A flexible manufacturing system (FMS) is a set of numerically controlled machine tools

1. - By Paarth Gupta

2. A flexible manufacturing system (FMS) is a set of numerically
controlled machine tools and supporting workstations connected by an
automated material handling system and all aspects of the system
controlled by a central computer.
 FMS is distinguished from an automated production line by its ability
to process more than one product style simultaneously.
 At any moment, each machine in the system may be processing a
different part type.
 FMS can let us make changes in production schedule in order to
meet the demands on different products.

4. NEEDOF FMS:-
External changes such as change in product design and production
system
Optimizing the manufacturing cycle time
Reduced production costs
Overcoming internal changes like breakdowns etc.

5. WHAT TYPE OF FLEXIBILITY:-
Machining flexibility
Process flexibility
Product flexibility
Routing flexibility
Volume flexibility
Market flexibility
Material handling
Production flexibility
Operation flexibility

6.  Flexible manufacturing systems can be distinguished
according to the number of machines in the system.
The following are typical categories:
 Single machine cell
 Flexible manufacturing cell
 Flexible manufacturing system

7. 1. SINGLE MACHINE CELL
• A single machine cell consists of one CNC machining center combined with a
parts storage system for unattended operation.
• Completed parts are periodically unloaded from the parts storage unit, and raw
work parts are loaded into it.

8. 2. FLEXIBLE MANUFACTURING CELL
• A flexible manufacturing cell consists of two or three processing workstations
(typically CNC machining centers) plus a part handling system.
• The part handling system is connected to a load/unload station.

9. 3. FLEXIBLE MANUFACTURING SYSTEM
• A flexible manufacturing system has four or more processing workstations
connected mechanically by a common part handling

11.  The two important equipments of FMS are:
1. Primary equipment: It adds value to the piece parts being
manufactured. It consists of work centers, which physically machine a
piece part, and process centers, which assemble, check or wash, etc. the
piece parts.
2. Secondary equipment: It is used to support the primary equipment in
achieving this goal. It consists of support stations such as pallet/fixture
load-unload stations and tool commissioning/setting area, etc. It also
consists of support equipments such as robots, pallet/fixture/stillage
stores, pallet buffer stations, tool stores, raw material stores, transport
system (AGVs, RGVs, robots) for tooling and piece parts, etc.

12.  The basic components of FMS are:
1. Workstations
2. Automated Material Handling and Storage system.
3. Computer Control System
4. Human labour system

13. 1. 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.

14. 2. 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) Compatible with computer control

15. 3. 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

16. 4. HUMAN LABOUR
• Human are needed to manage the operations of the FMS. Functions typically
performed by human includes:
Loading raw work parts into the system,
Unloading finished parts (or assemblies) from the system,
Changing and setting tools,
Equipment maintenance and repair,
NC part programming in a machining

17. THE FMS IS MOST SUITED FOR THE MID VARIETY, MID VALUE PRODUCTION RANGE:-

18.  Two types are distinguished here:
 Dedicated FMS:- A dedicated FMS is 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.
 Random-order FMS:- A random-order FMS is more appropriate
when
1. the part family is large
2. there are substantial variations in part configurations
3. there will be new part designs introduced into the system and
engineering changes in parts currently produced

19. A COMPARISONOF DEDICATED AND RANDOM-ORDER FMS TYPES:

20.  The basic layouts of FMS are:
1. Progressive or Line Type
2. Loop Type
3. Ladder Type
4. Open field type
5. Robot centered type

21. 1. IN LINE LAYOUT
• Straight line flow, well-defined processing sequence similar for all work units
• Work flow is from left to right through the same workstations
• May or may not be a secondary handling system

22. 2. LOOP TYPE
• One direction flow, but variations in processing sequence possible for different part
types
• Secondary handling system at each workstation

23. 3. LADDER TYPE
• Loop with rungs to allow greater variation in
processing sequence
• The loading and unloading station is typically
located at the same end.
• The sequence to the operation/transfer of parts
from one machine tool to another is in the form
of ladder.

24. 4. OPEN FIELD LAYOUT
• The loading and unloading station is typically
located at the same end.
• The parts will go through all the substations,
such as CNC machines, coordinate measuring
machines and wash station by the help of
AGV’s from one substation to another.

25. 5. ROBOT CENTERED LAYOUT
• Robot centered cell is a relatively new form of
flexible system in which one or more robots
are used as the material handling systems.
• Suited to the handling of rotational parts and
turning operations

26. NOW LET US DISCUSS ABOUT THE LATEST TRENDS
IN FMS

27. A FMS is a complex manufacturing system. It is normally composed of a
tool system, several automated production systems, a material
transportation system, several load/unload stations, a computer control
and management system, and an interface.
 In today’s manufacturing units several PLCs are used to switch on or
off robots , conveyer belts and other part of manufacturing systems.
 The advantages of PLC in automated systems made PLC one of the
main component of any Manufacturing.

28.  The PLC controls the FMS operation according to its user
program, which is embedded in the controller. The user
program defines a series of operations in the FMS, including
logical and sequential operations. When a fault occurs, the
current status of all sensors or actuators is saved as an array
of input or flag signals in the PLC memory. Therefore, the
program is the basis of the diagnosis models for operational
faults in a PLC controlled manufacturing system.

29.  State-of-the art PLC devices are used as controllers in assembly
lines, robots and other manufacturing facilities that facilitate precise
control measurements. Those devices can be digital or analog and
used as inputs to the system or outputs from the system.

31.  Minimizing the process cycle time: The process must be designed to
minimize machining and handling.
 Maximizing the utilization of each machine: This can be done by
balancing the work load in the system and real time scheduling.
 Backup capabilities: The system should be able to run even when
failures occur.
 Use of identification marking techniques: Bar codes and RFID tags
are now popular for identifying products as well as components. This
permits automatic tracking of workpieces and tools.

32.  Use of automated storage systems to keep work ready for
machines to process: The raw work parts must be replenished as
and when needed to avoid starving the work centres.
 Provision of adequate sensors for the detection of errors or
problems: This includes the detection of the presence and
absence of parts, jamming, tool wear, machine failures, and so on..

33.  Metal-cutting machining
 Metal forming
 Assembly
 Joining-welding (arc , spot), glueing
 Surface treatment
 Inspection
 Testing

34.  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