Introduction
•Manufacturing
is a collection of interrelated
activities
that includes product design and
documentation,
material selection, planning,
production,
quality assurance, management,
and
marketing of goods.
•The
fundamental goal of manufacturing is to
use
these activities to convert raw materials
into
finished goods on a profitable basis.
Introduction
•The
lessons learned in the 1970s and
1980s
resulted in changes across U.S.
industries.
•As
a result of improved manufacturing
practices,
U.S. industries reclaimed a
leadership
role by the mid-1990s and
will
continue that leadership role in the
next
millennium
.
Three
Stages of Manufacturing
Retreat:
1.Emergence
of small electronic consumer
goods
during the Vietnam War.
2.
Japanese practice of copying successful
U.S.
products.
3.
Offshore companies and rapid product
development
in the late 1980s.
External
Challenges Result from:
Niche market entrants, traditional
competition, suppliers, partnerships and
alliances, customers, global economy, cost
of money, and the Internet
Internal
Challenges Result in:
A
plan, process, or manufacturing
strategy
that forces congruence
between
the corporate objectives and
marketing
goals and production
capability
of a company
Product
Life Cycle Curve
Sales
Introduction Growth Maturity Decline/Commodity
Changing
the Product Life Cycle:
•Kaizen or improvement of current model
•Leaping or developing a new product
similar to the initial product
•Innovation or using genuine new product
invention to identify follow-up merchandise
Order-winning
Versus Order-
Qualifying
Criteria:
Market
share is increased when the
order-winning
criteria are understood
and
executed better than the
competition
Meeting
the Internal Challenges:
•Analyze every product and agree on the order-
qualifying and order-winning criteria for the
product at the current stage in it’s life
•Project the order-winning criteria for the future
stages in every product’s life
•Determine the fit between the required process
capability and the existing capability in
manufacturing
•Change/modify the marketing goals, or upgrade
the manufacturing processes and infrastructure to
force internal consistency
World-class
Order-winning Criteria:
•Setup time or time required to get a machine
ready for production
•Quality or % of defective parts produced or %
of total sales
•Manufacturing space ratio or a measure of how
efficiently manufacturing space is utilized
•Inventory: Velocity/residence time
World-class
Order-winning Criteria:
•Flexibility or a measure of the number of different
parts that can be produced on the same machine
•Distance or total linear feet of a part’s travel
through the plant from raw material in receiving
to finished products in shipping
•Uptime or % of time a machine is producing to
specifications compared to total time that
production can be scheduled
The Solution IS:
Computer-Integrated- Manufacturing
(CIM)
CIM has Different Definitions for
Different Users
i.
Shop communications
ii.
Recurring processes
iii.
Non-recurring processes
iv.
Engineering/manufacturing
communication
v.
Other users
vi.
Improving communication through
CIM
Computer
Integrated Manufacturing
Refers
to the technology, tool or method used to improve
entirely
the design and manufacturing process and increase
productivity,
to help people and machines to communicate. It
includes
CAD (Computer-Aided Design), CAM (Computer-
Aided
Manufacturing), CAPP (Computer-Aided Process
Planning,
CNC (Computer Numerical Control Machine tools),
DNC
(Direct Numerical Control Machine tools), FMS (Flexible
Machining
Systems), ASRS (Automated Storage and Retrieval
Systems),
AGV (Automated Guided Vehicles), use of robotics
and
automated conveyance, computerized scheduling and
production
control, and a business system integrated by a
common
database. (Houston Cole Library)
Computer
Integrated Manufacturing
Is
the process of automating various functions in a
manufacturing
company (business, engineering,
and
production) by integrating the work through
computer
networks and common databases. CIM
is
a critical element in the competitive strategy of
global
manufacturing firms because it lowers costs,
improves
delivery times and improves quality.
(Amatrol)
Computer-integrated
Manufacturing
Defined:
•CIM is the integration of the total manufacturing
enterprise through the use of integrated systems and
data communications coupled with new managerial
philosophies that improve organizational and
personal efficiency.
SME New Manufacturing Enterprise Wheel
What
is CIM?
•C + I + M
•C = Computer
i.
Enabling tool
ii.
Information flow
iii.
Information
management
What
is CIM?
•I = Integrated
i.
Integration vs. interfacing
ii.
Shared information
iii.
Shared functionality
•M = Manufacturing
i.
Production control
ii.
Production scheduling
iii.
Process design
iv.
Product design
v.
Manufacturing enterprise
Design
Man
Prod
Eng
Sales
& Mark
Sample CIM Sub-Systems
CIM
DATABASE
INS
ROB
AGV
ANA
CAE
MAR
CNC
CUS
BOM
EST
CAM
CAP
P
PUR
CAD
DOC
MRP
The Centrality of Manufacturing
in a Market-Oriented Economy
Production System Triad
Mkt
Des
Pro
Eng
Man
Production
Strategy Classification:
•Relative to customer lead time
•Relative to manufacturing lead time
•Manufacturing lead time and customer lead
time must be matched
Production
Strategies Used to Match
Customer
and Manufacturing Lead Times:
•Engineer to order (ETO)
•Make to order (MTO)
•Assemble to order (ATO)
•Make to stock (MTS)
Groover Chapter
1: Introduction
Production System Defined
A collection of people, equipment, and procedures
organized to accomplish the manufacturing
operations of a company
Two categories:
•Facilities – the factory and equipment in the facility and
the way the facility is organized (plant layout)
•Manufacturing support systems – the procedures used by
a company to manage production and to solve technical
and logistics problems in ordering materials, moving
work through the factory, and ensuring that products
meet quality standards
The Production System
Production System Facilities
Facilities include the factory, production machines and tooling,
material handling equipment, inspection equipment, and
computer systems that control the manufacturing operations
•Plant layout – the way the equipment is physically arranged
in the factory
•Manufacturing systems – logical groupings of equipment
and workers in the factory
–Production line
–Stand-alone workstation and worker
Manufacturing Systems
Three categories in terms of the human participation in
the processes performed by the manufacturing
system:
1.Manual work system - a worker performing one or more
tasks without the aid of powered tools, but sometimes
using hand tools
2.Worker-machine system - a worker operating powered
equipment
3.Automated system - a process performed by a machine
without direct participation of a human
Manufacturing Support Systems
Manufacturing support involves a sequence of
activities that consists of four functions:
1.Business functions - sales and marketing,
order entry, cost accounting, customer billing.
2.Product design - research and development,
design engineering, prototype shop.
3.Manufacturing planning - process planning,
production planning, MRP, capacity planning.
4.Manufacturing control - shop floor control,
inventory control, quality control.
Sequence of Information-Processing
Activities in a Manufacturing Firm
Automation in Production Systems
Two categories of automation in the
production system:
1.Automation of manufacturing systems in the
factory.
2.Computerization of the manufacturing support
systems.
•The two categories overlap because
manufacturing support systems are
connected to the factory manufacturing
systems.
–Computer-Integrated Manufacturing (CIM).
Computer Integrated Manufacturing
Automated Manufacturing Systems
Examples:
•Automated machine tools
•Transfer lines
•Automated assembly systems
•Industrial robots that perform processing or
assembly operations
•Automated material handling and storage systems
to integrate manufacturing operations
•Automatic inspection systems for quality control
Automated Manufacturing Systems
Three basic types:
1.Fixed automation
2.Programmable automation
3.Flexible automation
Fixed Automation
A manufacturing system in which the sequence of
processing (or assembly) operations is fixed by the
equipment configuration.
Typical features:
•Suited to high production quantities.
•High initial investment for custom-engineered
equipment.
•High production rates.
•Relatively inflexible in accommodating product variety.
Programmable Automation
A manufacturing system designed with the capability to change
the sequence of operations to accommodate different product
configurations.
Typical features:
•High investment in general purpose equipment.
•Lower production rates than fixed automation.
•Flexibility to deal with variations and changes in product
configuration.
•Most suitable for batch production.
•Physical setup and part program must be changed between
jobs (batches).
Flexible Automation
An extension of programmable automation in which
the system is capable of changing over from one job
to the next with no lost time between jobs.
Typical features:
•High investment for custom-engineered system.
•Continuous production of variable mixes of products.
•Medium production rates.
•Flexibility to deal with soft product variety.
Product Variety and Production
Quantity for Three Automation Types
Computerized Manufacturing
Support Systems
Objectives of automating the manufacturing support
systems:
•To reduce the manual and clerical effort in product
design, manufacturing planning and control, and
the business functions.
•Integrates computer-aided design (CAD) and
computer-aided manufacturing (CAM) in
CAD/CAM.
•CIM includes CAD/CAM and the business
functions of the firm.
Reasons for Automating
1.Increase labor productivity
2.Reduce labor cost
3.Mitigate the effects of labor shortages
4.Reduce or remove routine manual and
clerical tasks
5.Improve worker safety
6.Improve product quality
7.Reduce manufacturing lead time
8.Accomplish what cannot be done manually
9.Avoid the high cost of not automating
Manual Labor in Production Systems
Is there a place for manual labor in the modern
production system?
–Answer: YES
•Two aspects:
1.Manual labor in factory operations
2.Labor in manufacturing support systems
Manual Labor in Factory Operations
The long term trend is toward greater use of
automated systems to substitute for manual labor.
•When is manual labor justified?
–Some countries have very low labor rates and
automation cannot be justified.
–Task is technologically too difficult to automate
–Short product life cycle.
–Customized product requires human flexibility.
–To cope with ups and downs in demand.
–To reduce risk of new product failure.
Labor in Manufacturing Support
Systems
•Product designers who bring creativity to the design
task.
•Manufacturing engineers who:
–Design the production equipment and tooling.
–And plan the production methods and routings.
•Equipment maintenance.
•Programming and computer operation.
•Engineering project work.
•Plant management.
Automation Principles and Strategies
1.The USA Principle
2.Ten Strategies for Automation and Process
Improvement
3.Automation Migration Strategy
U.S.A Principle
1.Understand the existing process:
–Input/output analysis
–Value chain analysis
–Charting techniques and mathematical modeling
2.Simplify the process:
–Reduce unnecessary steps and moves
3.Automate the process:
–Ten strategies for automation and production systems
–Automation migration strategy
Ten Strategies for Automation and
Process Improvement
1.Specialization of operations
2.Combined operations
3.Simultaneous operations
4.Integration of operations
5.Increased flexibility
6.Improved material handling and storage
7.On-line inspection
8.Process control and optimization
9.Plant operations control
10.Computer-integrated manufacturing
Automation Migration Strategy
For Introduction of New Products
1.Phase 1 – Manual production:
–Single-station manned cells working independently.
–Advantages: quick to set up, low-cost tooling.
2.Phase 2 – Automated production:
–Single-station automated cells operating
independently.
–As demand grows and automation can be justified.
3.Phase 3 – Automated integrated production:
–Multi-station system with serial operations and
automated transfer of work units between stations.
Manufacturing:
Technological Definition
Application of physical and chemical processes to alter
the geometry, properties, and/or appearance of a given
starting material to make parts or products.
•Manufacturing also includes the joining of multiple
parts to make assembled products.
•Accomplished by a combination of machinery, tools,
power, and manual labor.
•Almost always carried out as a sequence of operations.
Manufacturing:
Technological Definition
Manufacturing: Economic Definition
Transformation of materials into items of greater
value by means of one or more processing and/or
assembly operations.
•Manufacturing adds value to the material
•Examples:
–Converting iron ore to steel adds value
–Transforming sand into glass adds value
–Refining petroleum into plastic adds value
Manufacturing: Economic Definition
Classification of Industries
1.Primary industries – cultivate and exploit natural
resources
–Examples: agriculture, mining
2.Secondary industries – convert output of primary
industries into products
–Examples: manufacturing, power generation,
construction
3.Tertiary industries – service sector
–Examples: banking, education, government, legal
services, retail trade, transportation
Manufacturing Operations
•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
Other Factory Operations
•Material handling and storage
•Inspection and testing
•Coordination and control
Material Handling and Storage
•Material transport:
–Vehicles, e.g., forklift trucks, AGVs, monorails
–Conveyors
–Hoists and cranes
•Storage systems
•Automatic identification and data capture: (AIDC)
–Bar codes
–RFID
–Other AIDC
Time Spent by a Part in a Typical
Metal Machining Batch Factory
Inspection and Testing
Inspection – examination of the product and its
components to determine whether they conform to
design specifications:
–Inspection for variables – measuring
–Inspection for attributes – gaging
Testing – observing the product (or part, material,
subassembly) during actual operation or under
conditions that might occur during operation.
Coordination and Control
•Regulation of the individual processing and
assembly operations:
–Process control
–Quality control
•Management of plant level activities:
–Production planning and control
–Quality control
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
Production Quantity
Number of units of a given part or product
produced annually by the plant.
•Three quantity ranges:
1.Low production – 1 to 100 units
2.Medium production – 100 to 10,000 units
3.High production – 10,000 to millions of units
Product Variety
Refers to the number of different product or part
designs or types produced in the plant.
•Inverse relationship between production quantity
and product variety in factory operations.
•Product variety is more complicated than a number:
–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
Low Production Quantity
Job shop – makes low quantities of specialized
and customized products.
•Includes 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
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
High Production
1.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
2.Flow line production – Multiple
workstations arranged in sequence
–Product requires multiple processing or
assembly steps
–Product layout is most common
Production Performance Metrics
•Cycle time T
c
•Production rate R
p
•Availability A
•Production capacity PC
•Utilization U
•Manufacturing lead time MLT
•Work-in-progress WIP
Operation Cycle Time
Typical cycle time for a production operation:
T
c = T
o + T
h + T
th
where
•T
c = cycle time
•T
o = processing time for the operation
•T
h = handling time (e.g., loading and unloading the
production machine), and
•T
th = tool handling time (e.g., time to change tools)
Production Rate
Batch production: batch time T
b
= T
su
+ QT
c
Average production time per work unit T
p = T
b/Q
Production rate R
p
= 1/T
p
Job shop production:
For Q = 1, T
p = T
su + T
c
For quantity high production:
R
p
= R
c
= 60/T
p
since T
su
/Q 0
For flow line production
T
c = T
r + Max T
o and R
c = 60/T
c
Availability
Availability = proportion uptime of the
equipment
Availability:
where MTBF = mean time between failures, and
MTTR = mean time to repair
MTBF MTTR
A
MTBF
Availability
Key: MTBF = mean time between failures, MTTR = mean time to repair.
Production Capacity
Defined as the maximum rate of output that a production
facility (or production line, or group of machines) is able
to produce under a given set of operating conditions
•When referring to a plant or factory, the term plant
capacity is used
•Assumed operating conditions refer to:
–Number of shifts per day
–Number of hours per shift
–Employment levels
Plant Capacity
Simplest case is quantity production in which there
are:
•n production machines in the plant and they all
produce the same part or product.
•Each machine produces at the same rate R
p.
PC = n H
pc R
p
where PC = plant capacity for a defined period (e.g. a
week),
H
pc = number of hours in the period being used to
measure plant capacity, hr/period
How to Adjust Plant Capacity
•Over the short term:
–Increase or decrease number workers w
–Increase or decrease shifts per week
–Increase or decrease hours per shift (e.g., overtime)
•Over the intermediate and long terms:
–Increase number of machines n
–Increase production rate R
p
by methods
improvements and/or processing technology
Utilization
Defined as the proportion of time that a
productive resource (e.g., a production
machine) is used relative to the time available
under the definition of plant capacity
Manufacturing Lead Time
Defined as the total time required to process a given part or product
through the plant, including any time for delays, material
handling, queues before machines, etc.
MLT = n
o (T
su + QT
c + T
no) where
•MLT = manufacturing lead time
•n
o = number of operations
•T
su = setup time
•Q = batch quantity
•T
c cycle time per part, and
•T
no
= non-operation time
Work-In-Process
Defined as the quantity of parts or products currently
located in the factory that either are being processed
or are between processing operations.
WIP = R
pph
(MLT)
where
•WIP = work-in-process, pc
•R
pph
= hourly plant production rate, pc/hr;
•MLT = manufacturing lead time, hr
Manufacturing Costs
•Two major categories of manufacturing costs:
1.Fixed costs - remain constant for any output level.
2.Variable costs - vary in proportion to production output level.
•Adding fixed and variable costs:
TC = FC + VC(Q)
where
TC = total costs
FC = fixed costs (e.g., building, equipment, taxes)
VC = variable costs (e.g., labor, materials, utilities)
Q = output level.
Manufacturing Costs
•Alternative classification of manufacturing
costs:
1.Direct labor - wages and benefits paid to workers
2.Materials - costs of raw materials
3.Overhead - all of the other expenses associated
with running the manufacturing firm
•Factory overhead
•Corporate overhead
Typical Manufacturing Costs (J Black)
Cost of Equipment Usage
Hourly cost of worker-machine system:
C
o = C
L(1 + FOHR
L) + C
m(1 + FOHR
m)
where
•C
o = hourly rate, $/hr;
•C
L = labor rate, $/hr;
•FOHR
L = labor factory overhead rate,
•C
m
= machine rate, $/hr;
•FOHR
m = machine factory overhead rate
Cost of a Manufactured Part
Defined as the sum of the production cost, material cost,
and tooling cost
Cost for each unit operation = C
oiT
pi + C
ti, where C
oi =
cost rate to perform unit operation i,
T
pi = production time for operation i,
C
ti = tooling cost for operation i
Total unit cost is the sum of the unit costs plus material
cost
C
pc = C
m + (C
oiT
pi + C
ti
), where
C
pc = cost per piece,
C
m
= cost of starting material
Chapter 4: Introduction to Automation
Sections:
1.Basic Elements of an Automated System
2.Advanced Automation Functions
3.Levels of Automation
Automation Defined
Automation is the technology by which a process or
procedure is accomplished without human
assistance.
•Basic elements of an automated system:
1.Power - to accomplish the process and operate the
automated system
2.Program of instructions – to direct the process
3.Control system – to actuate the instructions
Power to Accomplish the
Automated Process
•Power for the process
–To drive the process itself
–To load and unload the work unit
–Transport between operations
•Power for automation
–Controller unit
–Power to actuate the control signals
–Data acquisition and information processing
Program of Instructions
Set of commands that specify the sequence of steps in
the work cycle and the details of each step.
•Example: NC part program.
•During each step, there are one or more activities
involving changes in one or more process parameters.
–Examples:
•Temperature setting of a furnace
•Axis position in a positioning system
•Motor on or off
Decision-Making in a
Programmed Work Cycle
•Following are examples of automated work
cycles in which decision making is required:
–Operator interaction:
•Automated teller machine
–Different part or product styles processed by the
system:
•Robot welding cycle for two-door vs. four door car
models
–Variations in the starting work units:
•Additional machining pass for oversized sand casting
Control System – Two Types
1.Closed-loop (feedback) control system – a system
in which the output variable is compared with an
input parameter, and any difference between the
two is used to drive the output into agreement with
the input
2.Open-loop control system – operates without the
feedback loop
–Simpler and less expensive
–Risk that the actuator will not have the intended effect
(a) Feedback Control System and
(b) Open-Loop Control System
(a)
(b)
Positioning System Using
Feedback Control
A one-axis position control system consisting of a
leadscrew driven by a dc servomotor and using
an optical encoder as the feedback sensor
When to Use an
Open-Loop Control System
•Actions performed by the control system are
simple.
•Actuating function is very reliable.
•Any reaction forces opposing the actuation are
small enough as to have no effect on the
actuation.
•If these conditions do not apply, then a closed-
loop control system should be used.
Advanced Automation Functions
1.Safety monitoring
2.Maintenance and repair diagnostics
3.Error detection and recovery
Safety Monitoring
Use of sensors to track the system's operation and
identify conditions that are unsafe or potentially unsafe
•Reasons for safety monitoring
–To protect workers and equipment
•Possible responses to hazards:
–Complete stoppage of the system
–Sound an alarm
–Reduce operating speed of process
–Take corrective action to recover from the safety violation
Maintenance and Repair Diagnostics
•Status monitoring:
–Monitors and records status of key sensors and
parameters during system operation
•Failure diagnostics:
–Invoked when a malfunction occurs
–Purpose: analyze recorded values so the cause of the
malfunction can be identified
•Recommendation of repair procedure:
–Provides recommended procedure for the repair crew
to effect repairs
Error Detection and Recovery
1.Error detection – functions:
–Use the system’s available sensors to determine when a
deviation or malfunction has occurred
–Correctly interpret the sensor signal
–Classify the error
2.Error recovery – possible strategies:
–Make adjustments at end of work cycle
–Make adjustments during current work cycle
–Stop the process to invoke corrective action
–Stop the process and call for help
Levels of Automation
1.Device level – actuators, sensors, and other
hardware components to form individual control
loops for the next level.
2.Machine level – CNC machine tools and similar
production equipment, industrial robots, material
handling equipment.
3.Cell or system level – manufacturing cell or system.
4.Plant level – factory or production systems level.
5.Enterprise level – corporate information system.