Flexible Manufacturing Systems - An overview of the basic concepts, types of system and design parameters.

1. FLEXIBLE MANUFACTURING
SYSTEMS (FMS)
Author: Leicester College
Date created:
Date revised: 2009
Abstract: The use of flexible manufacturing systems in production is rapidly increasing. The rationale for the
use and some of the main design parameters are investigated. The different types and configurations are
identified with major design factors being discussed.
© Leicester College 2009. This work is licensed under
a Creative Commons Attribution 2.0 License.
Flexbile Manufacturing Systems

2.  Model Variations
Contents
 Requirements for Unattended Operation for Single and Batch...
 Requirements for Mixed Model Case – Flexible Manufacturing...
 Differences between implementing a manually operated mach...
 Benefits that can be expected from a FMS include:
 What is a FMS?
 Automated Manufacturing Cell
 Manufacturing flexibility:
 Differences between FMC and FMS
 Another classification of FMS is by its level of flexibil...
 Random Order FMS
 Flexibility criteria applied to dedicated FMS and random-...
 Basic Components of a FMS:
 Workstations
 Material Handling and Storage System
 FMS Layout Configurations
 Credits
These files support the Edexcel HN unit – Design for Manufacture (NQF L4)
File Name Unit Outcome Key Words
Design 1.1, 1.2,1.4 Overview, Cost, quality, reliability, assembly, guidelines
forassembly
FMS 2.2 Models, work cycles, volume, machine utilisation,
automation, flexible, systems
Geometric 3.1,3.2 Geometric, tolerance, system, symbols, orientation, BS,
Tolerancing ISO, location, runout, datum
Industrial Robots 2.2,2.3 Robot, industrial, robot arm, Cartesian, polar, cylindrical,
jointed arm
Jigs and Fixtures 2.1,2.3 Efficiency, production, jigs, fixtures, tooling, production,
For further information regarding unit outcomes go to Edexcel.org.uk/ HN/ Engineering / Specifications

3. Model Variations
 Single model case – One product or model is
produced that is identical from one unit to the next
 Batch model case – Different products or models
produced in batches
(Requires changeover between models)
Mixed model case – Different products or models
produced on same line or equipment with no
changeovers between models

4. Requirements for Unattended Operation for
Single and Batch Model Cases
o Programmed work cycle
o Parts storage subsystem
o Automatic transfer of workpieces between storage
subsystem and production machine
o Periodic attention of worker

5. Requirements for Unattended Operation for
Single and Batch Model Cases
o Resupply and removal of workpieces, tool
changes, minor repairs, maintenance
o Built-in safeguards to protect the system itself
and the work units processed by the system

6. Requirements for Mixed Model Case –
Flexible Manufacturing Systems (FMS)
 Identification of different models
o No problem for human workers
o For automated system, some means of
product identification is required

7. Requirements for Mixed Model Case –
Flexible Manufacturing Systems (FMS)
 Quick changeover of operating instructions
o For automated system, change part program
 Quick changeover of physical setup
o Change tooling and fixtures in very short time

8. FMS technology can be applied in
situations similar to those for cellular
manufacturing:
o Presently, the plant either (1) produces parts in batches,
or (2) uses manned GT cells and management wants to
automate
o 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 flexible
manufacturing system
o The parts or products made by the facility are in the mid-
volume, mid-variety production range. The appropriate
production volume range is 5000 to 75,000 parts per year

9. Stand-alone
High
CNC machines
Flexible
Medium manufacturing
systems
Transfer
Low
lines
Low Medium High
Production Volume
Application characteristics of flexible manufacturing systems.

10. Differences between implementing a
manually operated machine cell and a flexible
manufacturing system are:
 The FMS requires a significantly greater capital
investment because new equipment is being
installed rather than existing equipment being
rearranged
 The FMS is technologically more sophisticated for
the human resources who must make it work

11. Benefits that can be expected from a FMS
include:
 Increased machine utilisation
 Fewer machines required
 Reduction in factory floor space required
 Greater responsiveness to change.

12. Benefits cont…
o Reduced inventory requirements
o Lower manufacturing lead times
o Reduced direct labour requirements and higher
labour productivity
o Opportunity for unattended production

13. What is a FMS?
 A flexible manufacturing system is a highly
automated GT machine cell, consisting of a group of
processing workstations, interconnected by an
automated material handling and storage
system, and controlled by a distributed computer
system.
 FMS is called flexible because it is capable of
processing a variety of different part styles
simultaneously at the various workstations, and the
mix of part styles and quantities of production can be
adjusted in response to changing demand patterns.

14. oA FMS relies on the principles of group technology.
No manufacturing system can be completely flexible.
o There are limits to the range of parts or products
that can be made in a FMS.
oA FMS is designed to produce parts (or products)
within a defined range of styles, sizes, and processes.
oIn other words, it is capable of producing a single
part family or a limited range of part families.
A more appropriate term for FMS would be flexible
automated manufacturing system.

15. The word “automated” would distinguish this
technology from other manufacturing systems that
are flexible but not automated, such as a manned
GT machine cell.
The word “flexible” would distinguish it from other
manufacturing systems that are highly automated
but not flexible, such as a conventional transfer line.

16. Automated Manufacturing Cell
Machine Tool
Parts Carousel
Robot
Machine Work
table

17. To qualify as being flexible, a manufacturing
system should satisfy several criteria.
Four reasonable tests of flexibility:
1. Part variety test. Can the system process different
part styles in a non-batch mode?
2. Schedule change test. Can the system readily
accept changes in production schedule: changes in
either part mix or production quantities?

18. 3. Error recovery test. Can the system recover
gracefully from equipment malfunctions and
breakdowns, so that production is not completely
disrupted?
4. New part test. Can new part designs be
introduced into the existing product mix with
relative ease?

19. A robotic work cell satisfies the criteria if it:
o Can machine different part configurations in a mix
rather than in batches;
o Permits changes in production schedule and part
mix;

20. Cont….
o Is capable of continuing to operate even though
one machine experiences a breakdown - for
example, while repairs are being made on the
broken machine, its work is temporarily reassigned
to the other machine; and
o Allows development of new parts to be written
off-line and then downloaded to the system for
execution.

21. Manufacturing flexibility:
Flexibility
type Definition Dependant on..
Machine Capability to adapt a  Setup or changeover time.
flexibility given machine  Ease of machine
(workstation) in the reprogramming (ease with
system to a wide which part programs can
range of production be downloaded to
operations and part machines).
styles. The greater  Tool storage capacity of
the range of machines.
operations and part
 Skill and versatility of
styles, the greater the
machine flexibility. workers in the system.
Production The range or universe  Machine flexibility of
flexibility

22. Mix Ability to change the product  Similarity of parts in the mix.
flexibility mix while maintaining the  Relative work content times of
same total production parts produced
quantity; that is, producing  Machine Flexibility
the same parts only in
different proportions.
Product Ease with which design  How closely the new part
flexibility changes can be design matches the existing
accommodated. Ease with part family.
which new products can be  Off-line part program
introduced. preparation.
 Machine flexibility
Routing Capacity to produce parts  Similarity of parts in the mix
flexibility through alternative station  Similarity of workstations
sequences in response to  Duplication of workstations
equipm’t breakdowns, tool
 Cross-training of manual
failures, and other
interruptions at individual workers.
stations.  Common tooling.

23. Volume Ability to economically  Level of manual labour
flexibility produce parts in high performing production.
and low total quantities  Amount invested in
of production, given capital equipment.
the fixed investment in
the system.
Expansion Ease with which the  Expense of adding
flexibility system can be workstations.
expanded to increase  Ease with which layout
total production can be expanded.
quantities.
 Type of part handling
system used.
 Ease with which properly
trained workers can be
added.

24. FMSs’ can be distinguished according to the
number of machines.
•Single machine cell - One CNC machining center
combined with a parts storage system for unattended
operation.
•Flexible manufacturing cell - Consists of two or three
processing stations plus a parts handling system
connected to a load/unload station.
•Flexible manufacturing system - Four or more
processing workstations connected mechanically by a
common parts handling system and electronically by
a distributed computer system.

25. Differences between FMC and FMS
 Number of machines: a FMC has two or three
machines, while a FMS has four or more.
 FMS generally includes non-processing
workstations that support production but do not
directly participate in it (e.g., part/pallet washing
stations, coordinate measuring machines)
 Computer control system of a FMS is generally
larger and more sophisticated, often including
functions not always found in a cell, such as
diagnostics and tool monitoring.

26. Flexibility criteria applied to the 3 types of
manufacturing cells and systems.
Schedule New
System type Part variety change Error recovery part
Single Yes, but processing Yes Limited recovery Yes
machine cell sequential, not due to only one
(SMC) simultaneous machine
Flexible mfg Yes, simultaneous Yes Error recovery Yes
cell (FMC) production of limited by fewer
different parts machines than
FMS
Flexible mfg Yes, simultaneous Yes Machine Yes
system production of redundancy
(FMS) different parts minimises effect
of machine
breakdowns

27. Another classification of FMS is by its level
of flexibility:
Dedicated FMS –
Designed to produce a limited variety of part
styles, and the complete universe of parts to be
made on the system is known in advance.
 Part family is likely to be based on product
commonality rather than geometric similarity.

28. Dedicated FMS – cont…
Product design is stable, so the system can be
designed with a certain amount of process
specialization to make the operations more efficient.
• The machine sequence may be identical or nearly
identical for all parts processed, and so a transfer line
may be appropriate, in which the workstations
possess the necessary flexibility to process the
different parts in the mix (“flexible transfer line”)

29. Random Order FMS
 More appropriate when the part family is large,
substantial variations in part configurations, new
part designs introduced into the system and
engineering changes in parts currently produced,
and production schedule is subject to change.
 More flexible than the dedicated FMS.
 General purpose machines to deal with the
variations in product
 More sophisticated computer control system is
required.

30. Flexibility criteria applied to dedicated FMS
and random-order FMS
System Part variety Schedule Error New part
type change recovery
Dedicated Limited. All parts Limited Limited by New part
FMS known in changes can sequential introduction
advance. be tolerated. processes. is difficult.
Random- Substantial part Frequent Machine System
order variations and redundancy designed for
FMS possible. significant minimizes new part
changes effect of introductions
possible. machine
breakdowns

31. Basic Components of a FMS:
 Workstations
 Material handling and storage system
 Computer control system
 People are required to manage and operate
the system.

32. Workstations
 Load/Unload Stations - Physical interface: FMS and
factory.
 Machining Stations - Most common is the CNC
machining centre.
 Other Processing Stations – sheet-metal
fabrication, forging.
 Assembly - Industrial robots, component placement
machines.
 Other Stations and Equipment -inspection
stations, cleaning stations, central coolant delivery
and chip removal systems.

33. Material Handling and Storage System
 Functions of the Handling System
o Random, independent movement of workpieces
between stations.
o Handle a variety of workpiece configurations.
o Temporary storage.
o Convenient access for loading and unloading
workpieces.
o Compatible with computer control.

34. FMS Layout Configurations
o In-line layout
o Loop layout
o Ladder layout
o Open field layout
o Robot-centered cell

35. FLEXIBLE MANUFACTURING
SYSTEMS (FMS)

36. This resource was created Leicester College and released as an open educational resource through the Open
Engineering Resources project of the Higher Education Academy Engineering Subject Centre. The Open
Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.
© 2009 Leicester College
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Flexbile Manufacturing Systems