11-08-2012, 04:24 PM
Reconfigurable Manufacturing System
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Introduction:-
The concept of a Reconfigurable Manufacturing System (RMS) has been conceived to meet changes and uncertainties in a dynamic manufacturing environment. The uniqueness of Reconfigurable Manufacturing Systems (RMSs) is that the structure of the system as well as of its machines and controls can be rapidly changed in response to market changes (demand and products). A major component of RMSs is the reconfigurable machine tool (RMT). By contrast to conventional CNCs that are general-purpose machines, RMTs are designed for a specific, customized range of operation requirements and may be cost-effectively converted when the requirements change.
Reconfigurable Manufacturing System (RMS)- Definition & Concept:-
A reconfigurable manufacturing system is designed at the outset for rapid change in structure, as well as in hardware and software components, in order to quickly adjust production capacity and functionality within a part family in response to sudden changes in market or in regulatory requirements [Koren Y,et al. (2005).].
RMS consists of modular components. The system architecture is open to increase or reduce the number and types of modules. The system is capable of selecting a set of modules and assembling them into different system configurations. Each configuration is able to meet the requirements of a specific task optimally. From the viewpoint of a flexible system, some system modules have their adjustable components, such as motion axes of a CNC and actuated joints of a robot, these adjustable components can be manipulated to meet varying requirements in system operations. As a result, an RMS integrates adjustable components upon a modular architecture; system capability for changes and uncertainties is maximized. In comparison to low-cost high-volume mass production, an RMS has flexibility in product variations; in comparison to a flexible manufacturing system, an RMS has flexibility in product capacities. An RMS is an ideal paradigm to manufacture the product variations of the low volumes at a low cost. RMS the RMS facilitates a quick production launch of new products, and allows for adjustment of production quantities that might unexpectedly vary. The ideal reconfigurable system provides exactly the functionality and production capacity needed, and can be economically adjusted exactly when needed.
Modularity:-
The compartmentalization of production functions and requirements into operational units that can be manipulated between alternate production schemes to achieve the optimal arrangement to fit a given set of needs. In a reconfigurable manufacturing system, many components are typically modular ex.:- machines, axes of motion, controls, and tooling. When necessary, the modular components can be replaced or upgraded to better suit new applications. Modules are easier to maintain and update, thereby lowering life-cycle costs of systems. New calibration algorithms can be readily integrated into the machine controller, resulting in a system with greater accuracy. For example, integrating cross-coupling control [Koren, Y. and Katz (2003)] into CNC controllers substantially enhances its accuracy. The fundamental questions when designing with the modular approach are: (a) what are the appropriate building blocks or modules, and (b) how should they be connected to synthesize a functioning whole? Selection of basic modules and the way they are connected allow for the creation of systems that can be easily integrated, diagnosed, customized, and converted.
Customization:-
To design system/machine flexibility just around a product family, obtaining thereby customized-flexibility, as opposed to the general flexibility of FMS/CNC. This characteristic drastically distinguishes RMS from flexible manufacturing systems (FMS), and allows a reduction in investment cost. It enables the design of a system for the production of a part family, rather than a single part (as produced by DML) or any part (typical FMS). “Part family” means, for example, several types of engine blocks or several types of microprocessors, or all types of Boeing 747. In the context of RMS, a part family is defined as all parts (or products) that have similar geometric features and shapes, the same level of tolerances, require the same processes, and are within the same range of cost. The definition of the part family must ensure that most manufacturing system resources are utilized for the production of every member part. The RMS configuration must be customized to fit the dominant features of the whole part family by utilizing the characteristic of customized flexibility.. Customized flexibility for the part family allows the utilization of multiple tools (e.g., spindles in machining or nozzles in injection molding) on the same machine, thereby increasing productivity at reduced cost without compromising flexibility.