Flexible automation is an automated manufacturing system made of different work cells that manufactures different products. Flexible automation is a form of manufacturing technology, which is the culmination of a long evolution in production automation. In this article, the discussion of flexible automation is mainly focused on machining systems.
Flexible automation was hailed as a remedy for the competitive challenges that modern manufacturing was encountering through rising quality standards, shortened product life cycles, and greater demand for product variety. Some disappointment resulted from these great expectations. Some commentators suggested that the problem lay in the strategic misuse of the systems. For example, Hayes and Jaikumar suggested that managers using these new technologies in the same manner in which they used their previous conventional technologies were destined for disappointment. They stressed the need for a new mindset to experience the revolutionary benefits these new flexible systems promised. Hayes and Clark observe that productivity can fall for significant periods after the introduction of new production technologies, but enlightened management and reorganization can prevent this. Jaikumar observed a difference in the early usage (late 1970s, early 1986s) of these technologies between certain Japanese and American manufacturers. He noticed that the flexible systems in Japan were used more for their flexible benefits than in the US. He also noticed that Japanese managers introduced more products every year than their American counterparts. As a result, Japanese manufacturers also had fewer problems financially justifying these flexible technologies than American manufacturers. Hill suggests that a great deal of disappointment resulted from managers investing in flexible equipment believing that the possession of new flexible technologies would result in a strategic response to competitive pressures. One lesson appears to be that flexible automation is appropriate when its capabilities (e.g. producing multiple part types in medium volumes) are aligned with the companys needs and defined manufacturing and technology strategies. Much has been written about the economic justification of flexible technologies. There has been evidence to suggest conventional justification techniques are inappropriate for flexible automation and much activity has been directed at attempting to capture the more elusive benefits of flexible technologies. Foremost among these benefits is the flexibility of making multiple products simultaneously, and many authors have attempted to capture and characterize this flexibility through mathematical programming models, real option models, and empirical studies.
What is flexible automation?
Flexible automation (FA) is a type of manufacturing automation, which exhibits some form of "flexibility." Most commonly this flexibility is the capability of making different products in a short time frame. This "process flexibility" allows the production of different part types with overlapping life cycles. Another type of flexibility that comes with flexible automation is the ability to produce a part type through many generations. Clearly, there are several other manifestations of flexibility. Flexible automation allows the production of a variety of part types in small or unit batch sizes. Although FA consists of various combinations of technology, flexible automation most typically takes the form of machining systems, that is, manufacturing systems where material is removed from a workpiece. The flexibility comes from the programmability of the computers controlling the machines. Flexible automation is also observed in assembly systems. The most prominent form of flexible assembly is observed in the electronics industry, where flexible machines (automated surface mount technologies) are used to populate printed circuit boards with integrated circuits and other componentry. In this instance, manufacturers have found the machines far superior accuracy and reliability to be sufficient to warrant the significant investment. Overall, however, manufacturer tend to use automation for fabrication, and leave assembly to human operators who can adapt to a greater variety of changing circumstances more rapidly and easily than machines. In this article, the discussion of flexible automation is primarily focused on machining systems.
History of Flexible automation
Flexible automation is a form of manufacturing technology, which is the culmination of a long evolution in production automation. Most of the development in industrial automation, as we know it, has largely occurred during the twentieth century. Automation has long been the dream of engineers and scientists, whereby machines could undertake the simple, dirty, repetitive, and dangerous tasks traditionally done by people. More recently, this vision has been extended to complex physical, computational, and analytical tasks. Advances in computer technologies allowed this vision to automate several aspects of personal, administrative, industrial, and logistic activities. Initially, automation was fixed, that is, it could perform a single task, or small set of tasks, efficiently and effectively but changing this task set was difficult, costly, or impossible. This feature common to earlier of fixed automation is called "rigidity." Fixed automation commonly can do a small set of well-defined tasks particularly well, but has trouble doing anything else, without significant and time-consuming intervention from human operators.
Historically, automation was used as a substitute for general human activity. Automation where mechanical, electronic, or computational apparatus were substituted for human activity in an organised industrial context can be traced to the 18th century. Scale economics through fixed automation dominated the industry for much of the 20th century until competitive pressure, primarily from Japan, forced the American auto industry to change their focus to one of product variety and quick response to market needs. The emergence of the new flexible automation technologies enabled a more agile approach to cater to these pressures. The birth of numerical control (NC), resulting from the combination of conventional machine tools and computers in the 1940s, is credited to John Parsons. Further development occurred at MIT, funded by the US Air Force. The first full-fledged NC machine tool, which could machine complex shapes, was developed in 1952 at MIT. Parson used punched cards containing programs, which delivered instructions to hardwired machine tools. An NC controller succeeded the hardwired controller and the punched cards gave way to paper tape. These machine tools evolved into NC machine centres that could drill, bore, and mill. Developments during the 1960s included automated tool changers and indexing worktables.
Parallel developments in computing technologies resulted in much progress in the NC controller, allowing a centralised controller to issue commands to numerous numerical control machine tools. This direct numerical control (DNC) was appropriate when the available computing technology was bulky and expensive. However, as electronics and computers became miniaturized it became possible to place computer controllers within each machine tool, with a central controller responsible for a smaller array of operations, mostly real-time monitoring at the system level. The Sunstrand Corporation developed one of the earlier full-fledged flexible manufacturing in 1965. It involved eight NC machine tools with a computer automated roller conveyor. Although it did not have much process flexibility, it marked the advent of flexible automation where part programs for different part types could now be loaded quickly into local microprocessors and production could switch between different part types without significant setup time. Automated movement was done using relay switches. Developments since then have mostly refinements in the technologies and the variety of machine tools covered. Today, flexible automation technology is far more robust and cost significantly less.
Flexible automation in machining systems
The building block of flexible automation is the computer numerical controlled (CNC) machine tool which is typically augmented by automated materials handling systems, centralised controlling computers, automated storage and retrieval systems, and human operators. The variety of installations of flexible automation is numerous. Some typical configurations are discussed below. A CNC machine tool is a self-contained machine, where the tool cutting movements, a part program executed by the computer controller based at the machine tool controls spindle speeds, tool exchange, and other operations. The spindle is a spinning device which holds the tool used to cut into the workpiece. Conventional machine tools (e.g. lathes, drill presses, milling machines) are not computer controlled. Skilled craftsman typically does the operation of conventional tools. There can be variations to dimensions on parts made on a conventional tool, whereas this variation is decreased on CNC machine tools.
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|Posted : 10/21/2005|