Tài liệu Six SigmaLean Six Sigma brings together two business improvement methodologies pot

Sigma, from the Greek letter σ, is used by statisticians to measure the variability in any process; so the performance of an organisation can be assessed by the sigma level of its busine

Chapter 2: Six Sigma

Lean Six Sigma brings together two business improvement methodologies: Lean and Six Sigma It unites the emphasis on cutting waste from Lean, with a focus on reducing variation from Six Sigma It is not entirely clear when or where this combination arose, although some identify the source as Michael L Georges’ 2002 book entitled “Lean Six Sigma: Combining Six Sigma with Lean Speed” Since its publication, the fusion of these concepts has evolved to become one of the world’s foremost business improvement techniques

What is Six Sigma?

Sigma, from the Greek letter (σ), is used by statisticians to measure the variability in any process; so the performance of an organisation can be assessed by the sigma level of its business processes Traditionally, companies have accepted three or four sigma performance levels as the norm, even though these processes create between 6,200 and 67,000 defects for every million opportunities Adhering to the Six Sigma standard generates only 3.4 defects per million opportunities

Companies operating at three or four sigma performance typically spend between 25 and 40% of their revenues fixing problems (Cost of poor quality later is covered later.) Those functioning at the Six Sigma level typically spend less than 5%

The term Six Sigma process comes from the notion that if there are six standard deviations between the process mean and the nearest specification limit, as shown in the graph below, practically no items will fail to meet specifications Should there be a Four Sigma process, many items will fall outside the specification

Six Sigma is used to ensure a product or service is as good as it can Measuring the Six Sigma level of a process is a key part of this process It can be linked to customer assessments to develop a baseline from which improvements can be implemented and measured If the level of variation in the product or service can be reduced, this will cut costs for both the company and the customer, as performance moves towards the optimisation point

Six Sigma is applied in a number of phases that follow the DMAIC structure This acronym stands for Define, Measure, Analyse, Improve and Control In each of the phases, a number

of tools are used to assess quality All Six Sigma projects follow the DMAIC path

1 Define the goals of the improvement activity

2 Measure the existing processes and systems

3 Analyse the system and measures to understand how the process works

4 Improve the process

5 Control the new process

One of the central concepts of Six Sigma is that the output of any process or service is directly related to the input This is represented by the following equation, where Y is output and X is input:

Y = f(X)

Six Sigma tools and techniques are used to understand what the inputs are and how they influence the output The organisation can then focus on those inputs that have the biggest impact to reduce the variability and defects in the outputs

As well as reducing variations and defects, the aim of Six Sigma is to ensure processes meet customers’ requirements The chart below summarises this:

Six Sigma definitions:

• A management-driven, scientific methodology for product and process improvement that creates breakthroughs in financial performance and customer satisfaction (Source: Motorola.)

• A methodology that provides businesses with the tools to improve the capability of their business processes This increase in performance and decrease in process variation lead to defect reduction and improvement in profits, employee morale and quality of product (Source: ASQ.)

History of Six Sigma

Six Sigma is the name for a collection of tools and techniques that have their origins in a wide range of improvement and statistical analysis methodologies In many ways, Total Quality Management (TQM) was seen as the forerunner to the Six Sigma approach The TQM approach was developed by many notable business thinkers, including Deming, Ishikawa, Crosby and Juran At the core of TQM was the principle that everyone in the organisation should be focused on improving processes, products and services to raise the level of customer satisfaction

The father of Six Sigma is Bill Smith, who developed it while working for Motorola In

1986, he brought together a number of concepts, tools and approaches into the Six Sigma methodology The drive to improve the quality of products and services at Motorola had started many years earlier

During the early 1970s, Motorola produced televisions under the brand name of Quasar However its products were consistently being beaten by Japanese companies in terms of cost, quality and price In 1974, it finally admitted defeat and sold the factory to Matsushita, a Japanese producer of televisions under the Panasonic brand

Matsushita immediately went to work on improving the quality of the product made in the factory by reducing variations and defects In a short time, they were producing televisions with one twentieth the number of errors produced when Motorola ran the factory; despite using the same workforce, technology and designs This supported increasing sales and revenue, and reducing costs This was a massive wake-up call for Motorola; why could the Japanese management make such a massive difference when using fundamentally the same inputs When the then President and Chief Executive Bob Galvin asked in a meeting: “What's wrong with our company?”, many staff at the meeting gave a number of politically correct but predictable answers Until Art Sundry, a sales manager, famously stood up and shouted: “I'll tell you what's wrong with this company our quality stinks!"

Bob Galvin did not accept this assertion at face value He went to end users and customers

to ask them about their experience of his company He found that the market had moved on; competitors were making similar products that were more reliable and of a better quality at a lower cost He realised radical change rather than slow step-by-step evolution was required

Motorola set out a path for improving many aspects of its business, including the quality of its products This culminated in the development of the Six Sigma approach by Bill Smith, which was presented to, then championed by Bob Galvin He gave Bill Smith the mandate

to make the Six Sigma approach to quality the core of Motorola’s new culture

During the 1990s Six Sigma became more widely known and used In the mid-1990s, General Electric (GE) and Allied Signal developed Six Sigma programmes GE saved $12 billion over five years and Allied Signal has recorded over $800 million in savings since

1995

Chapter 3: Lean

What is Lean?

A Lean organisation understands customer value and directs its key processes on continuously increasing it The goal is to provide perfect value to the customer through a zero-waste creation process

To accomplish this, lean thinking changes the focus of management from optimising separate technologies, assets, and vertical departments to optimising the flow of products and services through the value stream

Eliminating waste along entire value streams, instead of at isolated points, creates processes that require less human effort, space, capital, and time to make products and services, at less cost and with fewer defects compared with traditional business systems

As a consequence, companies are able to respond to changing customer desires with high variety, high quality, low cost, and fast throughput times Also, information management becomes much simpler and more accurate

Lean manufacturing is underpinned by the five following principles:

1 Determine what is value for the customer

2 Identify the key steps along the process chain

3 Make the process flow smoothly

4 Drive the process by the customer ‘pulling’ value

5 Strive to continually remove waste

Lean definitions:

• A methodology that improves operations and the supply chain with an emphasis on reducing wasteful activities

• A practice that considers the expenditure of resources for anything other than creating value for the customer to be wasteful

History of Lean

Lean has its roots in the Toyota Motor Corporation’s production methods In response to the external challenges that were putting the future of the company in the balance, it developed a new way of making vehicles that would eventually see the company become the world’s biggest car manufacturer

The car industry is a good example to show the development of the Lean approach When cars first started to be produced in the 1900s, they were a bespoke product Designed and built individually by small groups of craftsmen, they were the preserve of the few that could afford their relatively high cost

As the twentieth century progressed, mass-production techniques were introduced into car manufacture Frederick Taylor was one of the first to apply science to engineering processes, developing a radical new system based around the separation of planning and production, where production was broken down into short repetitive tasks that required few skills This approach was outlined in his ground-breaking 1915 book, ‘The Principles of Scientific Management’

Henry Ford pioneered the development of mass-production for the 1908 Model T By standardising and reducing the number of parts in its engines, the manufacturing process could be vastly speeded up Parts were delivered to the production site and a moving assembly line installed

However, mass-production techniques also had some downsides Workers complained about the monotony and associated working conditions, and there was little sense of a shared purpose between workers and the company Quality was negatively impacted, with much checking and rework undertaken at the end of the production process

In 1950, Eiji Toyoda, whose family owned the Toyota car company, visited Ford’s Rouge plant in Detroit His company was in poor health and in danger of closing Following the end of the Second World War, a number of national initiatives meant demand for vehicles had collapsed In order for the company to survive, Toyota agreed a rescue package with the trade unions, whereby a quarter of the workforce was made redundant, the remaining employees received a guarantee of employment, and pay was graded according to seniority, experience and company profits One of the impacts of this change was that the workforce was now a fixed and not a variable cost; so the company had to get the most from its employees

On his return to Japan, Eiji Toyoda worked with production engineer Taiichi Ohno to develop a new production model for their company They decided that mass production was not the best way forward as it contained a lot of waste or ‘muda’, and so developed the Toyota Production System This was designed to reduce waste using the following approaches:

• A ‘pull’ system is used for the production process Products move through the process in a consistent way, avoiding bottle-necks Process steps are standardised and supported by visual management Where errors occur they are fixed there and then

• A continuous improvement culture is embedded throughout the process and the wider organisation

• People and teamwork are emphasised, with the organisation continually investing

in its workforce to improve and deliver benefits

• A long-term approach is taken over short-term quick wins

Ohno was critical of the Ford approach to production He felt that many of the specialist workers (foremen, specialist repairmen) added any value to the process; only assembly-line workers did this He also thought that those on the assembly assembly-line could do many of the jobs performed by these specialists and do them better

The initiatives that Ohno put in place with the Toyota Production System included:

• Grouping workers into teams with a team leader (not foreman) involved with production Teams are given sets of assembly steps and told to work together in the best way to get the job done

• Giving housekeeping tasks to the teams, such as repairs and checks

• Setting time aside for teams to suggest ways of improving the process

• Empowering workers to stop production to fix errors – eliminating reworking at the end of the line

Ohno also identified seven wastes that could occur within any process:

1 Over-production: processing too soon or too much than required

2 Defects: errors, mistakes or rework

3 Over-inventory: holding more inventory (material or information) than required

4 Over-processing: processing more than required

5 Over-transportation: moving items more than required

6 Waiting: employees and customers waiting

7 Motion: movement of people that does not add value

Deliverables of Lean Six Sigma

Lean Six Sigma is a fusion of the two approaches; the Lean element reduces waste, while the Six Sigma element focuses on the customer, and looks to reduce defects and variability in the process

When examining current practices, it uses the Lean tool of value stream mapping to analyse the process and the DMAIC framework to structure the review

[Does this need a little more work? A bullet point list of the ‘deliverable’s – outcomes, results benefits of Lean Six Sigma?]

Chapter 4: Selecting and Managing Lean Six Sigma Projects

The process for selecting a Lean Six Sigma improvement project will vary for each organisation For those organisations where Lean Six Sigma is firmly embedded and has the backing of senior management, existing tools and techniques (used to measure processes) will identify when a project is required to reduce variations or defects in a process and illustrate the benefits of delivering the project

The aim of the project should be to reduce the costs to the business and customers, and move the process closer to the optimisation point Projects should be selected that will help move the business closer to this point In order to fully embed the principles and benefits of Lean Six Sigma, it should be aligned with the implementation of a continuous improvement culture throughout the organisation Key data linked to improving products and services, such as customer assessments, should be collected and analysed on an ongoing basis

However, in other organisations Lean Six Sigma may yet not be embedded or may never

be Therefore, there may be a variety of reasons why a particular Lean Six Sigma project

is selected It could be because a senior manager feels the service could be improved and made more efficient Or there may have been a specific incident or error that points towards the process needing to be reviewed and improved In some cases, the motives for selection of a project may be as much political as business based

Organisations will choose Lean Six Sigma improvement project in different ways The most effective way is to select projects based on objective assessments to ensure they deliver real change and improvement for the organisation Outlined below is a project selection matrix showing the key elements that may be measured to indicate where a Lean Six Sigma project should focus

From this data, service area C would be the area to pick as the Lean Six Sigma project It has the lowest assessment from its customers, the second highest budget and sales falling

by 23%

There is no particular timescale for a Lean Six Sigma review Some books and guides say that a Lean Six Sigma review should take from three to six months However, as each organisation will undertake its reviews in a different way, it is not possible to define the length In many organisations, where the concepts of measuring and reducing customer and business costs to reach the optimisation point are ingrained in the organisation and are ongoing Where this approach is not present the standard three to six month timeline may be used as a guide

Project Charter

The project charter is a key element of any Lean Six Sigma project In many cases, it will

be the starting point or prompt for a project to be initiated Although it is completed at the outset of the project, it will be constantly reviewed and if required, updated as the project progresses

The project charter is the key link between two key players in the project; the project manager and the project sponsor The project manager is responsible for the delivery of the project Typically, in a Six Sigma environment they will be a Black Belt or a Green Belt that is being coached and mentored by a Black Belt The project sponsor has the authority

to authorise the project in the organisation They may be a managing director or service head and provide the project manager with the mandate to undertake the project

The project charter is owned by the project sponsor The role of the project charter is to provide the project manager with the authorisation to progress with the project It outlines the scope, aims, resources and timelines of the project These elements are agreed with the project sponsor and any amendments to them should be agreed and signed off by the sponsor

For every project, a project management plan should also be developed by the project manager This is more detailed than the one included in the project charter but is developed from the information included in it, such as resources and scope It will be managed by the project manager and the sponsor will only get involved in the plan, if it deviates from the terms set out in the project charter

Elements of the Project Charter

There is no one definitive project charter template Project charters have evolved and changed to meet the needs of different organisations However, below are some key elements of a project charter required for all Lean Six Sigma projects:

Project Title:

Outlines what the project is going to do

Project Team:

This should state all those people who will be involved in the delivery of the project The key roles where people are to be identified are:

• Project Sponsor

• Project Leader

• Team Members

Stakeholders:

All other people or roles that have a stake in the project should also be identified This may include the Six Sigma champion or Black Belt

Business Case:

This is an essential component of any project charter; it is the reason for the project being undertaken Without a sound business case the project should not proceed The business case explains the problem or issue that exists and why the project is being undertaken It clearly describes the purpose and justification for the project

This outlines the extent of the project and includes, such as services, departments and locations It may also show which processes are included and specifically excluded It will offer guidance to everyone involved in the project on what is covered in the review

Problem Statement:

In a Six Sigma organisation, the ongoing measurement of outputs through tools such as control charts and capability analysis will highlight when and where defects or variation are occurring The problem statement is a short sentence outlining the problem that the review is looking to resolve or improve It should explain what the problem is, how often it occurs and the impact

The statement should be ‘SMART’ – specific, measurable, achievable, relevant and time-bound – and should be tested against these criteria

Key advice for a typical problem statement includes:

• Keep it short

• Put a value on the problem

• Make it accessible – do not use jargon

• Refer to the scope of the project

Problem statement example 1:

From 20.10.2012 to 03.11.2012, 7% of all outputs from the chocolate-packing machine were oversized compared with the upper control limit of 3% This resulted in an extra cost to the business of £14,750 and a corresponding reduction in profit.

In many Lean Six Sigma reviews, the exact figures surrounding the problem statement will not be available Data such as the defect level and associated cost may not be derived until the measure and analyse stage

It may be the case that a Lean Six Sigma review has been instigated to improve the service

by reducing both the business and costumer costs Therefore the problem statement may quote a level of inefficiency or costs in the process that the review is tasked with reducing Again, this figure may not be identifiable until the measure stage has been completed An example of how such as problem statement may look is outlined below

Problem statement example 2:

It is estimated that up to X% of time and resources in X department comprises process waste and cost X organisation £X during the 2012/13 financial year.

Goal Statement:

The goal statement outlines the impact from undertaking the project It is a response to the problem statement and will outline how the problem will be resolved

As with the problem statement, it should be short and SMART The key elements required for the problem statement should also be present in the goal statement

Sometimes it may be difficult at the define stage to be specific about some of the measures represented in the goal statement In this case, an ‘X’ can be placed where the measurable will be and completed when this data is available

Goal statement example 1:

By 01.12.2012, the percentage of all outputs from the chocolate-packing machine that are oversized will be no greater than 3%, resulting in a saving of £25,000 for the remainder of the financial year.

As outlined above with the problem statement, the Lean Six Sigma review may not have derived from a specific problem but have been initiated to improve the service in general

An example for this scenario is shown below

Goal statement example 2:

Reduce the amount of process waste in X department by 10% during 2011, saving X organisation £X in efficiencies and cash savings.

Cost of Poor Quality Summary:

The Cost of Poor Quality (COPQ) refers to those costs to the organisation that are derived because there is poor quality in the way it operates For example, there may be some parts or roles in a production process that exist only because there is poor quality within the process, so the defective outcomes need to be identified and rectified

The problem statement will include the main cost of poor quality but there will be others Although this will be at the start of the project, all COPQs that currently exist in the process should be identified This information may be collected from ‘walking the process’ and speaking with staff involved in it

There are four different types of cost of poor quality:

1 Internal Failure costs: these costs occur before the product or service reaches the customer and so the cost is borne within the organisation

2 External Failure costs: costs associated with defects being detected after the product

or service has reached the customer

3 Appraisal costs: such costs are incurred in the process of ensuring that outputs from the process meet quality requirements This includes any systems, procedures or staff required to check outputs

4 Prevention costs: costs that are incurred in order to keep defects and appraisal costs

to a minimum It includes systems or procedures that prevent error

As the organisation moves through the DMAIC stages, the COPQs identified will highlight the benefits of reducing variations and defects These benefits will include both hard and soft benefits Hard benefits are those that can be measured financially, such as no longer employing a person to check outputs The soft benefits are non-financial, and include outcomes such as improved customer satisfaction and reputation

Key Customers:

Key customers of the organisation, process or service should be noted here Further analysis of these customers will be undertaken in the voice of the customer section

Outline Project Plan:

The key milestone dates for the project are listed here They should be developed with the help and assistance of some key stakeholders, especially the project sponsor It is important that the dates for the milestones are realistic and achievable

A template project charter is outlined below:

Project Charter

Project Title