Flexible Manufacturing Systems
1. What is an FMS?
What Makes It Flexible?
2. FMS Components
Material Handlingand Storage System
3. FMS Applications and Benefits
4. FMS Planning and Implementation Issues
FMS Planning and Design Issues
FMS Operational Issues
5. QuantitativeAnalysisof Flexible ManufacturingS ystems
Extended Bottleneck Model
Sizing the FMS
What the Equations Tell Us
The flexible manufacturing system (FMS) was identified in machine the last chapter as one of the cell types used to implement group technology. It is most automated and technologically scheme sophisticated of the GT cells. In our classification for manufacturing system (Section 13.2), an FMS typically possesses multiple automated stations and is capable of variable routings among stations (type II A).1 Its flexibility allows it to operate as a mixed model system (case X for part or product variety). An FMS integrates into one highly automated manufacturing system many of the concepts and technologies discussed in previous chapters, including: flexible automation (Section 1.3.1), CNC machines (Chapters 6 and 14),distributed computer control (Section 6.3), automated material handling and storage (Chapters 10 and ll).and group technology (Chapter 15).The concept for FMSs originated in Britain in the early 1960s (Historical Note 16.1).The first FMS installations in the United States were made starting around 19b7.These initial systems performed machining operations on families of parts using NC machine tools.
FMS technology can be applied in situations similar to those identified for group technology and cellular manufacturing; specifically,
Presently, the plant either (1) produces parts in batches or (2) uses manned GT cells and management wants to automate .
It must be possible to group a portion of the parts made in the plant into part families. whose similarities permit them to be processed on the machines in the FMS.
Part similarities can be interpreted to mean that (1) the parts belong to a common product, and/or (2) the parts possess similar geometries. In either case. the processing requirements of the parts must be sufficiently similar to allow them to be made on the FMS.
The parts or products made by the facility are in the mid-volume, mid-variety production range. The appropriate production volume range is 500075,000 part/yr. If annual production is below this range, than FMS is likely to be an expensive alternative. If' production volume is above this range, then a more specialized production system should probably be considered
The differences between implementing a manually operated machine cell and installing an FMS are: (1) the FMS requires a significantly greater capital investment because new equipment is being installed rather than existing equipment being rearranged. and (2) the FMS is technologically more sophisticated for the human resources who must make it work. However, the potential benefits are substantial. The benefits that can be expected from an FMS include:
increased machine utilization
fewer machines required
reduction in factory floor space required
greater responsiveness to change
reduced inventory requirements
lower manufacturing lead times
reduced direct labor requirements and higher labor productivity
opportunity for unattended production
We elaborate on these benefits in Section 16.3.2.
In this chapter, we define and discuss flexible FMSs: what makes them flexible, their components, their applications, and considerations for implementing the technology. In the final section, we present a mathematical model for assessing the performance of FMSs.