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Part I Overview of Manufacturing
Chapter 2 Manufacturing Operations
Manufacturingcan be defined as the application of physical
and chemical processes to alter the geometry, properties,
and appearance of a given starting material to make parts
or products; manufacturing also includes the joining ofmultiple parts to make assembled products.
The processes that accomplish manufacturing involve a
combination ofmachinery, tools, power, and manual labor.
Manufacturingis carried out as a sequence of operations.Each successive operation brings the material closer to the
desired final state.
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Chapter 2 Manufacturing OperationsDefinition of manufacturing as a technological process
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Chapter 2 Manufacturing OperationsDefinition of manufacturing as an economic process
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Manufacturing industries
Industry consists of enterprises and organizations that produce and/or
supply goods and/or service (primary, secondary and tertiary industries).
Primary industries:They cultivate and exploit natural resources, such as agriculture and mining.
Agriculture, forestry, fishing, livestock, quarrying, mining, petroleum
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Manufacturing industries
Secondary industries:
They convert the outputs of the primary industries into products.
Manufacturing is the principal activity in this category, but second
industries also include construction and power utilities.
Aerospace, apparel, automotive, basic metals, beverages, building
materials, chemicals, computers, construction, consumer appliances,
electronics, equipment, fabricated metals, food processing, glass,
ceramics, heavy machinery, paper, petroleum refining, pharmaceuticals,
plastics (shaping), power utilities, publishing, textiles, tire and rubber,
wood and furniture
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Manufacturing industries
Tertiary industries:
They constitute the service sector of economy.
Banking, communications, education, entertainment, financialservices, government, health and medical, hotels, information,
insurance, legal services, real estate, repair and maintenance,
restaurants, retail trade, tourism, transportation, wholesale trade
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTSInternational Standard Industrial Classification (ISIC) Codes
ISIC Code
Food, beverages, tobacco 31
Textiles, apparel, leather and fur products 32
Wood and wood products, cork 33 Paper, printing, publishing, bookbinding 34
Chemicals, coal, petroleum, & their products 35
Ceramics, glass, mineral products 36
Basic metals, e.g., steel, aluminum 37
Fabricated products, e.g., cars, machines, etc. 38
Other products, e.g., jewelry, toys 39
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Continuous production
It occurs when the production equipment is used exclusively for the
given product, and the output of the product is uninterrupted.
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Batch production
It occurs when the materials are processed in finite amounts or
quantities. The finite amounts or quantity of material is called a batch.
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Manufactured products
Manufacturing industries with their discrete products
(ISIC codes 38 and 39)
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2.1 MANUFACTURING INDUSTRIES AND PRODUCTS
Final products
Final products can be divided into two major classes:
Consumer goods Purchased directly by consumers such as cars,
computers, TVs, tires, toys, etc.
Capital goods Purchased by other companies to produce goods andsupply services, e.g., commercial aircraft, mainframe
computers, machine tools, railroad equipment and
construction machinery.
There are also companies in industry whose business is primarily toproduce materials, components and supplies for the companies that
make the final products, e.g., sheet steel, bar stocks, metal stampings,
machined parts, plastic moulding, cutting tools, lubricant, etc.
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2.2 MANUFACTURING OPERATIONS
Basic activities
There are certain basic activities that must be carried
out in a factory to convert raw materials into finished
products.
For discrete products:1. Processing and assembly operations
2. Material handling
3. Inspection and testing
4. Coordination and control
The first three activities are considered as physical
activities.
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2.2.1 Processing and Assembly Operations
Manufacturing processes can be divided into two basic types:
(1) Processing operations
A processing operation transforms a work material from
one state of completion to a more advanced state that iscloser to the final desired part or product.
(2) Assembly operations
An assembly operation joins two or more components tocreate a new entity, which is called an assembly or
subassembly.
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Classification of manufacturing processes
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2.2.1 Processing and Assembly Operations
Processing operations
Shaping operations
1. Solidification processes
2. Particulate processing
3. Deformation processes
4. Material removal processes
Property-enhancing operations (heat treatments)
Surface processing operations
Cleaning and surface treatments
Coating and thin-film deposition
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2.2.1 Processing and Assembly Operations
Processing operations Shaping operationsFour categories in terms of the state of the starting
material:
Solidification processes
Casting, moulding Particulate processing
Powder metallurgy, sintering, hot isostatic pressing
Deformation processesForging, extrusion, rolling, drawing, forming, bending
Material removal processesMachining such as turning, drilling, milling, grinding, nontraditional
processes based on lasers, electron beams, chemical erosion, electric
discharge, electrochemical energy
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2.2.1 Processing and Assembly OperationsProcessing operations Property-enhancing operations
These operations are designed to improve mechanical or
physical properties of the work material Heat treatments.
Sintering of powered metals and ceramics is also a heat
treatment.These operations do not alter part shape except
unintentionally in some cases, e.g., warping of a metal part
during heat treatment or shrinkage of a ceramic part during
sintering.
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2.2.1 Processing and Assembly OperationsProcessing operations Surface processing operations
Cleaning
Chemical and mechanical processes to remove dirt, oil and
other contaminants
Surface treatmentMechanical working such as shot peening and sand blasting,
and physical process such as diffusion and ion implantation
Coating and thin film deposition
Electroplating, anodizing, thermal spray, slurry/sintering,physical vapor deposition, chemical vapor deposition
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2.2.1 Processing and Assembly Operations
Assembly operations
Joining processes
Welding
Brazing and soldering
Adhesive bonding
Mechanical assembly
Threaded fasteners (e.g., bolts and nuts, screws)
Rivets
Interference fits (e.g., press fitting, shrink fits)
Other
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2.2.2 Other Factory Operations
Material handling and storage
Moving and storing materials between processing and/or
assembly operations
Inspection and testingQuality control activities, e.g., dimension tolerance
Coordination and control
Regulation of individual processing and assembly operations
and management of plant level activities
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2.2.2 Other Factory Operations
Time spent in material handling
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2.2.2 Other Factory Operations
Inspection and testing
Inspection Examination of the product and its
components to determine whether they
conform to design specifications
Inspection for variables Measuring
Inspection of attributes Gaging
Testing Observing the product (or part, material,
subassembly) during actual operation orunder conditions that might occur during
operation
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2.2.2 Other Factory Operations
Coordination and control
Regulation of individual processing and assembly
operations
Process control
Quality control Management of plant level activities
Production planning and control
Overall quality control
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2.3 PRODUCTION FACILITIES
A manufacturing company attempts to organize its
facilities in the most efficient way to serve the particular
mission of the plant.
Certain types of plants are recognized as the most
appropriate way to organize for a given type of
manufacturing.
The most appropriate type depends on:
Types of products made
Production quantity
Product variety
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2.3 PRODUCTION FACILITIES
Product variety
Number of different product or part designs or types
produced in the plant
Inverse relationship between production quantity and
product variety in factory operations
The higher the product variety, the lower the production quantity.
Product variety classification:
Hard product variety
Products differ greatly, few common components in an
assembly Soft product variety
Small differences between products, many common
components in an assembly
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2.3.1 Low Production Quantity
Job shop Make low quantities of specialized and
customized products (1 to 100 unit/year)
Also include production of components for these products
Products are typically complex (e.g., specialized machinery,
prototypes, space capsules)
Equipment is general purpose.
Plant layouts:
Fixed position
Process layout
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2.3.1 Low Production Quantity
Fixed-position layout
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2.3.1 Low Production Quantity
Process layout
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2.3.2 Medium Production Quantities
1. Batch production A batch of a given product is
produced, and then the facility is changed over to
produce another product
Changeover takes time Setup time Typical layout Process layout
Hard product variety
2. Cellular manufacturing A mixture of products is made
without significant changeover time between products Typical layout Cellular layout
Soft product variety
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2.3.2 Medium Production Quantities
Cellular layout
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2.3.3 High Production
Quantity production Equipment is dedicated to the
manufacture of one product.
Standard machines tooled for high production (e.g.,
stamping presses, molding machines) Typical layout Process layout
Flow line production Multiple workstations arranged in
sequence
Product requires multiple processing or assembly steps.
Product layout is most common.
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2.3.3 High Production
Product layout
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Relationships between plant layout and type of
production facility
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2.4.1 Production Quantity and Product Variety
Q = Production quantity, the number of units of a given part
or product that are produced annually by a plant
P= Product variety
j= Identifier of each part or product styleQj= Annual quantity of stylej
Total number of product units =
Product variety
Hard product variety = Differences between products
Soft product variety = Differences between models of
products
P
j
jf QQ1
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2.4.1 Production Quantity and Product Variety
P1 = Number of distinct product lines produced by the plant
Represents hard product variety
P2 = Number of models in a product line
Represents soft product variety
The total number of product models is given by
where the subscriptjidentifies the product line,j= 1, 2, , P1.
1
1
2
P
j
jPP
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Example 2.1
Product Lines and Product Models
A company specializes in home entertainment products. It
produces only TVs and audio systems. In its TV line it offers
15 different models, and in its audio line it offers 5 models.
What is the totality of product models?
Solution
2.4.1 Production Quantity and Product Variety
20515
1
1
2
P
j
jPP
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2.4.2 Product and Part Complexity
Qualitative and quantitative aspects
Product and part complexity
For assembled products, the more parts, the more
complex the product is.
For manufactured components, a possible measure
of part complexity is the number of processing steps
required to produce the component.
Product complexity np = Number of parts in product
Part complexity no = Number of operations per part
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2.4.2 Product and Part Complexity
Typical number of processing operations required to fabricate various parts
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2.4.2 Product and Part Complexity
Production plants distinguished by np
and no
values
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2.4.2 Product and Part Complexity
The total number of products made annually in a plant is the
sum of the quantities of individual products. The total number
of parts manufactured by the plant per year is
where Pis the total number of different part or product styles;
Qj is the annual quantity of product stylej; npj is the number
of parts in productj.
pj
P
j
jpf nQn
1
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2.4.2 Product and Part Complexity
The total number of processing operations performed by the
plant is
where nojk is the number of processing operations for each
part k, assumed over the number of parts in productj, npj.
The parameternofprovides a numerical value for the total
activity level in the plant.
p jn
kojkpj
P
jjof nnQn 11
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2.4.2 Product and Part Complexity
pjn
k
ojkpj
P
j
jof nnQn11
1153
2
3
3
3
4352
5
2
2210
Product 1 (Quantity = 10) and Product 2 (Quantity = 5)
Product 1 2 parts (Part 1 2 operations, Part 2 5 operations)
Product 2 3 parts (Part 1 4 operations, Part 2 3 operations,
Part 3 2 operations)
operations
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2.4.2 Product and Part Complexity
Simplified for purposes of conceptualization:
Assume that the number of products Pare in equal quantities Q ,
all products have the same number of components np, and all
components require an equal number of processing steps no.
Total number of product units Qf= PQ
Total number of parts produced npf= PQnp
Total number of operations nof= PQnpno
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2.4.2 Product and Part Complexity
Example 2.2
A Production System Problem
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 differentproduct styles, and for each product type the company wants to produce 10000
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 plant. Each processing step takes an average of I min. Determine
(a) how many products, (b) how many parts, and (c) how many productionoperations will be required each year, and (d) how many workers will be needed
for the plant, if it operates one eight-hour shift for 250 day/yr and one worker
works on one machine?
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2.4.2 Product and Part Complexity
Solution(a) The total number of units to be produced by the plant is
Q = PQ = 100 10000 = 106 products annually
(b) The total number of parts produced is
npf= PQnp = 106
1000 = 109
parts annually(c) The number of distinct production operations is
nof= PQnpno = 109 10 = 1010 operations
(d) The total time to be used to perform these operations is
H= 1010 1/60 = 1.67 108 hr
If each worker works 2000 hr/yr (250 day/yr 8 hr/yr), then the total
number of workers required is
workers833332000
1067.18
w
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2.4.3 Limitations and Capabilities of a Manufacturing Plant
Manufacturing capability - Technical and physical
limitations of a manufacturing firm and each of its plants
Three dimensions of manufacturing capability:
1. Technological processing capability - Available set ofmanufacturing processes
2. Physical size and weight of product
3. Production capacity (plant capacity) - Production quantity
that can be made in a given time. Plant capacity is often
measured in terms of output units such as annual tons of
steel produced by a steel mill, or number of cars produced
by a final assembly plant.
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2.5 LEAN PRODUCTION
Definition: Operating the factory with the minimum possible
resources and yet maximizing the amount of work
accomplished
Resources include workers, equipment, time, space,materials
Complete products in the minimum possible time and
achieve a very high quality level to completely satisfy the
customer In short, lean production means doing more with less, and
doing it better.
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2.5 LEAN PRODUCTION
Manufacturing activities can be divided into three
categories:
Value-adding activities
Contribute value to the work unit, including processing and assembly
operations that alter the part or product in a way towards the need of the
customer
Auxiliary activities
Support the value-adding activities but do not themselves contribute value
to the part or product Wasteful activities
Do not add value nor do they support the value adding activities. If not
performed, there would be no adverse effects on the product.
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2.5 LEAN PRODUCTION
The programs associated with lean production are
the following:
Just-in-time delivery of parts
Worker involvement Continuous improvement
Reduced setup times
Stop the process when something is wrong
Error prevention
Total productive maintenance
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