % 0,1 den düşük olmalıdır. Bunlar enjeksiyon, ekstrüzyon, kalıp üzerine kaplama (overmolding) ve film laminasyonu gibi termoplastik malzemeler için kullanılan metotlarla işlenebilmektedirler ve nem miktarı işlenebilmeyi yüksek oranda etkileyem bir özelliktir. Enjeksiyon için nem oranının %0,05’den düşük olması ve ekstrüzyon için %0,02 civarında olması gerekmektedir. En iyi şekilde nem oranını düşürmek için kurutma sisteminin uygun olmasına önem verilmesi gerekmektedir. Termoplastik poliüretanlar plastikleştiri ajanlar kullanılmadığı takdirde proses edilmeleri sonucunda geldikleri en düşük sertlik değeri 80 Shore A olmaktadır. Özellikle ayakkabı tabanı uygulamarında tercih edilen 65-70-75 Shore A sertlik değerlerini elde edebilmek için plastikleştirici ajanlar kullanılmaktadır. Plastikleştirici ajanların termoplastik poliüretan üretiminde ana hammadde olan izosiyanat ve dioller ile etkileşimleri üzerine yaptığımız bu çalışma ile plastikleştirici ajanların yüzde oranları ile gelinen sertlik değerleri tespit edilmiştir. Bununla birlikte termoplastik poliüretana uyumlu olan ve olmayan plastikleştici ajan çeşitleri de bulgular arasındadır. Özellikle son yıllarda REACH (Kimyasalların Kaydı, Değerlendirilmesi, İzni ve Kısıtlanması) listesine girmesi muhtemel olan ftalat bazlı plastikleştirici ajanların yerine termoplastik poliüretanda hangi ajanın kullanılabileceği çalışması yapılmıştır. Termoplastik poliüretan malzemeler tek ve iki basamaklı üretim yöntemleri ile üretilebilirler. Tek basamaklı sentezde, aynı anda solvent içine poliol, diizosiyanat ve zincir uzatıcı ilave edilir ve sistem 80 °C’nin üzerine ısıtılır. Bazı durumlarda reaksiyonu hızlandırmak için kataliz ilavesi yapılır. Bununla birlikte, poliüretan sentezi için en yaygın kullanılan yollardan biri iki basamaklı sentez veya pre-polimer sentezi yoludur. Bu metotta, ilk basamak diizosiyanat sonlu oligomer ara ürününü sentezlemek için poliol ile izosiyanat fazlasının reksiyonu sonucu oluşur. Tez çalışmamızda tek basamak proses ile çalışmalarımız tamamlanmıştır. Bunun yanı sıra TPU malzemesi plastikleştirici ajan olmadan da üretilerek içerisine dışarıdan plastikleştirici ajan konularak absorbsiyonu sağlanmıştır. 1 saat aralıklar ile karıştırılarak 24 saat sonunda sonuçlar elde edilmiştir. Bunun nedeni tek basamaklı proses ile ekstrüzyon makinesinde reaksiyona giremeyen bir plastikleştirici ajanın, absorbsiyon ile malzeme üzerinde aynı etkiyi oluşturuyor olabileceğinin anlaşılmasıydı. Ancak alınan sonuçlarda tek basamaklı prosesin daha verimli olduğu bulgusu elde edilmiştir. Bu çalışmada iki prosedür kullanılmıştır. Birincisi ekstrüzyon, ikincisi absorpsiyon prosesidir. Ftalat ester, benzoate ester, adipat ester, 1,2- siklohekzan dikarboksilik asit diizononil ester ve trikresil fosfat plastikleştirici ajanları kullanılmış ve her plastikleştiricileriden %10 -%20 -%30 oranında alınmış ve her prosedürden 15 numune hazırlanmıştır. İki prosedür için toplamda 30 örnek bulunmaktadır. Örnekler hazırlandıktan sonra numuneler test edilmiştir. Alınan TPU granülleri enjeksiyon makinesinde karakterizasyona hazır hale getirilmiştir. Çekme testleri, yırtılma testleri, yoğunluk, sertlik, uzama, %100 ve %300 mukavemetler, kütlesek erime akış indeksi, aşınma dayanımları ve sararma indeksi testleri uygulanmıştır. Bir poliüretan elastomer bloğunda, kopolimerin sert segmenti, zincir uzatıcının diizosiyanata katılmasıyla oluşur. Yumuşak kısım ise uzun, esnek polieter ya da poliester zinciri içerir. Sert, rijit kısım, camsı ya da yarı kristalin alanları oluştururken, poliol yumuşak kısımları, sert kısımların farklı oranlarda dağıldığı amorf ya da kauçuğumsu yapıyı oluşturur. Bu iki fazlı mikro yapıda, sert kısımlar, fiziksel çapraz bağlanma noktası iken, yumuşak segment, elastik matrikstir. Bu mikro faz ayırımının neticesinde yüksek modül ve yüksek tersinir deformasyon gibi iyi fiziksel ve mekaniksel özellikler sergilerler. Plastikleştirici ajanların bu iyi özelliklere ne yönde etki ettiğinin anlaşılması ve aradaki farkın bilinmesi için malzemelere mekanik testler uygulanmıştır. Çekme, uzama, modulüs ve yırtılma testleri malzemelerin mekanik özelliklerini karşılaştırmak için yapılmıştır. Sonuçta ftalatlı plastikleştiricilerin arkasından benzoat esteri plastikleştiricilen en iyisi olduğu görülmüştür. Erime akış indeksi TPU malzemesinin en önemli özelliğidir. Proses edilebilmesi için eriyik akış değerinin optimum düzeyde tutulması gerekmektedir. Aşınma dayanımı TPU malzemesini diğer termoplastiklerden ayıran çok iyi bir özelliğidir. Aşınma dayanımı çok iyi olarak sektörde tercih edilen TPU malzemesinde kullanılan plastikleştirici ajanlarda yine benzoat esteri olanlar en iyi değerlere sahip olduğu görülmüştür. Müşteri gerekleri doğrultusunda genelde masterbatch kullanan müşteriler ve şeffaf malzeme kullanacak olanlar, granüllerin şeffaf olmasını önemsediklerinden sararma indisi önemli bir kıstas haline geliyor. Proseslerini de kolaylaştıracağı için tezde baktığımız değerler arasına girmiştir. Ftalatlı malzemelerin en iyi sararmaya sahip olduğu ve arkasından benzoat esterlerinin geldiği sonucuna varılmıştır. Plastikleştirici ajan kullanıldığın malzemenin camsı geçiş sıcaklığı ve erime sıcaklığına yaptıkları etkiler için test yapılmıştır ve kullanılan oranların belli değerlerde ancak yüksek farklılık yapmadan etki ettiği görülmüştür.Thermoplastic polyurethane (TPU) elastomers offer a myriad of physical property combinations and processing applications. It's highly elastic, flexible and resistant to abrasion, impact and weather. At the same time, it has usage area in very different sectors due to its suitability for all kinds of shapes. The biggest advantage of polyurethanes compared to other materials is that products with very different hardness, density and elasticity can be obtained by changing formulations. This enables the production of suitable products for different usage areas by changing only raw materials in the same production line. TPU is very important as a raw material input because of the fact that industrial and personal products are robust, economical and useful. The most important advantage of TPU is its high resistance to abrasion, its flexibility in a wide range of temperatures and good resistance to a large number of oils and greases. The TPU can be used in a wide range of temperatures. In short and long applications, it can be used at temperatures from -40 °C to 80 °C. All mechanical properties depend on the temperature and show a short time resistance to temperatures above 120 °C. The thermoplastic polyurethane elastomers need to be dried to ensure good handling. Drying process is carried out in air circulating ovens at 100 -110 °C or in drying chambers for 1-2 hours. The amount of moisture contained in the granules should be as low as 0.1% by weight. They can be processed with methods used for thermoplastic materials such as injection, extrusion, overmolding and film lamination. The thermoplastic polyurethanes have a minimum hardness value of 80 Shore A after they are processed if plasticizing agents are not used. Plasticizing agents are used to obtain the hardness values of 65-70-75 Shore A which is preferred especially in footwear applications. In this study, on the interaction of these agents with isocyanates and diols, which are the main raw materials in thermoplastic polyurethane production, percentage ratios of plasticizing agents and Shore values were determined. However, variations of thermoplastic polyurethane compatible and non plasticizing agents are also findings. Especially in the last years, it has been studied which agent can be used in thermoplastic polyurethane instead of phthalate based plasticizers which are likely to be on the list of REACH (Registration, Evaluation, Authorization and Restriction of Chemicals). Thermoplastic polyurethane materials can be produced by one-shot and two-step production methods. In the one-shot synthesis, polyol, diisocyanate and chain extender are added to the solvent at the same time and the system is heated to 80 °C. In some cases, catalysis is added to accelerate the reaction. However, one of the most widely used routes for polyurethane synthesis is the two-step synthesis or pre-polymer synthesis route. In this method, the reaction of the isocyanate excess with the polyol occurs to synthesize the first-stage diisocyanate termine oligomer intermediate. Our work with the one-shot process has been completed. In addition to this, TPU material is also produced without plasticizing agent and absorbent is provided by putting plasticizing agent from outside. Results were obtained after 24 hours by mixing with 1 hour intervals. This was due to the fact that a plasticizer agent that could not enter the reaction with the one-shot process in the extrusion machine could have the same effect on the material as the absorption. However, the findings were that the one-shot process was more efficient. Two procedure were used in that study. First one was extrusion and second one was absorption process. Phthalate ester, benzoate ester, adipate ester, 1,2-cyclohexane dicarboxylic acid diisononyl ester and tricresyl phosphate plasticizers were used and 15 samples were prepared with 10%-20%-30% percentages of each plasticizers and in each procedure. There were 30 sample in two procedures. They were taken the test after the preparing the samples. TPU granules were made ready for characterizing of prepared samples in the injection molding machine. Tensile tests, tear tests, density, hardness, elongation, 100% and 300% strengths, massive melt flow index, abrasion resistance and warp index tests were applied. In a polyurethane elastomer block, the hard segment of the copolymer is formed by the addition of the chain extender diisocyanate. The soft part comprises a long, flexible polyether or polyester chain. The hard, rigid part forms the vitreous or semi-crystalline areas, while the polyol soft part forms an amorphous or rubbery structure in which the hard parts are dispersed at different ratios. In this biphasic microstructure, the hard segments are the physical crosslinking point, while the soft segment is the elastic matrix. As a result of this microphase separation, they exhibit good physical and mechanical properties such as high modulus and high reversible deformation. Mechanical tests have been applied to the materials in order to understand the effect of the plasticizing agents on these good properties and to know the difference between them. Tensile, elongation, modulus and tear tests were conducted to compare the mechanical properties of the materials. As a result, phthalate plasticizers were found to be the best benzoate esters and plasticizers. The melt flow index is the most important property of TPU material. In order to be able to process, it is necessary to keep the melt flow value at optimum level. Abrasion resistance is a very good property that distinguishes TPU material from other thermoplastics. The abrasion resistance is very good and it is seen that the plasticizer agents used in the TPU materials preferred in the sector still have the best values for the ones with benzoate abatement. Customers who use masterbatch in general in accordance with customer requirements, and those who will use transparent materials, regard the granules as transparent. In this case, the winding index becomes an important criterion. It was among the values we looked at in the thesis to make its processes easier. The result is that the phthalate materials have the best yellow color, followed by benzoate esters.Yüksek LisansM.Sc

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems

Thermomechanical Behavior of Polymer Composite Heat Exchangers

Industrial cooling with seawater, particularly at elevated temperature and salinity, shortens the useful lives of conventional metallic heat exchangers. Cost effective, corrosion-resistant heat exchangers are required to fully utilize available saline water resources. Polymer composites, which use carbon fibers for thermal and mechanical reinforcement, are a promising material for such heat exchangers. The present thesis provides a characterization and thermomechanical analysis of heat exchangers fabricated using thermally conductive polymers. The change in mechanical properties resulting from exposure to saltwater at elevated temperature is characterized for raw and reinforced polymers. Then, thermal performance of such heat exchangers is compared to that of heat exchangers fabricated from conventional corrosion-resistant materials. Finally, the mechanical and combined thermomechanical response of such heat exchangers to conditions typical of LNG operations is studied and compared to that of heat exchangers fabricated from conventional corrosion-resistant materials

Ultrasonic nodal point: a new configuration for ultrasonic moulding. Advances towards the complete industrialisation of the technology

Pla de Doctorats Industrials de la Generalitat de Catalunya(English) Ultrasonic moulding is a promising technology that could be used as a substitute for conventional injection moulding techniques. This relatively new technology has a lower energy consumption, and it could be a sustainable altemative in an industrial environment. In addition, the supply of material processed in ultrasonic moulding is delivered shot-by-shot, which makes this technology very adequate to process short batches of samples without wastage. However, up to now, ultrasonic moulding technology has not been adopted in industrials environrnents due to its lack of robustness and poor repeatability found in its results. In addition, the little knowledge about the influence of the process parameters in the polymer melt is also a handicap for the industrial operator. In this dissertation, applied research and numerical simulation was carried out to improve the ultrasonic moulding technology and to deepen the knowledge ofthe process to promote its industrialization. With this aim, this thesis presents three main areas of work. First, a study of the evolution of ultrasonic moulding machines and configurations was perforrned. This review analysed the experiments published in the literature along with the main conclusions and drawbacks found. On that basis, the developrnent and validation of a new configuration for ultrasonic moulding was done, leading to a great improvement over the performance of the method in terms of repeatability and reduction of impurities in the samples. This new configuration was applied to process polyexymethylene and cyclic olefin polymer, and the results were comparad to the conventional injection moulding. This analysis reveals that the developed rnethod is able to correctly process polymers in a repetitiva way, making ultrasonic moulding a reliable technology for the industry. Finally, research was carried out to study the viscoelastic behaviour of ultrasonic heating of polypropylene cylinders. Results obtained from the numerical simulation of the process were comparad to experimental measurements done with an infrared carnera. The analysis of the results showed an inhomogeneous temperatura distribution along the cylinder and different heating steps can be identified over time. In addition, the comparison between the nurnerical and the experimental results showed that the interaction between the sample and the rnould directly influences the temperatura distribution along the cylinder. Finally, the effect of the main parameters in ultrasonic heating was obtained, both numerically and experimentally, and comparad. As a result, the research perforrned in this dissertation improves the applicability of ultrasonic moulding technology in industrial environments by increasing its repeatability and robustness, and contributing to a better understanding of its main parameters.(Català) L'emmotllament per ultrasons és una tecnologia prometedora que podría utilitzar-se com a substitut de les técniques convencionals d'emmotllarnent per injecció. Aquesta nova tecnologia consumeix menys energia i seria una alternativa més sostenible en un entom industrial. A més a més. en l'emmotllament per ultrasons el material a processar es subministra cicle a cicle, la qual cosa fa que aquesta tecnología sigui molt adequada per tractar lots curts de mostres sense tenir malbaratarnent. Tanmateix, a horas d'ara la tecnologia d'emmotllarnent per ultrasons no s'ha adoptat en entorns industriaIs a causa de la manca de robustesa i la poca repetibilitat deis seus resultats. D'altra banda, el poc coneixement sobre la influencia dels parametres del procés en l'escalfarnent del polímer també és una dificultat afegida pera l'operador industrial. En aquesta tesi s'ha dut a terme investigació aplicada i simulació numérica per millorar la tecnologia d'emmotllament per ultrasons i aprofundir en el coneixernent del procés per impulsar la seva industrialització. Amb aquest objectiu, aquesta tesi presenta tres grans eixos de treball. En primer lloc, s'ha realitzat l'estudi de l'evolució de les maquines i configuracions d'emmotllament per ultrasons. Aquesta revisió ha analitzat els experiments publicats a la literatura juntament amb les principals conclusions i inconvenients trobats. Partint deis resultats anteriors, s'ha fet el desenvolupament i la validació d'una nova configuració pera l'emmotllarnent per ultrasons que millora rnolt el rendirnent del métode en termes de repetibilitat i reducció d'impureses a les mostres. Aquesta nova configuració s'ha aplicat per processar polieximetilé i polfmer d'olefina cíclica, i els resultats s'han comparat amb l'emmotllament per injecció convencional. L'analisi deis resultats revela que el métode desenvolupat és capa de processar correctarnent els polírmers de manera repetitiva, fet que el converteix en una tecnología candidata per a la indústria. Finalment, s'ha investigat l'estudi de l'escalfament ultrasónic de cilindres de polipropilé pel seu comportament viscoelastic. Els resultats obtinguts de la simulació numérica del procés s'han comparat amb mesures experimentals fetes amb una camera infraroja. L'analisi dels resultats mostra una distribució de temperatures no hornogénia al llarg del cilindre i es poden identificar diferents etapes d'escalfament al llarg del temps. A més a més, la comparació entre els resultats numérics i experirnentals identifica la interacció entre la mostra i el motile com una influencia important en la distribució de la temperatura al llarg del cilindre. Finalment, s'obté l'efecte dels principals parametres en l'escalfament per ultrasons tant numérica com experimentalrnent. Així doncs, la investigació realitzada en aquesta tesi millora l'aplicabilitat de la tecnología d'emmotllament per ultrasons en entorns industrials, augmentant la seva repetibilitat i robustesa, i contribuint a una millar comprensió dels seus factors principals.Postprint (published version