UNIT-4

1. UNIT 4
FLEXIBLE
MANUFACTURING
SYSTEM(FMS)
AND
AUTOMATED GUIDED
VEHICLE SYSTEM (AGVS)

2. Contents
Types of Flexibility - FMS – FMS
Components – FMS Application & Benefits
– FMS Planning and Control– Quantitative
analysis in FMS – Simple Problems.
Automated Guided Vehicle System (AGVS)
– AGVS Application – Vehicle Guidance
technology – Vehicle Management & Safety.

3. FMS
FMS may be defined as “a highly automated GT
machine cell, consisting of a group of processing
workstations (usually CNC machine tools),
interconnected by an automated material
handling and storage system, and controlled by a
distributed computer system.”
FMS employs a fully integrated handling system
with automated processing stations.

6. Flexibility and its Types
Flexibility is an attribute that allows a
manufacturing system to cope up with a
certain level of variations in part or product
type, without having any interruption in
production due to changeovers between
models.
Flexibility measures the ability to adopt “to
a wide range of possible environment”

7. Tests of Flexibility
Part variety test
Schedule change test
Error recovery test
New part test

9. Types of Flexibility
 Machine flexibility
 Production flexibility
 Mix (or Process) flexibility
 Product flexibility
 Routing flexibility
 Volume (or capacity) flexibility
 Expansion flexibility

10. Machine flexibility
 Definition: Machine flexibility is the capability to adapt a given
machine in the system to a wide range of production operations
and part types.
 Influencing factors:
Setup or change over time
Ease with which part-programs can be downloaded to machines
Tool storage capacity of machine
Skill and versatility of workers in the systems

11. Production flexibility
 Definition: Production flexibility is the range of part types that
can be produced by a manufacturing system.
 Influencing factors:
Machine flexibility of individual stations
Range of machine flexibilities of all stations in the system

12. Mix (or Process) flexibility
 Definition: Mix flexibility, also known as process flexibility, is
the ability to change the product mix while maintaining the
same production quantity. i.e., producing the same parts only in
different proportions
 Influencing factors:
Similarity of parts in the mix
Machine flexibility
Relative work content times of parts produced

13. Product flexibility
 Definition: Product flexibility is the ability to change over to a
new set of products economically and quickly in response to the
changing market requirements.
 Influencing factors:
Relatedness of new part design with the existing part family
Off-line part program preparation
Machine flexibility

14. Routing flexibility
 Definition: Routing flexibility is the capacity to produce parts on
alternative workstation in case of equipment breakdowns, tool
failure, and other interruptions at any particular station.
 Influencing factors:
Similarity of parts in the mix
Similarity of workstations
Common testing

15. Volume (or capacity) flexibility
 Definition: Volume flexibility, also known as capacity flexibility,
is the ability of the system to vary the production volumes of
different products to accommodate changes in demand while
remaining profitable.
 Influencing factors:
Level of manual labour performing production
Amount invested in capital equipment

16. Expansion flexibility
 Definition: Expansion flexibility is the ease with which the
system can be expanded to foster total production volume.
 Influencing factors:
Cost incurred in adding new workstations and trained workers
Easiness in expansion of layout
Type of part handling system

17. Four Tests of Flexibility Vs Seven Types of Flexibility
Sl No Flexibility Test Type of Flexibility
1 Part Variety  Machine
 Production
2 Schedule Change  Mix
 Volume
 Expansion
3 Error recovery  Routing
4 New part  Product

18. Types of FMS
 Classification based on the kinds of operations they perform
Processing operation
Assembly operation
 Classification based on the number of machines in the system
Single machine cell (SMC)
Flexible machine cell (FMC)
Flexible manufacturing system (FMS)
 Classification based on the level of flexibility associated with the system
Dedicated FMS
Random order FMS

19. Classification based on the kinds of
operations they perform
 Processing operation
Processing operation transforms a work material from one state to another
moving towards the final desired part or product.
It adds value by changing the geometry, properties or appearance of the
starting materials.
 Assembly operation
Assembly operation involves joining of two or more components to create a
new entity which is called an assembly.
Permanent joining processes include welding, brazing, soldering, adhesive
banding, rivets, press fitting and expansion fits.

20. Classification based on the number
of machines in the system
 Single Machine Cell (SMC)

21. Flexible machine cell (FMC)

22. Flexible manufacturing system (FMS)

23. Summary

25. Classification based on the level of
flexibility associated with the system
Dedicated FMS
A dedicated FMS is designed to produce a limited variety of part
configurations.
Thus the dedicated FMS usually consists of special purpose machines
rather than general purpose machines.
Random order FMS
The random order FMS is equipped with general purpose machines so as
to meet the product variations. Also FMS type requires a more
sophisticated computer control system.

28. Components/Elements of FMS
 Workstations
 Material handling and storage system
 Computer control system
 Human resources

29. FMS Workstations
 The workstations/processing stations used in FMS depends upon the
type of product manufactured by the system.
 The types of workstations that are usually found in a FMS are:
Load/unload stations
Machining stations
Assembly workstations
Inspection station
Other processing stations

30. Material handling and storage system
 FMS material handling and storage system include part
transportation, raw material and final product transportation
and storage of workpieces, empty pallets, auxiliary materials,
wastes, fixtures and tools.
 Functions of the material handling system
 Types of FMS layout
 Types of handling equipment used in FMS

31. Functions of the material handling
system
 Material handling may be defined as the functions and systems
associated with the transportation, storage, and physical control
to work-in-process material in manufacturing.
 The general purpose of material handling in a factory is to move
raw materials, work-in-process, finished parts, tools, and
supplies from one location to another to facilitate the overall
operations of manufacturing.

33. Types of FMS layout Configurations
 In-line layout
 Loop layout
 Ladder layout
 Open-field layout
 Robot-centered cell

34. In-line layout
 As the name suggests, the materials and handling systems are
arranged in a straight line in the in-line layout.

36. Loop layout
 In the loop layout, the workstations are arranged in a loop, as
shown in figure.

38. Ladder layout
 The ladder layout, an adaptation of the loop layout, consists of a
loop with rungs on which workstations are located.

40. Open-field layout
 The open field layout, also an adaptation of the loop
configuration, consists of multiple loops, ladders and sliding
organized to achieve the desired processing requirements.

42. Robot-centered cell
 In the robot-centered cell, one or more robots are used as the
material handling system.

44. Types of handling equipment used in
FMS
 Primary Handling System
 Secondary Handling System

45. Primary Handling System
 The primary handling system establishes the basic layout of the
FMS and is responsible for moving work parts between work
stations in the system.

47. Secondary Handling System
 The secondary handling system consists of transfer devices,
automatic pallet changers, and similar mechanisms located at
the workstations in the FMS.
 The functions of the secondary handling systems are:
To transfer work parts from the primary system to the machine
tool or other processing stations.
To position the work parts with sufficient accuracy and
repeatability at the workstation for processing.
To provide buffer storage of work parts at each workstation.

48. Types of Material Handling
Equipment
 The material handling equipment commonly used to move parts
between stations can be grouped under six categories,
 Conveyors
 Cranes and hoists
 Industrial trucks
 Monorails and other rail guided vehicles
 Automated guided vehicles (AGVs) and
 Industrial robots.

49. Computer control system
 In flexible manufacturing systems, computers are required to
control the automated and semi-automated equipment and to
participate in the over all coordination and management of the
manufacturing system.
 A typical FMS computer control system consists of a central
computer and micro computers controlling the individual
machines and other components.

50. Functions of a FMS computer control
system
 Workstation/processing station control
 Distribution of control instructions to workstations
 Production control
 Material handling system control
 Workpiece monitoring
 Tool control
 Quality control
 Failure diagnosis
 Safety monitoring
 Performance monitoring and reporting

51. Structure of FMS Application software systems

52. Types of FMS Data Files
 Part program file
 Routing file
 Part production file
 Pallet reference file
 Station tool file
 Tool life file

54. Human Resources
 In FMS, human labours are needed to perform the following functions
To load raw work parts into the system
To unload finished work parts from the system
For tool changing and tool setting
For equipment maintenance and repair
To program and operate the computer system
To accomplish overall management of the system

55. Example of Flexible
Manufacturing System
 FMS installed at Vought Aerospace in Dallas

57. FMS Applications
 Machining
 Assembly
 Sheet-metal press working
 Forging
 Plastic injection moulding
 Welding
 Textile machinery manufacture
 Semiconductor component manufacture

58. Economics of FMS
 5-20% reduction in personnel
 15-30% reduction in engineering design cost
 30-60% reduction in overall lead time
 30-60% reduction in work-in-process
 40-70% gain in overall production
 200-300% gain in capital equipment operating time
 200-500% gain in product quality
 300-500% gain in engineering productivity

59. Advantages of FMS
(Benefits of FMS)
 Increased machine utilization
 Reduced inventory
 Reduced manufacturing lead time
 Greater flexibility in production scheduling
 Reduced direct labour cost
 Increased labour productivity
 Shorter response time
 Consistent quality
 Reduced factory floor space
 Reduced number of tools and machines required
 Improved product quality

60. Disadvantages of FMS
 Very high capital investment is required to implement a FMS
 Acquiring, training and maintaining the knowledgeable labour
pool requires heavy investment
 Fixtures can sometimes cost much more with FMS, and software
development costs could be as much as 12-20% of the total
expense
 Tool performance and condition monitoring can also be
expensive since tool variety could undermine efficiency
 Complex design estimating methodology requires optimizing
the degree of flexibility and finding a trade off between
flexibility and specialization

61. FMS Planning and Control
(FMS Planning and Implementation
issues)
 FMS planning and design issues
 FMS control (or operational) issues

62. FMS Planning issues
 Part family considerations
 Processing requirements
 Physical characteristics of the work parts
 Production volume

63. FMS design issues
 Type of work stations
 Variations in process routings and FMS layout
 Material handling system
 Work-in-process and storage capacity
 Tooling
 Pallet fixtures

64. FMS operational issues
 Scheduling and dispatching
 Machine loading
 Part routing
 Part grouping
 Tool management
 Pallet and fixture allocation

65. Quantitative analysis of Flexible
Manufacturing System
 Flexible manufacturing system can be analysed using different
models. The four different categories of FMS analysis models
are:
Deterministic models
Queuing models
Discrete event simulation
Other techniques

66. Bottleneck model
 The bottleneck model is a simple and intuitive approach to
determine the starting estimates of FMS design parameters such
as production rate, capacity and utilization.

67. Terminology and symbols

70. FMS operational Parameters

72. System Performance Measures

75. Automated Guided Vehicle System
(AGVS)
 An Automated Guided Vehicle System (AGVS) is a computer
controlled, driverless vehicle used for transporting materials
from point to point in a manufacturing setting.
 An AGVS uses independently operated, self-propelled vehicles
that are guided along pre-defined paths, and are powered by
means of on-board batteries.
 The AGVs are highly flexible, intelligent, and versatile material
handling systems used to transport materials from various
loading locations to various unloading locations throughout the
manufacturing facility.

76. Strengths of AGVs
 Space
 Economical
 Agile
 Flexible
 Dynamic
 Redundancy

77. Benefits of AGVs
 Labour
 Damage
 Shipping accuracy
 Energy
 Safety

79. Types of AGVs
 Guided driverless trains
 Guided pallet trucks
 Guided unit load carriers

80. Guided Driverless Trains
 The Guided driverless trains, also known as towing vehicles or
automated guided tractors, are most commonly used for
transporting large amount of bulky and heavy materials from
the warehouse to various locations in the manufacturing plant.

81. Guided Pallet Trucks
 The guided pallet trucks are designed to lift and transport palletized
loads.
 It is used for picking up or dropping off loads from and on to floor level.
Thus it eliminates the need for fixed load stands.
 There is no need for any special accessories for loading and unloading
the guided pallet except that the loads should be on a pallet.
 Usually the following sequence of operations are being carried out in
pallet trucks
Loads are pulled off onto a pallet forks
Lowering of the pallet forks to the floor
Pulling out from the pallet
Finally automatically returns empty to the loading area.

83. Guided unit load carriers
 Guided unit load carries have a deck that permits unit-load
transport operation.
 They are used in settings with short/medium guide paths, high
volume, and need for independent and versatility.
 They are used in warehousing and distribution systems.
 They can operate in an environment where there is not much
room and movement is restricted.

85. Applications of AGVS
 Automated Guided Vehicles are used in a variety of areas to
support processing and handling throughout a manufacturing
facility.
Assembly
Kitting
Transportation
Staging
Warehousing
Order picking
Parts/just-in-time delivery
Transfer/shuttle

86. Applications of AGVs based on
types of AGVs employed
 Driverless train operations
 Storage and distribution operations
 Assembly line applications
 Flexible manufacturing systems.

87. Vehicle Guidance Technology
 The goal of an AGVS guidance system is to keep the AGV on track
or on predefined path.
 Types of AGV Guidance approach
Fixed-route guidance method
Free – route guidance method

88. Fixed-route guidance method
 Fixed route guidance is to set medium guidance information in
the path, AGV can drive with it, such as electromagnetic
guidance, tape guidance, etc.

89. Free – route guidance method
 Free-route guidance stores the size of the coordinates, AGV can
identify current position and decide driving path, such as laser-
guidance and image recognition guidance.

90. Types of vehicle Guidance
Technologies
 There are many AGV guidance technologies/methods available
and their selection will depend on need, application, and
environmental constraints.
Wire guidance system
Paint strips system
Self-guided vehicles

93. Vehicle Management
 Traffic control
 Vehicle dispatching

94. Traffic control
 The purpose of traffic control in an automated guided vehicle
system is to minimise interference between vehicles and
prevent collisions.
 Methods of traffic control
Forward-sensing control
Zone sensing control
Combinational control

95. Forward-sensing control system

96. Zone sensing control

97. Vehicle Dispatching
 For an effective functioning of AGVS, AGVS must be dispatched in
a timely manner, as and when they are needed.
 Dispatching methods:
Vehicle Dispatching using On-board control panels
Vehicle Dispatching using Remote call stations
Vehicle Dispatching using Supervisory central computer control
Combinatorial method

98. Vehicle Safety
 An automated guided vehicle system should be designed taking
into account the safety of human personnel in the shop floor.
 Safety features provided for AGVs:
Movement speeds of less than walking pace
Automatic stopping of the vehicle
Obstacle detection sensors on the vehicle
Emergency bumper
Additional features