Automation in manufacturing five unit vtu, mechanical engineering notes pdf download

2016
Kiran Vijay Kumar
6/7/2016
AUTOMATION IN
MANUFACTURING

CONTENTS
Page
Unit 1: Introduction to automation
1. Introduction 1
2. Production System 1
3. Facilities 1
4. Manufacturing Support System 2
5. Automation in Manufacturing Systems 4
6. Reasons for Automating 5
7. Automation Principles 5
8. Automation Strategies 6
9. Automation Migration Strategy 7
10. Advantages of Automation Migration Strategy 8
Unit 2: Manufacturing Operation
11. Introduction 9
12. Manufacturing Operations 9
13. Manufacturing processes 9
14. Product/Production Relationships 11
15. Production concepts and Mathematical Models 12
16. Costs of Manufacturing Operations 15
17. Other Factory Operations 17
18. WIP Ratio 18
19. TIP Ratio 18
20. Worked Examples 19

Unit 6: Quality control systems
21. Introduction 23
22. Quality 23
23. Traditional Quality Control 23
24. Modern Quality Control 24
25. Quality Control Technologies 25
26. Taguchi Methods In Quality Engineering 25
27. Statistical Process Control 29
28. Control charts 29
29. Histograms 30
30. Pareto 31
31. Check Sheets 31
32. Defect Concentration Diagrams 32
33. Scatter Diagrams 32
34. Cause and Effect Diagrams 33
Unit 7: Inspection technologies
35. Introduction 34
36. Automated Inspection 34
37. Type I and Type II errors in automated system 35
38. Coordinate Measuring Machines (CMM) 36
39. CMM Construction 36
40. CMM Operation and Programming 40
41. Other CMM Software’s 41
42. CMM Applications and Benefits 42
43. Flexible Inspection Systems 42

44. Inspection Probes on Machine Tools 43
45. Machine Vision 43
46. Machine Vision Applications 45
47. Optical Inspection Methods 45
48. Non-contact Non-optical Inspection Techniques 47
Unit 8: Manufacturing support system
49. Process Planning 48
50. Computer-Aided Process Planning 50
51. Concurrent Engineering 52
52. Advanced Manufacturing Planning 53
53. Just-In-Time Production Systems 55
54. Lean Production 57
55. Agile Manufacturing 58
56. Market Forces and Agility 59
57. Reorganizing the Production System for Agility 59
58. Managing Relationships for Agility 59
59. Agility versus Mass Production 60
60. Comparison of Lean and Agile 60
REFERENCE

Automation in Manufacturing
Kiran Vijay Kumar
Syllabus:-
Introduction: Production System Facilities, Manufacturing Support systems, Automation in Production systems,
Automation principles & Strategies
Brief Introduction:-
• The word Manufacturing was derived from two Latin words,
that combination means made by hand
• The use of automated equipment in Manufacturing rather than manual worker is known as
Production systems:-
• The production system is the collection of people, equipment, and procedures organized to accomplish the
manufacturing operations of a company
• Production systems can be divided
1.
2.
1. Facilities :-
• The facilities of the production system consist of the factory, the equipment in the factory, and the way
the equipment is organized.
• Facilities also include the plant layout,
• The equipment is usually organized into
the workers who operate them as the
• There are three basic categories of manufacturing systems (a) manual work systems, (b) worker
systems and (c) automated systems.
a. Manual Work Systems:
• A manual work system consists of one or more worker performing one or
powered tools.
• Manual material handling tasks are common activities in manual work systems.
• Production tasks commonly require the use of
by the strength and skill of the human user.
• When using hand tools, a work holder
processing.
• Examples A machinist using a file to round the edges.
Unit – 1
Introduction to Automation
Production System Facilities, Manufacturing Support systems, Automation in Production systems,
The word Manufacturing was derived from two Latin words, Manus (Hand) and
made by hand.
The use of automated equipment in Manufacturing rather than manual worker is known as
Automation in Manufacturing.
is the collection of people, equipment, and procedures organized to accomplish the
company (or other organization).
Production systems can be divided into two categories or levels,
Facilities
Manufacturing support systems
The facilities of the production system consist of the factory, the equipment in the factory, and the way
plant layout, which is the way the equipment is physically arranged in the factory.
The equipment is usually organized into logical groupings, and we refer to these equipment arrangements and
them as the manufacturing systems in the factory.
There are three basic categories of manufacturing systems (a) manual work systems, (b) worker
systems and (c) automated systems.
Manual Work Systems:-
A manual work system consists of one or more worker performing one or more tasks without the aid of
Manual material handling tasks are common activities in manual work systems.
sks commonly require the use of hand tools. A hand tool is a small tool that is manually operated
kill of the human user.
work holder is often employed to hold the work part and position it securely during
Examples A machinist using a file to round the edges.
P a g e | 1
Production System Facilities, Manufacturing Support systems, Automation in Production systems,
(Hand) and Factus (Make), so
The use of automated equipment in Manufacturing rather than manual worker is known as
is the collection of people, equipment, and procedures organized to accomplish the
The facilities of the production system consist of the factory, the equipment in the factory, and the way
equipment is physically arranged in the factory.
logical groupings, and we refer to these equipment arrangements and
There are three basic categories of manufacturing systems (a) manual work systems, (b) worker-machine
more tasks without the aid of
. A hand tool is a small tool that is manually operated
the work part and position it securely during

Kiran Vijay Kumar
b. Worker-Machine Systems:
• In a worker-machine system, human workers operate power equipment such
production machine.
• This is one of the most widely used manufacturing systems.
• Worker – machine systems include combination of one or more workers and one or more pieces of equipment.
• Examples of worker – machine system
part for a custom-designed product.
c. Automated system :-
• An automated system is one in which a process is performed by a machine without the direct participation of a
human worker.
• Automation is implemented using a program of instructions combined with a control system that executes the
instructions.
• Power is required to drive the process and to operate the program and control system.
• There is not always a clear distinction between worker machine system and automated systems, because many
worker-machine systems operate with some degree of automation.
2. Manufacturing Support System
• This is the set of procedures used by the company to manage production and to solve the technical and
logical problems encountered in ordering materials, moving work through the factory and ensuring that
products meet quality standards
• Manufacturing support involves a cycle of information
• The information-processing cycle
(1) Business functions
(2) Product design
(3) Manufacturing planning
(4) Manufacturing control.
Machine Systems:-
m, human workers operate power equipment such
This is one of the most widely used manufacturing systems.
machine systems include combination of one or more workers and one or more pieces of equipment.
machine system are a machinist operating an engine lathe in a tool room to fabricate a
designed product.
An automated system is one in which a process is performed by a machine without the direct participation of a
Automation is implemented using a program of instructions combined with a control system that executes the
required to drive the process and to operate the program and control system.
There is not always a clear distinction between worker machine system and automated systems, because many
machine systems operate with some degree of automation.
turing Support System :-
is the set of procedures used by the company to manage production and to solve the technical and
standards.
Manufacturing support involves a cycle of information-processing activities,
processing cycle consist of four functions:
P a g e | 2
as machine tool or other
machine systems include combination of one or more workers and one or more pieces of equipment.
a machinist operating an engine lathe in a tool room to fabricate a
An automated system is one in which a process is performed by a machine without the direct participation of a
Automation is implemented using a program of instructions combined with a control system that executes the
required to drive the process and to operate the program and control system.
There is not always a clear distinction between worker machine system and automated systems, because many
is the set of procedures used by the company to manage production and to solve the technical and

Kiran Vijay Kumar
1. Business Functions:-
• The business functions are the principal means of communicating
• They are, therefore, the beginning and the end of the information
• Included in this category are sales a
billing.
2. Product Design:-
• If the product is to be manufactured to customer
The manufacturer's product design department
• If the product is to be produced to customer
contracted to do the design work for the
• The departments of the firm
development, design engineering, drafting, and perhaps a prototype shop.
3. Manufacturing Planning:
• The information-processing activities in manufacturing planning include
requirements planning and capacity planning
• Process planning consists of determining the
needed to produce the part.
• The master production schedule
quantities.
• Raw materials must be purchased or requisitioned from storage. Purchased parts must be ordered from
suppliers, and all of these items must be planned so that they are available when needed. This
called capacity requirements planning.
• In addition, the master schedule must
producing each month with number of machines and manpower.
• A function called capacity planning
4. Manufacturing Control :
• Manufacturing control is concerned with managing and
implement the manufacturing plans
• The flow of information is from pla
• The manufacturing control functions are
• Shop floor control deals with the problem of monitoring the progress of the product
assembled, moved and inspected in the factory
The business functions are the principal means of communicating with the customer.
therefore, the beginning and the end of the information- processing cycle.
Included in this category are sales and marketing, sales forecasting, order entry, cost accounting, and customer
If the product is to be manufactured to customer design, the design will have been provided by the
The manufacturer's product design department will not be involved.
f the product is to be produced to customer specifications, the manufacturer's product des
do the design work for the product as well as to manufacture it.
that are organized to accomplish product design might include research
development, design engineering, drafting, and perhaps a prototype shop.
Manufacturing Planning:-
activities in manufacturing planning include process planning,
and capacity planning.
consists of determining the sequence of individual processing and assembly operations
master production schedule is a listing of the products to be made, when to be delivered
be purchased or requisitioned from storage. Purchased parts must be ordered from
these items must be planned so that they are available when needed. This
requirements planning.
In addition, the master schedule must not list more quantities of products than the factory is capable of
with number of machines and manpower.
y planning is planning the manpower and machine resources of the firm.
Manufacturing Control :-
Manufacturing control is concerned with managing and controlling the physical ope
implement the manufacturing plans.
The flow of information is from planning to control.
he manufacturing control functions are shop floor control, inventory control and quality control
deals with the problem of monitoring the progress of the product
ed in the factory
P a g e | 3
rder entry, cost accounting, and customer
will have been provided by the customer.
manufacturer's product design department maybe
ct design might include research and
process planning, master scheduling,
sequence of individual processing and assembly operations
when to be delivered and in what
be purchased or requisitioned from storage. Purchased parts must be ordered from
these items must be planned so that they are available when needed. This entire task is
not list more quantities of products than the factory is capable of
the manpower and machine resources of the firm.
controlling the physical operations in the factory to
shop floor control, inventory control and quality control.
deals with the problem of monitoring the progress of the product as it is being processed,

Kiran Vijay Kumar
• Inventory control attempts to strike a proper balance between the danger of
cost of too much inventory.
• It deals with such issues as deciding the right quantities of materials to
when stock is low.
• The mission of quality control is to ensure that the quality of the product and its components
specified by the product designer.
• Final inspection and testing of the finished product is
product.
Automation in Manufacturing Systems
• Some elements of the firm's production system are likely to be automated, whereas others
manually or clerically.
• For our purposes here, automation
mechanical, electronic, and computer
• The automated elements of the production system can be separated into two categories:
(1) Automation of the manufacturing systems in the factory and
(2) Computerization of the manufacturing support systems.
• In modern production systems, the two categories
(1) Automation of the manufacturing systems :
• Automated manufacturing systems operate in the factory on the physical product.
• They perform operations such as processing, assembly, inspection, or material handling, in some
accomplishing more than one of these operations in the same system.
• They are called automated because they perform their operations with a reduced level of human participation
compared with the corresponding manual process.
• In some highly automated systems,
• Examples of automated manufacturing
1. Automated machine tools that process parts
2. Transfer lines that perform a series of machining operations
• Automated manufacturing systems can be classified into three basic types
(ii) Programmable automation and (iii) F
(i) Fixed Automation :
• Fixed automation is a system in which the sequence of processing
equipment configuration.
• Each of the operations in the sequence is usually simple, involving
an uncomplicated combination of the two
• Its Features are,
i. High initial investment
ii. High production rate.
iii. Low product variety
• E.g. machining transfer lines and automated assembly machines.
attempts to strike a proper balance between the danger of too little inventory and the carrying
It deals with such issues as deciding the right quantities of materials to order and when to re
is to ensure that the quality of the product and its components
specified by the product designer.
of the finished product is performed to ensure functional quality and appearance of
Automation in Manufacturing Systems:-
Some elements of the firm's production system are likely to be automated, whereas others
automation can be defined as a technology concerned with the application of
computer-based systems to operate and control production.
The automated elements of the production system can be separated into two categories:
Automation of the manufacturing systems in the factory and
of the manufacturing support systems.
In modern production systems, the two categories overlap to some extent.
Automation of the manufacturing systems :-
cturing systems operate in the factory on the physical product.
operations such as processing, assembly, inspection, or material handling, in some
accomplishing more than one of these operations in the same system.
mated because they perform their operations with a reduced level of human participation
compared with the corresponding manual process.
In some highly automated systems, there is virtually no human participation.
Examples of automated manufacturing systems include:
utomated machine tools that process parts.
ransfer lines that perform a series of machining operations.
Automated manufacturing systems can be classified into three basic types (i) Fixed automation,
Programmable automation and (iii) Flexible automation.
:-
is a system in which the sequence of processing (or assembly) operations is fixed by the
in the sequence is usually simple, involving perhaps a plain linear or rotational
an uncomplicated combination of the two.
igh initial investment.
High production rate.
product variety.
and automated assembly machines.
P a g e | 4
e inventory and the carrying
hen to reorder a given item
is to ensure that the quality of the product and its components meet the standards
nctional quality and appearance of
Some elements of the firm's production system are likely to be automated, whereas others will be operated
as a technology concerned with the application of
operate and control production.
The automated elements of the production system can be separated into two categories:
operations such as processing, assembly, inspection, or material handling, in some cases
mated because they perform their operations with a reduced level of human participation
(i) Fixed automation,
(or assembly) operations is fixed by the
perhaps a plain linear or rotational motion or

Kiran Vijay Kumar P a g e | 5
(ii) Programmable Automation :-
• In programmable automation, the production equipment is designed with the capability to change the sequence
of operations to accommodate different product configuration.
• The operation sequence is controlled by a program.
• New programs can be prepared and entered into the equipment to produce new products.
• Its features are,
i. High initial investment
ii. Lower production rate.
iii. High product variety.
iv. Suitable for batch production.
• E.g. Numerically Controlled (NC) machine tools, industrial robots, and programmable logic controllers.
(iii) Flexible Automation :-
• Flexible' automation is an extension of programmable automation.
• A flexible automated system is capable of producing a variety of parts with virtually no time lost for
changeovers from one part style to the next.
• There is no lost production time while reprogramming the system and altering the physical setup.
• Its features are,
i. High initial investment.
ii. Medium production variety.
iii. Medium production rate.
iv. Flexibility to deal with product design variations.
• E.g. the flexible manufacturing systems for performing machining operations.
(2) Computerization of the manufacturing support systems :-
• Automation of the manufacturing support systems is aimed at reducing the amount of manual and clerical effort
in product design, manufacturing planning and control, and the business functions of the firm.
• Nearly all modem manufacturing support systems are implemented using computer systems.
• Indeed, computer technology is used to implement automation of the manufacturing systems in the factory as well.
• The term computer integrated manufacturing (CIM) denotes the pervasive use of computer systems to design
the products, plan the production, control the operations, and perform the various business-functions needed in a
manufacturing firm.
• True CIM involves integrating all of these functions in one system that operates throughout the enterprise.
• For example, computer-aided design (CAD) denotes the use of computer systems to support the product design
function.
• Computer-aided manufacturing (CAM) denotes the use of computer systems to perform functions related to
manufacturing engineering, such as process planning and numerical control part programming.
• Some computer systems perform both CAD and CAM.
Reasons for Automating:-
1. To increase labor productivity.
2. To reduce labor cost.
3. To mitigate the effects of labor shortages.
4. To reduce or eliminate routine manual and clerical tasks.
5. To improve worker safety.
6. To improve product quality.
Automation (or USA) Principles:-
• The USA Principle is a good first step in any automation project.
• USA stands for,
1. Understand the existing process.
2. Simplify the process.
3. Automate the process.

1. Understand the existing process :-
• The obvious purpose of the first step in the USA approach is to comprehend the current process in all of its
details.
• What arc the inputs? What are the outputs? What exactly happens to the work unit between input and output?
What is the function of the process? How does it add value to the product? What are the upstream and
downstream operations in the production sequence, and can they be combined with the process under
consideration?
• Some of the basic charting tools used in methods Application of these tools to the existing process provide a
model of the process that can be analyzed and searched for weaknesses (and strengths).
• Mathematical models of the process may also be useful to indicate relationships between input parameters and
output variables.
2. Simplify the process :-
• Once the existing process is understood, then the search can begin for ways to simplify.
• This often involves a checklist of Questions about the existing process. What is the purpose of this step or this
transport? Is this step necessary? Can steps be combined? Can steps be performed simultaneously? Can steps be
integrated into a manually operated production line?
• Some of the ten strategies at automation and production systems are applicable to try to simplify the process.
3. Automate the process :-
• Once the process has been reduced to its simplest form, then automation can be considered.
• The possible forms of automation include the ten strategies.
• An automation migration strategy might be implemented for a new product that has not yet proven itself.
Automation Strategies:-
If automation seems a feasible solution to improving productivity, quality, or other measure of
performance, then the following ten strategies provide a road map to search for these improvements.
1. Specialization of operations:-
The first strategy involves the use of special-purpose equipment designed to perform one operation with the
greatest possible efficiency.
2. Combined operations:-
• Production occurs as a sequence of operations. Complex parts may require dozens, or even hundreds, of
processing steps.
• The strategy of combined operations involves reducing the number of distinct operation? Reduction machines
or workstations through which the part must be routed.
• This is accomplished by performing more than one operation at a given machine; thereby reducing the number
of separate machines needed which in turn reduces setup time.
3. Simultaneous operations:-
• A logical extension of the combined operations strategy is to simultaneously perform the operations that are
combined at one workstation.
• In effect, two or more processing (or assembly) operations are being performed simultaneously on the same
work part. Thus reducing total processing time.

4. Integration of operations:-
• Another strategy is to link several workstations together into a single integrated mechanism, using automated
work handling devices to transfer parts between stations.
• In effect, this reduces the number of separate machines through which the product must be scheduled with more
than one workstation.
• Several parts can be processed simultaneously, thereby increasing the overall output of the system.
5. Increased flexibility:-
• This strategy attempts to achieve maximum utilization of equipment for job shop and medium-volume
situations by using the same equipment for a variety of parts or products.
• It involves the use of the flexible automation concepts.
• Prime objectives are to reduce setup time and programming time for the production machine. This normally
translates into lower manufacturing lead time and less work-in-process.
6. Improved material handling and storage:-
• A great opportunity for reducing nonproductive time exists in the use of automated material handling and
storage systems.
• Typical benefits include reduced work-in-process and shorter manufacturing lead times.
7. On-line inspection:-
• Inspection for quality of work is traditionally performed after the process is completed which means that any
poor-quality product has already been produced by the time it is inspected.
• Incorporating inspection into the manufacturing process permits corrections to the process as the product is
being made.
• This reduces scrap and brings the overall quality of the product closer to the nominal specifications intended by
the designer.
8. Process control and optimization :-
• This includes a wide range of control schemes intended to operate the individual processes and associated
equipment more efficiently.
• By this strategy, the individual process times can be reduced and product quality improved.
9. Plant operations control:-
• This strategy is concerned with control at the plant level.
• It attempts to manage and coordinate the aggregate operations in the plant more efficiently.
• Its implementation usually involves a high level of computer networking within the factory.
10. Computer-integrated manufacturing (CIM) :-
• Taking the previous strategy one level higher, we have the integration of factory operations with engineering
design and the business functions of the firm.
• CIM involves extensive use of computer applications, computer data bases, and computer networking
throughout the enterprise.
Automation Migration Strategy:-
• If the product turns out to be successful and high future demand is anticipated, then it makes sense for the
company to automate production.
• The improvements are often carried out in phases.
• Many companies have an automation migration strategy: that is, a formalized plan for evolving the
manufacturing system, used to produce new products as demand grows.
• A typical automation migration strategy is as shown in fig.

Kiran Vijay Kumar
Phase 1: Manual production using single
introduction of the new product for reasons already
Phase 2: Automated production using single
product grows, and it becomes clear that
labor and increase production rate. Work units are
Phase 3: Automated integrated production
automated transfer of work units between stations.
mass quantities and for several years, then integration of the single
reduce labor and increase production
Advantages of Automation Migration Strategy
1. It allows introduction of the new product in the shortest possible
workstations are the easiest to design and implement
2. It allows automation to be introduced gradually (in planned phases), as demand for
engineering changes in the product are made, and time i
manufacturing system.
3. It avoids the commitment to a high lev
for the product will not justify it
using single-station manned cells operating independently.
introduction of the new product for reasons already mentioned: quick and low-cost tooling to get started
using single-station automated cells operating independently.
product grows, and it becomes clear that automation can be justified, then the single stations are automated to reduce
production rate. Work units are still moved between workstations manua
Automated integrated production using a multi-station automated system
automated transfer of work units between stations. When the company is certain that the product will be produced in
for several years, then integration of the single-station automated cells is warranted to further
reduce labor and increase production rate.
Migration Strategy:-
It allows introduction of the new product in the shortest possible time, since production
workstations are the easiest to design and implement.
It allows automation to be introduced gradually (in planned phases), as demand for
engineering changes in the product are made, and time is allowed to do a thorough design job on the automated
a high level of automation from the start, since there is
for the product will not justify it.
P a g e | 8
operating independently. This is used for
cost tooling to get started.
operating independently. As demand for the
automation can be justified, then the single stations are automated to reduce
workstations manually.
with serial operations and
When the company is certain that the product will be produced in
automated cells is warranted to further
time, since production cells based on manual
It allows automation to be introduced gradually (in planned phases), as demand for the product grows,
to do a thorough design job on the automated
always a risk that demands

Kiran Vijay Kumar
Syllabus:-
Manufacturing Operations, Product/Production Relationship, Production concepts and Mathematical Models &
Costs of Manufacturing Operations.
Introduction:-
• Manufacturing can be defined as is application of physical
geometry, properties, and/or appearance of a given starting material to make parts
• Manufacturing also includes the joining of multiple parts to make assembled products.
• The processes that accomplish manufacturing involve a combination of machinery,
manual labor.
Manufacturing Operations:-
• There are certain basic activities that must be carried out in a factory to convert raw materials into
finished products.
• Limiting our scope to a plant engaged in making discrete products, the factory activities are:
(1) Processing and assembly operations, (2) Material handling, (3) Inspection and test, and
(4) Coordination and control.
• Our viewpoint is that value i
the product.
• Unnecessary operations, whether they are processing, assembly, material handling or inspection.
Must be eliminated from the sequence of steps performed to complete a given
Manufacturing processes:-
Manufacturing
Process
Unit – 2
Manufacturing Operation
Costs of Manufacturing Operations.
can be defined as is application of physical and chemical processes to alter the
geometry, properties, and/or appearance of a given starting material to make parts
Manufacturing also includes the joining of multiple parts to make assembled products.
The processes that accomplish manufacturing involve a combination of machinery,
-
There are certain basic activities that must be carried out in a factory to convert raw materials into
Limiting our scope to a plant engaged in making discrete products, the factory activities are:
(4) Coordination and control.
Our viewpoint is that value is added through the totality of manufacturing operations performed on
Unnecessary operations, whether they are processing, assembly, material handling or inspection.
Must be eliminated from the sequence of steps performed to complete a given
Processing
Operation
Shaping
Operation
Solidification
Process
Particulate
Processing
Deformation
Process
Meterial
Removal
Process
Property -
Enhancing
Operation
Heat
Treatment
Surface
Processing
Operation
Cleaning
Surface
Teatment
Coating &
thin fim
depositionAssemmbly
Operation
Permanent
Joint
Temporary
Joint
P a g e | 9
and chemical processes to alter the
geometry, properties, and/or appearance of a given starting material to make partsor products;
Manufacturing also includes the joining of multiple parts to make assembled products.
The processes that accomplish manufacturing involve a combination of machinery, tools, power, and
There are certain basic activities that must be carried out in a factory to convert raw materials into
Limiting our scope to a plant engaged in making discrete products, the factory activities are:
s added through the totality of manufacturing operations performed on
Unnecessary operations, whether they are processing, assembly, material handling or inspection.
Must be eliminated from the sequence of steps performed to complete a given product.
Solidification
Process
Particulate
Processing
Deformation
Process
Meterial
Removal
Process
Treatment
Cleaning
Surface
Teatment
Coating &
thin fim
deposition

Processing Operations:-
• A processing operation transforms a work material from one state of completion to a more advanced
state that is closer to the final desired part or product.
• It adds value by changing the geometry, properties or appearance of the starting material.
• Material is fed into the process. Energy is applied by the machinery and tooling to transform the
material and the completed work part exits the process.
• Most production operations produce waste or scrap, either as a natural byproduct at the process.
• More than one processing operation is usually required to transform the starting material into final
form.
• An important objective in manufacturing is to reduce waste in either of these forms.
• In general, processing operations are performed on discrete work parts, but some processing
operations are also applicable to assembled items.
• For example painting a welded sheet metal car body.
• Three categories of processing operations are distinguished: (1) shaping operations, (2) property-
enhancing operations and (3) surface processing operations.
1. Shaping Operations:-
Shaping operations apply mechanical force or heat or other forms and combinations of energy to
effect a change in geometry of the work material.
• The classification have Four categories:
1. Solidification processes:
The important processes in this category arc casting and molding, in which the starting material is a
heated liquid or semi fluid, in which state it can be poured or otherwise forced to flow into a mold cavity
where it cools and solidifies, taking a solid shape that is the same as the cavity.
2. Particulate processing:
The starting material is a powder. The common technique involves pressing the powders in a die cavity
under high pressure to cause the powders to take the shape of the cavity. Then it is sintered heated to a
temperature below the melting point, which causes the individual particles to bond together.
3. Deformation processes:-
In most cases, the starting material is a ductile metal that is shaped by applying stresses that exceed the
metal's yield strength.Deformation processes include forging, extrusion and rolling. Also included in this
category are sheet metal processes such as drawing, forming; and bending.
4. Material removal processes:-
The starting material is solid, from which excess material is removed from the starting work piece so
that the resulting part has the desired geometry. Most important in this category are machining operations
such as milling, drilling and turning. Other material removal processes are known as nontraditional
processes because they do not use traditional cutting and grinding tools. Instead, they are based on lasers,
electron beams, chemical erosion, electric discharge, or electrochemical energy.
2. Property enhancing operations:-
• These are Operations designed to improve mechanical or physical properties of the work material.
• The most important property-enhancing operations involve heat treatments, which include various
temperature-induced strengthening and/or toughening processes for metals and glasses.
• Property-enhancing operations do not alter part shape, except unintentionally in some cases, for
example, warping of a metal part during heat treatment or shrinkage of a ceramic part during
sintering.

3. Surface processing operations:-
• It include: (1) cleaning, (2) surface treatments and (3) coating and thin film deposition processes.
• Cleaning includes both chemical and mechanical processes to remove dirt, oil, and other
contaminants from the surface.
• Surface treatments include mechanical working, such as shot peening and sand blasting, and physical
processes, like diffusion and ion implantation.
• Coating and thin film deposition processes apply a coating of material to the exterior surface of the
work part. Common coating processes include electro plating of aluminum, and organic coating.
Assembly Operation:-
• The second basic type of manufacturing operation is assembly, in which two or more separate parts
are joined to form a new entity.
• Components of the new entity are connected together either permanently or temporarily.
• Permanent joining processes include welding, brazing, soldering and adhesive bonding. They
combine parts by forming a joint that cannot be easily disconnected.
• A temporary joining process is method available to fasten two (or more) parts together in a joint that
can be conveniently disassembled.
• The uses of threaded fasteners (e.g. screws, bolts, nuts) are important traditional methods in this
category.
Product/Production Relationships:-
• Companies organize their manufacturing operations and production systems as a function of the
particular products they make.
• It is instructive to recognize that there are certain product parameters that are influential in
determining how the products are manufactured
• Let us consider four key parameters: (1) production quantity, (2) product variety, (3) complexity of
assembled products, and (4) complexity of individual parts.
Production Quantity and Product Variety:-
Let Q = production quantity and P = product variety. Thus we can discuss product variety and
production quantity relationships as PQ relationships. Q refers to the number of units of a given part or
product that are produced annually by a plant. Let us identify each part or product style by using the
subscript j. so that Qj = annual quantity of style j. Then let Qf = total quantity of all parts or products made
in the factory. Qj and Qf are related as follows:
Qf = ∑
P refers to the different product designs or types that are produced in a plant. Let us divide the
parameter P into two levels P1 & P2. P1 refers to the number of distinct product lines produced by the
factory (i.e. hard product variety) and P2 refers to the number of models in a product line (i.e. soft product
variety). Product variety P is given by,
P = ∑
Product and Part Complexity:-
For a Fabricated component, a possible measure of part complexity is the number of processing
steps required to produce it. For an assembled product, one possible indicator of product complexity is its
number of components - more the parts, more complex the product is. Let np = the number of parts per
product and we have processing complexity of each part as the number of operations required to make it;
let no = the number of operations or processing steps to make a part.

Let us develop some simple relationships among the parameters P, Q, np and n0 that indicate the
level of activity in a manufacturing plant. We will ignore the differences between Pl and P2 here.
Assuming that the products are all assembled and that all component parts used in these products are
made in the plant, then the total number of parts manufactured by the plant per year is given by:
npf = ∑
Where, npf = total number of parts made in the factory (pc/yr), Qj = annual quantity of product style j
(products/yr), and npj = number of parts in product j (pc/product).
Finally, if all parts are manufactured in the plant, then the total number of processing operations
performed by the plant is given by:
nof = ∑ ∑
Where, nof = total number of operation cycles performed in the factory (ops/yr), and nojk = number of
processing operations for each part k.
For Problem Purpose:-
We might try to simplify this to better conceptualize the situation by assuming that the number of product
designs P are produced in equal quantities Q, all products have the same number of components np, and
all components require an equal number of processing steps no. In this case, the total number of product
units produced by the factory is given by:
Qf = PQ
The total number of parts produced by the factory is given by:
npf = PQnp
And the total number of manufacturing operation cycles performed by the factory is given by,
nof = PQnpn0
Production concepts and Mathematical Models:-
1. Ideal Cycle Time, Tc:-
It is the time that one work unit spends being processed or assembled.
• Expressed as,
Tc= To + Th + Tt (in min/piece)
Or
Tc = Tr + [ To]max
Where,
Tr is time to transfer work units between stations each cycle (min/piece),
To is actual processing or assembly operation time(in min/piece)
Th is handling time (in min/piece)
Tt is tool handling time (in min/piece)
[To]max is operation time at the bottleneck station
• In above equation we use the max To because the longest service time establishes the pace of the
production line.
• The remaining stations with smaller service times will have to wait for the slowest station. The other
stations will be idle.

2. Actual average production time, Tp :-
It is the total time required to produce or assemble a work unit.
• Expressed as,
Tp = (in min/piece)
Where,
Tsu is setup time (in min/piece)
Q is batch quantity
Tc is Operation cycle time (in min/piece)
• For job shop production when quantity, Q = 1 ═> Tp = Tsu + Tc
• For quantity type mass production, Q becomes very large, (Tsu/Q) → 0 ═> Tp = Tc .
3. Ideal or mass production rate, Rc :-
It is the reciprocal of the Ideal Cycle Time.
• Expressed as,
Rc = (in piece/min)
Where,
Tc is Ideal Cycle Time (in min/piece)
4. Actual average production rate, Rp:-
It is the reciprocal of the actual average production time.
• Expressed as,
Rp = (in piece/min)
Where,
Tp is actual average production time (in min/piece)
5. Production Capacity, PC:-
Production capacity is defined as the maximum rate of output that a production facility
is able to produce under a given set of assumed operating conditions.
• The production facility usually refers to a plant or factory, and so the term plant capacity is often used
for this measure.
• The number of hours of plant operation pet week is a critical issue in defining plant capacity.
• Expressed as,
PC = nSwHshRp
Where,
PC = production capacity of the facility (output units/wk),
n= = number of work centers producing in the facility.
Sw = number of shifts per period (shift/wk),
Hsh = hr/5hift (hr), and
Rp = hourly production rate of each work center (output units/hr).

6. Utilization, U:-
Utilization refers to the amount of output of a production facility relative to its capacity.
• Utilization can be assessed for an entire plant, a single machine in the plant, or any other productive
resource (i.e., labor).
• Utilization is usually expressed as a percentage.
• Expressing this as an equation,
U =
Where,
U = utilization of the facility,
Q = actual quantity produced by the facility during a given time period (i.e. pc/wk),and
PC = production capacity for the same period (piece/wk.).
7. Availability, A:-
Availability is a common measure of reliability for equipment.
• It is especially appropriate for automated production equipment.
• Availability is defined using two other reliability terms, mean time between failure (MTBF) and mean
time to repair (MTTR).
• The MTBF indicates the average length of time the piece of equipment runs between breakdowns.
• The MTTR indicates the average time required to service the equipment and put it back into operation
when a breakdown occurs.
• Expressed as,
A =
8. Manufacturing Lead Time, MLT:-
We define manufacturing lead time as the total time required to process a given part or
product through the plant.
• Production usually consists of a series of individual processing and assembly operations.
• Between the operations are material handling, storage, inspections, and other nonproductive activities.
• Let us therefore divide the activities of production into two main categories, operations and
nonoperation elements.
• An operation is performed on a work unit when it is in the production machine.
• The nonoperation elements include handling, temporary storage, inspections, and other sources of
delay when the work unit is not in the machine.
• Expressed as,
MLT = no (Tsu + QTc +Tno) (in min)
Where,
MLT is average manufacturing lead time for a part or product (min).
n0 is the number of separate operations (machines).
9. Work-in-Process, WIP:-
Work in process (WIP) is the quantity of parts or products currently located in the
factory that are either being processed or are between processing operations.
• WIP is inventory that is in the state of being transformed from raw material to finished product.
• Work-in-process represents an investment by the firm, but one that cannot be turned into revenue
until all processing has been completed.
• Many manufacturing companies sustain major costs because work remains in-process in the factory
too long.

• An approximate measure of work-in-process can be obtained from the following,
WIP = !"# $
Where
WIP = work-in-process in the facility (pc),
A = availability,
U = utilization,
PC = production capacity of the facility (pc/wk),
MLT = manufacturing lead time, (wk),
Sw = number of shifts per week (shift/wk), and
Hsh = hours per shift (hr/shift).
Costs of Manufacturing Operations:-
Manufacturing cost can be classified as,
1. Fixed and Variable Costs
2. Direct Labor, Material, and Overhead cost
3. Cost of Equipment Usage
1. Fixed and Variable Costs:-
• A Fixed Cost (FC) is one that remains constant for any level of production output.
• Examples include the cost of the factory building and production equipment, insurance, and property taxes.
• All of the fixed costs can be expressed as annual amounts.
• Expenses such as insurance and property taxes occur naturally as annual costs.
• Capital investments such as building and equipment can be converted to their equivalent uniform
annual costs using interest rate factors.
• A Variable Cost (VR) is one that varies in proportion to the level of production output. As output
increases, variable cost increases.
• Examples include direct labor, raw materials, and electric power to operate the production equipment.
• The ideal concept of variable cost is that it is directly proportional to output level. When fixed cost
and variable cost are added,
• we have the following total cost equation:
TC = FC + VC (Q)
Where,
TC = total annual cost ($/yr),
FC = fixed annual cost ($/yr),
VC = variable cost ($/pc), and
Q = annual quantity produced (pc/yr)

Kiran Vijay Kumar
When comparing automated and manual production methods
the automated method is high relative to the manual
relative to the manual method, as pictured in Figure.
quantity range, while automation has an advantage for high quantities.
2. Direct Labor, Material, and
• The direct labor cost is the sum of the wages and benefits paid to the workers who operate the
production equipment and perform the processing and assembly tasks.
• The material cost is the cost of all raw materials used to make the product. In the case of a stamping
plant, the raw material consists of the steel sheet stock used to make stampings.
• For the rolling mill that made the sheet stock, the raw material is the iron ore or scra
which the sheet is rolled.
• In the case of an assembled product, materials include component parts manufactured by supplier
firms. Thus, the definition of "raw material" depends on the company.
• The final product of one company can be the raw
• Overhead costs are all of the other expenses associated with running the manufacturing firm.
• Overhead divides into two categories: (
(a) Factory overhead:
It consists of the costs of operating the factory other than direct labor and materials. Factory overhead
is treated as fixed cost, although some of the items in our list could be correlated with the output level of
the plant.
(b) Corporate overhead:
It is the cost of running the company other than its manufacturing activities.
Many companies operate more than one factory, and this is one of the reasons for dividing
overhead into factory and corporate categories. Overhead costs can be allocated according to a number of
different bases, including direct labor
When comparing automated and manual production methods, it is typical
the automated method is high relative to the manual method, and the variable cost of automation is low
relative to the manual method, as pictured in Figure. The manual method has a cost advantage in the low
automation has an advantage for high quantities.
Direct Labor, Material, and Overhead cost:-
is the sum of the wages and benefits paid to the workers who operate the
production equipment and perform the processing and assembly tasks.
is the cost of all raw materials used to make the product. In the case of a stamping
For the rolling mill that made the sheet stock, the raw material is the iron ore or scra
In the case of an assembled product, materials include component parts manufactured by supplier
Thus, the definition of "raw material" depends on the company.
The final product of one company can be the raw material for another company.
are all of the other expenses associated with running the manufacturing firm.
Overhead divides into two categories: (a) factory overhead and (b) corporate overhead.
consists of the costs of operating the factory other than direct labor and materials. Factory overhead
cost of running the company other than its manufacturing activities.
labor cost, material cost, direct labor hours, and space.
P a g e | 16
it is typical that the fixed cost of
iable cost of automation is low
he manual method has a cost advantage in the low
is the sum of the wages and benefits paid to the workers who operate the
is the cost of all raw materials used to make the product. In the case of a stamping
For the rolling mill that made the sheet stock, the raw material is the iron ore or scrap iron out of
In the case of an assembled product, materials include component parts manufactured by supplier
material for another company.
are all of the other expenses associated with running the manufacturing firm.
) corporate overhead.
consists of the costs of operating the factory other than direct labor and materials. Factory overhead
direct labor hours, and space.

Kiran Vijay Kumar
3. Cost of Equipment Usage
• The trouble with overhead rates as we have developed them here is that they are based on labor cost
alone.
• A machine operator who runs an old, small engine lathe whose book value is zero will be
the same overhead rate as an operator running a new CNC turning center.
• If differences in rates of different production machines are not recognized, manufacturing costs will
not be accurately measured by the overhead rate structure.
• To deal with this difficulty, it is appropriate to divide the cost of a worker running a machine into two
components: (1) direct labor and (2) machine
• These costs apply not to the entire factory operations, but to individual work centers.
• A work center is a production cell consisting of (1) One worker and one machine. (2) One worker and
several machines. (3) Several workers operating one machine or (4) several workers and machines.
• In any of these cases, it is advantageous to separate the labor expe
estimating total production costs.
Other Factory Operations:-
(1) Material handling (2) inspection and test and (3) coordination a
1. Material handling and storage:
• A means of moving and storing materials between processing and/or assembly operations is
common task in industries.
• In most manufacturing plants, materials spend more time being moved and stored than being
processed.
• In some cases, the majority of the
storing materials.
• It is important that this function be carried out as efficiently as possible.
Eugene Merchant, an advocate and spokesman for the machine tool industry for
materials in a typical metal machining batch factory or job shop
in processing.
The observations made by him are,
• About 95% of a part's time is spent either moving or waiting (temporary storage).
• Only 5% of its time is spent on the machine tool.
• Out of this 5%, less than 30% of the
taking place & the remaining 70% is required for loading and unloading,
positioning, tool position
Cost of Equipment Usage:-
The trouble with overhead rates as we have developed them here is that they are based on labor cost
A machine operator who runs an old, small engine lathe whose book value is zero will be
the same overhead rate as an operator running a new CNC turning center.
If differences in rates of different production machines are not recognized, manufacturing costs will
not be accurately measured by the overhead rate structure.
h this difficulty, it is appropriate to divide the cost of a worker running a machine into two
(1) direct labor and (2) machine.
These costs apply not to the entire factory operations, but to individual work centers.
tion cell consisting of (1) One worker and one machine. (2) One worker and
In any of these cases, it is advantageous to separate the labor expense from the ma
estimating total production costs.
handling (2) inspection and test and (3) coordination and control.
Material handling and storage:
A means of moving and storing materials between processing and/or assembly operations is
In most manufacturing plants, materials spend more time being moved and stored than being
cases, the majority of the labor cost in the factory is consumed in handling, moving, and
It is important that this function be carried out as efficiently as possible.
Eugene Merchant, an advocate and spokesman for the machine tool industry for
materials in a typical metal machining batch factory or job shopspend more time waiting or being moved than
The observations made by him are,
About 95% of a part's time is spent either moving or waiting (temporary storage).
5% of its time is spent on the machine tool.
f this 5%, less than 30% of the time on the machine is time during which actual cutting
he remaining 70% is required for loading and unloading,
oning, gaging, and other elements of nonprocessing time.
P a g e | 17
The trouble with overhead rates as we have developed them here is that they are based on labor cost
A machine operator who runs an old, small engine lathe whose book value is zero will be casted at
If differences in rates of different production machines are not recognized, manufacturing costs will
h this difficulty, it is appropriate to divide the cost of a worker running a machine into two
These costs apply not to the entire factory operations, but to individual work centers.
tion cell consisting of (1) One worker and one machine. (2) One worker and
nse from the machine expense in
nd control.
A means of moving and storing materials between processing and/or assembly operations is a
In most manufacturing plants, materials spend more time being moved and stored than being
labor cost in the factory is consumed in handling, moving, and
Eugene Merchant, an advocate and spokesman for the machine tool industry for many years, observed that
spend more time waiting or being moved than
About 95% of a part's time is spent either moving or waiting (temporary storage).
time on the machine is time during which actual cutting is
he remaining 70% is required for loading and unloading, part handling and
ng time.

2. Inspection and test:
• Inspection and test are quality control activities.
• The purpose of inspection is to determine whether the manufactured product meets the established
design standards and specifications.
• For example, inspection examines whether the actual dimensions of a mechanical part are within the
tolerances indicated on the engineering drawing for the part.
• Testing is generally concerned with the functional specifications of the final product rather than with
the Individual parts that go into the product.
• For example, final testing of the product ensures that it functions and operates in the manner specified
by the product designer.
3. Coordination and Control:
• Coordination and control in manufacturing includes both the regulation of individual processing and
assembly operations as well as the management of plant level activities.
• Control at the process level involves the achievement of certain performance objectives by properly
manipulating the inputs and other parameters of the process.
• Control at the plant level includes effective use of labor, maintenance of the equipment, moving
materials in the factory, controlling inventory, shipping products of good quality on schedule, and
keeping plant operating costs at a minimum possible level.
• The manufacturing control function at the plant level represents the major point of intersection
between the physical operations in the factory and the information processing activities that occur in
production.
WIP Ratio:-
It is the ratio of the Work In Process to the Total No. of Machines.
• Expressed as,
WIP ratio =
%&
'
=
(
!"# $
)
( * +)
Where,
no = no. of machines processing or assembly.
nm = total no. of machines in the factory.
TIP Ratio:-
It refers to Time In Process ratio. It gives the measure of total time the product lies in the
plant relative to the time it actually undergoes processing.
• Expressed as,
TIP Ratio =
,

WORKED EXAMPLES
E.g. 1 Suppose a company has designed a new product line and is planning to build a new plant to
manufacture this product line. The new line consists of 100 different product types, and for each product
type the company wants to produce 10,000 units annually. The products average 1000 components each,
and the average number of processing steps required for each component is 10. All parts will be made in
the factory. Each processing step takes an average of 1 min. Determine: (a) How many products. (b) How
many parts, and (c) How many production operations will be required each year, and (d) How many
workers will be needed for the plant, if it operates one shift for 250 day/yr?
Solution:
(a) The total number of units to be produced by the factory is given by,
Q = PQ = 100 X 10,000 = 1,000,000 products annually.
(b) The total number of parts produced is:
npf = PQnp= 1,000,000 X 1000 = 1,000,000,000 parts annually.
(c) The number of distinct production operations is:
nof = PQnpn0 = 1,000,000,000 X 10 = 10,000,000,000operations.
(d) To find the number of workers required. First consider the total time to perform these operations. If
each operation takes 1 min (1/60 hr),
Total time = 10,000,000.000 X 1/60 = 166,666,667 hr
If each worker works 2000 hr/yr (40 hr/wk x 50 wk/yr), then the total number of workers required is:
w =
-..,...,..0
1222
= 83,333 workers.
E. g. 2 An average of 20 new orders is started through a certain factory each month. On average, an order
consists of 50 parts to be processed through 10 machines in the factory. The operation time per machine
for each part = 15 min. The nonoperation time per order at each machine averages 8 hr, and the required
setup time per order = 4 hr. There are 25 machines in the factory, 80% of which are operational at any
time (the other 20%are in repair or maintenance). The plant operates 160 hr/month. (a) What is the
manufacturing lead time for an average order? (b) Production Rate (c) What is the plant capacity (on
monthly basis) (d) What is the utilization of the plant according to the definition given in the text? (e)
Determine the average level of work-in-process (number of parts- in-process) in the plant (f) WIP Ratio
(g) TIP Ratio.
Solution:
(a) Manufacturing Lead Time:
MLT = no (Tsu + QTc +Tno) = 10[4 + (50 ×
-4
.2
) + 8] = 245hrs
(b) Production Rate:
Rp =
-
56
=
-
7
89:;<8=
<
>
=
-
7
?; @ × .B@
@
>
= 3.03parts/hour
(c) Plant Capacity:
PC =
CD
C
(SwHsh) Rp =
14
-2
(160) 3.03 = 1212parts/month
(d) Plant utilization:
U=
E
FG
=
12×42
-1-1
= 0.825 or 82.5%
(e) Work In Process:
WIP =
!"# $
=
2.H ×2.H14 -1-1 1I4
-.2
= 1224.87parts
(f) WIP Ratio:
[WIP]ratio =
JKF
=
-11I.H0
14
= 48.99 : 1

(g) TIP Ratio:
[TIP]ratio =
LM5
5=
=
1I4
-2×2.14
= 98 : 1
E. g. 3 A certain part is routed through six machines in a batch production plant. The setup and operation
time' for each machine are given in the table below. The batch size is 100 and the average nonoperation
time per machine is 12 hr. Determine: (a) manufacturing lead time and (b ) production rate for operation .
Machine Setup time (hrs) Operation time (min)
1. 4 5
2. 2 3.5
3. 8 10
4. 3 1.9
5. 3 4.1
6. 4 2.5
Solution:
(a) Manufacturing Lead Time:
MLT = nm (Tsu + QTc +Tno)
1. For first machine:
[MLT]1 = 1[4 +{100×
4
.2
} + 12] = 24.33hrs
2. For second machine:
[MLT]2 = 1[2 +{100×
O.4
.2
} + 12] = 19.83hrs
3. For third machine:
[MLT]3 = 1[8+{100×
-2
.2
} + 12] = 36.66hrs
4. For fourth machine:
[MLT]4 = 1[3 +{100×
-.P
.2
} + 12] = 18.16hrs
5. For fifth machine:
[MLT]5 = 1[3 +{100×
I.-
.2
} + 12] = 21.83hrs
6. For sixth machine:
[MLT]6 = 1[4 +{100×
1.4
.2
} + 12] = 20.16hrs
(b) Production Rate:
Rp =
-
56
=
-
7
89:;<8=
<
>
=
E
Q59: E5=R
1. For first machine:
[Rp]1 =
-22
7I -22S
@
T
U>
= 8.10part/hrs
2. For second machine:
[Rp]2 =
-22
71 -22S
V.@
T
U>
= 12.76part/hrs
3. For third machine:
[Rp]3 =
-22
7H -22S
W
T
U>
= 4.05part/hrs

4. For fourth machine:
[Rp]4 =
-22
7O -22S
W.X
T
U>
= 16.21part/hrs
5. For fifth machine:
[Rp]5 =
-22
7O -22S
?.W
T
U>
= 10.16part/hrs
6. For sixth machine:
[Rp]6 =
-22
7I -22S
B.@
T
U>
= 12.24part/hrs
E.g. 4 The following data are given: direct labor rate $10.00/hr; applicable factoryoverhead rate on labor
= 60%; capital investment in machine = $100,000; service life of the machine = 8 yr; rate of return =
20%; salvage value in 8 yr = 0; and applicable factory overhead rate on machine = 50%. The work center
will be operated one 8-hr shift, 250 day/yr. determine the appropriate hourly rate for the work center.
Solution:
Labor cost per hour = CL (1+ FOHRL) = $10.00(1 + 0.60) = $16.00/hr
Now the uniform annual cost can be determined:
UAC = IC S
Y - Y Z
- Y Z -
U = 100,000 S
2.1 - 2.1 [
- 2.1 [ -
U = $26,060.00/yr =
1.2.2.22
H×142
= $13.03/hr
The factory overhead rate = Cm (1 + FOHRm) = $13.03(1 + 0.50) = $19.55/hr
Total cost rate is, Co = Labor cost per hour + Factory overhead rate
Co = 16.00 + 19.55 = $35.55/hr.
E. g. 5 Suppose that all costs have been compiled for a certain manufacturing firm for last year. The
summary is shown in the table below. The company operates two different manufacturing plants plus a
corporate headquarters. Determine: (a) the factory overhead rate for each plant and (b) the corporate
overhead rate. These rates will be used by the firm in the following year.
Solution:
(a) A separate factory overhead rate must be determined for each plant.
FOHR =
#
]
For plant l,
FOHR1 =
1,222,222
H22,222
= 2.5 or 250%
For plant 2,
FOHR2 =
-,-22,222
I22,222
= 2.75 or 275%

(b) The corporate overhead rate is based on the total labor cost at both plants
COHR =
#
]
COHR =
0,122,222
-,122,222
= 6.0 or 600%
E.g. 6 A customer orders of 50 parts are to be processed through plant 1 of the previous example. Raw
materials and tooling are supplied by the customer. The total time for processing the parts (including
setup and other direct labor) is 100 hr. Direct labor cost is $l0.00/hr. The factory overhead rate is 250%
and the corporate overhead rate is 600%. Compute the cost of the job.
Solution:
(a) The direct labor cost for the job is = (100 hr) ($l0.00/hr) = $1000.
(b) The allocated factory overhead charge, at 250% of direct labor is,
FOHR =
#
]
2.5000 =
^_`G
-222
FOHC = ($1000) (2.50) = $2500.
(c) The allocated corporate overhead charge, at 600% of direct labor, is
COHR =
#
]
6.0000 =
^_`G
-222
COHC = ($1000) (6.00) = $6000.

UNIT - 6
Quality Control Systems
Sylabus:-
Traditional and Modern Quality Control Methods, Taguchi Methods in Quality Engineering, Introduction
to SQC Tools.
Introduction:-
In the 1980s. The issue of quality control (QC) became a national concern in the United States.
The Japanese automobile industry had demonstrated that high-quality cars could he produced at relatively
low cost. This combination of high quality and low cost was a contradiction of conventional wisdom in
the United States, where it was always believed that superior quality is achieved only at a premium price.
Cars were perhaps the most visible product area where the Japanese excelled.In the United States, quality
control has traditionally been concerned with detecting poor quality in manufactured products and taking
corrective action to eliminate it. The term quality assurance suggests this broader scope of activities that
are implemented in an organization to ensure that a product (or service) will satisfy (or even surpass) the
requirements of the customer.
Quality:-
The dictionary" defines quality as "the degree of excellence which a thing possesses," or "the
feature that makes something what it is"-its characteristic elements and attributes.
Definitions,
Conformance to requirements, fitness for use and is customer satisfaction.
- By Crosby & Juran
The totality of features and characteristics of a product or service that bear on its ability to satisfy given
need.
- By American Society for Quality Control
(ASQC)
Traditional Quality Control:-
Traditional QC focused on inspection. In many factories, the only department responsible for QC was
the inspection department. Much attention was given to sampling and statistical methods. The term
statistical quality control (SQC) was used to describe these methods.
• In SQC, inferences (or inspection) are made about the quality of a population of manufactured items
(e.g. components, subassemblies, products] based on a sample taken from the population.
• The sample consists of one or more of the items drawn at random from the population & each item in
the sample are inspected for certain quality characteristics of interest.
• Two statistical sampling methods dominate the field of SQC: (1) control charts and (2) acceptance
sampling.
(1) Control charts:-
• A control chart is a graphical technique in which statistics on one or more process parameters of
interest are plotted over time to determine if the process is behaving normally or abnormally.
• The chart has a central line that indicates the value of the process mean under normal operation.
• Abnormal process behavior is identified when the process parameter strays significantly from the
process mean. Control charts are widely used in statistical process control.

(2) Acceptance sampling:-
• Acceptance sampling is a statistical technique in which a sample drawn from a batch of parts is
inspected, and a decision is made whether to accept or reject the batch on the basis of the quality of
the sample.
• Acceptance sampling is traditionally used for various purposes: (1) receiving inspection of raw
materials from a vendor, (2) deciding whether or not to ship a batch of parts or products to a
customer, and (3) inspection of parts between steps in the manufacturing sequence.
• In statistical sampling, which includes both control charts and acceptance sampling, there are risks
that defects will slip through the inspection process, resulting in defective products being delivered to
the customer.
• With the growing demand for 100% good quality, the use of sampling procedures has declined over
the past several decades in favor of 100% automated inspection.
The management principles and characteristics of traditional QC included the following,
• Customers are external to the organization: - The sales and marketing department is responsible
for relations with customers.
• The company is organized by functional departments: - There is little appreciation of the
interdependence of the departments in the larger enterprise, the loyalty and viewpoint of each
department tends to be centered on itself rather than on the corporation. There tend, to exist an
adversarial relationship between management and labor.
• Quality is the responsibility of the inspection department: - The quality function in the
organization emphasizes inspection and conformance to specifications, its objective is simple:
elimination of defects.
• Inspection follows production: - The objectives of production (to ship product) often clash with the
objective, of QC (to ship only good product).
• Knowledge of SQC techniques resides only in the minds of the QC experts in the organization,
Workers' responsibilities are limited, Managers and technical staff do all the planning. Workers
follow instructions.
• There is an emphasis on maintaining the status quo.
Modern Quality Control:-
High quality is achieved by a combination of good management and good technology. The two
factors must be integrated to achieve an effective quality system in an organization. The management
factor is captured in the frequently used term-total quality management: The technology factor includes
traditional statistical tools combined with modern measurement and inspection technologies.
• Total quality management (TOM) denotes a management approach that pursues three main
objectives: (1) achieving customer satisfaction, (2) continuous improvement, and (3) encouraging
involvement of the entire work force.
• These objectives contrast sharply with the practices of traditional management regarding the QC
function.

Factors which reflect the modern view of quality management with the traditional approach to quality
management:
• Quality is focused on customer satisfaction. Products are designed and manufactured with this quality
focus. Juran's definition, "quality is customer satisfaction," defines the requirement for any product.
The technical specifications, the product features must be established to achieve customer satisfaction.
The product must be manufactured free of deficiencies.
• The quality goals of an organization are driven by top management, which determines the overall
attitude toward quality in a company. The quality goals of a company are not established in
manufacturing; they are defined at the highest levels of the organization.
Does the company want to simply meet specifications set by the customer, or does it want to make products that
go beyond the technical specification? Does it want to be known us the lowest price supplier of the highest
quality producer in its industry?
Answers to these kinds of questions define the quality goals of the company. These must be set
by top management. Through the goals they define, the actions they take, and the examples they set,
top management determines the overall attitude toward quality in the company.
• Quality control is pervasive in the organization, not just the job of the inspection department. It
extends from the top of the organization through all levels. There is recognition of the important
influence that product design has on product quality. Decisions made in product design directly impact
the quality that can be achieved in manufacturing.
• In manufacturing, the viewpoint is that inspecting the product after it is made is not good enough.
Quality must be built into the product. Production workers must inspect their own work and not rely
on the inspection department to find their mistakes.
• Quality is the job of everyone in the organization. It even extends outside the immediate organization
to the suppliers. One of the tenets of a modem QC system is to develop close relationships with
suppliers.
• High product quality is a process of continuous improvement. It is a never-ending chase to design
better products and then to manufacture them better.
Quality Control Technologies:-
Good technology also plays an important role in achieving high quality.
Modern technologies in QC include:
(1) Quality engineering
(2) Quality function deployment.
Other technologies in modern QC include,
(3) Statistical process control,
(4) 100% automated inspection,
(5) On-line inspection,
(6) Coordinate measurement machines for dimensional measurement and
(7) Non-contact sensors such as machine vision for inspection.
Taguchi Methods In Quality Engineering:-
• The areas of quality engineering and Total Quality Management overlap to a significant degree, since
implementation of good quality engineering is strongly dependent on management support and
direction.
• The field of quality engineering owes much to G. Taguchi, who has had an important influence on its
development, especially in the design area-both product design and process design.
• In this section, we review some of the Taguchi methods: (1) off-line and on-line quality control, (2)
robust design, and (3) loss function.

Kiran Vijay Kumar
(1) Off-line and on-line quality control
Taguchi believes that the quality system must be distributed throughout the organization,
divided quality system into two basic functions: off
Off line quality control:-
This function is concerned with design issues, both product and process design. It is applicable
prior to production and shipment of
precedes on-line control.
• Off-line quality control consists of two stages:
• The product design stage is concerned with the development of a new pr
existing product. The goals in product design are to properly identify customer needs and to design a
product that meets those needs but can also be manufactured consistently and economically.
• The process design stage is concern
standards, documenting procedures, and developing dear and workable specifications for
manufacturing. It is a manufacturing engineering function.
A three-step approach applicable to both of thes
parameter design, and (c) tolerance design
(a) System design:-
• System design involves the application of engineering knowledge and analysis to develop a prototype
design that will meet customer needs.
• In the product design stage, system design refers to the final product configuration and features,
including starting materials, components and subassemblies. For example, in the design of a new car,
system design includes the size of the car, its styling,
target it for a certain market segment.
• In process design, system design means selecting the most appropriate manufacturing methods. For
example, it means selecting a forging operation rather than casting to
Obviously, the product and process design stages overlap because product design determines the
manufacturing process to a great degree. Also, the quality of the product is impacted significantly by
decisions made during product design.
(b) Parameter design:-
• Parameter design is concerned with determining optimal parameter settings for the product and
process.
• In parameter design, the nominal values for the product or process parameters are specified.
• Examples of parameters in product design include the dimensions of components in an assembly or
the resistance of an electronic component.
line quality control: -
Taguchi believes that the quality system must be distributed throughout the organization,
divided quality system into two basic functions: off-line and on-line quality control.
prior to production and shipment of the product. In the sequence of the two functions off
line quality control consists of two stages: (1) product design and (2) process design
stage is concerned with the development of a new product or a new model of an
stage is concerned with specifying the processes and equipment, setting work
manufacturing. It is a manufacturing engineering function.
step approach applicable to both of these design stages is outlined:
parameter design, and (c) tolerance design.
involves the application of engineering knowledge and analysis to develop a prototype
design that will meet customer needs.
In the product design stage, system design refers to the final product configuration and features,
system design includes the size of the car, its styling, engine size and power, and other features that
target it for a certain market segment.
In process design, system design means selecting the most appropriate manufacturing methods. For
example, it means selecting a forging operation rather than casting to produce a certain component.
uct design.
is concerned with determining optimal parameter settings for the product and
In parameter design, the nominal values for the product or process parameters are specified.
Examples of parameters in product design include the dimensions of components in an assembly or
the resistance of an electronic component.
P a g e | 26
Taguchi believes that the quality system must be distributed throughout the organization, so he
line quality control.
the product. In the sequence of the two functions off-line control
(1) product design and (2) process design.
oduct or a new model of an
ed with specifying the processes and equipment, setting work
e design stages is outlined: (a) system design, (b)
involves the application of engineering knowledge and analysis to develop a prototype
In the product design stage, system design refers to the final product configuration and features,
engine size and power, and other features that
In process design, system design means selecting the most appropriate manufacturing methods. For
produce a certain component.
is concerned with determining optimal parameter settings for the product and
In parameter design, the nominal values for the product or process parameters are specified.
Examples of parameters in product design include the dimensions of components in an assembly or

• Examples of parameters in process design include the speed and feed in a machining operation or the
furnace temperature in a sintering process.
• The nominal value is the ideal or target value that the product or process designer would like the
parameter to be set at for optimum performance.
• It is in the parameter design stage that a robust design is achieved.
(c) Tolerance design:-
• In tolerance design, the objective is to specify appropriate tolerances about the nominal values
established in parameter design.
• A reality that must be addressed in manufacturing is that the nominal value of the product or process
parameter cannot be achieved without some inherent variation.
• A tolerance is the allowable variation that is permitted about the nominal value.
• The tolerance design phase attempts to achieve a balance between setting wide tolerances to facilitate
manufacture and minimizing tolerances to optimize product performance.
• Tolerance design is strongly influenced by the Taguchi loss function.
On-line quality control:-
This function of quality assurance is concerned with production operations and customer
relations. In production, Taguchi classifies three approaches to quality control:
1. Process diagnosis and adjustment. In this approach, the process is measured periodically and
adjustments are made to move parameter of interest toward nominal values.
2. Process prediction and correction. This refers to the measurement of process parameter, at periodic
intervals so that trends can be projected. If projections indicate deviations from target values,
corrective process adjustments are made.
3. Process measurement and action. This involves inspection of all units (100%) to detect deficiencies
that will be reworked or scrapped. Since this approach occurs after the unit is already made. It is less
desirable than the other two forms of control.
The Taguchi on-line approach includes customer relations, which consists of two elements.
• First, there is the traditional customer service that deals with repairs, replacements, and complaints.
• And second, there is a feedback system in which information on failures, complaints. and related data
are communicated back to the relevant departments in the organization for correction.
For example, customer complaints of frequent failures of a certain component are communicated
back to the product design department so that the components design can be improved.
(2) Robust design:-
• The objective of parameter design in Taguchi's off-line/on-line quality control is to set specifications
on product and process parameters to create a design that resists failure or reduced performance in the
face of variations.
• Taguchi call, the variations noise factors. A noise factor is a source of variation that is impossible or
difficult to control and that affects the functional characteristics of the product.
Three types of noise factors can be distinguished:
1. Unit-to-unit noise factors: - These are inherent random variations in the process and product caused
by variability in raw materials, machinery, and human participation. They are associated with a
production process that is in statistical control.
2. Internal noise factors: - These sources of variation are internal to the product or process. They
include: (1) time-dependent factors, such as wear of mechanical components, spoilage of raw
materials, and fatigue of metal parts; and (2) operational errors such as improper settings on the
product or machine tool.
3. External noise factors: - An external noise factor is a source of variation that is external to the
product or process, such as outside temperature, humidity, raw material supply, and input voltage.

Kiran Vijay Kumar
• A robust design is one in which the function and performance of the product or process are relatively
insensitive to variations in any of these noise factors
• In product design, robustness means that the product can maintain consistent performance with
minimal disturbance due to variations in uncontrollable factors in its operating environment.
• In process design, robustness means that the process continues t
effect from uncontrollable variations in its operating environment.
(3) Taguchi loss function:-
• The Taguchi loss function is a useful concept in tolerance design. Taguchi defines quality as "the loss
a product costs society from the time the product is released for shipment".
• Loss includes costs to operate, failure to function, maintenance and repair costs, customer
dissatisfaction, injuries caused by poor design, and similar costs.
• Some of these losses are difficult to qu
• Defective products (or their components) those are detected, repaired, reworked, or scrapped before
shipments are not considered part of this loss.
• Instead, any expense to the company resulting fro
manufacturing cost rather than a quality Joss.
Loss occurs when a product's functional characteristic differ from
When the dimension of a component deviates from its nominal value,
adversely affected. No matter how small the deviation, there is some loss in function. The loss increases
at an accelerating rate as the deviation grows, according to Taguchi. If we let
x = the quality characteristic of interest and
N = its nominal value,
Then the loss function will be a U
curve:
Where, L( x) = loss function;
is one in which the function and performance of the product or process are relatively
insensitive to variations in any of these noise factors.
In product design, robustness means that the product can maintain consistent performance with
process design, robustness means that the process continues to produce good product with minimal
effect from uncontrollable variations in its operating environment.
The Taguchi loss function is a useful concept in tolerance design. Taguchi defines quality as "the loss
y from the time the product is released for shipment".
Loss includes costs to operate, failure to function, maintenance and repair costs, customer
dissatisfaction, injuries caused by poor design, and similar costs.
Some of these losses are difficult to quantify in monetary terms but they are nevertheless real.
Defective products (or their components) those are detected, repaired, reworked, or scrapped before
shipments are not considered part of this loss.
Instead, any expense to the company resulting from scrap or rework of defective product is a
manufacturing cost rather than a quality Joss.
Loss occurs when a product's functional characteristic differ from its nominal or target value.
When the dimension of a component deviates from its nominal value, the component's function is
at an accelerating rate as the deviation grows, according to Taguchi. If we let
= the quality characteristic of interest and
Then the loss function will be a U-shaped curve as in. Taguchi uses a quadratic equation to describe this
L(x) = k(x - N)2
= loss function; k = constant of proportionality
P a g e | 28
is one in which the function and performance of the product or process are relatively
In product design, robustness means that the product can maintain consistent performance with
o produce good product with minimal
The Taguchi loss function is a useful concept in tolerance design. Taguchi defines quality as "the loss
Loss includes costs to operate, failure to function, maintenance and repair costs, customer
antify in monetary terms but they are nevertheless real.
Defective products (or their components) those are detected, repaired, reworked, or scrapped before
m scrap or rework of defective product is a
its nominal or target value.
the component's function is
shaped curve as in. Taguchi uses a quadratic equation to describe this

Kiran Vijay Kumar
Statistical Process Control (SPC)
Statistical process control
process. SPC methods are applicable in both manufacturing and nonmanufacturing situations, but most of
the applications are in manufacturing. The overall objectives of SPC are to (1) improv
process output, (2) reduce process variability and achieve process stability, and (3) solve processing
problems.
There are seven principal methods or tools used in SPC; these tools are sometimes referred to as
the "magnificent seven".
1. Control charts
2. Histograms
3. Pareto charts
4. Check sheet
5. Defect concentration diagrams
6. Scatter diagrams
7. Cause and effect diagrams
1. Control charts:-
Control charts are the most widely used method in SPC. The underlying principle of contro
charts is that the variations in any process divide into two types, as previously described: (1) random
variations, which are the only variations present if the process is in statistical control; and (2) assignable
variations, which indicate a departure
The purpose of a control chart is to identify when the process has gone out of statistical
control, thus signaling the need for some corrective action to be taken.
• A control chart is a graphical technique in which statistics computed from measured values of a
certain process characteristic are plotted over time to determine if the process remains in statistical
control.
• The general form of the control chart is illustrated in Figure
• The chart consists of three horizontal lines that remain constant over time: a center, a lower control
limit (L CL), and an upper control limit (VCL).
• The center is usually set at the nominal design value & the VCL and LCL are generally set at ±3
standard deviations of the sample means.
• It is highly unlikely that a sample drawn from the process lies outside the VCL or LCL while the
process is in statistical control.
• Therefore, if it happens that a sample value does
the process is out of control.
• An investigation is undertaken to determine the reason for the out
appropriate corrective action is taken to eliminate the condition.
(SPC):-
Statistical process control (SPC) involves the use of various methods to measure and analyze a
the applications are in manufacturing. The overall objectives of SPC are to (1) improv
5. Defect concentration diagrams
7. Cause and effect diagrams
Control charts are the most widely used method in SPC. The underlying principle of contro
variations, which indicate a departure from statistical control.
control, thus signaling the need for some corrective action to be taken.
is a graphical technique in which statistics computed from measured values of a
The general form of the control chart is illustrated in Figure.
The chart consists of three horizontal lines that remain constant over time: a center, a lower control
limit (L CL), and an upper control limit (VCL).
The center is usually set at the nominal design value & the VCL and LCL are generally set at ±3
ard deviations of the sample means.
It is highly unlikely that a sample drawn from the process lies outside the VCL or LCL while the
process is in statistical control.
Therefore, if it happens that a sample value doesfall outside these limits, it is inte
the process is out of control.
An investigation is undertaken to determine the reason for the out-of
appropriate corrective action is taken to eliminate the condition.
P a g e | 29
(SPC) involves the use of various methods to measure and analyze a
the applications are in manufacturing. The overall objectives of SPC are to (1) improve the quality of the
Control charts are the most widely used method in SPC. The underlying principle of control
is a graphical technique in which statistics computed from measured values of a
The chart consists of three horizontal lines that remain constant over time: a center, a lower control
The center is usually set at the nominal design value & the VCL and LCL are generally set at ±3
It is highly unlikely that a sample drawn from the process lies outside the VCL or LCL while the
fall outside these limits, it is interpreted to mean that
of-control condition and

Kiran Vijay Kumar
There are two basic types of control charts:
attributes.
(a) Control charts for variables:
• Control charts for variables require a measurement of the quality characteristic of interest.
• A process that is out of statistical control manifests thi
(1) process mean and/or (2) process variability.
• Corresponding to these possibilities, there are two principal types of control charts for variables:
chart and (2) R chart.
• The a̅ chart (call it "x bar chart") is used to plot the average measured value of a certain quality
characteristic for each of a series of samples taken from the production process. It indicates how the
process means changes over time.
• The R chart plots the range of each
whether if changes over time.
(b) Control charts for attributes:
• Control charts for attributes monitor the number of defects present in the sample or the fraction defect
rate as the planed statistic.
• Examples of these kinds of attributes include number of defects per automobile, fraction of
nonconforming parts in a sample, existence or absence of flash in a plastic molding, and number of flaws
in a roll of sheet steel.
• Inspection procedures that involve GO/NO
whether a part is good or bad.
• The two principal types of control charts for attributes are:
defect rate in successive samples; and (2) the
nonconformities per sample.
2. Histograms:-
• The histogram is a basic graphical tool in statistics.
• After the control chart, it is probably the most important member of the SPC tool kit.
• A histogram is a statistical graph consisting of bars representing different values or ranges of values,
in which the length of each bar is proportional to the frequency or relative frequency of the value or
range as shown in Figure.
• It is a graphical display of the
There are two basic types of control charts: (a) control charts for variables and (b) control charts for
Control charts for variables:-
Control charts for variables require a measurement of the quality characteristic of interest.
A process that is out of statistical control manifests this condition in the form of significant changes in:
(2) process variability.
Corresponding to these possibilities, there are two principal types of control charts for variables:
bar chart") is used to plot the average measured value of a certain quality
process means changes over time.
plots the range of each sample, thus monitoring the variability of the process and indicating
Control charts for attributes:-
Control charts for attributes monitor the number of defects present in the sample or the fraction defect
Examples of these kinds of attributes include number of defects per automobile, fraction of
ple, existence or absence of flash in a plastic molding, and number of flaws
Inspection procedures that involve GO/NO-GO gaging are included in this group since they determine
s of control charts for attributes are: (1) the p chart,
defect rate in successive samples; and (2) the c chart, which plots the number of defects, flaws or other
The histogram is a basic graphical tool in statistics.
After the control chart, it is probably the most important member of the SPC tool kit.
is a statistical graph consisting of bars representing different values or ranges of values,
the length of each bar is proportional to the frequency or relative frequency of the value or
It is a graphical display of the frequency distribution of the numerical data.
P a g e | 30
(a) control charts for variables and (b) control charts for
Control charts for variables require a measurement of the quality characteristic of interest.
s condition in the form of significant changes in:
Corresponding to these possibilities, there are two principal types of control charts for variables: (1) cd
bar chart") is used to plot the average measured value of a certain quality
sample, thus monitoring the variability of the process and indicating
Control charts for attributes monitor the number of defects present in the sample or the fraction defect
Examples of these kinds of attributes include number of defects per automobile, fraction of
ple, existence or absence of flash in a plastic molding, and number of flaws
are included in this group since they determine
, which plots the fraction
which plots the number of defects, flaws or other
After the control chart, it is probably the most important member of the SPC tool kit.
is a statistical graph consisting of bars representing different values or ranges of values,
the length of each bar is proportional to the frequency or relative frequency of the value or

Automation in manufacturing five unit vtu, mechanical engineering notes pdf download

Automation in manufacturing five unit vtu, mechanical engineering notes pdf download

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Automation in manufacturing five unit vtu, mechanical engineering notes pdf download

Similar to Automation in manufacturing five unit vtu, mechanical engineering notes pdf download (20)

Recently uploaded

Recently uploaded (20)

Automation in manufacturing five unit vtu, mechanical engineering notes pdf download