A design of DSS for mass production machining systems

http://bulletin.pan.pl/(57-3)265.pdfInternational audienceIn this paper, we present a decision support tool (DSS) for preliminary design of transfer machines with rotary or mobile tables. In these transfer machines, the machining operations are executed on working positions equipped by standard multi-spindle heads. A part is sequentially machined on m working positions and is moved from one position to the next using a rotary or a mobile table. The operations are grouped into blocks, where the operations of the same block are simultaneously performed by one multi-spindle head. At the preliminary design stage, the goal is to select the number of working positions and to decide which spindle heads will be installed minimizing the machine cost while respecting a given production rate. The paper presents the overall approach and depicts mathematical and decision-support methods developed and implemented in a software for the optimization of preliminary design (or reconfiguration) of such machining systems

Design and construction of a novel reconfigurable micro manufacturing cell

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Demands for producing small components are increasing. Such components are usually produced using large-size conventional machining tools. This results in the inadequate usage of resources, including energy, space and time. In the 1990s, the concept of a microfactory was introduced in order to achieve better usage of these resources by scaling down the size of the machine tool itself. Several industries can benefit from implementing such a concept, such as the medical, automotive and electronics industries. A novel architecture for a reconfigurable micro-manufacturing cell (RMC) is presented in this research, aiming at delivering certain manufacturing strategies such as point of use (POU) and cellular manufacturing (CM) as well as several capabilities, including modularity, reconfigurability, mobility and upgradability. Unlike conventional machine tools, the proposed design is capable of providing several machining processes within a small footprint (500 mm2), yet processing parts within a volume up to 100 mm3. In addition, it delivers a rapid structure and process reconfiguration while achieving a micromachining level of accuracy. The approach followed in developing the system is highly iterative with several feedback loops. It was deemed necessary to adopt such an approach to ensure that not only was the design relevant, but also that it progresses the state-of-the-art and takes into account the many considerations in machine design. Following this approach, several design iterations have been developed before reaching a final design that is capable of delivering the required manufacturing qualities and operational performance. A prototype has been built based on the specifications of the selected design iteration, followed by providing a detailed material and components selection process and assembly method before running a performance assessment analysis of the prototype. At this stage, a correlation between the Finite Element Analysis (FEA) model and prototype has been considered, aiming at studying the level of performance of the RMC when optimising the design in the future. Then, based on the data collected during each stage of the design process, an optimisation process was suggested to improve the overall performance of the system, using computer aided design and modelling (CAD/CAM) tools to generate, analyse and optimise the design

Evaluation of machining systems from a complexity and cost perspectives

Manufacturing systems, specifically machining, are typically designed as either dedicated or flexible; representing two very different paradigms. Measures for manufacturing flexibility have been proposed; generally, according to behaviour of system or product mix. Attempts have also been made to relate flexibility to subsequent costs. In this thesis, System Design is presented as a property of inherent attributes determined at the design stage. This provides the \u27Flexibility Level\u27 and its measurement is based on physical-functional attributes. Hence, System Design is viewed as a continuous quality, which describes both the level of flexibility and/or dedicated nature of a system. This metric is related to cost in a model which describes system design in its entirety; including manufacturing complexity in relation to cost as a tool to minimize manufacturing costs. Consequently, system behaviour is investigated given alternate manufacturing conditions such as varying product mix and production volume requirements. Industrial examples are used

Dimensional metrology and positioning operations: basics for a spatial layout analysis of measurement systems

Dimensional metrology and positioning operations are used in many fields of particle accelerator projects. This lecture gives the basic tools to designers in the field of measure by analysing the spatial layout of measurement systems since it is central to dimensional metrology as well as positioning operations. In a second part, a case study dedicated to a synchrotron storage ring is proposed from the detection of the magnetic centre of quadrupoles to the orbit definition of the ring.Comment: 60 pages, presented at the CERN Accelerator School CAS 2009: Specialised Course on Magnets, Bruges, 16-25 June 200

Design principles of reconfigurable machines

Abstract Reconfigurable machines form a new class of machines that are designed around a specific part family of products and allow rapid change in their structure. They are designed to allow changes in machine configuration according to changes in production requirements. The reconfiguration may be related to changes in machine functionality or its scalability, i.e., the change in production volumes or speed of operation. Reconfigurable machines represent a new class of machines that bridges the gap between the high flexibility and high cost of totally flexible machines and the low flexibility and low cost of fully dedicated machines. The design principles of reconfigurable machines follow a similar philosophy, which was derived for reconfigurable manufacturing systems, and present an approach for the design of machines to be used mainly in high-volume production lines. This paper introduces design principles for reconfigurable machines, which may be applied in different fields of manufacturing. Based on these design principles, three types of reconfigurable machines were designed for various types of production operations such as: machining, inspection and assembly. This paper shows how the suggested design principles were utilized in the design of several full-scale machine prototypes and tested experimentally

Resource selection and route generation in discrete manufacturing environment

When put to various sources, the question of which sequence of operations and machines is best for producing a particular component will often receive a wide range of answers. When the factors of optimum cutting conditions, minimum time, minimum cost, and uniform equipment utilisation are added to the equation, the range of answers becomes even more extensive. Many of these answers will be 'correct', however only one can be the best or optimum solution. When a process planner chooses a route and the accompanying machining conditions for a job, he will often rely on his experience to make the choice. Clearly, a manual generation of routes does not take all the important considerations into account. The planner may not be aware of all the factors and routes available to him. A large workshop might have hundreds of possible routes, even if he did know it all', he will never be able to go through all the routes and calculate accurately which is the most suitable for each process - to do this, something faster is required. This thesis describes the design and implementation of an Intelligent Route Generator. The aim is to provide the planner with accurate calculations of all possible production routes m a factory. This will lead up to the selection of an optimum solution according to minimum cost and time. The ultimate goal will be the generation of fast decisions based on expert information. Background knowledge of machining processes and machine tools was initially required, followed by an identification of the role of the knowledge base and the database within the system. An expert system builder. Crystal, and a database software package, DBase III Plus, were chosen for the project. Recommendations for possible expansion of and improvements to the expert system have been suggested for future development

Parametric Modeling of Machine Tools

The chapter deals with the problems of machine tool computer-aided design (CAD) based on the methods and means of parameterization for the main components of metal-cutting machine and equipment in the CAD “APM WinMachine” environment. The models and algorithms of parametric modeling for the configurations of machine tool milling and multioperational type by the criteria of maximum rigidity and minimum reduced load on the front spindle support are developed. The express procedure for generating the transverse layout of the main drive in the multivariate design mode has been implemented

Optimal choice of machine tool for a machining job in a CAE environment

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Developments in cutting tools, coolants, drives, controls, tool changers, pallet changers and the philosophy of machine tool design have made ground breaking changes in machine tools and machining processes. Modern Machining Centres have been developed to perform several operations on several faces of a workpiece in a single setup. On the other hand industry requires high value added components, which have many quality critical features to be manufactured in an outsourcing environment as opposed to the traditional in-house manufacture. The success of this manufacture critically depends on matching the advanced features of the machine tools to the complexity of the component. This project has developed a methodology to represent the features of a machine tool in the form of an alphanumeric string and the features of the component in another string. The strings are then matched to choose the most suitable and economical Machine Tool for the component’s manufacture. Literature identified that block structure is the way to answer the question ‘how to systematically describe the layout of such a machining centre’. Incomplete attempts to describe a block structure as alphanumeric strings were also presented in the literature. Survey on sales literature from several machine tool suppliers was investigated to systematically identify the features need by the user for the choice of a machine tool. Combining these, a new alphanumeric string was developed to represent machine tools. Using these strings as one of the ‘key’s for sorting a database of machine tools was developed. A supporting database of machine tools was also developed. Survey on machining on the other hand identified, that machining features can be used as a basis for planning the machining of a component. It analysed various features and feature sets proposed and provided and their recognition in CAD models. Though a vast number of features were described only two sets were complete sets. The project was started with one of them, (the other was carrying too many unwanted details for the task of this project) machining features supported by ‘Expert Machinist’ software. But when it became unavailable a ‘Feature set’ along those lines were defined and used in the generation of an alphanumeric string to represent the work. Comparing the two strings led the choice of suitable machines from the database. The methodology is implemented as a bolt on software incorporated within Pro/Engineer software where one can model any given component using cut features (mimicking machining operation) and produce a list of machine tools having features for the machining of that component. This will enable outsourcing companies to identify those Precision Engineers who have the machine tools with the matching apabilities. Supporting software and databases were developed using Access Database, Visual Basic and C with Pro/TOOLKIT functions. The resulting software suite was tested on several case studies and found to be effective