Synthesis of Manufacturing Systems Using Co-Platforming

Modern manufacturing environment is characterized by frequent changes within product design in order to satisfy evolving customer requirements. Various strategies are implemented in order to efficiently manage the consequences arising from the product design changes starting from design of the product, planning, manufacturing…etc. This dissertation focuses mainly on the manufacturing phase in which a new concept in manufacturing system synthesis is proposed. A new concept in manufacturing system synthesis has been introduced and coined as “Co-platforming”. Co-platforming is the synthesis of manufacturing systems through mapping product platform features and components to platform machines on one side, and non-platform product features and components to non-platform machines on the other side, in order to reduce the manufacturing system investment cost and prolong the manufacturing system useful life as product variants evolve and change. Tools and methods are developed to synthesize the manufacturing system based on Co-platforming within functional and physical levels. At the functional level, the group of platform and non-platform machines and the number of each machine type are determined. A new matrix based mapping model is proposed to determine the platform and non-platform machines candidates. A ranking coefficient is formulated which ranks the platform machines according to their machining capabilities in order to assist manufacturing firms in decision making concerning which type of platform machine to choose. Furthermore, a new mathematical programming optimization model is proposed in order to provide the optimum selection of machine types among machine candidates and their numbers. Moreover, a new mathematical programming model is proposed which synthesizes manufacturing systems taking into consideration machine level and system level changes based on co-platforming. At the physical level, the manufacturing system configuration is determined which is concerned with determining the number of stages, types of machines in each stage and the number of machines in each stage. A new mathematical programming optimization model is proposed which determines, in addition to the type and number of each machine, the optimal manufacturing system configuration based on co-platforming. The Co-platforming methodology is being applied in two case studies from automotive industry. The first case study is concerned with machining of automotive cylinder blocks taken from Mitsubishi Heavy Industries and the second case study is concerned with the assembly of automotive cylinder heads taken from ABB flexible automation. The results obtained from the co-platforming methodology indicate that cost reduction can be achieved when synthesizing the manufacturing system based on co-platforming

Analytical and finite element modeling of a machining system to minimize inaccuracy in milling and using rapid prototyping for die manufacturing

The end milling process is used extensively in a gamut of manufacturing areas. It accounts for up to 40% of the cost of fabrication of non-electrical parts for a high performance aircraft. This economically justifies the effort to find ways to reduce inaccuracy caused in milling by workpiece deformation, fixture deflection and cutter deflection to improve the quality of parts. The process is also used extensively for roughing and finishing of dies. However, the conventional die manufacturing process, which uses the milling process, is too time consuming because of the extensive CNC programming involved. Furthermore skilled labor required for CNC programming accounts for the high cost of die manufacturing. Therefore new processes need to be developed that will eliminate CNC programming and possibly reduce the usage of the milling process thereby reducing the cost and time required to produce parts;An analytical non-linear optimization model has been developed which can determine the maximum inaccuracy due to workpiece deformation and the optimal clamping forces that are required to minimize work piece deformation while ensuring that the workpiece will not slip during machining. However, this model assumes rigid fixturing elements and is only suitable for simple workpiece shapes;A finite element model and a simple novel algorithm has been developed which has the same objective as the analytical non-linear optimization model. This model can be used for any complex shaped workpiece or fixture. The model also takes into account the flexibility of fixtures;Inaccuracy in machining is also caused by deflection of the tool. A study of the deflection of a milling cutter due to the action of the cutting forces was performed. An analytical equation was developed to determine the deflection of an end mill under a cutting force. The equation was verified by modeling the complete geometry of a four flute milling cutter using the finite element analysis module of I-DEAS software. The deflections obtained by the finite element model were exactly the same as those obtained by using the analytical equation. Previous researchers modeled the milling cutter as a simple cylinder which resulted in some error in the result;Three die manufacturing processes are proposed, namely, the casting prototype process, the EDM milling process and the copy milling process. All three processes use rapid prototyping to eliminate costly and time consuming CNC programming. All the three processes are economical compared to conventional processes provided there are large number of surfaces on the part. If the part has very few surfaces the conventional process will require less time for CNC programming making it more efficient. The Casting prototype process does not use milling whereas the EDM milling uses milling for rough machining. These two process would minimize inaccuracy in parts by eliminating milling or using milling to remove the rough stock only. The copy milling process uses milling but the models developed here can be used to minimize error in this process. All three processes have the additional advantage that they are more time efficient and economical than the conventional process of making dies

Process planning for an Additive/Subtractive Rapid Pattern Manufacturing system

This dissertation presents a rapid manufacturing process for sand casting patterns using a hybrid additive/subtractive approach. This includes three major areas of research that will enable highly automated process planning; a critical need for a rapid methodology. The first research area yields a model for automatically determining the locations of layers, given the slab height, material types and part geometry. Layers are chosen such that it will avoid catastrophic failures and poor machining conditions in general. First, features that are possible thin material machining positions are defined, and methods for detecting these feature positions from an STL model are studied. Next, a layer thickness calculation model is presented according to positions of these features. The second area focuses on tools and parameters for the subtractive side of processing each layer. A tool size and machining parameter selection model is presented that can automatically select tool sizes and machining parameters, given layer thickness, part geometry, and material types. Machining strategies and related machining parameters are studied first. Then the method for Stepdown parameter calculation is presented. Finally, an algorithm based on both accessibility and machining efficiency is proposed for the selection of tool sizes for the rough cutting operation, finish cutting operation and optional semi-rough cutting operation. The final research area focuses on a cutting force analysis for thin material machining with additional layer thickness & tool size interaction. Popular cutting force models are reviewed, and a suitable model for cutting force calculation in this process is evaluated. Then, a cantilever beam model is used to analyze the thin material machining failure problem, and a minimum layer thickness model is presented. Third, a combined layer thickness & tool size model is constructed based on the machining tool deflection under cutting forces. This rapid pattern manufacturing process and related software has been implemented, and experimental data is presented to illustrate the efficacy of this system and its process planning methods

Continuous improvement of a machining process by designing a new jig

This thesis report gives an insight on how an often overlooked, jig and fixture used as a manufacturing aid to produce a product and essential for delivering products reliably and repeatedly with high quality. This continuous improvement project of an exciting machining process of winding cones used overhead garage doors. The improvement was a necessity with a forecast for 2019 estimating the need for 43% faster production cycle (takt time) compared to the previous year. Hence, the main objective was to reduce the machining time required per part by designing a modular jig system, ideally with 12 parts per cycle. To make the work in an organized structure the project was dived into four phases namely: research, design, machining and implementation. The research phase included in the study of the old jig in use, analysing the process and sketching the basic requirements. The design phase was based on the methodology of Design for Six Sigma methodology for the fixture. Different kind of jig components was designed and assembled using SOLIDWORKS CAD model. The critical review of design iteration was analysed using SWO analysis (short version of the standard SWOT analysis) for design. The machining of most components of the jig was done in-house with tacit knowledge of the machinist instead of using CAM software’s making it first of its kind project in developing knowledge management in the company for future jig requirements. The critical outcomes of the project were harvested from the implementation phase. The newly machined modular jig system proved to have increased the number of parts machined per day by 32% with expected savings of more than €6000 per annum. The added benefit of a modular jig system was that one base (skeleton of the jig) could be used in machining different products. Also, future projects now have the intellectual and physical resources of making jigs and fixtures in-house. This drastically reduces the lead times for new parts, which is crucial for a small-medium enterprise stay competitive.Este relatório dá uma visão sobre como um acessório usado pode auxiliar na produção de forma a produzir um produto e os elementos essenciais para a sua entrega de forma confiável e repetida com alta qualidade. Este é um projeto de melhoria contínua de um processo de maquinagem de cones de enrolamento, usados em portas de garagem suspensas. A melhoria surjiu de uma necessidade com a previsão para 2019, estimando a necessidade de um ciclo de produção 43% mais rápido (takt time) em comparação com o ano anterior. Assim, o objetivo principal passava por reduzir o tempo de maquinagem necessário por peça, projetando um sistema de gabarit modular, idealmente com 12 partes por ciclo. Para realizar o trabalho numa estrutura organizada, o projeto foi dividido em quatro fases: pesquisa, projeto, maquinagem e implementação. As fases de pesquisa foram incluídas no estudo do antigo gabarit em uso, analisando o processo e esboçando os requisitos básicos. A fase de projeto foi baseada na metodologia de Design for Six Sigma para um dispositivo. Foram projetados e montados diferentes tipos de componentes de gabarit usando o modelo SOLIDWORKS CAD. A revisão crítica da iteração do projeto foi analisada usando a análise SWO (versão reduzida da análise SWOT convencional) para projeto. A maquinagem da maioria dos componentes do gabarit foi feita internamente com conhecimento tácito do responsável técnico, recorrendo ao software CAM, tornando-o o primeiro de seu tipo no desenvolvimento da gestão do conhecimento na empresa para futuros requisitos de gabarit. Os principais resultados e conclusões dos projetos foram descritos na fase de implementação. O sistema de gabarit modular recém-maquinado provou ter aumentado o número de peças maquinadas por hora em 32%, com economias comprovadas de mais de € 6.000 por ano. O benefício adicional de um sistema de gabarit modular consiste de criar uma base (esqueleto do gabarit) usada na maquinagem de diferentes produtos, e projetos futuros, permitindo à empresa deter os recursos intelectuais e físicos de criar gabarits e acessórios internos. Assim, foi reduzido drasticamente o tempo de espera para novas peças, o que é crucial para uma pequena média empresa permanecer competitiva

Process planning for the subtractive rapid manufacturing of heterogeneous materials: Applications for automated bone implant manufacturing

This research presents a subtractive rapid manufacturing process for heterogeneous materials, in particular for custom shaped bone implants. Natural bone implants are widely used in the treatment of severe fractures or in tumor removal. In order for the human body to accept the bone implant material and heal properly, it is essential that the bone implant should be both mechanically and biologically compatible. Currently, the challenge of having correctly shaped natural bone implants created from an appropriate material is met through hand-shaping done by a surgeon. CNC-RP is a rapid machining method and software that can realize a fully automated Subtractive Rapid Prototyping (RP) process, using a 3-axis milling machine with a 4th axis indexer for multiple setup orientations. It is capable of creating accurate bone implants from different clinically relevant material including natural bone. However, there are major challenges that need to be overcome in order to implement automated shape machining of natural bones. They are summarized as follows: (1) Unlike homogeneous source materials for which a part can be machined from any arbitrary location within the original stock, for the case of donor bones, the site and orientation of implant harvest need to consider the nature of the heterogeneous internal bony architecture. (2) For the engineered materials, the source machining stock is in the convenient form of geometrically regular shapes such as cylinders or rectangular blocks and the entities of sacrificial supports can connect the part to the remaining stock material. However, irregularly-shaped bones and the heterogeneity of bone make the design of a fixture system for machining much more complicated. In this dissertation, two major areas of research are presented to overcome these challenges and enable automated process planning for a new rapid manufacturing technique for natural bone implants. Firstly, a new method for representing heterogeneous materials using nested STL shells is proposed. The nested shells model is called the Matryoshka mode, based in particular on the density distribution of human bone. The Matryoshka model is generated via an iterative process of thresholding the Hounsfield Unit (HU) data from a computed tomography (CT) scan, thereby delineating regions of progressively increasing bone density. Then a harvesting algorithm is developed to determine a suitable location to generate the bone implant from within the donor bone is presented. In this harvesting algorithm, a density score and similarity score are calculated to evaluate the overall effectiveness of that harvest site. In the second research area, an automated fixturing system is proposed for securing the bone implant during the machining process. The proposed method uses a variant of sacrificial supports (stainless surgical screws) to drill into appropriate locations and orientations through the free-form shaped donor bone, terminating at proper locations inside the solid part model of the implant. This automated fixturing system has been applied to machine several bone implants from surrogate bones to 3D printed Matryoshka models. Finally, the algorithms that are developed for setup planning are implemented in a CAD/CAM software add-on called CNC-RPbio . The results of this research could lead to a clinically relevant rapid machining process for custom shaped bone implants, which could create unique implants at the touch of a button. The implication of such high accuracy implants is that patients could benefit from more accurate reconstructions of trauma sites, with better fixation stability; leading to potentially shorter surgeries, less revisions, shorter recovery times and less likelihood of post-traumatic osteoarthritis, to name a few

A concurrent approach to automated manufacturing process planning

textWith the increasing demand of fast-paced and hybrid manufacturing processes in modern industry, it is desirable to expedite the iterations between design and manufacturing through intelligent computational techniques. In this research, we propose a concurrent approach of this kind to streamline the design and manufacturing processes. With this approach, a CAD design is automatically analyzed in terms of its manufacturability in the early design stage. If the part is manufacturable, a set of process plans optimized in time, cost, fixture quality and tolerance satisfaction are reported in real time. If the part is not manufacturable, the potential design changes are provided for better manufacturing. In the approach, the geometric information of 3D models and the empirical knowledge in manufacturing processes, fixtures, and tolerances are combined and encapsulated into a graph-grammar based reasoning. The reasoning systematically extracts meaningful manufacturing details that later constitute complete process plans for any given solid model. The plans are then evaluated and optimized using a specially designed multi-objective best first search technique. The complete approach enables a concurrent and efficient manufacturability analysis tool that closely resembles real manufacturing planning practice. Numerous case studies with real engineering parts are presented to characterize the novelty and contributions of this approach. The optimality of the suggested plans is verified through computational comparisons, and the practicality of the plans is validated with hands-on implementations on the shop floor.Mechanical Engineerin

E -commerce for the metal removal industry

The popularity of outsourcing fabrication introduces a problem, namely an inevitable loss of data as information is translated from design to fabrication or from one system to another. Unsatisfactory information, delivered to the outsourcing facility, and inefficient communications between design and fabrication certainly cause enormous economic losses from late product delivery or bad product quality. To overcome these data transferring problems and to improve communications between the design and fabrication sides, a design and manufacturing methodology for custom machined parts in E-Commerce is suggested and implemented in this dissertation. This methodology is based on the idea of a Clean Interface like the Mead-Conway approach for VLSI chip fabrication [MEAD81]. Essential design information for fabricating parts properly with NC (Numerical Controlled) milling machines is expressed in machining/manufacturing features, fabrication friendly terminologies, and is represented by a new language called NCML (Numerical Control Markup Language). NCML is based on XML (Extensible Markup Language)---the document-processing standard proposed by the World Wide Web Consortium (W3C). NCML is designed to include the minimum requisite information necessary for the manufacturer to produce the product. The designer defines NCML, which overcomes geographical separation between design and manufacturing, and minimizes unnecessary interactions caused from lack of information. To prove the possibility of custom machine part fabrication and E-Commerce with NCML, three software systems are implemented. These three systems are FACILE/Design, FACILE/Fabricate, and E-Mill. FACILE is a prototype CAD/CAM system developed to verify NCML feasibility as an Electronic Data Interchange (EDI) format. FACILE/Design is a system based on manufacturing features like holes, contours, and pockets. It can be used to create geometric models, verify the design, and create NCML files. The NCML file is imported by FACILE/Fabricate and turned into G-codes by applying appropriate cutting conditions. Simplified machining simulation and cost estimation tools using NCML inputs are also developed to show some examples of NCML applications that can help design and manufacturing activities. To demonstrate how NCML could be used in a web-based application, an E-Business model called E-Mill has been implemented. E-Mill is a market place for machined parts whose data is encoded in NCML. To make E-Mill a feasible E-Commerce model, two-way communication based on NCML data and the visualization of 3D geometric models in the Virtual Reality Modeling Language (VRML) are equipped with a competitive matchmaking mechanism. In this dissertation, a whole system based on NCML bridges the gap between design and manufacturing. As a part of the NCML validation process for the new system, the pros and cons of NCML design features are discussed. A system for cost estimation is calibrated and compared to real cutting results for the purpose of validation

A design-with-features approach for rotational machined components

A major problem in integrating Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) arises from the difference in thinking between the design and manufacturing people. Designers think of designing a new product in terms of its intended function whereas manufacturing engineers think in terms of decomposing a product design into a set of manufacturing operations. Feature Recognition and Designing with Features have been recognised as alternative approaches to the integration of design and manufacturing functions. In this thesis the second approach has been investigated by developing a feature-based front-end to a CAD solid modeller. This produces the geometric representation of the component in terms of manufacturing features and processes, and simultaneously captures this information in a form suitable for an outline process plan. [Continues.

Automated CNC Tool Path Planning and Machining Simulation on Highly Parallel Computing Architectures

This work has created a completely new geometry representation for the CAD/CAM area that was initially designed for highly parallel scalable environment. A methodology was also created for designing highly parallel and scalable algorithms that can use the developed geometry representation. The approach used in this work is to move parallel algorithm design complexity from an algorithm level to a data representation level. As a result the developed methodology allows an easy algorithm design without worrying too much about the underlying hardware. However, the developed algorithms are still highly parallel because the underlying geometry model is highly parallel. For validation purposes, the developed methodology and geometry representation were used for designing CNC machine simulation and tool path planning algorithms. Then these algorithms were implemented and tested on a multi-GPU system. Performance evaluation of developed algorithms has shown great parallelizability and scalability; and that main algorithm properties are required for modern highly parallel environment. It was also proved that GPUs are capable of performing work an order of magnitude faster than traditional central processors. The last part of the work demonstrates how high performance that comes with highly parallel hardware can be used for development of a next level of automated CNC tool path planning systems. As a proof of concept, a fully automated tool path planning system capable of generating valid G-code programs for 5-axis CNC milling machines was developed. For validation purposes, the developed system was used for generating tool paths for some parts and results were used for machining simulation and experimental machining. Experimental results have proved from one side that the developed system works. And from another side, that highly parallel hardware brings computational resources for algorithms that were not even considered before due to computational requirements, but can provide the next level of automation for modern manufacturing systems