Production systems engineering Production systems design PhD Eng Agnieszka Stachowiak Lectures

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

13

The process is described by its operations

R1 R2 R3

A

3

2

1

4

5

6

7

8

R1 R2 R3

14

Alternative process designs with the same operations

3

2

1

4

5

6

7

8

R1 R2 R3

3

2

4

5

6

7

8

1R3

R2

R1

Parallel Processing Production Line

15

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

6

3

212

14

R1 R2 R3

13

9

47

8

10

15

16

17

18

511

20

1

19

16

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)

18

The models must describe multiple products

Product A Product B Product C

VA

2

1

R2

7

3

8

A

5

4

R1

6

2

1

R3

4

3

VB

4

2

18

10

12

R1 R2 R3

9

6

35

711

13

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

19

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.



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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.



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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

http://en.wikipedia.org/wiki/Machine

http://en.wikipedia.org/wiki/Human

http://en.wikipedia.org/wiki/Space_shuttle

http://en.wikipedia.org/wiki/Control_theory

http://en.wikipedia.org/wiki/Computer

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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

http://www.robotsltd.co.uk/robot-guide.htm

http://www.kcrobotics.com/cincinnati-milacron-robots.htm

http://www.kcrobotics.com/nachi-robots.htm

http://www.kcrobotics.com/fanuc-robots.htm

http://www.kcrobotics.com/panasonic-robots.htm

http://www.kcrobotics.com/mitsubishi-robots.htm

http://www.kcrobotics.com/OTC-daihen-robots.htm

http://www.kcrobotics.com/motoman-robots.htm

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


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


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


Serial Engineering

DESIGN MANUFACTURINGPLANNING

MANUFACTURING CUSTOMER

SUPPORT??


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


CONCURRENTDESIGN

A Concurrent Engineering Model

PRODUCTMANUFACTURING

CONCEPT

PRODUCTMAINTENENCE

CONCEPT

PRODUCTFUNCTIONAL

CONCEPT

DISCIPLINE INPUTS

• ENGINEERING

• MARKETING

• PRODUCTION

• CUSTOMERS

• WORKERS


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


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


Workers operate at their own pace trying to maximise outputPush system


Lead timePush system


Pull system synchronised with demand. Lot size = 1


Pull system Lead time


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

Documents

Production systems engineering Production systems design PhD Eng Agnieszka Stachowiak Lectures