production systems engineering production systems design phd eng agnieszka stachowiak lectures
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Production systems engineeringProduction systems design
PhD Eng Agnieszka StachowiakLectures
Production systems engineeringProduction system design
1. Production system – definition, model of production system
2. Division of production systems3. Tool management4. Renovation economy (maintenance, reviews,
repairs)5. Transportation6. Warehouse management7. Quality control
Enterprise
• The task of the enterprise is economic decision-making and optimization of objectives in all aspects (Durlik I. 1993): marketing, product development, purchase
of the necessary elements for the production,
processing organization (final product and service),
sales and customer service.
Company’s operation comprise following areas:• Production and technical area,• Organizational and administrative area,• The financial and economic area,• Legal area.
The company is composed of one or more production systems
Implementation can be :• Long-term• Short-term• Repetitive• Non repetitive
Production systems
• Production system – is deliberately designed and organized arrangement of material, energy and information used by humans and aimed to manufacture certain products (goods or services) in order to meet the needs of consumer
(Durlik I. 1993).
Production system consists of five basic elements:1. Input vector (data input),2. Output vector (data output), 3. Processing (input into output),4. Management system,5. Feedback
Value-Added-Process
The difference between the cost of inputs and the value or price of outputs.
Inputs
Land
Labor
Capital
Transformation/
Conversion
process
Outputs
Goods
Services
Control
Feedback
FeedbackFeedback
Value added
10
The production
system may be very complex
M1M1
R1 R2 R3
M1
M1M1
M2
M1M1
M3
M1M1
M4
M1M1
M5
M1 M2
M3
M5
M4
M7
M6
Offices
V
M1M1
M6
Operations Machines Resources
Raw Materials
11
Many design issues arise for the production system
Business Design
Product Design Schedule Design
Process DesignControl System
Design
Facility Design
Distribution Design
Service System Design
Production System Design
Machine Design
Manufacturing system – production system
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The process is described by its operations
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A
3
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Alternative process designs with the same operations
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1R3
R2
R1
Parallel Processing Production Line
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The process model admits greater detail
Sequence/Volume of Demand
Operation/Process/Machine
Transportation/Facility Layout/Material Handling
Inspection/Quality Control
Delays/Production Control/System Design
Storage/Inventory Control/Production Control
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3
212
14
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9
47
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10
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1
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Numerical parameters describe components
• Operation
• Transportation
• Inspection
O1 P1 M1 O1 (operation time, loss, M1)+ +
Material Handling+
(time, distance, cost)
O1
I1
Quality Control (Standard Time, Proportion removed )
17
Operations Involving Waiting
• Delays
• Storage
System Design + Production Control
(Mean Delay, Standard Deviation)
System Design + Inventory Control
(Safety Stock, Value, Turnover)
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The models must describe multiple products
Product A Product B Product C
VA
2
1
R2
7
3
8
A
5
4
R1
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2
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R3
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VB
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R1 R2 R3
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A
A
VC
Operation of Production Systems and Production Planning Involve
• Planning and execution of the activities that use workers, energy, information, and equipment to convert raw materials into finished products
• Delivering products with the desired functions, aesthetics, and quality to the customers at right time and with minimum cost
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Production and Inventory Control- Introduction (20)
High Profitability
LowCosts
Low UnitCosts
High Throughput
Less Variability
High Utilization
LowInventory
QualityProduct
HighSales
Many products
Fast Response
MoreVariability
High Inventory
LowUtilization
ShortCycle Times
High CustomerService
Production Objectives
Classification of production systems
1. Flexible Manufacturing systems2. Quick Response Manufacturing3. Computer Integrated Manufacturing4. Concurrent Engineering5. Mass Customization6. Lean Manufacturing, Toyota Production System7. Canon Production System8. Electrolux Manufacturing System9. Kanban System10. CONVIP System
What Is A Flexible Manufacturing System?
Flexible Manufacturing System:
- “A system that consists of numerous programmable machine tools connected by an automated material handling system” (2)
History of FMS
• FMS first proposed in England in 1960’s
• “System 24” operates 24 hours a day
• Automation is main purpose in beginning
Components of Flexible Manufacturing Systems
• NC• CNC• DNC -• Robotics• AGV-• ASRS
• Automated Inspection
• Cells and Centers(automatic guided vehicles)
(automated storage and retrieval systems)
(Direct numerical control)
(Computer numerical control)
(Numerical control)
Flexible Automation
• Ability to adapt to engineering changes in parts
• Increase in number of similar parts produced on the system
• Ability to accommodate routing changes
• Ability to rapidly change production set up
Integration of FMS
FMS
Manufacturing Technology CIM Robotics
Making FMS Work
– By implementing the components of robotics, manufacturing technology and computer integrated manufacturing in a correct order one can achieve a successful Flexible Manufacturing System
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• Using automated machines (DNC) & materials handling equipment together
• Often connected to centralized computer
• Also called automated work cell
Computer
Machine 1
Machine 2
Robotor AGV
Auto ToolChg.
Auto ToolChg.
Production TechnologyFlexible Manufacturing Systems (FMS)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
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Production TechnologyFMS - Pros & Cons
• Advantages– Faster, lower-cost changes from one part to another– Lower direct labor costs– Reduced inventory– Consistent, and perhaps better quality
• Disadvantages– Limited ability to adapt to product or product mix changes– Requires substantial preplanning and capital
expenditures– Technological problems of exact component positioning and
precise timing– Tooling and fixture requirements
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Production TechnologyFlexible Manufacturing Systems
11
10 100 1000 10000 100000 1000000
10
100
1000Work cells
CIM
Focusedautomation
Dedicatedautomation
Volume
Prod
ucts Flexible
ManufacturingSystem
Generalpurpose
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• Manufacturing system that combines CAM with engineering (CAD), & production & inventory control & shipping
• Computer-aided design (CAD) creates code to run DNC machines
DNC Robots
PIC
AGV
CAD
TopMgmt
CAM
Production TechnologyComputer Integrated Manufacturing (CIM)
A Real World Example
TheFord
Motor Company
Ford’s Problem
• At Ford Powertrain they faced the following challenges
- outdated cell controller- lack of flexibility because of it- causing loss of efficiency
Solution
• Implemented a cell control based on an open architecture, commonly available tools, and industry standard hardware, software, and protocols. (3)
Benefits
• Enabled Ford to mix and match machine tools from different vendors (3)
• Reduced the number of man-years required to implement the application (3)
Benefits Continued
• The budget for the fully automatic closed-loop controller was less than 1/10th the cost for a system built in language.
• No formal training was required for the floor shop operators
Computer Integrated Manufacturing
• CIM: “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 personnel efficiency.” (4)
Components of CIM
• CAD Computer Aided Design
• CAM Computer Aided Manufacturing
• CAE Computer Aided Engineering
Origin
The term "CIM" is both a method of manufacturing and the name of a computer-automated system in which individual engineering, production, marketing, and support functions of a manufacturing enterprise are organized
In a CIM system functional areas such as design, analysis, planning, purchasing, cost accounting, inventory control, and distribution are linked through the computer with factory floor functions such as materials handling and management, providing direct control and monitoring of all the operations.
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Design TechnologyComputer-Aided Design (CAD)
• Refers to the use of computers to interactively design products and prepare engineering documentation (drafting and three-dimensional drawings)
• Allows designers to save time and money by shortening development cycles for virtually all products. The payoff is particularly significant because most product costs are determined at the design stage.
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Engine CAD Drawing
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Design Tecnology. CAD Extensions
• Extensions:– Design for Manufacture and Assembly (DFMA) -
enables testing of design integration before manufacturing. Software that allows designers to look at the effect of design on manufacturing of the product.
– 3-D Object Modeling - enables the building of small models of the product (prototypes). 3-D object modeling builds up a model in very thin layers of synthetic materials for evaluation. It avoids a more lengthy and formal manufacturing process.
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
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CAD systems have moved to the Internet through e-commerce, where they link computerized design with purchasing, outsourcing, manufacturing, and long-term maintenance.
This move supports rapid product change and the growing trend toward “mass customization”.
With CAD on the Internet, customers can enter a suppliers’s design libraries and make design changes. The supplier’s software can then automatically generate the drawings, update the bill of material, and prepare instructions for the supplier’s production process. The result is customized products produced faster and cheaper.
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Production Technology• Numerically controlled machines
– Numerical control– Computer numerical control– Direct numerical control
• Process control• Vision systems• Robots• Automated storage and retrieval systems• Automated guided vehicles• Flexible manufacturing systems• Computer integrated manufacturing
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Production TechnologyProcess Control - Operation
• Is the use of information technology to monitor and control a physical process. For example, process control is used to measure the moisture content and thickness of a paper.
• To determine and control temperatures, pressures, and quantities in petroleum refineries, petrochemical processes, cement plants, steel mills, nuclear reactors and other product-focused facilities.
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Production TechnologyProcess Control - Operation
• Sensors, often analog devices, collect data• Analog devices read data on some periodic basis,
perhaps once a minute or once a second• Measurements are translated into digital signals, and
transmitted to a digital computer• Computer programs read the file (the digital data) and
analyze the data• Output may be a: message on printer or console, signal
to a motor to change a value setting, warning light or horn, process control chart, etc.
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
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Production TechnologyVision Systems
• Combine video and computer technology • Often used in inspection roles• Consistently accurate, do not become
bored, of modest cost
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Machine Vision System
•Image Acquisition
•Image Analysis
•Image Interpretation
• Machines that hold, move, or grasp items
• Perform monotonous or dangerous tasks
• Used when speed, accuracy, or strength are
needed
Production TechnologyRobots
Industrial robots are classified by the International Standards Organization as:
Automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes.
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Robots• A robot is a mechanical device that can perform
preprogrammed physical tasks. A robot may act under the direct control of a human (eg. the robotic arm of the space shuttle) or autonomously under the control of a pre-programmed computer. Robots may be used to perform tasks that are too dangerous or difficult for humans to implement directly (e.g. the space shuttle arm) or may be used to automate repetitive tasks that can be performed more cheaply by a robot than by the employment of a human (e.g. automobile production).
• Movies: http://www.robots.com/index.html
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Where Used and Applied• Welding
• Painting
• Surface finishing
• Aerospace and automotive industries
• Light assembly such as in the micro-electronics industries, or consumer products industries
• Inspection of parts (e.g., CMM)
• Underwater and space exploration
• Hazardous waste remediation
Where Used and Applied• Welding
• Painting
• Surface finishing
• Aerospace and automotive industries
• Light assembly such as in the micro-electronics industries, or consumer products industries
• Inspection of parts (e.g., CMM)
• Underwater and space exploration
• Hazardous waste remediation
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Robots• Basic Guide: http://www.robotsltd.co.uk/robot-guide.htm
• Industrial robots manufacturers:Cincinnati Milacron RobotsNachi RobotsFanuc RobotsPanasonic RobotsMitsubishi RobotsOTC Daihen RobotsMotoman Robots
QUICK RESPONSE MANUFACTURING SYSTEM
Quick response manufacturing
• QRM is rooted in the concept of Time-based competition (TBC) pioneered by Japanese enterprises in the 1980s and first formulated by George Stalk Jr. in his 1988 article entitled Time – The Next Source of Competitive Advantage.
Quick-Response Manufacturing System
A. Defining Quick-Response Manufacturing Systems
• A computer integrated manufacturing CIM system integrates the physical manufacturing system and the manufacturing resource
planning (MRP II) systems.• A quick-response manufacturing system is a CIM system that is
integrated with advanced integration technologies.
Physical Manufacturing
System
Physical Manufacturing
System
CADD CAM
ManufacturingResource Planning
(MRP II)
ManufacturingResource Planning
(MRP II)
MRP
Computer Integrated Manufacturing (CIM) System
Electronic DataInterchange (EDI)
Automatic Identifcation
Advanced Integration Technologies
Quick response manufacturing
• Design the company's operations with a focus on customer response time.
• Separate your office and shop floor into cells of five to 10 employees.
• Each cell is focused on a particular segment of the market, but the members of that cell may be required to handle multiple tasks.
• Dedicate the necessary resources only for that cell and locate them where all members can easily access them.
CONCURRENT ENGINEERING
63
Concurrent Engineering Defined
• How would you define concurrent engineering (CE)?
• Definition: “Integrated approach to product-design that takes into account all stages of a product’s life cycle from design to disposal – including costs, quality, testing, user needs, customer support, and logistics”
• What is an example of this?- BusinessDictionary.com
Field warranty service
Production system
PrototypingProcess design GD&T
Quality control
Product design GD&T
Engineering Modeling
Market analysis, R&D
Computer Aided Design (CAD)
Computer Aided Manufacturing
(CAM)
Rapid Prototyping
Cell, Quick Response
Manufacturing
Statistic Process Control (SPC)
Manufacturing in the Product Life Cycle
65
CE Illustration
http://www.similesystems.com.au/Manufacturing/ManufacturingLifeCycle.htm
Concurrent Engineering
Form DesignForm Design
Functional Design
Functional Design Production
Design
Production Design
Revising and testing prototypes
Manufacturing Specifications
Design Specifications
Feasibility Study
Feasibility Study
IdeaGeneration
IdeaGeneration
Suppliers R&D Customers
MarketingCompetitors
Product or Service concept
Performance Specifications
Pilot run and final tests
Pilot run and final tests
Final Design and process plans
Product LaunchProduct Launch
Preliminary Design
Commercial Design Process
Linear Process
Concurrent engineering
• Has to be supported by top management.• All product development team members should bededicated for the application of this strategy.• Each phase in product development has to be carefullyplanned before actual application.• New product’s lifecycle has to fit in in the existingproduct program lifecycles in a company.
Benefits of Concurrent Engineering•Reduces time from design concept to market launch by 25% or more• Reduces Capital investment by 20% or more• Supports total quality from the start of production with earlieropportunities for continuous improvement• Simplifies after-sales service• Increases product life-cycle profitability throughout the supplysystem
Assembly in the Context of Product Development
How dose CE reduce time?
Traditional Design and Production Process
the main problems/difficulties associated with traditional design and production process:
FOR COMPLEX PRODUCTS:• Cycle Time Too Long • Facility Intensive • Cost High • Convergence Not Assured
Computer Integrated Manufacturing Systems
Goals of Concurrent Engineering in CIM (1)
• Primary Goal is to Assure Rationalization in Early Stages to Avoid Cost/Improve Product– Operational Concept– Physical Concept– Manufacturing Concept– Maintenance Concept– Disposal Concept
Computer Integrated Manufacturing Systems
Goals of Concurrent Engineering in CIM (2)
• Secondary Goal is Lead Time Reduction– Administrative Lead Time
• Design and Rationalization of Product• Approval and Acquisition of Facilities
– Manufacturing Lead Time• Scheduling and Execution• Storage and Distribution• Measure of Exposure to Risk/Changes
Computer Integrated Manufacturing Systems
Traditional Process of Serial Engineering
• Functions Separated• Functions Serially Executed• No Interaction• Maintenance Usually an Afterthought• Time Consuming• Costly• Product a Series of Suboptimal
Reconsiderations
Computer Integrated Manufacturing Systems
Serial Engineering
DESIGN MANUFACTURINGPLANNING
MANUFACTURING CUSTOMER
SUPPORT??
Computer Integrated Manufacturing Systems
Concurrent vs. Serial Engineering
• All Viewpoints Solicited• Interdisciplinary Teams• Life Cycle Cost Considered• Attempt to Embody Concept Early - Before
Committing to Detail Design• Data/Information/Knowledge Exchange
Planned and Encouraged• Cycle Time and Cost Reduced
Computer Integrated Manufacturing Systems
CONCURRENTDESIGN
A Concurrent Engineering Model
PRODUCTMANUFACTURING
CONCEPT
PRODUCTMAINTENENCE
CONCEPT
PRODUCTFUNCTIONAL
CONCEPT
DISCIPLINE INPUTS
• ENGINEERING
• MARKETING
• PRODUCTION
• CUSTOMERS
• WORKERS
Computer Integrated Manufacturing Systems
Virtual Concurrent Engineering
• Always a Virtual Endeavor– Groups Are Always Geographically (and Culturally)
Distributed• How Far is Too Far Apart?
– Information Generated/Stored in Various Formats and Locations
• Single Plant + Customers• Multiple Plants (Same Organization) + Customers• Multiple Organizations + Customers
Computer Integrated Manufacturing Systems
Keys to Concurrent Engineering
• Supportive Culture• Clear Understanding and Documentation of
Requirements• Technical Competence/Experiences• Technical Tool Availability (CAx Tools)• Communication Competence• Communication and Information Tool
Availability
MASS CUSTOMIZATION
Mass customization
• production of high quality, individually tailored products and services at low production costs” production of high quality, individually tailored products and services at low production costs”
Michael Dell is to MASS CUSTOMIZATION
as Henry Ford was toMASS PRODUCTION
MASS CUSTOMIZATION IS• drawing on a large collection of modules
to build unique products and services that exactly match the needs and desires of individual customers who have already ordered what does not yet exist.
• accepting payment for finished products and services before paying for the components of which they are made.
CONTRASTS
MASS PRODUCTION• Inventory is free• Time is free• Either
standardization at low cost or flexibility at high cost
• One size fits all• Market share focus• Selling goods and
services
MASS CUSTOMIZATION• Inventory is NOT• Time is everything• Low cost and high
flexibility• Customers are
particular• Market fragment and
variety focus• Selling service and
experiences
WHAT MUST WE CHANGE TO GET INTO THE MASS CUSTOMIZATION BUSINESS?
• Change employee– Recruiting– Incentives– Training– Working
conditions• Change processes
– Modularization– Flexible systems
• Change relationships– Suppliers– Customers
• Change marketing– Direct to customer– Active listening
• Change organization– Empowerment– Integrated teams
• Change focus– Intellectual capital– Customer driven
HOW CAN WE GET EXTRA FUNDS TO GROW OUR MASS CUSTOMIZATION BUSINESS?
On average, Dell collects from its customers six business days before it pays its suppliers:
$ 31.2 billion / 260 business days per year * 6 business days = $ 720 million
When you eliminate supply inventories, work in progress, and finished goods inventories, you can use your suppliers’ capital to grow your business.
PRODUCTION SPEED
• Integrate order processing, supply chain management, production control, shipping, and customer billing into a single, seamless process.
• Negotiate exclusive, just-in-time contracts with your suppliers.
• Build real time communication links with customers and suppliers.
• Reduce or eliminate paperwork.
LEAN MANUFACTURINGTOYOTA PRODUCTION SYSTEM
Toyota Production System• After World War II, Toyota was almost bankrupt.• Post war demand was low and minimising the cost per unit
through economies of scale was inappropriate. This led to the development of demand-led pull systems.
• The Japanese could not afford the expensive mass production facilities of the type used in the USA so they instead focused on reducing waste and low cost automation.
• Likewise, Toyota could not afford to maintain high inventory levels.
Taiichi Ohno (1912 †1990)
Shigeo Shingo1909 †1990
Founders of the Toyota Production System (TPS)
Just-in-Time Manufacturing“In the broad sense, an approach to achieving excellence in a
manufacturing company based upon the continuing elimination of waste (waste being considered as those things which do not add value to the product). In the narrow sense, JIT refers to the movement of material at the necessary time. The implication is that each operation is closely synchronised with subsequent ones to make that possible” APICS Dictionary 1987.
JIT became part of Lean Manufacturing after the publication of Womack’sMachine that Changed the World in 1991
Waller, D.L.,,1999,”Operations Management: A Supply Chain Approach”, (Thompson, London)
Lean Manufacturing goals
Lean Manufacturing• Arose in Toyota Japan as the Toyota Production System• Replacing complexity with simplicity • A philosophy, a way of thinking• A process of continuous improvement• Emphasis on minimising inventory• Focuses on eliminating waste, that is anything that adds cost
without adding value• Often a pragmatic choice of techniques is used
Toyota Production System• Technologies and practices can be copied.• Most of the philosophies and techniques are widely
disseminated.• However, Toyota remains at the forefront, primarily because it
is a learning organisation. • Problem solving methods are applied routinely and are
completely ingrained.• The employees are continually engaged in Kaizen (continuous
improvement).• Many aspects of TPS are based upon embedded tacit
knowledge.
TPS: How the work is done• Every activity is completely specified, then applied routinely
and repetitively.Because:• All variation from best practice leads to poorer quality, lower
productivity and higher costs.• It hinders learning and improvement because variations hide
the link between the process and the results.It is necessary to make sure that the person performing the
activity can perform it correctly and that the correct results are achieved.
7 Forms of Waste ‘Muda’• Overproduction – most serious waste because it discourages the
smooth flow of material and inhibits productivity and quality.• Waiting – wastes time and money.• Transport• Inappropriate processing – e.g. use of complex processes rather than
simple ones. Over complexity encourages over production to try and recover the investment in over complex machines.
• Unnecessary inventory – increases lead-times and costs.• Unnecessary motion – relates to poor ergonomics where operators
have to stretch, strain etc. This makes them tired.• Defects – physical waste. Regarded as an opportunity to improve.
Defects are caused by poor processes.
Lean Manufacturing• Philosophy• Techniques – usually applied very pragmatically.
Lean Techniques
• Manufacturing techniques• Production and material control• Inter-company Lean• Organisation for change
Manufacturing Techniques• Gemba Kanri• Cellular manufacturing• Set-up time reduction• Smallest machine concept• Fool proofing (Pokayoke)• Pull scheduling• Line stopping (Jikoda)• I,U,W shaped material flow• Housekeeping
• System by which standards for running the day-to-day business are established, maintained controlled and improved .
Includes a number of methods:• 5Ss• Standard operations• Skill control, including the assessment of individuals
capabilities, the identification of job requirements, the development of a comparison matrix and the identification of training needs;
• Kaizen is a cost cutting approach that continuously makes small improvements to processes (Wikipedia, 2005);
• Visual management, the provision of notice boards for control information, stock, materials movement, health and safety and work methods.
‘Genba Kanri’ – Workplace Management
5SsWaller, D.L.,,1999,”Operations Management: A Supply Chain Approach”, (Thompson, London)
Functional layout
Cellular layout
Askin G.G & Standridge C.R. (1993) Modelling and Analysis of Manufacturing Systems, John Wiley ISBN 0-471-57369-8
© Siemens Power Generation Systems
Functional layout
Manufacturing cells© Siemens Power Generation Systems
Multifunction double gantry mill
© Siemens Power Generation Systems
A single machine acting as a cell
Group Technology / Cellular Manufacturing
• Improved material flow• Reduced queuing time• Reduced inventory• Improved use of space• Improved team work• Reduced waste• Increased flexibility
Set-up Time Reduction• Single minute exchange of dies (SMED) - all changeovers <
10 mins.1. Separate internal set-up from external set-up. Internal set-
up must have machine turned off.2. Convert as many tasks as possible from being internal to
external3. Eliminate adjustment processes within set-up4. Abolish set-up where feasibleShingo, S. (1985),”A Revolution in Manufacturing: the SMED
System”, The Productivity Press, USA.
Set-up Analysis• Video whole set-up operation. Use camera’s time and date
functions• Ask operators to describe tasks. As group to share
opinions about the operation.
Three Stages of SMED1. Separating internal and external set-up
doing obvious things like preparation and transport while the machine is running can save 30-50%.
2. Converting internal set-up to external set-up 3. Streamlining all aspects of the set-up operation
Single Minute Exchange of Dies (SMED)
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Increases flexibilityMakes it easier to reduce batch sizeReduces waste
Overall Equipment Effectiveness• Open time – total time an operator available to work on a
machine e.g. 8 hours per day• Operator pause – coffee breaks, chatting, toilet breaks etc.• Machine breakdowns• Unplanned interruptions e.g. having to make
modifications• Machine set-up• Low performance – throughput less than design.• Scrap products
Waller, D.L.,,1999,”Operations Management: A Supply Chain Approach”, (Thompson, London)
Overall Equipment Effectiveness
Using several small machines rather than one large one allows simultaneous processing, is more robust and is more flexible
Slack, N. Chambers, S. and Johnson, R, 2004,”Operations Management, 4th Edition”, Prentice Hall
Small Machine Concept
Lean Material Control• Pull scheduling• Line balancing• Schedule balance and smoothing (Heijunka)• Under capacity scheduling• Visible control• Point of use delivery• Small lot & batch sizes
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Workers operate at their own pace trying to maximise outputPush system
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Lead timePush system
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Pull system synchronised with demand. Lot size = 1
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Pull system Lead time
Waller, D.L., 2003,”Operations Management: a Supply Chain Perspective 2nd Edition”, Thompson, London
Flexible workers in Leancombine WP2 & 3
Production after 1 hour:WP1: 180WP2&3 combined: 180Increase = 36 per hour Waller, D.L., 2003,”Operations Management: a Supply Chain
Perspective 2nd Edition”, Thompson, London
“Pull” Systems• Work centres only authorised to produce when it has
been signalled that there is a need from a user / downstream department
• No resources kept busy just to increase utlilisationRequires:• Small lot-sizes• Low inventory• Fast throughput• Guaranteed quality
Pull SystemsImplementations vary• Visual / audio signal• “Chalk” square• One / two card Kanban
Lean Purchasing• Lean purchasing requires predictable (usually
synchronised) demand• Single sourcing• Supplier quality certification• Point of use delivery• Family of parts sourcing• Frequent deliveries of small quantities• Propagate Lean down supply chain, suppliers need
flexibility• Suppliers part of the process vs. adversarial relationships
Lean Purchasing
• Controls and reduces inventory• Reduces space• Reduces material handling• Reduces waste• Reduces obsolescence
Notice placed prominently at the door at Faurecia
More detail
Organisation for Change• Multi-skilled team working• Quality Circles, Total Quality Management• Philosophy of joint commitment• Visible performance measurement
– Statistical process control (SPC)– Team targets / performance measurement
• Enforced problem solving• Continuous improvement
Total Quality Management (TQM)• Focus on the customer and their requirements• Right first time• Competitive benchmarking• Minimisation of cost of quality
– Prevention costs– Appraisal costs– Internal / external failure costs– Cost of exceeding customer requirements
• Founded on the principle that people want to own problems
The Deming Cycle
Hill, T. 2005, “Operations Management, 2nd Edition”, Palgrave Macmillan
Cause/effect (fishbone) diagram
Hill, T. 2005, “Operations Management, 2nd Edition”, Palgrave Macmillan
Lean Flexibility
• Set-up time reduction• Small transfer batch sizes• Small lot sizes• Under capacity scheduling• Often labour is the variable resource• Smallest machine concept
Reducing Uncertainty
• Total Preventative Maintenance (TPM) / Total Productive Maintenance
• 100% quality• Quality is part of the process - it can’t be inspected in• Stable and uniform schedules• Supplier quality certification
Total Preventative Maintenance (TPM)
• Strategy to prevent equipment and facility downtime• Planned schedule of maintenance checks• Routine maintenance performed by the operator• Maintenance departments train workers, perform
maintenance audits and undertake more complicated work.
The problem with inventory
Reduce the level of inventory (water) to reveal the operations’ problems
WIPDefective materials
ReworkScrap
Downtime
productivity problems
WIPDefective materials
ReworkScrap
Downtime
productivity problemsSlack, N. Chambers, S. and Johnson, R, 2004,”Operations Management, 4th Edition”, Prentice Hall
Operational prerequisites• Level schedules• Frozen schedules• Fixed routings• Frequent set ups• Small and fixed order quantities• High quality conformance• Low process breakdowns• Labour utilisation not the key factor• Employee involvement
Lean in the North East of England
• Regional Development Agency the North East Productivity Alliance to disseminate Lean expertise.
• The initiative involves about 150 companies in the region.• A pilot of 16 companies resulted in total savings of £4.36m.
Several companies would have otherwise have gone out of business.
• There were dramatic improvements in efficiency, delivery performance and productivity.
CANON PRODUCTION SYSTEM
• the aim of the system is the production of goods of higher quality at a lower cost in less time.
Wastes to be eliminated by Canon Production System:
• - Stocking items not immediately needed,• -Producing defective products,• - Idle machinery and breakdowns, taking to long for setup,• - Overinvesting for required output,• - Excess personnel due to bad indirect labor system,• - Employing people for jobs that can be mechanized or
assigned to less skilled people,• - Not working according to the best work standards,• - Producing products with more functions than necessary,• - A slow start in the production of a new product.
Benefits of Canon Production System application:
• Helps employees become problem-conscious,• Helps them move from operational
improvement to system improvement,• Helps employees recognize the need for self-
development.
ELECTROLUX MANUFACTURING SYSTEM
• Electrolux Manufacturing System - prefers the highest standards of production, supply, logistics and quality. It uses best practices for Production Organization to respond quickly to customer needs.
Elektrolux manufacturing system
• Working in Teams,• People Development & Involvement,• Leadership, • Productive Maintenance,• Quality,• Demand Flow,• Continuous Improvement,• Waste Elimination & standard Work,• Safety,• Visual Factory.
CONWIP
145
CONWIP
• Assumptions:1. Single routing2. WIP measured in units
• Mechanics: allow next job to enter line each time a job leaves (i.e., maintain a WIP level of m jobs in the line at all times).
• Modeling:– MRP looks like an open queueing network– CONWIP looks like a closed queueing network– Kanban looks like a closed queueing network with blocking
. . .
146
CONWIP Controller
PC
R G
PC
PN Quant–— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— ––––––— –––––Indicator Lights
Work Backlog
LAN
. . .
Workstations
147
CONWIP vs. Pure Push
• Push/Pull Laws: A CONWIP system has the following advantages over an equivalent pure push system:
1) Observability: WIP is observable; capacity is not.
2) Efficiency: A CONWIP system requires less WIP on average to attain a given level of throughput.
3) Robustness: A profit function of the form
Profit = pTh - hWIP
is more sensitive to errors in TH than WIP.
148
CONWIP Efficiency Example
• Equipment Data:– 5 machines in tandem, all with capacity of one
part/hr (u=TH·te=TH)– exponential (moderate variability) process times
• CONWIP System:
• Pure Push System:
41)(
0
w
wr
Ww
wwTH b
TH
TH
u
uTHw
15
15)(
PWC formula
5 M/M/1 queues
149
CONWIP Efficiency Example (cont.)
• How much WIP is required for push to match TH attained by CONWIP system with WIP=w?
150
CONWIP Robustness Example
• Profit Function:
• CONWIP:
• Push:
• Key Question: what happens when we don’t choose optimum values (as we never will)?
hww
wp
4Profit(w)
TH
THhpTH
1
5Profit(TH)
hwpTH Profit
need to find “optimal”WIP level
need to find “optimal”TH level (i.e., releaserate)
151
CONWIP vs. Pure Push Comparisons
-20
-10
0
10
20
30
40
50
60
70
0.00% 20.00% 40.00% 60.00% 80.00% 100.00% 120.00% 140.00%
Control as Percent of Optimal
Pro
fit
Push
CONWIPOptimum
Efficiency
Robustness
152
Modeling CONWIP with Mean-Value Analysis
• Notation:
• Basic Approach: Compute performance measures for increasing w assuming job arriving to line “sees” other jobs distributed according to average behavior with w-1 jobs.
wjwWIP
wwTH
wwCTwCT
wjwCT
wjwu
j
n
j j
j
j
level with WIPline CONWIPin station at level WIPaverage)(
level with WIPline CONWIP of throughput)(
level with WIPline CONWIP of timecycle )()(
level with WIPline CONWIPin station at timecycle )(
level with WIPline CONWIPin station ofn utilizatio )(
1