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AUTOMATION IN PRODUCTION SYSTEMS
Some components of the firm's production system are likely to be automated. Whereas others will be operated manually or clerically. The automated clements of the production system can be sepatated into two categories:
(1) automation of the manufacturing systems tn the factory
(2) computerization of the manufacturing support svstems
In modern production systems, the two categories overlap to some extent, because the automated manulacturing systems operating on the lactory floor are themselves usually implemented by computer systems and connected to the computerized manufacturing support systems and management information system operating at the plant and enterprise levels. The term computerintegrated manufacturing is used to indicate this extensive use of computers in production systems.
1.1 Automated Manufacturing Systems
Automated manufacturing systems operate in the factory on the physical product. They perform operations such as processing, assembly, inspection. and material handling. in some cases accomplishing more than one of these operations in the same system. Thev are called automated because they perform their operations with a reduced level of human participation compared with the corresponding manual process. In some highly automated systems, there is virtually no human participation. Examples of automated manufacturing systems include:
Automated machine tools that process parts Transfer lines that perform a series of machining operations Automated assembly systems Manufacturing systems that use industrial robots to perform processing or assembly operations Automatic material handling and storage systems to integrate manufacturing operations Automatic inspection systems for quality control.
Automated manufacturing systems can be classified into three basic types: (1) fixed automation, (2) programmable automation. and (3) flexible automation. Thev generally operate as fully automated systems although semi-automated systems are common in
Production system Computer integrated
Manufacturing
Manufacturing support system
Facilities: Factory and Equipment
Potential automation applications
Potential computerization applications
Fixed Automation. Fixed automation is a system in which the sequence of processing (or
assembly) operations is fixed by the equipment configuration. Each operation in the sequence ts usually simple, involving perhaps a plain linear or rotational motion or an uncomplicated combination of the two, such as the feeding of a rotating spindle. It is the integration and coordination of many such operations into one piece of equipment that makes the system complex. Typical features of fixed automation are (1) high initial investment for custom- engineered equipment, (2) high production rates, and (3) relative inflexibility of the equipment to accommodate product variety.
The economic justification for fixed automation is found in products that are produced in very large quantities and at high production rates. The high initial cost of the equipment can be spread over a very large number of units, thus making the unit cost attractive compared with alternative methods of production. Examples of fixed automation include machining transfer lines and automated assembly machines.
Programmable Automation. In programmable automation, the production equipment is designed with the capability to change the sequence of operations to accom: modate different product configurations. The operation sequence is controlled by 4 program, which is a set of instructions coded so that they can be read and interpreted by the system. New programs can be prepared and entered into the equipment to produce new products. Some of the features that characterize programmable automation include :
(1) high investment in general purpose equipment
(2) lower production rates than fixed automation
(3) flexibility to deal with variations and changes in product configuration.
(4) high suitability for batch production.
Programmable automated production systems are used in low- and men volume production. The parts or products are typically made in batches. To pre a cach new batch of a different product, the system must be reprogrammed with the set of machine instruction that correspond to the new product. The physical setup of the machine must also be changed Tools must he loaded. fixtures must be attached to the machine table, aud ihe regutrcd machine settings must be entered. This changeover procedure takes time. Consequently, the typical cycle for a given product includes a period during which the setup and reprogramming takes place. followed by a period in which the parts in the batch are produced. Examples of programmable automation include numerically controlled (NC) machine tools, industrial robots, and programmable logic controllers.
Flexible Automation. Flexible automation is an extension of programmable automation. A flexible automated system is capable of producing a variety of parts (or products) with virtually no time lost for changeovers from one part style to the next. There is no lost production time
These four functions form a cycle of events that must accompany the physical production activities but do not directly touch the product.
1 .3 Reasons for Automating
Compamies undertake projects in manufacturing automation and compuler-integrated manufacturing for a variety of good reasons. Some of the reasons used to justify automation are the following:
- To increase labor productivity. Automating a manufacturing operation usually increases production rate and labor productivity. This means greater output per hour of labor input.
- To reduce labor cost. Ever-increasing labor cost has been and continues to be the trend in the world’s industrialized societies. Consequently, higher investment in automation has become economically justifiable to replace manual operations. Machines are increasingly being substituted for human labor to reduce unit product cost.
- To mitigate the effects of labor shortages. There is a general shortage of labor in many advanced nations. and this has stimulated the development of automated operations as a substitute for labor.
- To reduce or eliminate routine manual and clerical tasks. An argument can be put forth that there is social value in automating operations that are routine, boring, fatiguing, and possibly irksome. Automating such tasks improves the general level of working conditions.
- To improve worker safety. Automating a given operation and transferring the worker from active participation in the process to a monitoring role, or removing the worker from the operation altogether, makes the work safer. The safety and physical wellbeing of the worker has become a national objective with the enactment of the Occupational Safety and Health Act (OSHA) in 1970. This has provided an impetus for automation.
- To improve product quality. Automation not only results in higher production rates than manual operation, it also performs the manufacturing process with greater uniformity and conformity to quality specifications.
- To reduce manufacturing lead time. Automation helps reduce the elapsed time between customer order and product delivery, providing a competitive advantage to the manufacturer for future orders. By reducing manufacturing lead time, the manufacturer also reduces work-in-process inventory.
- To accomplish processes that cannot be done manually. Certain operations cannot be accomplished without the aid of a machine. These processes require precision. miniaturization, or complexity of geometry that cannot be achieved manually. Examples include certain integrated circuit fabrication operations, rapid prototyping processss based on computer graphics (CAD) models, and the machining of complex, mathematically defined surfaces using computer numerical control. These processes can only be realized by computer controlled systems.
- To avoid the high cost of not automating. There is a significant competitive advantage gained in automating a manufacturing plant. The advantage cannot easily be demonstrated on a company’s project authorization form. The benefits of automation often show up in unexpected and intangible ways, such as in improved quality, higher sales, better labor relations, and better company image. Companies that do not automate are likely to find themselves at a competitive disadvantage with their customers, their employees, and the general public.
REFERENCES
1) BLACK,J.T., The design of the Factory with a Future , McGraw-Hill, Inc.,
NY, 1991.
2) ENGARDIO,P.,” A New World Economy,” BussinessWeek , August 22/29,
2005 , pp 52-61.
