lean manufacturing & six sigma: a short introduction

Lean Manufacturing&

Six Sigma:

A Short Introduction

Part I:Lean Manufacturing

The Lean Production Concept

-Originated from the work of Eiji Toyoda, Taiichi Ohno and Shigeo Shingo at Toyota.

- After WW II, U.S needed large mass production to satisfy demand for products.

- The Allied victory and the massive quantities of material behind it caught the attention of Japanese industrialists.

The Lean Production Concept

- Japanese engineers visit the US to learn/help reconstruct the Japanese industrial engine.

They studied American production methods with particular attention to:

- Ford practices

- SPC practices of Ishikawa, Deming, and Juran

- Japanese market was much smaller, so more flexible systems were needed to produce smaller quantities of different items in the same equipment.

The Lean Production Concept• Toyoda and Ohno develop a system that would help them

survive:

• Eliminate inefficiencies that don’t add value

• Flexible machinery

• Involve employees in the solution of problems

• Manufacture the right product at the right time, in the right quantities

• Quick Changeover

• Flexible Machines

Trivia• The current Toyota Mark consists of three ovals:

• the two perpendicular center ovals represent a relationship

of mutual trust between the customer and Toyota.

• These ovals combine to symbolize the letter "T" for Toyota.

• The space in the background implies a global expansion of

Toyota's technology and unlimited potential for the future.

The Lean PhilosophyIdea: continuously improve quality and cost.

Do more with less… time space human effort machinery materials

while meeting customer demands.

Just-in-timeAfter many years, Toyota established the following strategy:

1. Kanban based pull production.2. Waste elimination is guide philosophy.3. Faith in importance and value of quality.4. “Kaizen” or continuous improvement as a daily strategy.5. Emphasis on setup reduction on all machines.6. Integrate suppliers and material acquisition into the

planning process.7. Cellular layouts with balanced flow.

Basic Tenets of Lean, JIT Production

Categories Improving Production

Environment

Quality Engineering

Improving Material Flow

I. Improving Production

Environment

1. Eliminate Waste

2. Employee Cross-Training and Job Rotation

3. Employee Empowerment and Involvement

4. JIT Purchasing

5. Reduction of Variability

6. Mistake-Proof Processes

7. Reduce Setup Times

Some Terminology

Muda: Japanese term for any human activity

which abosrbs resources but creates no real value.

Kaizen: process of continuous incremental

improvement through the identification

/elimination of muda.

Kaizen blitz: an event where a team of managers,

engineers and line workers coordinated by a

facilitator come together for three days to focus

on improvements on an area of a plant.

Some Terminology

Typical strategy in Kaizen Event is asking

“why” five times until the root cause or

motivation for an action is discovered.

Golden Rule: Use everyone’s knowledge to

identify and implement improvements

quickly and cost effectively.

1. Eliminate Waste

Original scientific approach was to dissect a

large system into small pieces and make each

piece optimal.

Japanese approach: develop a system that

connects the pieces.

Ex. Instead of tracking production statistics and

inspecting “out” defective products, eliminate

any production of defective items.

Seven Types of Wastecommonly found in industry.

A. Waste from Overproduction

Why make products that won’t be sold?

Before, supervisors were evaluated through quotas.

Machine utilization needed to be maximized.

New idea: machines and humans should only be

busy when they have useful tasks to accomplish.


B. Waste of Motion

Eliminate motions that do not add value.

Look at workplace design, process

planning, detailed job procedures,

material handling.


C. Transportation Waste

Position work and storage areas such

that material moves are short.

Keep tooling near its point-of use.


D. Processing Waste

Eliminate non-value added operations.

May need to go back to product design

and revise features and tolerances.


E. Wasted Time (queuing)

Plan for:

Small lot sizes

Ordered production and release of dependent Items

Good coordination will achieve small WIP and

throughput time.


F. Defective Products…

Cost money

Deplete resources

Negatively impact customer perception

Reduce throughput


G. Excess Inventory yields added costs due

to…

Space, obsolescence, opportunity costs,

handling, among others.

Avoid excess inventory.

Can achieve via modular components.

Negotiate long term contracts with suppliers

to ensure a steady stream of high-quality parts.

Make only what has/will be sold immediately.


Can train over time to do variety of tasks in

their work area.

Can then rotate through different positions.

Benefits:

Enhances worker flexibility and

enthusiasm.

Prevents boredom, fresh perspectives and

ideas for improvements.

Gives context of communication between

workers on same team.

Benefits (continued):

Minimizes fatigue and repetitive stress injuries.

Can move workers around to eliminate

temporary bottlenecks.

In U-shaped cells, workers can operate more

than one machine at a time.


3. Employee Empowerment andInvolvement

Why hire a body when it comes with a brain?

Employees are a great source of ideas for

improvement.

Employees must be allowed and encouraged

to do so.

This includes authority to stop production

and correct a problem in production.

The goal is to identify problems early.


A usual approach to empower is via a switch to

stop production.

This warning system is called Jikoda.

Jikoda is the concept where if there is a

defect it is identified and solved

immediately.


For an example if there is a problem in machine,

the production line will be stopped and the

problem will be fixed immediately.

The warning light system is called andon.

Usually a bank of three lights is used: green,

yellow and red.


One light is always on, indicating station

status.

Red light signals a line stoppage and

location of problem to other workers.

Nearby workers assist with the problem,

get additional help if necessary.

Identifier and solver of problem

are rewarded.


Employees should be involved in

developing procedures.

Workers take pride in job if they know

they are helping meet customer

expectations.


Worker area should also be kept clean and organized.

This helps in pride and dedication.

5S’s: Sort, Straighten, Sanitize, Sweep and

Sustain (more later).

Organized workplace reduces:

Misplacing

Contamination

Brightens up atmosphere

Gives feeling system is under control.

Conveys that sloppiness is not tolerated.

4. JIT Purchasing

Changes that can be implemented

1. Sole source vs. multiple supply sources.

- Idea: better negotiate long-term contracts

with single supplier.

- This encourages cooperation instead of

competing over terms.

- Supplier’s long term interest is now to

provide high quality on time at a fair price to

ensure customer’s success.

4. JIT Purchasing


2. Frequent delivery of small lots vs quantity

discounts.

- Traditional approach: occasional deliveries of

large quantities of parts.

- Parts were inspected via sampling.

-Now, no inspection is needed since vendor

product quality has been certified and meets

requirements. (If not, get a new supplier).

4. JIT Purchasing


3. Flexible ordering vs. paperwork.

- Contracts usually call for steady flow

of product +/- 10%

- Customer can change order quantity on

short notice with little hassle.

- Requires some reserve capacity by vendor.

4. JIT Purchasing


4. Vendor owns and manages inventories.

-Vendor can hold inventory on customer’s

site.

- Customer gets billed only when extracting

parts.

- Supplier has responsibility to keep enough

inventory level.

5. Reduction of Variability

Variability reduces efficiency.

If supplies, yields or machine availability are

unpredictable, the tendency is to have large

safety stocks of inventory.

Idea:

Eliminate variability from production

processes.


This involves eliminating opportunities for

errors.

Idea:

Design processes to avoid producing

defective items.

Be able to detect defects before more

production steps are done.

Poka-Yoke: “mistake proofing a process.”


Basic ideas:

100% of units should be inspected.

Identify defects as close to the source as

possible.

Stop production immediately and take

corrective action right after a defect is

detected.

Design processes to avoid producing

defects.


Some Poka-Yoke Techniques

Checklists and worker source

inspection.

Worker checks his own work.

Problem: humans tend to approve their

own work.

Checklists help ensure all steps have been

completed in station.



Successive check systems

Worker checks incoming parts from

previous station before starting his own

operation.

Worker must approve work by previous

worker or defects must be communicated

to previous worker right away.



Mistake-proof part and fixture design.

Design parts so that they can only fit in a

tooling fixture in proper orientation.

Reshape symmetrical parts to exaggerate

asymmetries – easier to detect

misalignments.

7. Reduce Setup Times

Usually the MOST productive investment that can be

made to improve production system performance.

Techniques (*):

- Design parts for manufacturability

- Design parts for standard tools.

- Develop standard methods for setups.

- Divide setup activities into external/internal tasks.

- Design procedures to perform setup tasks in parallel.

- Modular fixturing

- Eliminate adjustments.

- Use power clamps.

Transitioning from Traditional to Lean

1900’s Philosophy Worker was immigrant, uneducated, spoke little

English.

Worker is like a machine designed to perform a limited

set of tasks well.

Product customization was not an issue for customers

(all model T’s were the same).

2000 Lean Philosophy Worker: most flexible machine.

If properly educated, worker can solve problems and

adapt to new situation.

The customer expects customization.


Old Production Mentality:

Process-Based Organization

Economic Order Quantities

Large Unit Handling Loads

Receiving Inspection

Maximize Equipment Use


New Lean Thinking

Product Cell Layouts

Single-Unit mixed model production

Continuous material flow

Mistake proofing

Balanced production line

Problems in Implementing Lean Cannot make it happen without the support of

floor operators.

Culture change needs to happen. Old philosophy: run large batches to amortize setup

costs of the largest number of parts and products.

New philosophy: demand based production.

Management not fully involved.

Loss of interest by top management and workers. After initial implementation, no hard benefits seen in

bottom line.

Might have implemented Lean in wrong areas.

Transition Stages in Lean Thinking(Ford Motor Company)

Phase 1: Process Stabilization

Improve production environment - predictable/reliable

processes -

total productive maintenance - total quality – poka yoke

- setup time reduction - standard procedures - clean &

organize the workplace -train employees in lean

thinking.

Phase 2: Continuous Flow

Reduce WIP and batch sizes. No need to run machines

at full capacity. Unit parts can plow in small or single

quantities between workstations.

Transition Stages in Lean Thinking(Ford Motor Company)

Phase 3: Synchronous production.

Follow weekly production schedules.

Phase 4: Pull authorization

To authorize production, parts must be “pulled” by

successive workstations. Kanbans dictate production.

Phase 5: Balanced production

All process produce at a constant level and

continuous rate. Every part type is made daily; parts

flow continuously.

Lean Production Toolbox 5S Quick Changeover TPM (Total Productive Maintenance) Value Stream Mapping Kanban / Visual Management Improvement Activities – Kaizen Continuous Flow JIT

What is 5S? A system for higher productivity, less defects

and a safer workplace. A method to improve and sustain the workplace

organization. 5 constant behaviors to maintain a visual

workplace First step towards Lean Manufacturing Reduces clutter and time to look for tools Improves efficiency and appearance Motto: A place for everything and everything

in its place.

The Five S’s Seiri (Sort)

Remove all unnecessary materials / equipment Set in Order (Seiton)

Make it obvious where things belong Shine (Seiso)

Clean everything inside and out. Standardize (Seiketsu)

Establish policies/procedures to maintain 5S Sustain (Shitsuke)

Train, daily cleaning activities The 6th ‘S’: Safety

Commit to safety in all activities.

Value Stream Mapping A pencil and paper tool that helps you to see

and understand the flow of material and information as a product makes its way through the value stream.

Follow a product’s production path from customer to supplier

Carefully draw a visual representation of every process in the material and information flow.

Then ask a set of key questions and draw a “future state”map of how value should flow.

VSM Goals Improve the “value Added” process

through step-by-step review and identification of connections, activities, information, and flow.

Aim: Create a picture of the system of processes from beginning to end.

Example of Value Stream Mapping

Part II:Introduction to 6 Sigma

What is Six Sigma (6s)?

A movement focused on business process

improvement.

It is a quality measurement and improvement

program

Focuses on the control of a process to the point of

± six sigma (standard deviations) from a centerline.

Provides businesses with the tools to improve the

capability of their business processes. (Cp)


A disciplined methodology

Uses data and statistical analysis to

measure and improve a company's

operational performance

Helps identifies and eliminates

"defects" in manufacturing and

service-related processes.

History

Credit for coining the term "Six Sigma" goes

to Motorola engineer named Bill Smith

It is a Motorola registered trademark

1980s: Motorola developed the methodology

and needed cultural change associated with

it.

Six Sigma helped Motorola realize powerful

bottom-line results in their organization.

Six Sigma is a tool to achieve success.

Six Sigma Basics

Std Deviation (σ)–Most common measure of

statistical dispersion, measuring how spread out

the values are from their mean (average)

Computing the Std Deviation –Data Set:•5,6,8,9

Six Sigma Basics 6 Sigma Focuses on the Reduction of

Variation that Generates Defects for Customers

Defect Reduction due to Variation Achieved by eliminating root causes of variation that

affect the amount of variation in the process output

Six Sigma Basics Achieved by Eliminating Root Causes of Variation

which move the mean performance of the process output

Six Sigma Basics

Six Sigma Philosophy

Six Sigma Tools

Process Mapping Tolerance Analysis Structure Tree Components Search Pareto Analysis Hypothesis Testing Gauge R & R (Repeatability and Reproducibility)

Regression Rational Subgrouping DOE Baselining SPC

Six Sigma Methodologies - DMAIC vs DMEDI

DMAIC (Define, Measure, Analyze, Improve, Control):

an analytical, data-driven approach to eliminating weaknesses in active processes, products and services.

focuses on reducing variation and defects, produces incremental improvements.

Six Sigma Methodologies - DMAIC vs DMEDI

DMEDI (Define, Measure, Explore, Develop, Implement):

a creative approach to designing new robust processes, products and services.

A roadmap focused on obtaining significant competitive advantages or quantum leaps over current environments.

DMEDI projects typically require more time and resources to complete.

Six Sigma Methodology

The greatest difference between the two roadmaps lies in their unique purposes.

DMAIC roadmap resources are spent on reducing waste, cost or time in a process.

DMEDI resources are focused on preventing potential losses

DMAIC Methodology

DMEDI Methodology

DMAIC vs DMEDIDMAIC Define – Determine Project

Scope, Objectives, Resources, Constraints

Measure – Determine Customer Groups, Determine CCRs, Obtain Data to Quantify Process Performance

Analyze - Analyze Data to Identify Tangible Root Causes of Defects

Improve – Intervene in the Process to Improve Performance, Pilot New Process

Control – Implement a Control System to Maintain Performance Over Time

DMEDI Define – Very Similar to DMAIC

Measure – Define Customers and Needs Using Voice of the Customer and QFD, Determine CCRs

Explore – Develop Design Concepts, and High-Level Design

Develop - Develop and Optimize Detailed Design

Implement – Validate Design with Pilot, Establish Controls, Full-Scale Implementation

DMAIC vs DMEDITransactional Business Environment:

> Reduce cycle time and errors on service orders> Increase first call resolution on support calls> Reduce service order cycle time

Service Manufacturing Environment:

> Reduce product manufacturing/assembly cycle time> Provide IT solutions – improve backup and recovery time, reduce patching time > Identify causes and eliminate defects in molds> Eliminate false server alerts

Product Development Environment:

> Reduce product development cycle time> Identify causes of defects in a copier design> Reduce defects released in new software versions

DMAIC vs DMEDITransactional Business Environment:

> Design a new project management office> Develop a new service order handling process> Develop a new contract renewal process

Service Manufacturing Environment:

> Major redesign of manufacturing process (conversion from gasoline to alcohol engines)> Weld new materials> Design new triage process for new technologies> Develop new formats for storing larger data files

Product Development Environment:

> New fuel injection design> New material development> Next generation ink delivery system

DMAIC vs DMEDI: which to use?

Green Belts, Black Belts, Master Black Belts

Green Belts

- Employees who take up Six Sigma implementation along with their other job responsibilities.

– Lead and execute important process improvement projects.

–Are proficient in the basic tools (Courses 1-7) of Six Sigma and can characterize their processes.

–Typically work part-time on projects.

- Operate under the guidance of Black Belts and support them in achieving the overall results.


Black Belts:

– Lead and execute more strategic, high impact process improvement projects.

–Are proficient in both the basic and advanced tools (Courses 8-14) of Six Sigma and can both characterize and optimize their processes.

–They devote 100% of their time to Six Sigma.

- Operate under Master Black Belts to apply Six Sigma methodology to specific projects.


Master Black Belts:

- Focus on identifying projects/functions for Six Sigma.

- Act as in-house expert coach for the organization on Six Sigma.

- Devote 100% of their time to Six Sigma.

- Apart from the usual rigor of statistics, their time is spent on ensuring integrated deployment of Six Sigma across various functions and departments.


Champions

-Responsible for the Six Sigma implementation across the organization in an integrated manner.

-The Executive Leadership draws them from the upper management.

- Champions also act as mentor to Black Belts.

Putting the Two Together…Lean Six Sigma

Lean:-A philosophy of “Continuous Improvement” in quality and cost.

-It is the elimination of all types of waste in any type of process.

-Launched Toyota to the top of the automobile industry, while other companies fell to mediocre levels.

-Do more with less…-Time - Space-Human effort - Machinery-Materials

while meeting the customer’s demands.


Six Sigma:-The application of the DMAIC Methodology

-Supplemented with concepts extracted from the principles of lean.

-Combined together, they provide a sustainable process for increasing velocity, managing inventory/capacity and reducing waste.


Shortcomings of each:

•Six Sigma will eliminate defects but it will not address the question of how to optimize process flow.

•Lean principles exclude the advanced statistical tools often required to achieve the process capabilities needed to be truly 'lean‘.

Utilizing both methods simultaneously holds the promise of being able to address all types of process

problems with the most appropriate toolkit.

Benefits of Lean Six Sigma

• Achieve total customer satisfaction and improved operational effectiveness and efficiency

• Remove wasteful/non-value added activities

• Decrease defects and cycle time, and increase first pass yields

• Improve communication and teamwork through a common set of tools and techniques (a disciplined, repeatable methodology)

• Develop leaders in breakthrough technologies to meet stretch goals of producing better products and services delivered faster and at lower cost

Conclusions

•Excessive variation increases the cost of poor quality

•DMAIC Methodology is used to improve existing products and process

•DMEDI methodology is used to create new products and processes

•Lean is a natural fit with Six Sigma

•Process management is critical to sustain the gains

Sources and references:

Askin, Ronald et al “Design and Analysis of Lean Production Systems” Wiley 2002

Florida International University – Global and Corporate Programs (Lean Six Sigma Certification Course - 2006)

http://www.asq.org/certification/six-sigma/bok.html

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

http://books.google.com/books?id=9ObvCcJsz1kC&dq=definition+of+visual+workplace&pg=RA1-PA91&ots=tQqmfyJZez&sig

=cYcXnDI0ycIWYMIJo6ZbTYQzpxg&prev=http://www.google.com/search%3Fhl%3Den%26q%3Ddefinition%2Bof%2Bvisual%2Bworkplace&sa=X&oi=print&ct=result&cd=2#PRA1-PA2,M1

http://www.semizone.com/product-file/22/sixs1522/overview_notes.pdf

http://www.isixsigma.com/library/content/c060313a.asp

http://www.isixsigma.com/library/content/c060313a.asp

http://www.sme.org/cgi-bin/get-mag.pl?&&03sem002&000007&2003/03sem002&ARTME&SME&

http://www.sme.org/cgi-bin/get-mag.pl?&&03sem005&000007&2003/03sem005&ARTME&SME&

http://www.sme.org/cgi-bin/get-newsletter.pl?SIGMA&20070129&1&

http://www.semizone.com/product-file/22/sixs1522/overview_notes.pdf

lean manufacturing & six sigma: a short introduction

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