Within manufacturing systems, process planning and scheduling are two interrelated problems that are often treated independently. Process planning involves deciding which operations are required to produce a finished product and which resources will perform each operation. Scheduling involves deciding the sequence that operations should be processed by each resource, where process planning decisions are known a priori. Integrating process planning and scheduling offers significant opportunities to reduce bottlenecks and improve plant performance, particularly for complex job shops. This research is motivated by the coating and laminating (CandL) system of a film manufacturing facility, where more than 1,000 product types are regularly produced monthly. The CandL system can be described as a complex job shop with sequence dependent setups, operation re-entry, minimum and maximum wait time constraints, and a due date performance measure. In addition to the complex scheduling environment, products produced in the CandL system have multiple feasible process plans. The CandL system experiences significant issues with schedule generation and due date performance. Thus, an integrated process planning and scheduling approach is needed to address large scale industry problems. In this research, a novel proxy measure based local search (PBLS) approach is proposed to address the integrated process planning and scheduling for a complex job shop. PBLS uses a proxy measure in conjunction with local search procedures to adjust process planning decisions with the goal of reducing total tardiness. A new dispatching heuristic, OU-MW, is developed to generate feasible schedules for complex job shop scheduling problems with maximum wait time constraints. A regression based proxy approach, PBLS-R, and a neural network based proxy approach, PBLS-NN, are investigated. In each case, descriptive statistics about the active process plan set are used as independent variables in the model. The resulting proxy measure is used to evaluate the effect of process planning local search moves on the objective function sum of total tardiness. Using the proxy measure to guide a local search reduces the number of times a detailed schedule is generated reducing overall runtime. In summary, the proxy measure based local search approach involves the following stages: • Generate a set of feasible schedules for a set of jobs in a complex job shop. • Evaluate the parameters and results of the schedules to establish a proxy measure that will estimate the effect of process planning decisions on objective function performance. • Apply local search methods to improve upon feasible schedules. Both PBLS-R and PBLS-NN are integrated process planning and scheduling heuristics capable of addressing the challenges of the CandL problem. Both approaches show significant improvement in objective function performance when compared to local search guided by random walk. Finally, an optimal solution approach is applied to small data sets and the results are compared to those of PBLS-R and PBLS-NN. Although the proxy based local search approaches investigated do not guarantee optimality, they provide a significant improvement in computational time when compared to an optimal solution approach. The results suggest proxy based local search is an appealing approach for integrated process planning and scheduling in complex job shop environment where optimal solution approaches are not viable due to processing time. / Ph. D.

The 21st century demand for innovation is leading towards a revolution in the way products are perceived. This will have a major impact on manufacturing technologies as current product innovation is constrained by the available manufacturing processes, which function independently. One of the most significant developments is the emergence of hybrid manufacturing technologies integrating various individual manufacturing processes. Hybrid processes utilise the advantages of the independent processes whilst minimising their weaknesses as well as extending application areas. Despite the fact that the drawbacks of the individual processes have been significantly reduced, the application of state of the art hybrid technology has always been constrained by the capabilities of their constituent processes either from technical limitations or production costs. In particular, it is virtually impossible to machine complex parts due to limited cutting tool accessibility. By contrast, additive manufacturing (AM) techniques completely solve the tool accessibility issue, but this increased flexibility and automation is achieved by compromising on part accuracy and surface quality. Furthermore, the shape and size of raw materials have to be specific for each hybrid process. More importantly, process planning methods capable of effectively utilising manufacturing resources for hybrid processes are highly limited. In this research, a hybrid process, entitled iAtractive, combining additive, subtractive and inspection processes is proposed. An experimental methodology has been designed and implemented, by which a generative reactionary process planning algorithm (GRP2A) and feature-based decision-making logic (FDL) is developed. GRP2A enables a complex part to be accurately manufactured as one complete unit in the shortest production time possible. FDL provides a number of manufacturing strategies, allowing existing parts to be reused and transformed into final parts with additional features and functionalities. A series of case studies have been manufactured from zero and existing parts, demonstrating the efficacy of the iAtractive process and the developed GRP2A and FDL, which are based on a manual process. The major contribution to knowledge is the new vision for a hybrid process, which is not constrained by the capability of the individual processes and raw material in terms of shape and size. It has been demonstrated that the hybrid process together with GRP2A and FDL provides an effective solution to flexibly and accurately manufacture complex part geometries as well as remanufacture existing parts.

Additive Manufacture (AM) is a novel manufacturing method; it is a process of forming components by adding materials. Owing to material saving and manufacturing cost saving, more and more research has been focused on metal AM technologies. WAAM is one AM technology, using arc as the heat sources and wire as the material to create parts with weld beads on a layer-by-layer basis. The process can produce components in a wide range of materials, including aluminum, titanium and steel. High deposition rate, material saving and elimination of tooling cost are critical characteristics of the process. Cost estimation is important for all companies. The estimated results can be used as a datum to create a quote for customers or evaluate a quote from suppliers, an important consideration for the application of WAAM is its cost effectiveness compared with traditional manufacture methods. The aim of this research is to find a way to develop a cost estimating method capable of providing manufacturing cost comparison of WAAM with CNC. A cost estimation model for CNC machining has been developed. A process planning approach for WAAM was also defined as part of this research. An Excel calculation spreadsheet was also built and it can be easily used to estimate and compare manufacture cost of WAAM with CNC. Using the method developed in this research, the cost driver analysis of WAAM has been made. The result shows that reduced material cost is the biggest cost driver in WAAM. The cost comparison of WAAM and CNC also has been made and the results show that with the increase of buy-to-fly ratio WAAM is more economical than CNC machining.

This doctoral thesis aims the theoretical and exploratory study of methodologies and mechanisms for automating 4D modeling, applied in the processes planning of volumetric construction in steel. We assume that in architecture, planning is the link of cohesion between design and construction. Hypothetically, we propose that through the study of methodologies and planning tools, we could get to know the mechanisms to extend the digitized information at rendering the design of the building, organizing it, in such a way that will be operable even in its industrialized production. In the area of visual communication in architecture and design, we have noticed a growing interest by the use of these innovations, the transition from CAD to BIM platforms, as well as the implementation of the CAVT (Computer Advanced Visualization Tools), whence 4D technology originated. We find particularly motivating for the realization of this work, the updating in 3D, 4D (3D + time) modeling techniques and its multidimensional progression; besides the verification of the possibilities of integration and synchronization of information, through built-in mechanisms of these new tools. From them, we draw general objective, know and describe how to prepare dynamic animation of assembly movements, a means of representation and communication almost absent in architecture and construction. In the exploratory proposal of the thesis we suggests, if in a 4D dynamic simulation model, ensures that the movements, and in general, the parametrized behavior of 3D graphic entities, occur in accordance with the logic of the construction sequence, then, the information used to represent the design of a building, would be used also for represent the construction process and develop the virtual environment of planning, where movements would be displayed upon executing the operations, the strategy evaluated and the length of its construction quantified. With this work, we intend to overcome the characteristic use of animation in the representation of the design; witch in part has caused the production of static images, preventing the virtual and dynamic representation of the construction processes. Then, on the basis of the analyzed fundamentals, we explore and disclose how to develop a 4D model ¿as built¿, detailing the 3D graphical entities that represent the integral parts of the objects of the building, and even the resources required to build them. Subsequently, we describe how linked together with the construction operations, in an exercise known as process modeling. Mainly we propose a strategy for the elaboration of the two virtual environments of the volumetric construction in steel, through the respective models of dynamic simulation 4D, where the assembly operations in site and offsite production of a modular building come alive virtually. To carry it out, we justify the integration of mechanical design platform, 4D and BIM, (Inventor, Navisworks, and Revit) from Autodesk. In the application of the thesis, we will approach to achieve integration of information from design and construction, for digitizing the complete cycle of industrial production of a modular building. We provide a series of procedures, recommendations, and qualitative appreciations, to capture and manage, the know-how of the logic of construction. Keywords: 4D technology, visual simulation, process planning, virtual construction. / La presente tesis doctoral, tiene por objeto el estudio teórico y exploratorio de las metodologías y mecanismos de automatización del modelado 4D, aplicados en la planificación de procesos de construcción. En este caso, de la construcción volumétrica en acero. Partimos del supuesto de que en la arquitectura, la planificación es el vínculo de cohesión del diseño con la construcción. Hipotéticamente planteamos, que a través del estudio de las metodologías y herramientas de planificación, podríamos llegar a conocer los mecanismos que permitan extender la información digitalizada al representar el diseño de la edificación, organizándola de tal manera, que sea operable hasta en su producción industrializada. En el contexto de la investigación, revisamos la literatura, las metodologías y las referencias significativas en los avances para la planificación de procesos. Se presentan los antecedentes y se justifica la elección de la tecnología de simulación visual 4D, integrada con el modelado multidimensional y los prototipos virtuales, como la nueva herramienta de análisis, que permite disminuir el riesgo en la industria de la construcción. Además, conveniente para que el arquitecto aproveche sus conocimientos de modelado 3D en la elaboración de entornos virtuales de construcción, que proveen la inexistente posibilidad en la arquitectura, de ensayar antes de construir: try before built. En el área de la comunicación visual en la arquitectura y el diseño, hemos percibido un creciente interés por la utilización de estas innovaciones, la transición entre las plataformas CAD al BIM, así como la implementación de las CAVT (Computer Advanced Visualization Tools), de donde proviene la tecnología 4D. Particularmente encontramos motivante para la realización de este trabajo, la actualización en las técnicas de modelado 3D, 4D (3D+tiempo) y su progresión multidimensional; además de la verificación de las posibilidades de integración y sincronización de la información, a través de mecanismos incorporados en estas nuevas herramientas. A partir de ellos, trazamos como objetivo general, conocer y describir cómo elaborar la animación dinámica de los movimientos de ensamblaje, un medio de representación y comunicación prácticamente inexistente en la arquitectura y la construcción.

Dual head placement machines are commonly used in industry for placing components on circuit cards with great speed and accuracy. This thesis evaluates a novel approach for prescribing process plans for circuit card assembly on dual head placement machines. Process planning involves assigning component types to heads and to feeder slots associated with each head and prescribing appropriate sequences of picking, placing and nozzle-changing steps. The approach decomposes these decisions into four inter-related problems: P1, P2, P3 and P4. This thesis reviews this approach; presents a new heuristic to address P1; a method to facilitate P2 and P3 solutions; a method to control nozzle changes in P4; tests approaches to P1, P2, P3 and P4; and presents a thorough analysis of computational results to evaluate the efficacy of the approach which aims to balance workloads on machine heads to maximize assembly line throughput.

<p>The objective of this thesis is to find and develop methods that enhance and support the creation of evolvable master process plans with possibilities to challenge productivity and meet changing design requirements. The condition for achieving this is primarily that both the fundamental thinking and the results behind a process plan can be described. How should this be done?</p><p>The focus is laid on process planning of gear transmission parts for heavy vehicles like trucks and coaches.</p><p>Process planning is the activity where design and manufacturing are brought together with the common target to achieve both a competitive product and production process. There are many factors that influence the process planner when a new product or process shall be introduced for production. Process planning is, in most cases, performed by an experienced, skilled person but without any defined methodology or way of working. Much of the process planning is based on the retrieval of solutions already used.</p><p>Much research effort has been devoted to developing systems for computer-aided process planning (CAPP). Yet CAPP systems have not been accepted and spread over a wide front within the manufacturing industry, much because of the functional incompleteness combined with the difficulties of adopting knowledge and changing requests.</p><p>A method for systematic process planning is proposed as a way to perform and describe the procedure of creating a process plan. The method facilitates the interpretation and understanding of the plan, not only immediately for the process planner responsible, but also for designers, engineers, researchers and other interest groups involved in a manufacturing process.</p><p>In the last chapter is a case study regarding manufacturing of a bevel gear pinion presented to exemplify use of the proposed method for systematic process planning.</p> / KUGG

No description available.

No description available.

O planejamento de processos é uma atividade essencial nas diversas etapas do ciclo de manufatura, em particular nas indústrias que produzem peças através de processos de usinagem. O uso de sistemas CAPP tem implicado em uma evolução nos sistemas de planejamento. A determinação da máquina, da ferramenta e das condições operacionais adequadas visando a otimização das diversas operações é fundamental para o sucesso do processo produtivo e da empresa, podendo ser melhorado pelo uso do CAPP. Estudam-se, assim, os fatores que influenciam esse tipo de processo, propondo-se um modelo de sistema protótipo para o seu planejamento, de forma a se ter no final uma especificação teórica da profundidade de corte, do avanço e da velocidade de corte, considerando aspectos como a usinabilidade do material da peça, os tempos de fabricação secundários e auxiliares, e a própria logística aplicada ao fluxo de peças no chão-de-fábrica através da definição quanto à máquina empregada ser ou não gargalo além de considerações sobre a disponibilidade de carga-máquina. Procurou-se elaborar um critério de otimização que considere não apenas o intervalo de máxima eficiência como proposto por vários autores, mas discuta a aplicação de seus limites e as restrições do sistema máquina-ferramenta-peça. Além do planejamento teórico o sistema possui um módulo de ensaios práticos visando refinar os valores teóricos da velocidade de corte adotada para garantir a sua perfeita aplicação com a máquina e a ferramenta adotados. A proposta do sistema é semi-generativa, unindo soluções algorítmicas e baseadas em conhecimento, com uma interface simples e amigável ao usuário. / Process planning is an essential activity in the several stages of the manufacturing cycle, particularly in industries which produce parts by means of machining processes. The use of CAPP systems has implied in a planning systems evolution. The determination of machine, tooling and suitable operational conditions looking at the optimization of the several operations is fundamental to the success of the productive process and of the enterprise, and can be improved by use of CAPP systems. It was studied the factors which influence this kind of process and it was proposed a prototype system model for this planning and for obtaining a theoretical specification of the depth of cut, feed and cutting speed, taking into consideration aspects like machinability of the part material, secondary and auxiliary manufacturing times, and the logistics applied to the flow of parts at the shop-floor through the definition of the used machine to be or not a production neck beyond considerations on the availability of machine capacity. It was proposed an optimization criterion which considers not only the maximum efficiency interval as quoted by many authors but also discuss the application of its limits and the restrictions of the system machine-tool-part. Besides the theoretical planning the system has a practical testing module intended to refine the theoretical values of the adopted cutting speed to guarantee its application to the defined machine and tooling. The system approach is semi-generative, with algorithmic and knowledge based solutions, with a simple and user-friendly interface.

O planejamento de processos é uma atividade essencial nas diversas etapas do ciclo de manufatura, em particular nas indústrias que produzem peças através de processos de usinagem. O uso de sistemas CAPP tem implicado em uma evolução nos sistemas de planejamento. A determinação da máquina, da ferramenta e das condições operacionais adequadas visando a otimização das diversas operações é fundamental para o sucesso do processo produtivo e da empresa, podendo ser melhorado pelo uso do CAPP. Estudam-se, assim, os fatores que influenciam esse tipo de processo, propondo-se um modelo de sistema protótipo para o seu planejamento, de forma a se ter no final uma especificação teórica da profundidade de corte, do avanço e da velocidade de corte, considerando aspectos como a usinabilidade do material da peça, os tempos de fabricação secundários e auxiliares, e a própria logística aplicada ao fluxo de peças no chão-de-fábrica através da definição quanto à máquina empregada ser ou não gargalo além de considerações sobre a disponibilidade de carga-máquina. Procurou-se elaborar um critério de otimização que considere não apenas o intervalo de máxima eficiência como proposto por vários autores, mas discuta a aplicação de seus limites e as restrições do sistema máquina-ferramenta-peça. Além do planejamento teórico o sistema possui um módulo de ensaios práticos visando refinar os valores teóricos da velocidade de corte adotada para garantir a sua perfeita aplicação com a máquina e a ferramenta adotados. A proposta do sistema é semi-generativa, unindo soluções algorítmicas e baseadas em conhecimento, com uma interface simples e amigável ao usuário. / Process planning is an essential activity in the several stages of the manufacturing cycle, particularly in industries which produce parts by means of machining processes. The use of CAPP systems has implied in a planning systems evolution. The determination of machine, tooling and suitable operational conditions looking at the optimization of the several operations is fundamental to the success of the productive process and of the enterprise, and can be improved by use of CAPP systems. It was studied the factors which influence this kind of process and it was proposed a prototype system model for this planning and for obtaining a theoretical specification of the depth of cut, feed and cutting speed, taking into consideration aspects like machinability of the part material, secondary and auxiliary manufacturing times, and the logistics applied to the flow of parts at the shop-floor through the definition of the used machine to be or not a production neck beyond considerations on the availability of machine capacity. It was proposed an optimization criterion which considers not only the maximum efficiency interval as quoted by many authors but also discuss the application of its limits and the restrictions of the system machine-tool-part. Besides the theoretical planning the system has a practical testing module intended to refine the theoretical values of the adopted cutting speed to guarantee its application to the defined machine and tooling. The system approach is semi-generative, with algorithmic and knowledge based solutions, with a simple and user-friendly interface.