Final Fms
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BACKGROUND ON FLEXIBLE MANUFACTURING SYSTEM: Batch manufacturing has always had inherent limitations on account of the midvolume, mid-variety nature of manufacturing. Work in process levels are generally high and machine utilization tends to be low. This leads to loss of time which was generally spend waiting for a machine to be setup, waiting to be moved or waiting for other jobs on the machines to be completed. Batch production often requires an army of expeditors’ progress chasers to keep jobs flowing through the manufacturing facilities. Advancements in the field of manufacturing technology have had an impact on process design. Versatile machines that are capable of handling the work of several traditional machines have provided some relief in simplifying process flow. These machines also provide considerable flexibility to address some of the issues pertaining to mid-volume, mid-variety manufacturing systems. Of the several developments, Flexible Manufacturing Systems have been most prominent. DEFINITION: A flexible manufacturing system (FMS) is a manufacturing system in which there is some amount of flexibility that allows the system to react in the case of changes, whether predicted or unpredicted. It involves substituting machines capable of performing a wide variety of tasks for machines dedicated to the performance of specific tasks. FMS can also be programmed to handle new products, thus extending the machines' life cycles. Thus they represent a change from "standardized goods produced by customized machines" to "customized goods produced by standardized machines". This volume contains new and updated material in this field, and will be of great interest to researchers, managers and students concerned with problems related to flexible manufacturing systems. This flexibility is generally considered to fall into two categories, which both contain numerous subcategories. This are listed below: 1. Machine Flexibility: This is related to the ease of making changes required to produce a given set of part types. Measurement of these changes includes, for example, time to change tools in a tool magazine to produce a different part family, time to assemble new fixtures and so on. Technological progress, proper operation assignment and technological capability of bringing part and tool together etc. will improve this flexibility. •
Process flexibility and Mix flexibility: This is the ability to produce a given set of part types, each possibly using different materials in several ways. This, in essence, relates to the mix of jobs, which the system can process simultaneously. Process flexibility increases as the machine setup cost decreases, and by having multipurpose adaptable CNC machines.
•
Product flexibility: It is the ability to produce a new set of products economically and quickly. Product flexibility can be measured from the time required to switch from one part mix to another.
2. Routing flexibility: This is the ability to handle breakdowns and to continue processing the given set of part types. This ability exists if either a part type can be processed via several routes or each operation can be performed by more than one machine. •
Volume flexibility: This is a measure of the ability to operate an FMS profitably at different production volumes. This flexibility can be measured by how small the volumes can be for all part types with the system still being run profitably.
•
Expansion flexibility: It is the capability to build a system and expand it as the need arises, easily and in a modular fashion.
FEATURES OF FLEXIBLE MANUFACTURING SYSTEM: • • • • •
Attempts to solve the production problem of mid-volume and mid-variety parts for which neither high production rate transfer lines nor highly flexible standalone NC machines are suitable. Designed to process, simultaneously, several types of parts in the given mix. Equipped with sophisticated flexible machine tools that are capable of processing a sequence of different parts with negligible tool change over time. Parts are transferred from machine to machine by a computer controlled Material Handling System (MHS). It consists of three sub-systems: the machining system, the material handling system and the control system.
A schematic representation of the structure of FMS is given below: System Controller
Load Unload
Primary MHS
Machine Tools
Secondary MHS
Auxiliary Equipment
Information flow Material flow Machine tools are the main machines used in manufacturing while auxiliary equipments are those used for other purpose such as measuring quality using coordinate measuring machine and automatic washing machine. The primary MHS transports the work pieces from one location to another in an FMS. On the other hand, MHS transports work pieces from the machine table to the storage point in front of the machine tool. ADVANTAGES: • • • •
Productivity increment due to automation Preparation time for new products is shorter due to flexibility Saved labor cost, due to automation Improved production quality, due to automation
DISADVANTAGES:
Process flexibility and Mix flexibility: This is the ability to produce a given set of part types, each possibly using different materials in several ways. This, in essence, relates to the mix of jobs, which the system can process simultaneously. Process flexibility increases as the machine setup cost decreases, and by having multipurpose adaptable CNC machines.
•
Product flexibility: It is the ability to produce a new set of products economically and quickly. Product flexibility can be measured from the time required to switch from one part mix to another.
2. Routing flexibility: This is the ability to handle breakdowns and to continue processing the given set of part types. This ability exists if either a part type can be processed via several routes or each operation can be performed by more than one machine. •
Volume flexibility: This is a measure of the ability to operate an FMS profitably at different production volumes. This flexibility can be measured by how small the volumes can be for all part types with the system still being run profitably.
•
Expansion flexibility: It is the capability to build a system and expand it as the need arises, easily and in a modular fashion.
FEATURES OF FLEXIBLE MANUFACTURING SYSTEM: • • • • •
Attempts to solve the production problem of mid-volume and mid-variety parts for which neither high production rate transfer lines nor highly flexible standalone NC machines are suitable. Designed to process, simultaneously, several types of parts in the given mix. Equipped with sophisticated flexible machine tools that are capable of processing a sequence of different parts with negligible tool change over time. Parts are transferred from machine to machine by a computer controlled Material Handling System (MHS). It consists of three sub-systems: the machining system, the material handling system and the control system.
A schematic representation of the structure of FMS is given below: System Controller
Load Unload
Primary MHS
Machine Tools
Secondary MHS
Auxiliary Equipment
Information flow Material flow Machine tools are the main machines used in manufacturing while auxiliary equipments are those used for other purpose such as measuring quality using coordinate measuring machine and automatic washing machine. The primary MHS transports the work pieces from one location to another in an FMS. On the other hand, MHS transports work pieces from the machine table to the storage point in front of the machine tool. ADVANTAGES: • • • •
Productivity increment due to automation Preparation time for new products is shorter due to flexibility Saved labor cost, due to automation Improved production quality, due to automation
DISADVANTAGES:
