Flexible
Manufacturing Systems (FMS)
“FMS consists of a group of processing work stations
interconnected by means of an automated material handling and storage system
and controlled by integrated computer control system.” Or FMS is called
flexible due to the reason that it is capable of processing a variety of
different part styles simultaneously at the workstation and quantities of
production can be adjusted in response to changing demand patterns.
Fig.6:
Flexible manufacturing system
BASIC
COMPONENTS OF FMS
The basic components of FMS are:
A.
Workstations
B.
Automated
Material Handling and Storage system.
C.
Computer
Control System
A. Workstations: In present day
application these workstations are typically computer numerical control (CNC)
machine tools that perform machining operation on families of parts. Flexible
manufacturing systems are being designed with other type of processing
equipments including inspection stations, assembly works and sheet metal
presses. The various workstations are
(i) Machining centers
(ii) Load and unload
stations
(iii) Assembly work stations
(iv) Inspection stations
(v) Forging stations
(vi) Sheet metal processing,
etc.
B. Automated Material
Handling and Storage system: The various automated material handling systems are
used to transport work parts and subassembly parts between the processing
stations, sometimes incorporating storage into function. The various functions
of automated material handling and storage system are
(i) Random and
independent movement of work parts between workstations
(ii) Handling of
a variety of work part configurations
(iii) Temporary
storage
(iv) Convenient
access for loading and unloading of work parts
(v) Compatible
with computer control
C. Computer Control
System: It
is used to coordinate the activities of the processing stations and the
material handling system in the FMS. The various functions of computer control
system are:
(i) Control of each work
station
(ii) Distribution of control
instruction to work station
(iii) Production control
(vi) Traffic control
(v) Shuttle control
(vi) Work handling system
and monitoring
(vii) System performance
monitoring and reporting
The FMS is most suited for the mid
variety, mid value production range
Fig.7:
Application Characteristic of FMS
AIMS
OF FMS
·
To
reduce costs
·
Better
utilization of the production equipment reduction of stocks (ex: Work in
progress— capital shorter through put times)
·
Reduction
of piece part unit costs.
·
To
increase Technical Performance:
·
Increased
production levels
·
Greater
product mixture
·
Simultaneous
product mixture manufacturing
·
Integration
of the production system into the factory’s logistical system
·
Smaller
batch sizes
·
Shorter
or zero change over or reset of times
·
To
improve Order Development:
·
Shorter
lead times/delivery times
·
Determination
of production capacities
·
To
assist future Corporate Security:
·
Increased
Competitiveness
·
Increased
Quality
·
Improved
Company Image
OBJECTIVES
OF FMS:
The principle objectives of FMS are
A. To
improve operational control through:
Ø Reduction in the number
of uncontrollable variables.
Ø Providing tools to
recognize and react quickly to deviations in the manufacturing plan
Ø Reducing the dependence
of human communication.
B. To
reduce direct labor:
Ø Removing operators from
the machining site (their responsibilities activities can be broadened).
Ø Eliminating dependence
on highly skilled machines (their manufacturing skills can be better utilized
in manufacturing engineering functions).
Ø Providing a catalyst to
introduce and support unattended or lightly attended machining operation.
C. To
improve short run responsiveness consisting of:
Ø Engineering changes
Ø Processing changes
Ø Machining downtime or
unavailability
Ø Cutting tool failure
Ø Late material delivery
D. To
improve long-run accommodations through quicker and easier assimilation of:
Ø Changing product volumes
Ø New product additions
and introductions
Ø Differentiation part
mixes
Ø Increase Machine
Utilization by:
·
Eliminating
machine setup
·
Utilizing
automated features to replace manual intervention
·
Providing
quick transfer devices to keep machines in the cutting cycle
Ø Reduce inventors by:
·
Reducing
lot sizes
·
Improving
inventors turn-over
·
Providing
the planning tools for JIT manufacturing
Advantages
of Flexible manufacturing system
§ Faster, lower-cost
changes from one part to another which will improve capital utilization
§ Lower direct labor cost,
due to the reduction in number of workers
§ Reduced inventory, due
to the planning and programming precision
§ Consistent and better
quality, due to the automated control
§ Lower cost/unit of
output, due to the greater productivity using the same number of workers
§ Savings from the
indirect labor, from reduced errors, rework, repairs and rejects
§
Disadvantages
of Flexible manufacturing system
§ Limited ability to adapt
to changes in product or product mix (ex. machines are of limited capacity and
the tooling necessary for products, even of the same family, is not always feasible
in a given FMS)
§ Substantial pre-planning
activity
§ Expensive, costing
millions of dollars
§ Technological problems
of exact component positioning and precise timing necessary to process a
component
§ Sophisticated
manufacturing systems
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