Automation in Manufacturing (Unit-6) by Varun Pratap Singh.pdf

Automation in Manufacturing
(MEPD-4010/4014)
Mechatronics/Mechanical Engineering
Unit 6: Flexible manufacturing systems
By
Varun Pratap Singh

Disclaimer
This document does not claim any originality and cannot be used as a substitute for prescribed textbooks. The
information presented here is merely a collection by the subject faculty members for their respective teaching
assignments, research articles, subject books, and any other sources of information. Various sources, as mentioned on
each slides or at the end of the document as well as freely available material from the internet, were consulted for
preparing this document. The ownership of the information lies with the respective authors or institutions. Further, this
document is not intended to be used for commercial purposes and the subject faculty members are not accountable for
any issues, legal or otherwise, arising out of the use of this document. The subject faculty members make no
representations or warranties concerning the accuracy or completeness of the contents of this document and
specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. The subject faculty
members shall be liable for any loss of profit or any other commercial damages, including but not limited to special,
incidental, consequential, or other damages.

Content
1. Introduction to FMS
2. Types of FMS
3. FMS components
4. Applications and benefits of FMS
5. Planning and implementation issues in FMS
6. Quantitative analysis of FMS
7. Case Study

Syllabus
Unit 1: Production systems Lectures
Categories of manufacturing systems, manufacturing support systems, automation in production systems, automated
manufacturing systems, opportunities for automation and computerization, types of automation, computerized manufacturing
support systems, reasons for automating, automation principles and strategies, the USA principle, ten strategies for automation,
automation migration strategy.
8
Unit 2: Automation and control technologies in production system Lectures
Basic elements of an automated system, advanced automation functions, levels of automation, continuous and discrete
control systems, computer process control, common measuring devices used in automation, desirable features for
selection of measuring devices.
8
Unit 3: Material handling system Lectures
Material handling equipment, design considerations for material handling system, material transport equipment, analysis of
material transport systems, storage systems and their performance and location strategies, conventional and automated storage
systems, overview of automatic identification and data capture, bar code technology, RFID, other AIDC technologies.
8
Unit 4: Production and assembly systems Lectures
Automated production lines- fundamentals, system configurations, work part transfer mechanisms, storage buffers, control of
production line, applications. Automated assembly systems- fundamentals, system configurations, parts delivery at work
stations, applications.
8
Unit 5: Cellular manufacturing Lectures
Group technology, part families, parts classification and coding, production flow analysis, Opitz coding system, composite part
concept, machine cell design, applications of GT.
7
Unit 6: Flexible manufacturing systems Lectures
Introduction to FMS, types of FMS, FMS components, applications and benefits, planning and implementation issues in FMS,
6

Suggested Text/Reference Books
Text Book:
1. Mikell P. Groover, Automation, Production Systems,
and Computer-integrated Manufacturing, prentice Hall.
Reference Book:
1. Theory of Automation of Production Planning and of Tooling:
Algorithms for Designing
Machine Tools in Automated Industrial Plants, By G. K.
Goranskiĭ"
2. Serope Kalpakjian and Steven R. Schmid, Manufacturing –
Engineering and
Technology, 7th Edition, Pearson.
3. Yoram Koren, Computer control of manufacturing system, 1st
edition.
4. Ibrahim Zeid , CAD/CAM : Theory & Practice, 2nd edition.
MOOC:
Flexible Manufacturing System- NPTEL Online Courses:
1. https://www.youtube.com/watch?v=YoslM2Sxihs
Video Lectures:
Flexible Manufacturing System- NPTEL Online Courses:
1. https://www.youtube.com/watch?v=YoslM2Sxihs
YouTube Channel/videos:
1. https://www.youtube.com/watch?v=F01K1f5owTQ
2. https://www.youtube.com/watch?v=Wov8lgnjVis
3. https://www.youtube.com/watch?v=IF9VRZv2Dpk
In Class
For knowledge

Introduction to FMS
The flexible manufacturing system (FMS) is alone of the machine cell types used to implement group technology. It is the
most automated and technologically sophisticated of the GT cells.
In our classification scheme for manufacturing systems, an FMS typically possesses multiple automated stations and is
capable of variable routings among stations (type II A). Its flexibility allows it to operate as a mixed model system (case X
for part or product variety). An FMS integrates into one highly automated manufacturing system many of the concepts and
technologies discussed in previous unit, including: flexible automation, CNC machines, distributed computer control,
automated material handling and storage and group technology. The concept for FMSs originated in Britain in the early
1960s.The first FMS installations in the United States were made starting around 1967.These initial systems performed
machining operations on families of parts using NC machine tools.
FMS technology can be applied in situations similar to those identified for group technology and cellular manufacturing;
specifically,
• Presently, the plant either (1) produces parts in batches or (2) uses manned GT cells and management wants to automate.
• 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 FMS.
The parts or products made by the facility are in the mid-volume, mid-variety production range.
The appropriate production volume range is 5000-75,000 parts/yr. If annual production is below this range, an FMS is likely
to be an expensive alternative. If production volume is above this range, then a more specialized production system should
probably be considered.
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by M.P. Groover.
Portion of this section are based on M.P. Groover; Fundamentals of manufacturing: Materials, processes and systems

Introduction to FMS
WHAT IS A FMS:
A flexible manufacturing system (FMS) is 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.
The reason the FMS is called flexible is that 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. The FMS is most suited for the mid-variety, mid-volume production range.
The initials FMS are sometimes used to denote the term flexible machining system. The machining process is presently the
largest application area for FMS technology. However, it seems appropriate to interpret FMS in its broader meaning,
allowing for a wide range of possible applications beyond machining.
A more appropriate term for an FMS would be flexible automated manufacturing system. The use of the word "automated"
would distinguish this type of production technology from other manufacturing systems that arc flexible but not
automated, such as a manned GT machine cell. On the other hand, tile word "flexible" would distinguish it from other
manufacturing systems that are highly automated but not flexible, such as a conventional transfer line. However, the
existing terminology is well established.

Introduction to FMS
The differences between implementing a manually operated machine cell and installing an FMS are:
(1) the FMS requires a significantly greater capital investment because new equipment is being installed rather than existing
equipment being rearranged. and
(2) the FMS is technologically more sophisticated for the human resources who must make it work.
However, the potential benefits are substantial. The benefits that can be expected from an FMS include:
• increased machine utilization
• fewer machines required
• reduction in factory floor space required
• greater responsiveness to change
• reduced inventory requirements
• lower manufacturing lead times
• reduced direct labor requirements and higher labor productivity
• opportunity for unattended production

What Makes It Flexible?
The issue of manufacturing system flexibility was discussed previously in unit-4. In that discussion, we identified three
capabilities that a manufacturing system must possess to be flexible:
1. The ability to identify and distinguish among the different part or product styles processed by the system,
2. Quick changeover of operating instructions, and
3. Quick changeover of physical setup. Flexibility is an attribute that applies to both manual and automated systems. In
manual systems, the human workers are often the enablers of the system's flexibility.
To qualify as being flexible, a manufacturing system should satisfy several criteria. The
following ale four reasonable tests of flexibility in an automated manufacturing system:
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, and changes in either part mix or production quantities?
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?
If the answer to all of these questions is "yes" for a given manufacturing
system, then the system can be considered flexible. The most important
criteria are (1) and (2). Criteria (3) and (4) are softer and can be implemented
at various levels.

Types of FMS
Having considered the issue of flexibility and the
different types of flexibility that are exhibited by
manufacturing systems, let us now consider the various
types of FMSs. Each FMS is designed for a specific
application, that is, a specific family of parts and
processes Therefore, each FMS is custom engineered;
each FMS is unique. Given these circumstances, one
would expect to find a great variety of system designs
to satisfy a wide variety of application requirements.
Flexible manufacturing systems can be distinguished
according to the kinds of operations they preform :(l)
processing operations or (2) assembly operations.
An FMS is usually designed to perform one or the
other but rarely both. A difference that is applicable to
machining systems is whether the system will process
rotational parts or non-rotational parts. Flexible
machining systems with multiple stations that process
rotational parts are much less common than systems
that process non-rotational parts. Two other ways to
classify FMSs are by: (1) number of machines and (2)
level of flexibility.

Types of FMS
Number of Machines. Flexible manufacturing
systems can be distinguished according to the
number of machines in the system. The following
are typical categories:
• Single machine cell (type I A)
• Flexible manufacturing cell (usually type II A,
sometimes type III A)
• Flexible manufacturing system (usually type II A,
sometimes type III A)
A single machine cell (SMC) 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. The
cell can be designed to operate in either a batch mode or a flexible mode or in combinations of the two. When operated in a
batch mode, the machine processes parts of a single style in specified lot sizes and is then changed over to process a batch of
the next part style.
When operated in a flexible mode, the system satisfies three of the four f1exibili1y tests. It is capable of :
(1) processing different part styles,
(2) responding to changes in production schedule, and
(3) accepting new part introductions criterion
(4) error recovery, cannot be satisfied because if the single machine breaks down, production stops.

Types of FMS
A flexible manufacturing all (FMC) consists of two or three processing workstations (typically CNC machining centers or
turning centers) plus a part handling system. The part handling system is connected to a load/unload station. In addition, the
handling system usually includes a limited parts storage capacity. One possible FMC is illustrated in Figure 16.3. A flexible
manufacturing cell satisfies the four flexibility tests discussed previously.
A flexible manufacturing system (FMS) has four or more processing workstations connected mechanically by a common
part handling system and electronically by a distributed computer system. Thus, an important distinction between an FMS and
an FMC is the number of machines: an FMC has two or three machines, while an FMS has four or more.
A second difference is that the FMS generally includes non-processing workstations that support production but do not directly
participate in it. These other stations include part/pallet washing stations, coordinate measuring machines, and so on. A third
difference is that the computer control system of an FMS is generally larger and more sophisticated, often including functions
not always found in a cell, such as diagnostics and tool monitoring. These additional functions are needed more in an FMS
than in an FMC because the FMS is more complex.

Types of FMS

Another classification of FMS is according to the level of flexibility designed into the system. This method of classification
can be applied to systems with any number of workstations, but its application seems most common with FMCs and FMSs.
Two categories are distinguished here:
• Dedicated FMS
• Random-order 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. The term special manufacturing system has also been used in reference to this FMS type.
The part family is likely to be based on product commonality rather than geometric similarity. The product design is
considered stable, and so the system can be designed with a certain amount of process specialization to make the operations
more efficient. Instead of using general-purpose machines, the machines can be designed for the specific processes required to
make the limited part family, thus increasing the production rate of the system. In some instances, 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. Indeed, the term flexible transfer line is sometimes
used or this case.
Types of FMS
A random-order FMS is more appropriate when the pair family is large, there are substantial variations in part
configurations, there will be new part designs introduced into the system and engineering changes in parts currently
produced, and the production schedule is subject to change from day-to-day, To accommodate these variations, the random-
order FMS must be more flexible than the dedicated FMS. It is equipped with general-purpose machines to deal with the
variations in product and is capable of processing parts in various sequences (random-order). A more sophisticated computer
control system is required for this FMS type.

FMS components

FMS components
There are several basic components of an FMS: (1) workstations, (2) material handling and storage system, and (3) computer
control system. In addition, even though an FMS is highly automated, (4) people are required to manage and operate the system.
Workstations
The processing or assembly equipment used in an FMS depends on the type of work accomplished by the system. In a system
designed for machining operations, the principle types of processing station are CNC machine tools. However, the FMS concept
is also applicable to various other processes as well. Following are the types of workstations typically found in an FMS.
• Load/Unload Stations
• Machining Stations.
• Processing Stations
• Assembly
Material Handling and Storage System
The second major component of an FMS is its material handling and storage system. In this subsection, we discuss the
functions of the handling system, material handling equipment typically used in an FMS, and types of FMS layout.
Functions of the Handling System. The material handling and storage system
in an FMS performs the fol1owing functions:
• Random, independent movement of work parts between stations.
• Handle a variety of work part configurations.
• Temporary storage.
• Convenient accessory loading and unloading work parts.
• Compatible with computer control.

FMS components
There are several basic components of an FMS: (1) workstations, (2) material handling and storage system, and (3)
computer control system. In addition, even though an FMS is highly automated, (4) people are required to manage and
operate the system.
Workstations
The processing or assembly equipment used in an FMS depends on the type of work accomplished by the system. In a system
designed for machining operations, the principle types of processing station are CNC machine tools. However, the FMS concept
is also applicable to various other processes as well. Following are the types of workstations typically found in an FMS.
• Load/Unload Stations
• Machining Stations.
• Processing Stations
• Assembly
Material Handling and Storage System
The second major component of an FMS is its material handling and storage system. In this subsection, we discuss the
functions of the handling system, material handling equipment typically used in an FMS, and types of FMS layout.
Functions of the Handling System. The material handling and storage system
in an FMS performs the fol1owing functions:
• Random, independent movement of work parts between stations.
• Handle a variety of work part configurations.
• Temporary storage.
• Convenient accessory loading and unloading work parts.
• Compatible with computer control. Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by M.P. Groover.

FMS components
Computer Control System
The FMS includes a distributed computer system that is interfaced to the workstations, material handling system, and other
hardware components. A typical FMS computer system consists of a central computer and microcomputers controlling the
individual machines and other components. The central computer coordinates the activities of the components to achieve
smooth overall operation of the system. Functions performed by the FMS computer control system can be grouped into the
following categories:
1. Workstation control. 2. Distribution of control instructions to workstations. 3. Production control.
4. Traffic control. 5. Shuttle control. 6. Work piece monitoring. 7. Tool control.
8. Performance monitoring and reporting. 9. Diagnostics.
Human Resources
One additional component in the FMS is human labor. Humans are needed to manage the operations of the FMS. Functions
typically performed by humans include:
(1) loading raw work parts into the system,
(2) unloading finished parts (or assemblies) from the system.
(3) changing and setting tools.
(4) equipment maintenance and repair,
(5) NC part programming in a machining system,
(6) programming and operating the computer system, and
(7) overall management of the system

Typical FMS Performance Reports

Applications and benefits of FMS
FMS Applications
The concept of flexible automation is applicable to a variety of manufacturing operations. In this section, some of the
important FMS applications are reviewed. FMS technology is most widely applied in machining operations. Other
applications include sheet metal press working, forging, and assembly. Here some of the applications are examined using case
study examples to illustrate.
Flexible Machining Systems: Historically, most of the applications of flexible machining systems have been in milling and
drilling type operations (non-rotational parts), using NC and subsequently CNC machining centers. FMS applications for
turning (rotational parts) were much less common until recently, and the systems that are installed tend to consist of fewer
machines. For example, single machine cells consisting of parts storage units, part loading robots, and CNC turning centers are
widely used today, although not always in a flexible mode. Let us explore some of the issues behind this anomaly in the
development of flexible machining systems.
Other FMS Applications: Press working and forging arc two other manufacturing processes in which efforts are being made
to develop flexible automated systems. The FMS technologies involved, The following example illustrates the development
efforts in the press working area.

Benefits of FMS
FMS Benefits
A number of benefits can be expected in successful FMS applications. The principal benefits are the following:
Increased machine utilization. FMSs achieve a higher average utilization than machines in a conventional batch production
machine shop. Reasons for this include:
(1) 24 hour/day operation.
(2) automatic tool changing at machine tools.
(3) automatic pallet changing at workstations.
(4) queues of parts at stations, and
(5) dynamic scheduling of production that takes into account irregularities from normal operations.
It should be possible to approach 80-90% asset utilization by implementing FMS technology.
• Fewer machine required: Because of higher machine utilization. fewer machines are required.
• Reduction in factory floor space required: Compared with a job shop of equivalent capacity, an FMS generally requires
less floor area.
• Reductions in floor space requirements are estimated to he 40-50%.

Benefits of FMS
FMS Benefits
• Greater responsiveness to change: An FMS improves response capability to part design changes. introduction of new
part s, changes in production schedule and product mix. machine breakdowns. and cutting tool failures. Adjustments can
be made in the production schedule from one day to the next to respond to rush orders and special customer requests.
• Reduced inventory requirements: Because different parts are processed together rather than separately in batches.
work-in-process (WIP) is less than in a batch production mode. The inventory of starting and finished parts can be
reduced as well. Inventory reductions of 60-80% are estimated.
• Lower manufacturing lead times: Closely correlated with reduced WIP is the time spent in process by the parts. This
means faster customer deliveries
• Reduced direct labor requirements and higher labor productivity: Higher production rates and lower reliance on
direct labor translate to greater productivity per labor hour with an FMS than with conventional production methods.
Labor savings of 30-50%, ar3 estimated.
• Opportunity for unattended production: The high level of automation in an FMS allows it to operate for extended
periods of time without human attention. In the most optimistic scenario, parts and tools are loaded into the system at the
end of the day shift, and the FMS continues to operate throughout the night so that the finished parts can be unloaded the
next morning.

Planning and implementation issues in FMS
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. 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. The term product commonality refers to different components used on the same
product. Many successful FMS installations arc designed to accommodate part families defined by this criterion.
• Processing requirements: The types of parts and their processing requirements determine the types of processing
equipment that will be used in the system.
• Physical characteristic of the work parts, 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.

Planning and implementation issues in FMS
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 stations.
• Variations in process routings and FMS layout: If variations in process sequence are minimal. then an in-line 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.
• 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 non-rotational 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.

Quantitative analysis of FMS
Most of the design and operational problems identified can be addressed using quantitative analysis techniques.
FMSs have constituted an active area of interest in operations research, and many of the important contributions are
included in our list of references. FMS analysis techniques can be classified as follows:
(l) deterministic models,
(2) queueing models,
(3) discrete event simulation, and
(4) other approaches, including heuristics.
To obtain starting estimates of system performance, deterministic models can be used.

Case Study of FMS

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