Integrated process planning and scheduling for common prismatic parts in a 5-axis CNC environment

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A new geometric-and-physics model of milling and an effective approach to medial axis transforms of free-form pockets for high performance machining

Mechanical part quality and productivity depend on many parameters in CNC milling processes, such as workpiece material, cutters, tool paths, feed rate, and spindle speed, etc. To pursue high performance machining, the cutting parameter optimization is in high demand in industry, though it is quite challenge. This innovative research successfully addresses some essential problems in optimizing the cutting parameters by developing a new geometric-and-physics integrated model of milling and proposing an effective approach to the medial axis transforms of free-form pockets. In this research, an original geometric model of 21/2- and 3-axis CNC milling is developed and integrated with a well-established mechanistic model. A main research contribution is that this integrated model can predict complex milling processes in higher fidelity with instantaneous material remove rates, cutting forces and spindle powers, compared to prior machining models. In the geometric model, an in-process workpiece model is introduced by using a group of discrete Z-layers and applying the B-Rep scheme to represent the workpiece shape on each layer, in order to accurately represent instantaneous cutter-and-workpiece engagement in 2Yz- and 3-axis milling. Hence, the un-deformed chip geometry can be found even for complex part milling, which is then fed to the mechanistic model to predict instantaneous cutting forces. By using this integrated model, cutting parameters can be optimized for profiling, pocketing, and surface milling to ensure steady cut and the maximum material removal rates. This model has been verified by experiments, and will be implemented into a software tool for Bombardier Aerospace. Another important research in this work is to propose aggressive roughing of free-form pockets for ultimately high cutting efficiency. For this purpose, an accurate, efficient approach to the medial axis transforms of free-form pockets and an optimal approach to multiple cutters selection and their path generation are proposed. The main contributions of this research include (1) a new mathematical model of medial axis point, (2) an innovative global optimization solver, the hybrid global optimization method, (3) an optimization model of selecting multiple cutters for the maximum material removal rate. This research can substantially promote aggressive roughing in the machining industry to increase cutting efficiency of free-form pockets. The technique has been validated using considerable number of cutting tests and can be directly implemented into commercial CAD/CAM softwar

Framework proposal for selecting a hybrid renewable generation mix at a prosumer connecting point in the context of micro smart grids

Considering the thematic of climate change, numerous strategies have been adopted in order to struggle with such problem. In electrical systems and power supply, the use of clean technologies is considered the mostacceptable solution. In thiscontext,emergesthe concept of microgrids (MGs). MGs are local energy providers that can potentially reduce energy expenses and emissions by utilizing distributed energyresources(DERs). A mong a variety of DER susedon microgrids,it is widelyac cepted that renewable sources, especially solar and wind generation, play a significant role in providing sustainable energy, as they are both inexhaustible and less polluting. Because of that, the microgrids and renewable energy sources are receiving increasing attention from power system operators, since they can aid to transform the current high pollutant power system into a "greener"system.How ever ,there is still much to beconsidered and proven in relation to the implementation of such technologies. The intermittent nature and the uncertainties associated with solar and wind generation pose sufficient technological and economical challenges for system planners. Besides, the supply of electricity interferes the society as a whole, which makes the implementation of microgrids and renewable energies an even more complex problem, dependent on a wide spectrum of players, interests and constraints. In this context ,the present work is a first effortin establis hing a frame work that is capable of dealing with such heterogeneous problem. More than that, this thesis contributes with a broader view of microgrid implementation, suggesting a collection of tools which are suitable for observing the effects of penetration of clean technologies on society. The proposed frame work is afivestage planning strategy which allows the system planners to consider all aspects ranging from uncertainty in resources, technological feasibility, economics, and environmental impacts of the system and choose an optimal design suited to their localized conditions. The motivation behind using such strategy lies not only in the optimization of the individual systems or disciplines but also their interactions between each other. In short, the suggested approach is an iterative procedure divided in five stages, named microgrid coordination, operation optimization, reliability assessment, contingency assessment, and searching mechanism. The microgrid coordination stage has the function of modeling the philosophy used by the energy management system (EMS) to control the power balance in microgrids. The models of EMS are developed using the Petri net formalism. Optimization stage performs a constrained cost minimization analysis of microgrid considering the operation and maintenance (O&M) cost, pollutants emission, and stoc hastic variables(generation and loaddemand).Afte rthat ,it is executed the reliability assessment ,where the power system reliability indexes are estimated by means of a Monte Carlo Simulation (MCS),taking into a ccount the EMS philosophy of microgridin isolated mode. Next, using the reliability indexes, the contingency probability is calculated using the steady state analysis of a Markov chain, which aims to assess the distribution power system admitting all possible mode transition. Finally, since the DER selection involves multiple criteria and interests of different parts, it is required a multi-attribute decision system providing a list of possible configuration based on their relative importance as denoted by the stakeholders. Because of that, the Particle Swarm Optimization (PSO) is used to search the best DER combination using two distinct solvers - multi-objective weighted function and Pareto front. As result, the framework provides the rated power of each DER that must be installed in the microgrid in order to have an optimal balance between technical, economical, social, and environmental aspects. Regarding the heterogeneous quality of planning problem, this strategy is effective in the sense of incorporating several aspects into the same analysis framework. In addition, the proposed framework contributes helping the planners to handle the penetration of renewable resources in a systematic way. To have realistic results, the framework is performed on a case of study of a potential campus microgrid program

Application of ”ART SIMULATOR” for Manufacturing Similarity Identification in Group Technology Design - Chapter 10

This chapter 10 carried out the exceptional implementation of ART-1 neural network in the analysis of the manufacturing similarity of the cylindrical parts within the group technology design. Established concept of the group technology design begins from the complex part of the group or the group representative. Group representative has all the geometrical elements of the parts in group, and manufacturing procedure may be applied to the machining of any part in the group. The complex part may be realistic or a hypothetical one. The ART-1 artificial neural network provided manufacturing classification according to the geometrical similarities of work-pieces for the group of cylindrical parts. For the manufacturing similarity identification within the group technology design, software package "ART Simulator" is developed and presented in this chapter

Feasibility analysis of using special purpose machines for drilling-related operations

This work focuses on special purpose machine tools (SPMs), providing a modular platform for performing drilling-related operations. One of the main challenges in using SPMs is selecting the most appropriate machine tool among many alternatives. This thesis introduces a feasibility analysis procedure developed to support decision-making through the assessment of the strengths and limitations of SPMs. To achieve this, technical and economic feasibility analyses, a sensitivity analysis, and an optimisation model were developed and a case study was provided for each analysis. The results indicated that although technical feasibility analysis leads decision-makers to select a feasible machine tool, complementary analyses are required for making an informed decision and improving profitability. Accordingly, a mathematical cost model was developed to perform economic and sensitivity analyses and investigate the profitability of any selected SPM configuration. In addition, an optimisation procedure was applied to the cost model in order to investigate the effect of process parameters and the SPM configuration on the decision-making. Finally, the developed analyses were then integrated into a model in a proper sequence that can evaluate whether the SPM is appropriate for producing the given part and achieving higher productivity. To validate this integrated model three different case studies were presented and results were discussed. The results showed that the developed model is a very useful tool in assisting manufacturers to evaluate the performance of SPMs in comparison with other alternatives considered from different perspectives

Smart automated computer-aided process planning (ACAPP) for rotational parts based on feature technology and STEP file

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe concept of smart manufacturing comprises high levels of adaptability with rapid design changes, digital information technology, and more data training. This differs from traditional manufacturing, which depends on constant inputs for the generation of process planning to manufacture a part or requires human intervention if any of the input changes. Smart manufacturing has become a vital issue in the manufacturing industry since the start of the twenty-first century, in terms of time and production cost. One of the most effective concepts for achieving a smart manufacturing industry is the use of Computer-Aided Process Planning (CAPP) which is the key technology that connects Computer-Aided Design (CAD) and the Computer-Aided Manufacturing (CAM) processes. A lot of effort has been spent taking CAPP systems to the next upgraded level that is Automated Computer- Aided Process Planning (ACAPP) in order to provide complete information about the product, in a way that is automated, fast, and accurate. One of the most import aspects in creating an ACAPP system is the use of feature technology, as it is the first step in converting the design to manufacturing features. This includes in particular the development of efficient Automatic Feature Recognition (AFR) systems and solving features intersecting issues. The implementation of AFR techniques is an indispensable concept for transferring product data between CAD and ACAPP systems. Different international Product Data Exchange (PDE) standards, such as Drawing Exchange Format (DXF), Initial Graphic Exchange Specification (IGES), and Standard for the Exchange of Product (STEP) files are used to accomplish this purpose. Although many AFR techniques and systems have been developed to serve this aim, each of them has limitations. For example, each system is restricted to recognise a specific set of predefined manufacturing features; hence, if new features are included in the model design, they will not be recognised. In this work, a novel and smart interactive AFR (SI-AFR) system has been proposed for recognising features of rotational parts. A parser has been developed to extract the geometrical and topological information of a part design from a STEP file and to send it to the next steps. Then, the system manipulates the extracted information to facilitate the feature recognition process. During this progression, the system contributes to solving issues considered drawbacks in previous works, such as identifying the convexity and concavity of toroidal surfaces and efficiently isolating faces that belong to holes and internal shapes. Finally, the feature recognition process has been divided into two parts: recognition of predefined features and smart interactive feature recognition. This has been written using C# coding to extract the features’ geometrical and topological information from the STEP file. Whilst the first part of the proposed system has the ability of recognising 54 predefined features, the main contribution of this research is concentrated in the second part of the system which allows new features to be detected, identified, and added to the predefined feature set. This is achieved by extracting the type and specification of each face, the geometrical and topological relation between each two adjacent faces, and the number of the faces that form the new feature. Due to its ability in identifying predefined and new features, it is believed that the system represents a new generation of feature recognition systems. Also, a “features subtraction” system has been created as an optimal solution for complex features intersecting cases. It takes the final manufacturing features from the SI-AFR system as an input. The system has seven steps for analysing, processing, and calculating intermediate features. The intermediate features represent layers of material to be removed, in an optimal sequence. These are recognised by scanning in all directions of the part, to determine the intersecting areas between the final manufacturing features. Such a system provides a whole vision of transferring a blank into the desired shape via step-by-step rough turning, drilling, and boring processes. The results from the SI-AFR and features subtraction systems depend on the geometrical and topological information of the pre-defined and new features. These are analysed for the purpose of automatically generating CAPP outputs, such as the process selection, cutting tools, sequence of operations, and generating G-code. This is to reduce the time and production cost, as well as human intervention, and hence significantly contributes to an organisations efforts in sustainability. The proposed ACAPP system has been practically validated, clearly demonstrating how it surpasses the capabilities of traditional CAM software, since all the outputs are achieved automatically, which CAM software are currently not capable of. The final manufacturing features of the part have been produced accurately, compared to the design features, in terms of specified design dimensions and tolerances. The current version of the system covers rotational symmetrical parts, however this work can be extended to include rotational non-symmetrical and prismatic parts.Republic of Iraq Ministry of Higher Education & Scientific Researc

Analysis, optimization, FE simulation of micro-cutting processes and integration between Machining and Additive Manufacturing.

La seguente Tesi di Dottorato riguarda i processi di Micro-Machining (MM) applicati su materiali ottenuti per fabbricazione additiva. I processi MM sono un insieme di tecnologie di produzione utilizzate per fabbricare componenti o realizzare features di piccole dimensioni. In generale, i processi di taglio sono caratterizzati da un'interazione meccanica tra un pezzo e un utensile che avviene lungo una determinata traiettoria. Il contatto determina una rottura del materiale lungo un percorso definito, ottenendo diverse forme del pezzo. Più precisamente, la denominazione di microlavorazione indica solo le lavorazioni di taglio eseguite utilizzando un utensile di diametro inferiore a 1 mm. La riduzione della scala dimensionale del processo introduce alcune criticità non presenti negli analoghi processi su scala convenzionale, come l'effetto dimensionale, la formazione di bave, la rapida usura dell'utensile, le forze di taglio superiori alle attese e l'eccentricità del moto dell'utensile. Negli ultimi decenni, diversi ricercatori hanno affrontato problemi relativi alla microlavorazione, ma pochi di loro si sono concentrati sulla lavorabilità dei materiali prodotti per Additive Manufacturing (AM). L’AM è un insieme di processi di fabbricazione strato per strato che possono essere impiegati con successo utilizzando polimeri, ceramica e metalli. L'AM dei metalli si sta rapidamente diffondendo nella produzione industriale trovando applicazioni in diversi rami, come l'industria aerospaziale e biomedica. D’altro canto, la qualità del prodotto finale non è comparabile con gli standard ottenibili mediante i metodi convenzionali di rimozione del materiale. Lo svantaggio principale dei componenti realizzati mediante AM è la bassa qualità della finitura superficiale e l'elevata rugosità; pertanto, sono solitamente necessari ulteriori trattamenti superficiali post-processo per adeguare le superfici del prodotto ai requisiti di integrità superficiale. L'integrazione tra le due tecnologie manifatturiere offre opportunità rilevanti, ma la necessità di ulteriori studi e indagini è evidenziata dalla mancanza di pubblicazioni su questo argomento. Questa ricerca mira ad esplorare diversi problemi connessi alla microlavorazione di leghe metalliche prodotte mediante AM. Le prove sperimentali sono state eseguite utilizzando il centro di lavoro ultrapreciso a 5 assi “KERN Pyramid Nano”, mentre i campioni AM sono stati forniti da aziende e gruppi di ricerca. L'attrezzatura sperimentale è stata predisposta per eseguire la micro-fresatura e per monitorare il processo in linea misurando la forza di taglio. Il comportamento di rimozione del materiale è stato studiato e descritto per mezzo di modelli analitici e simulazioni FEM. I metodi FE sono stati utilizzati anche per eseguire un confronto tra le forze di taglio previste e i carichi sperimentali, con lo scopo finale di affinare la legge di flusso dei materiali lavorati. La ricerca futura sarà focalizzata sulla simulazione FE dell'usura dell'utensile e dell'integrità della superficie del pezzo.This thesis is focused on Micro-Machining (MM) processes applied on Additively Manufactured parts. MM processes are a class of manufacturing technology designed to produce small size components. In general, cutting processes are characterized by a mechanical interaction between a workpiece and a tool. The contact determines a material breakage along a defined path, obtaining different workpiece shapes. More specifically, the micro-machining designation indicates only the cutting processes performed by using a tool with a diameter lower than 1 mm. The reduction of the process scale introduces some critical issues, such as size effect, burr formation, rapid tool wear, higher than expected cutting forces and tool run-out. In the last decades, several researchers have tackled micro-machining related issues, but few of them focused on workability of Additive Manufactured materials. Additive Manufacturing (AM) is a collection of layer-by-layer building processes which can be successfully employed using polymers, ceramics and metals. AM of metals is rapidly spreading throughout the industrial manufacturing finding applications in several branches, such as aerospace and biomedical industries. Moreover, the final product quality is not comparable with the standards achievable through the conventional subtractive material removal methods. The main drawback of additively manufactured components in metals is the low quality of the surface finish and the high surface roughness, therefore further post-process surface treatments are usually required to finish and to refine the surfaces of the build product. The embedding between the two technologies offers relevant opportunities, but the necessity of further studies and investigation is highlighted by the lack of publication about this topic. This research aimed to explore several micro-machining issues with regards to Additive Manufactured metals. Experimental tests were performed by using the ultraprecision 5-axes machining center “KERN Pyramid Nano”, while the AM samples were provided by companies and research groups. The experimental equipment was set-up to perform micro-milling and to monitor the process online by measuring the cutting force. The material removal behavior was investigated and described by means of analytical models and FEM simulations. FE methods were employed also to perform a comparison between the predicted cutting forces and the experimental loads, with the final purpose of refining the flow stress law of the machined materials. The future research will be focused on the FE simulation of the tool wear and the workpiece surface integrity by means of specific subroutines

Analysis of the Integration of DFM Techniques and Effective Machining Parameter Selection in Metal Parts Manufacturing

This dissertation investigates the minimization of part design with self-locating features. The research focuses primarily on self-fastening characteristics, standardization of parts, and minimal use of fasteners. Further, the present research studies the design for base parts in the construction of a moving joint system, in order to locate potential part and system design improvements. This process may then be extended to industrial applications in the manufacturing industry. Relatively little work to date has examined the significance of Design for Manufacturing Techniques (DFMT), with their inherent machine element systems and machining parameters to investigate which DFMT has the most influence on cost reduction and increasing throughput, and under which circumstances. As such, this dissertation analyzes the inter-operational and synergistic elements of the DFMT, machine element systems, and machining parameters. The parametric specifications for the DFMT are examined and integrated with the cost and productivity-related information. In sum, this research applies DFMT to product design. The trade-off between cost of manufacturing and productivity in terms of DFM alternatives was subject to preliminary model development and sensitivity analysis. For each DFMT and associated machine element systems and Machining parameters, process planning was used effectively with computer-aided tools to enhance the evaluation impact of the dialogue between the design and manufacturing functions. Expert systems and systematic algorithms are inherently incorporated into the software tools used herein. Generative process planning software is used to measure and analyze sensitivity in plan effectiveness, particularly where material property attributes are changed. The shift that occurs according to process plan attributes is explored. These attributes are presented by manufacturing cost and production rate with respect to variations in specific material properties. The research analyzes four DFMT: Modifying the selection of raw material Modifying quality Modifying geometry Modifying the selection of process/es In terms of organizing and evaluating the work, a systematic algorithm was developed, discussed, and tested in this dissertation. This algorithm has sequenced elements to investigate and analyze each DFMT. This analysis identifies several potential process plans, from which the plan with the lowest projected cost and highest production rate is selected and constructed. The developed process plans illustrate the importance of alternative DFMT, without impacting product functionality. Each process plan attempts to decrease production cost, maintain quality, and increase throughput. The results of these plans show their respective effectiveness in relation to part utilization, process, and system-level parameters (such as surface finish, tolerance, heat treated condition of the material, geometry, material hardness, melting point, production quantity, cutting tools, cutting fluids, cutting conditions, and machine tools). The criteria for effectiveness include machining cost, tool cost, and throughput. From this data, the current study determines the most appropriate DFMT and examines underlying alternate machine element systems and machining parameters for each process plan. The effects of DFMT and inherent use of varying machine element systems and machining parameters on cost and productivity-based objectives are also examined. This enables exploration of the selected DFMT choice, according to effective cost reduction and production rate improvement for varying product design. The modified process plan is then compared to the original process plan to highlight areas of improvement. In this comparison, the results of DFMT analysis show significant influence on cost reduction and production rates. These findings suggest that further beneficial outcomes and variety might be obtained by applying this algorithm