FMS PLANNING AND IMPLEMENTATION ISSUES
Implementation of an FMS represents a major investment and commitment by the user company. It is important that the installation of the system be preceded by thorough planning and design, and that its operation be characterized by good management of all resources: machines, tools, pallets, parts, and people. Our discussion of these issues is organized along these lines: (1) FMS planning and design issues and (2) FMS operational issues.
FMS Planning and Design Issues
The initial phase of FMS planning must consider the parts that will he produced by the system. The issues are similar to those in GT machine cell planning (Section 15.4.2).They include:
Part family considerations. Any FMS must be designed to process a limited range of part (or product) styles. The boundaries of the range must be decided. In effect, the part family that will be processed 011the FMS must be defined. rhe definition of part families to be processed un the FMS can be based on product commonality as well as on part similarity. The term product commonality refers 10 different components used on the same product. Many successful FMS installations arc designed to accommodate part families defined by this criterion. This allows all of the components required to assemble a given product unit to be completed just prior to beginning of assembly,
Processing requirements. The types of parts and their processing requirements determine the types of processing equipment that will be used in the system. In machining applications. Non-rotational parts are produced by machining centers, milling machines, and like machine tools: rotational parts are machined by turning centers and similar equipment.
Physical characteristics of the workparts, The size and weight of the parts determine the size of the machines at the workstations and the size of the material handling system that must be used
Production volume, Quantities to be produced by the system determine how many machines Will be required. Production volume is also a factor in selecting the most appropriate type of material handling equipment for the system.
After the part family, production volumes, and similar part issues have been decided. design of the system can proceed. Important factors that must be specified in FMS design include:
Types of workstations. The types of machines are determined by part processing requirements. Consideration of workstations must also include the load/unload station(s).
Variations in process routings and FMS layout. If variations in process sequence are minimal. then an inline flow is most appropriate. As product variety increases, a loop is more suitable. If there is significant variation in the processing, a ladder layout or open field layout are the most appropriate
Material handling system. Selection of the material handling equipment and layout are closely related, since the type of handling system limits the layout selection to some extent. The material handling system includes both primary and secondary handling systems (Section 16.2.2).
Work-in-process and storage capacity. The level of WIP allowed in the FMS is an important variable in determining utilization and efficiency of the FMS. lf the WIP level is too low, then stations may become starved for work, causing reduced utilization. If the WIP level is too high, then congestion may result. The WIP level should be planned, not just allowed to happen. Storage capacity in the FMS must be compatible with WIP level,
Tooling. Tooling decisions include types and numbers of tools at each station. Consideration should also be given to the degree of duplication of tooling at the different stations. Tool duplication tends to increase routing flexibility (Table 16.1).
Pallet fixtures. In machining systems for nonrotational parts, the number of pallet fixtures required in the system must be decided. Factors influencing the decision include: levels of WIP allowed in the system and differences in part style and size. Parts that differ too much in configuration and size require different fixturing.
FMS Operational Issues
Once the FMS is installed, then the existing resources of the FMS must be optimized to meet production requirements and achieve operational objectives related to profit. quality, and customer satisfaction, The operational problems that must be solved include , ."
Scheduling: and dispatching. Scheduling of production in the FMS is dictated b)' the master production schedule (Section 26.1). Dispatching is concerned with launching of parts into the system at the appropriate times. Several of the problem areas below are related to the scheduling issue.
Machine loading. This problem is concerned with allocating the operations and tooling resources among the machines in the system to accomplish the required production schedule.
Part routing. Routing decisions involve selecting thc routes that should be followed by each part in the production mix to maximize use of workstation resources.
Part grouping. This IS concerned with the selection of groups of part types for simultaneous production, given limitations on available tooling and other resources a' workstations.
• Tool management. Managing the available tools includes decisions on when to change tools, allocation of tooling to workstations in the system, and similar issues.
Pallet and fixture allocation. This problem is concerned with the allocation of pal lets and fixtures to the parts being produced in the system.