Photo credit: Anne Hornyak

Visual Management Systems

What role do visual management systems play in achieving lean goals?  Their primary purpose is to make it very clear whether everything is performing as planned.  Lean uses the principles of standard work to deliver consistent quality and velocity from a process.  Visual control systems are put in place to easily identify any out of standard conditions so that they can be rectified as quickly as possible.  By reacting to these abnormal conditions quickly, and then preventing them happening again, it becomes possible to run a very smooth, efficient lean process and be cost effective.

Andon

One of the most well known visual management systems is Andon.  This is a visual system where workers have a fast, simple method for notifying management that there is a problem in the flow of production.  This can take the form of a button or cord pull.  Once the assembly line worker triggers the andon, an audible alert sounds to notify the relevant parties that there is a problem such as defects or part shortages.  The andon is also often linked to an electronic signboard.  The illuminated sign displays production status and makes it easy to see at a glance whether everything is running as planned.

This is a system that can be adapted for other fields.  For example, in the service industry, some open-plan call centres staff are supplied with “panic cards”.  During a difficult customer interaction, the staff member can raise their “panic card” and a manager or expert can come to assist.  It’s a useful, visual way of ensuring that resources are deployed to where they are needed.

Another simple example of an andon is the little red flag on US mailboxes.  These make it easy to see at a glance if any mail has been delivered.  The lights above checkouts in the supermarket are also a form on andon, used to get the attention of a supervisor without leaving the till unmanned.

Kanban

The kanban system, developed by Toyota, uses electronic signboards to show available stock levels at each part of the manufacturing process.  The numbers are color-coded, turning red when supply levels are reaching a critical point and allowing management to begin a stock refresh.

This is essential for Just In Time (JIT) manufacturing and helps promote the 5S lean practices in the workplace.  Obviously, it can be applied to any industry where there is a flow of tangible goods, such as manufacturing or retail.  There is also an opportunity to use it in other fields: to monitor customer demand in the form of phone calls or mail received, and measure it against available manpower resource.

The most useful kind of kanban is a live system which automatically collates information and displays it on an electronic signboard or large screen.  If you just need a quick win, or if you can’t implement this for budgetary or other reasons, it’s possible to find other solutions, such as monitoring demand in Excel or a similar package.

Systems such as these provide a reliable and instant system for responding to individual events.  For more long-term activity, you can drive the lean process by using visual management tools such as visual control charts and team accountability boards.

Common visual control charts include:

• 5S Scorecard: allowing teams to grade and monitor their adherence to 5S procedures.
• Results Metrics: keep these regularly updated to let your team know how they’ve succeeded, and what they need to keep working on.
• Strategic Planning Boards: provide a constant visual reminder of where your team is heading and how the journey is progressing.
• Lean Assessments: let your team know the wasteful processes that have been identified to date, making everyone aware of what needs to be done and providing the satisfaction of crossing items off as you reach your lean goals.

Team Accountability Boards are usually simple pinboards where the key metrics of your lean project can be displayed, and goals for individuals, managers and departments can be added as sticky notes.  This not only gives a simple visual cue for managing outstanding improvements, it also emphasises that this is a team project.  Teamwork is the key to a lean project, especially if you want the results to be sustained.  By having your team work together towards common goals, and using visual management systems to track progress, you’ll soon begin to eliminate waste and increase profit.

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Lean Maintenance Training Can Help Your Organisation in More Ways than One

Lean maintenance training will help you learn how to effectively eliminate waste in your projects and day-to-day facility maintenance operations.  A well designed program will teach you how to create a lean project from start to finish, how to develop strategies that instantly gain the support of top management executives and how to plan and execute a project that receives minimum resistance and maximum results.

If you want to learn how to uncover and eliminate unnecessary waste in your organisation and enhance your knowledge of lean maintenance a course may be just what you need.  People who have taken the course report they reduced their company’s operating costs and increased up-time while decreasing maintenance costs.

Successful graduates learn methods for uncovering waste, redesign procedures to increase productivity and are able to sell lean projects to management while delivering results quickly.  There are lean maintenance courses for all levels of maintenance personnel including managers, supervisors, maintenance workers and maintenance engineers.

You can transform your company from a traditional maintenance operation to a lean maintenance operation in less time than you think.  You can benchmark the performance of maintenance personnel directly within your organisation and across industries so everyone in the company is on the same page.

Who should attend lean maintenance training?  Most training workshops can accommodate the needs of supervisors, directors, controllers, engineers, superintendents and team leaders.  In fact, everyone in your organisation who is involved in maintenance, project management, plant operations management and engineering should take a course to increase the company’s output while decreasing or eliminating waste altogether.

The Importance of Total Productive Maintenance

In today’s modern manufacturing industry it is not uncommon to see complicated machinery that needs constant maintenance just to keep them running properly.  These machines are necessary simply because it’s nearly impossible to meet the demands of today’s marketplace without some sort of help from machines.

Machines help businesses accomplish more in less time.  They are accurate and the only thing they require is a little maintenance from time to time.  Proper maintenance is important if you don’t want a piece of machinery breaking down at the worst possible time.

One way businesses can deal effectively with this issue is to implement a Total Productive Maintenance (TPM) program for the all the equipment in the production area.  However, in order to effectively communicate this information to the front line and their immediate supervisors, it is advised to create some sort of presentation where everyone in the organisation is required to attend.

Each employee must understand that anything that prevents the machinery from operating properly has to be addressed as soon as it’s noticed.  A reduction in output can have a detrimental effect on a company’s bottom line so it’s important to implement a Total Productive Maintenance (TPM) program as soon as possible.  A good 5S program will also help to identify abnormal conditions such as oil leaks that impact machine uptime.

Finally, one of the most important things employees must learn is that the company’s machinery has to be inspected regularly, if not every day, so that it continues to function properly.  A well planned presentation can get the point across to everyone in the organisation at the same time so everyone is in the loop.

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OEE – Overall Equipment Effectiveness

Overall Equipment Effectiveness, or OEE, is a measure used to evaluate the losses in a production process.  It gives an indication of the utilisation of a manufacturing operation.

Calculating OEE

OEE is calculated by multiplying three factors together.  The three factors that are used in the OEE calculation are:

• Availability
• Performance
• Quality

The OEE calculation then is shown below:

OEE = Availability x Performance x Quality

Availability

Availability is a measure of downtime in a process.  The numerator for availability is the actual time spent running the process.  The denominator for availability is the scheduled time that the process should run.  Dividing the numerator by the denominator gives a percentage of uptime for the process.  If no downtime has occurred then the actual time and scheduled time are the same.  Dividing one by the other in this case, gives an availability of 1 or 100%.

If the actual time is less than the scheduled time then availability will be less than 100%.  Reasons for availability to be less than 100% include:

• Machine breakdown
• Startup losses
• Tooling changeovers
• Material Unavailable
• Operator Unavailable

Performance

Performance is a measure of speed in the process.  The numerator for performance is the number of actual units produced by the process.  The denominator for performance is the number of units expected based on the actual time that the process ran.  Dividing the numerator by the denominator gives a percentage of production against the designed production rate.  If the process has run according to the cycle time in the standard work, then the actual units and expected units will be the same.  Dividing one by the other in this case, gives a performance of 1 or 100%.

If the cycle time is not adhered to and less units are produced than expected, the performance will be less than 100%.  Conversely, if more units are produced than expected, the performance will be greater than 100%.  However, the latter would indicate that the cycle times used to determine the expected units are incorrect and need to be reviewed and updated.

Quality

Quality is a measure of the precision in a process.  The numerator for quality is the number of good units produced according to the design of the product.  The denominator for quality is the total number of units produced.  Dividing the numerator by the denominator gives a percentage of acceptable units for the process.  If no defects have been produced, then the good units and total units will be the same.  Dividing one by the other in this case, gives a quality of 1 or 100%.

If the number of good units is less than the total number produced, then quality will be less than 100%.  Reasons for quality to be less than 100% include:

• Damage
• Contamination
• Loose or overtightened parts (Torque)
• Leaks
• Missing parts or components
• Incorrect components fitted

OEE – Overall Equipment Effectiveness

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What is Lean Six Sigma?

In order to answer the question, what is lean six sigma, it is first necessary to understand the two constituent parts which are lean manufacturing and 6 Sigma.  These are two different business improvement methodologies that have become popular due to the many documented successful implementations.

What is Lean Manufacturing?

Lean manufacturing is a process improvement methodology based upon the highly acclaimed Toyota Production System (TPS).  The main focus in lean manufacturing is the removal of waste from a value stream.  Waste in this instance is defined as anything that consumes resource but does not add value for the customer.  By removing the waste in a value stream it becomes possible to only produce the right material, in the quantity desired by the customer, at exactly the right time.  This results in a process that is more efficient and delivers product to the customer more quickly.  The elements within a value stream that add value for the customer tend to represent a very small percentage of the total process.  Therefore focusing on removing the waste, or non-value adding elements represents a significant opportunity for improvement in many businesses.

 “Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.”

~ Antoine de Saint Exupery

A common method that is used to drive improvements is a rapid improvement workshop or kaizen event.  In such a workshop, a team will work through multiple iterations of the PDCA cycle to improve the process.  The PDCA cycle asks the following questions:

• What is the performance gap?
• What is preventing the target from being met? (5 Whys, Fishbone, Man/Method/Machine/Material)
• What are the root causes in order of importance? (Pareto)
• What countermeasures will prevent the most important causes from recurring?

Once these questions are answered, the team will make a Plan based on their hypothesis.  They will execute the plan during the Do phase.  The team then either confirm or disprove their hypothesis by performing a Check on the output of the process.

This process is often documented on a one-page or A3 report.  The A3 report serves multiple purposes such as documenting the status of the problem, a tool for reporting out to managers and is also useful for building consensus.

The emphasis in a lean workshop is rapid improvement to the process.  Often they can be less than a week in duration.  The operators from the shop floor are empowered to run these improvement events as they know the process inside out.

What is 6 Sigma?

6 Sigma is a popular quality improvement methodology made famous by the likes of Motorola and GE.  6 Sigma focuses on reducing the variation within a process.  The term 6 sigma itself, relates to a level of performance where only 3.4 defects are produced per million opportunities.  This is achieved by using careful measurement and statistical analysis to understand which ‘levers’ to pull to create the desired output.

Instead of the PDCA cycle, 6 Sigma relies on the DMAIC cycle which is used to fix problems with existing processes.  The five stages of the DMAIC process are:

• Define the opportunity
• Measure the baseline performance
• Analyse the root causes
• Improve the process
• Control the improved process to prevent regression

There are many possible reasons for variation in a process.  Examples include different operators, fatigue, different equipment, completing tasks in a different sequence, machine/tool wear, different raw materials, environmental changes (temperature, humidity, light etc).  6 Sigma aims to understand the influence of these variables so that they can be controlled to give more consistent, better quality outputs from the process.

Where a lean event might only last for a week, a typical 6 sigma project can typically last for up to 6 months.  They tend to be led by a project manager known as a 6 Sigma Black Belt.  The project team will be comprised of subject matter experts from each department within the business.

What is Lean Six Sigma?

Lean six sigma then is a methodology that looks to combine the best of both the lean manufacturing and the 6 Sigma approaches.  In particular the emphasis is on obtaining the benefits of both methodologies, whilst minimizing any potential weaknesses.  For instance, trying to take advantage of the velocity inherent in the lean method, whilst maintaining the statistical rigour of the 6 Sigma style.  Using a combination of both approaches, also opens up the number of tools and techniques available to solve any particular problem.

Further Reading

To find out more about Lean Six Sigma, check out The Lean Six Sigma Pocket Toolbook: A Quick Reference Guide to 70 Tools for Improving Quality and Speed
by Michael L. George, John Maxey, David Rowlands & Mark Price.

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5S Lean – Common Problems (And What You Should Do About Them)

Although 5S lean is generally considered to be one of the fundamental building blocks in a lean process, it is also, in my experience, easily misinterpreted and poorly implemented.  By exploring the problems with 5S, maybe we can address some of the underlying issues and produce better results in the future.

What is 5S Lean?

5S lean is a term used to describe workplace practices aimed at improving visual control in a factory and helping to reduce waste. The name 5S itself is based on the 5 Japanese words for the stages of the process which all start with the letter S. They are:

• Seiri (Sort)
• Seiton (Set In Order)
• Seiso (Shine)
• Seiketsu (Standardise)
• Shitsuke (Sustain)

The 5 stages of 5S Lean

Sort

The aim of this stage is to verify what is needed to complete the job based on the standard work. Anything that is not required should be red tagged and removed from the area. Material or tools that are used infrequently should also be removed and identified for local storage (ie not directly in the work area).

Common problems at this stage include:

• Not removing all unnecessary items (material, tools etc) from the work area.
• Not designating a red tag area.
• Not completing the red tags and/or documenting what was removed.
• Not getting approval to remove red tagged items from all 3 shifts.
• Not having an independent adjudicator to settle any disagreements.

Tips to avoid these problems:

• Train all operators in 5S and its benefits.
• Designate a safe area, large enough to store all of the anticipated red-tagged items.
• Explain the importance of completing the tags for recording purposes.
• Designate one team member to control the red tag area. They should not allow anything into the area unless it is tagged properly.
• Give all operators across shifts a chance to review what has been tagged.
• When a disagreement occurs, don’t compromise: if in doubt, move it out! That said, respect that this is somebody’s workplace and apply reasonable judgement when it comes to personal possessions. Better to allow them to feel like a part of the change than to disengage them completely.

Set

During the set phase of a 5S lean implementation, the team find locations for all of the remaining items after the red tagging. Anything that is left has been deemed necessary to do the job and therefore needs a storage location.

Common problems at this stage include:

• Not adhering to ergonomic design principles
• Not locating each part in the optimal position
• Not making it easy to return parts to their location
• Not using visual management principles

Tips to avoid these problems:

• Adhere to ergonomics guidelines
• Locate parts based on frequency of use. The more frequently it is used, the closer at hand it should be.
• Utilise spring balancers for tools, so the operator can just let go to return it to it’s location.
• Use labelling, colour coding and shadow boards to help any operator identify where things go.

Shine

The third phase of 5S lean is shine. This is where the team clean the work area and all the equipment, not only for the sake of cleaning, but also to inspect the condition of equipment.

Common problems at this stage include:

• Cleaning may have been neglected for a long time, meaning that a day spent cleaning by the team is not sufficient.
• People only clean what they can see.
• Belief that this is just cleaning for the sake of it.
• Belief that cleaning isn’t part of their job.
• Belief that this is a one-time activity / something to do when the line is down.

Tips to avoid these problems:

• Initially, it may be beneficial to get equipment deep cleaned by a specialist company.
• Train operators to clean above, behind, below, inside and around.
• Explain that the point of cleansing is to inspect equipment for any abnormal conditions, such as leaks. By doing this regularly, it is possible to reduce machine downtime and improve productivity.
• Explain that it is everybody’s responsibility to maintain a clean and tidy work environment. Putting the responsibility onto the people who work in the area makes them more likely to keep it tidy and take pride in their workplace. This also applies to management and office areas.
• Make 5S a regular part of everybody’s daily routine. Schedule 15 minute clean-up sessions at the end of every shift and include the maintenance team.

Standardise

The fourth phase of the 5S lean process is to standardise. This means taking the three previous stages and making them consistent across all areas of the factory. The benefit of doing this is that as operators move around different work stations, they know what to expect when they get there, where to find tools and work instructions etc. This reduces the time they spend acclimatising to the new station, ultimately making them more productive.

Common problems at this stage include:

• Islands of excellence – some areas deploy 5S better than others.
• Kaizen events only focus on one station which results in the rest of the assembly line not adhering to the standards.

Tips to avoid these problems:

• Use job rotation to get operators who are well versed in 5S to support areas that are struggling.
• Create a kaizen event schedule. Aim to get around all the stations as quickly as possible without sacrificing the quality of the results.
• Create simple checklists for operators to follow.
• Make 5S part of the new starter induction training. Explain that 5S is the way we work around here.
• Use consistent visual controls in the Set stage. Keep the colour coding consistent across the facility to avoid confusion.

Sustain

The fifth and final phase is sustain. This is the most difficult part and the one where most problems occur. Ideally, once the first four phases are complete, the team should operate in the environment and stop to fix any abnormal conditions that arise. These will be easily evident because of the standards established earlier on.

Common problems at this stage include:

• Losing focus on 5S after the team adjourns when the kaizen event finishes.
• New team members start and current team members move on.
• The 5S end of shift time becomes less disciplined and eventually stops altogether.
• Management get distracted by firefighting and neglect to enforce 5S discipline.
• Standards do not get updated as improvements are made, making them less relevant until they become ignored.

Tips to avoid these problems:

• Conduct regular 5S audits to uncover abnormal conditions.
• Conduct root cause analysis to determine why the abnormal condition occurred.
• Implement a countermeasure to prevent the root cause from occuring again.
• Implement layered audits so that the team leader audits the line. The supervisor then audits to check the team leader is completing their audits correctly. The manager then audits to check the supervisor is doing their audits correctly.
• Recognise the good behaviours that you wish to promote.
• Where necessary, use disciplinary procedure to enforce how important 5S is to the business.
• Involve everybody in 5S lean – make it part of the culture.

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What is 6 Sigma?

Answering the question what is 6 sigma can be difficult due to the large amount of literature on the subject.  Some authors focus on 6 sigma as a quality metric whereas others define it as a business management philosophy. Below are some examples:

Six Sigma has evolved to become very much an all-encompassing management tool for change and customer quality.

Six Sigma: SPC and TQM in Manufacturing and Services

Six Sigma: A comprehensive and flexible system for achieving, sustaining and maximising business success. Six Sigma is uniquely driven by close understanding of customer needs, disciplined use of facts, data, and statistical analysis, and diligent attention to managing, improving, and reinventing business processes.

The Six Sigma Way: How GE, Motorola, and Other Top Companies are Honing Their Performance

Six Sigma implies 3.4 defects or mistakes or errors or failures per million opportunities. Here Sigma is a term used to represent the variation about the average of a process. The focus of ‘Six Sigma’ is not on counting the defects in processes, but the number of opportunities within a process that could result in defects.

World Class Applications of Six Sigma: Real World Examples of Success

A disciplined method of using extremely rigorous data gathering and statistical analysis to pinpoint sources of errors and ways of eliminating them.

Six SIGMA: The Breakthrough Management Strategy Revolutionizing the World’s Top Corporations

Fundamentally, 6 sigma is a vehicle that allows a company to focus on their customers and to create competitive advantage through consistently reliable products. Originally it was simply a measure of quality, but since its creation over twenty years ago it has evolved into a business management philosophy. Drawing upon various subjects such as statistics, change management, project management and team-working, 6 sigma provides a disciplined, data-driven methodology of eliminating variation from processes.

What is 6 Sigma – The Metric

6 Sigma & Standard Deviation

In a perfect world, all the components to come off a production line would be absolutely identical and the variation in a particular characteristic (length etc.) would therefore be zero. However, in the real world, variation is inevitable and therefore the aim of 6 sigma is to reduce it as much as possible. In a process with a large amount of variation, the standard deviation (represented by the Greek letter sigma) is high. In statistical terms, that means that the data in a population is widely dispersed about the arithmetic mean.

6 sigma is a target used in quality. It refers to a process in which six standard deviations fit between the target value and the customer’s specified limits (LSL & USL) as shown on the left hand side of the diagram below. In order for six standard deviations to fit, the standard deviation itself has to be smaller than if say three sigma (right hand side of the diagram) was the quality goal.

Note that although it may appear that the entire process distribution is contained within the specification limits, this is not the case and is merely due to the constraints of the graphics package used. The distribution is positive for all values (-∞, ∞).

Essentially, the higher the sigma value the less likely it is for a defect to occur, because more of the process distribution is contained within the specification.

BENDELL, T. (2000). What Is Six Sigma? Quality World. January 2000 Issue. pp. 14-17.

This begins to explain the buzz surrounding six sigma. A typical process in a business would perform at a level between three and four sigma (according to World Class Applications of Six Sigma: Real World Examples of Success). A company achieving 6 sigma levels of performance will therefore have a significant competitive advantage.

Assuming that the statistical population is normally distributed, a 6 sigma process will produce a yield of 99.9999998%. In other words, out of every billion components produced, only two would be defective. Whereas, a 3 sigma process would produce a yield of 99.73% which equates to 2700 defects per million opportunities (DPMO). In 6 sigma the term defect is used to describe a value that falls outside the customers’ specification limits. An opportunity is defined as the chance of a defect occurring.

The 1.5 Sigma Shift

So far the values considered are defined as short-term capabilities – they do not represent what would happen over the long term. Motorola determined from years of data collection that processes drift over time. They called it the long term dynamic mean variation. Although it tends to vary between 1.4 and 1.6 standard deviations, the convention in 6 sigma is to use the value of 1.5 to adjust sigma scores.

So why do processes drift over time? One way to answer this question is to consider a 6 sigma project. Immediately after it has been implemented, the sigma level can be calculated but it will only be relevant to the short term. The reason for this is that the data collection during the project is likely to have occurred over a very short period of time and therefore the experience base is limited. This means that the data will only account for what is known as common cause variation, that is, variation that is predictable probabilistically. However, over the long term, it is likely that variation will occur outside of the historical experience base. This variation is completely unpredictable and is commonly known as assignable or special cause variation. Considering a CNC machining process as an example, common cause variation could be due to normal wear and tear of the tool, whereas a power surge or computer crash would be an assignable cause. Because short-term data does not contain this special cause variation, it is likely to show less variation, indicating better performance. This difference is the 1.5 sigma shift.

In Six SIGMA: The Breakthrough Management Strategy Revolutionizing the World’s Top Corporations (2000), Harry & Schroeder write:

By offsetting Normal distribution by a 1.5 standard deviation on either side, the adjustment takes into account what happens to every process over many cycles of manufacturing… Simply put, accommodating shift and drift is our ‘fudge factor,’ or a way to allow for unexpected errors or movement over time. Using 1.5 sigma as a standard deviation gives us a strong advantage in improving quality not only in industrial process and designs, but in commercial processes as well. It allows us to design products and services that are relatively impervious, or ‘robust,’ to natural, unavoidable sources of variation in processes, components, and materials.

The reporting convention of 6 sigma is to use the long-term value, as this is what the customer experiences. Taking this long term drift into account means that a performance level of 6 sigma now only yields 99.9997% or 3.4 DPMO. The next diagram shows the distribution curve for a 6 sigma process. The blue curves are shifted by ±1.5 sigma and therefore more of the distribution falls outside the specification limits.

The following table compares processes performing at different sigma levels:

The next graph shows the distribution curves for processes performing at different sigma levels:

The advantages of achieving 6 sigma seem rather intuitive: reduced cycle times, lower costs and increased customer satisfaction. Six sigma is widely regarded as a world class level of performance and only a few companies have managed to achieve it.

What is 6 Sigma – A Business Process Improvement Methodology

Structured Application of Quality Tools

One of the main criticisms of 6 sigma is the fact that it is merely a fashionable new repackaging of old concepts:

Six Sigma presents absolutely nothing new to the quality field of defect prevention.

STAMATIS, D. H. (2000). Who Needs Six Sigma, Anyway? Quality Digest [Online]. May 2000 Issue.

Is there anything really new about the tools and methods of six sigma? No, the basic statistical tools such as experimental design and control charts have been around for years.

VINING, G. G. (2003). A Personal Perspective on Six Sigma. ASQ Six Sigma Forum Maga- zine. Vol. 2. No. 4. p 8.

However, advocates of the methodology are eager to defend these claims:

Some technical, but non-statistical topics are included, such as quality function deployment (QFD) and failure modes and effects analysis (FMEA). Thus, Six Sigma tends to combine traditional statistical tools with tools from other disciplines, such as engineering design (FMEA), organisational effectiveness, problem solving (mistake proofing, multi-vari), or quality improvement (QFD).

HOERL, R. (2001). Six Sigma Black Belts: What Do They Need to Know? Journal of Quality Technology. Vol. 33. No. 4. pp. 391-406.

Although Six Sigma’s tools and methods include many of the statistical tools that were employed in other quality movements, here they’re employed in a systematic project-oriented fashion through the define, measure, analyse, improve and control (DMAIC) cycle.

RAMBERG, J. S. (2000). Six Sigma: Fad or Fundamental? Quality Digest [Online]. May 2000 Issue.

Six Sigma relies on tried and true methods that have been around for decades. In fact, Six Sigma discards a great deal of the complexity that characterized Total Quality Management (TQM).

PYZDEK, T. (2000). The Six Sigma Revolution. Tucson: Pyzdek Consulting Inc.

What is new about 6 sigma therefore is the structured application of old tools in the DMAIC problem solving methodology.

There are many models which can be used to improve a process or solve a problem, many of which are based on the work of Shewhart. His PDCA cycle consisted of four steps, Plan-Do-Check-Act. Deming improved upon this with his PDSA cycle, Plan-Do-Study-Act. DMAIC is a further progression of the cycle.

The DMAIC Cycle

Once a company has identified an opportunity that requires improvement by a 6 sigma project, the DMAIC cycle begins. For more information on the application of the DMAIC process check out this post.

Through the use of the DMAIC process, we can answer what is 6 sigma, by saying it is a structured application of statistical and quality control tools, many of which are derived from earlier quality management strategies.

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Lean Manufacturing Tools

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What are Lean Manufacturing Tools?

Many of the lean manufacturing tools have increased in popularity as a result of the recent growth in lean deployments in both manufacturing and transactional environments.  Like many other business process improvement methodologies, lean manufacturing has a wide range of tools associated with it.  Some of them are more conceptual: guiding principles if you will, whereas others are tangible devices that support lean production.

The following post will explore a number of the popular lean manufacturing tools and explain the basic premise.  This is not intended to be an exhaustive review.  Think of it more as a glossary – use it to see which tools and techniques fit your particular need and then explore those topics further.  Over time we will be adding links from this page to more detailed explorations of each of the subjects.

Enter the Lean Manufacturing Tools

Pull Replenishment

Pull replenishment is a method of production control that aims to reduce the waste of overproduction.  The aim of a pull system is to deliver the correct quantity of material, only when the downstream activity signals that it is ready to receive it.  This applies to both internal material replenishment between a stores area and an assembly line, and to extended value streams between suppliers, manufacturers and customers.  By only producing what is consumed by the customer, pull replenishment prevents inventory accumulation between processes.  This is in contrast to a more traditional push strategy that controls production based on a forecast, where build ups of stock and work in progress are common.

Continuous Flow

This refers to a state in which material and information moves seamlessly from one activity to the next.  It is also sometimes referred to as one piece flow.  In order to achieve continuous flow, all elements within a process need to operate efficiently and be balanced.  If there is an activity in the process where the cycle time is significantly longer than for the preceding activities, a bottleneck will be created.  Inventory will accumulate before this activity and it will soon become overburdened.  Creating continuous flow then is about balancing the cycle times of the process to match the pacemaker activity.  This should then also be matched to the Takt time – the rate of customer demand.  Where continuous flow is not possible, an inventory buffer called a supermarket is often used.  This can be useful where two processes are geographically isolated for instance.

Standard Work

Today’s standardization… is the necessary foundation on which tomorrow’s improvements will be based.  If you think of ‘standardization’ as the best you can do today, but which is to be improved tomorrow – you get somewhere.  But if you think of standards as confining, then progress stops.

~ Henry Ford

Standard work is a lean manufacturing tool that is used to define and document the best known method of performing an activity.  By performing a task in the same manner repeatedly, variation can be reduced leading to consistent quality for the customer.  The standard work document explains all the elements that must be carried out in order to complete the task.  It also documents the sequence in which they should be carried out, how long each element should take, any key points to watch out for and which tools should be used.  The intent is that the task should be performed consistently regardless of who conducts it.  By making the standard clear, it becomes easy to spot when an abnormal condition has occurred and therefore much easier to rectify.  The standard work however is only the best current method for doing a job.  If an operator discovers a more efficient, consistent or safer method to complete a task, then that becomes the new standard.  This can then be taught to other operators so that everybody benefits from the new standard.

…Highly productive efficiency has been maintained by preventing the recurrence of defective products, operational mistakes, and accidents, and by incorporating workers’ ideas.  All of this is possible because of the inconspicuous standard work sheet.

~ Taiichi Ohno

Heijunka

“Heijunka” is a Japanese term that means levelling the load.  By studying the variation in customer demand it is not uncommon to find that volume varies from one day to the next.  The mix of product may also be inconsistent.  This is typical of batch production where one part is run for a period and then switched over to another.  Heijunka seeks to level the variation by creating small but frequent withdrawals.  This can be measured by the EPEx metric which monitors how often every part is produced e.g. every part every week, every part every day.  These smaller, more regular withdrawals can insulate the manufacturing process, by moving the variation to the end of the process as finished goods inventory.  The production process then replenishes the finished goods supermarket as consistently as possible, while the buffer level in the supermarket absorbs the variation in actual customer demand.

5S

5S is a discipline used in lean manufacturing to improve the workplace.  The term 5S refers to the five stages, which all begin with the letter S:

• Sort
• Set
• Shine
• Standardise
• Sustain

Thorough 5S ensures that everything has a place, and that everything is in it’s place.  It makes it easy to spot out of standard conditions such as oil leaks on a machine, or a missing tool for instance

Another associated term used with 5S is red tagging.  This is a process where labels or tags are applied to items that are no longer required in an area.  This happens during the Sort phase of 5S.

Five Whys

The five whys is a questioning technique used to find the root cause of a problem.  When the problem is stated, the question “Why?” is asked a minimum of five times to try and drill down past the symptoms of the problem to the underlying issue.  The root cause is the one that, if addressed, will prevent the problem recurring.  Five whys is often used during a PDCA lean process.

Value Stream Mapping (VSM)

This is a simple, graphical representation of the process, suppliers and customers involved in a value stream.  Usually a current state map is created first by walking the process.  The author captures the material flows and also the information flows.  They also record any wastes that they observe, such as overproduction or excess inventory.  A future state value stream map is then created showing how the material and information should flow if all the issues identified in the current state get fixed.  It is recommended that value stream maps are hand drawn in pencil to avoid over complicating them.

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What is a Value Stream Map

A value stream map is a tool that is used in lean manufacturing to document and analyse a business.  The technique originated at Toyota, where it is called material and information flow mapping.  The value stream map represents the business processes from wall to wall.  Sometimes this is known as the order to delivery process.  This covers everything from receipt of an order from a customer, through procurement and production, to delivery of a finished item.  The value stream map (VSM) is used to identify waste at the value stream level, such as excess inventory or transportation.

The value stream map captures the process as a snapshot in time.  Obviously as the processes run, the inventory levels will change as transactions occur. However, the value stream map is enough to highlight where the problems are.  In order to do this fully though, there are four elements required in the value stream map.

The 4 key elements of a Value Stream Map

Customer

The first thing to draw on the value stream map is the customers.  Always start value stream maps at the shipping area and work upstream.  As well as drawing the customer symbol on the map, include a data box which shows the customer’s demand.  This can then be used to calculate the Takt time.  This tells the company how often they need to produce a unit to keep up with customer demand.  This becomes important when compared to the cycle times of the processes in the product flow.  Straight away, if a cycle time is greater than the Takt time it indicates a bottleneck or constraint process to be dealt with.

Supplier

Next draw on the suppliers.  It is not necessary to draw every individual supplier on the map.  Sometimes it is more efficient to just include one of each type of supplier.  This could be by geographical region (for instance, capture each of an American, European and Asian supplier) to at least cover the major flow paths of inbound material.

Product Flow

The product flow shows how material is moved through the process.  How do the purchased components or raw materials transform into a finished good that can be sold to the customer?  Each part of the production routing is captured here, whether they are fabrication areas, machining centres, assembly workstations or paint booths.  Each process box is accompanied by a data box that details information about that process such as:

• cycle time
• changeover time
• uptime
• # shifts
• # operators
• # available time

Information Flow

The information flow governs the product flow.  This documents how the process is controlled.  Key areas to consider at this stage are:

• How do we get demand from each customer?
• How do we send schedules to our suppliers?
• How do we plan our production processes?

Further Information

For more information on Value Stream Mapping, check out Learning to See: Value Stream Mapping to Add Value and Eliminate Muda (Lean Enterprise Institute)
by Mike Rother & John Shook.

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photo credit: ElbtheProf via photo pin cc

What Is Waste?

There are 7 wastes of lean manufacturing that are commonly referenced.  Before considering these 7 types of waste though, it is important to consider what is meant by the term waste.  Waste can be defined as any activity that consumes resources but creates no value for the customer.  It is an activity that the customer is not willing to pay for.  Within most business processes, the activities that actually create value as perceived by the customer make up a small percentage of the total activities.  Reducing the number of these wasteful activities represents a significant opportunity for businesses to improve their performance.  Elimination of the 7 wastes of lean can reduce costs, increase profits, improve employee engagement, reduce rework and improve delivery time.

Muda.  It’s the one word of Japanese you really must know.  It sounds awful as it rolls off your tongue and it should, because mud a means “waste,” specifically any human activity which absorbs resources but creates no value: mistakes which require rectification, production of items no one wants so that inventories and remaindered goods pile up, processing steps which aren’t actually needed, movement of employees and transport of goods from one place to another without any purpose, groups of people in a downstream activity standing around waiting because an upstream activity has not delivered on time, and goods and services which don’t meet the needs of the customer.

Lean Thinking~ James P. Womack & Daniel T. Jones

The 7 Wastes of Lean Manufacturing

Waiting

Waiting is perhaps the most obvious of the 7 wastes of lean manufacturing.  It is easily identifiable as lost time due to poor flow: parts shortages, bottlenecks, and equipment breakdowns.  In an office based environment, this may take the form of slow software loading times or waiting for an important phone call.  This is also frustrating for the employees involved, which can lead to reduced morale.

Over Production

Over production is the most important of the 7 types of waste.  It is building more of a product than the customer ordered or wanted.  Remembering that waste is anything for which the customer is not willing to pay, it is easy to see why over production is a waste.  However over production actually drives all of the other six types of waste as well.  The excess product now has to be stored somewhere which means excess motion, transportation and inventory.  Also, over production means that if a reject is found, there will be more units that need to be reworked.

Rejects

Parts that do not comply with the specifications of the customer lead to rework.  Worse still they can lead to scrap and the necessary production of new parts.  Usually, rejects have to be sent back down the production line again to be put right.  This consumes valuable production time.  Sometimes a separate rework area is required, which increases labour and duplicates tooling.

Excess Motion

This is wasted movement that is made while working.  It could take the form of having to walk to another area to collect a tool, part or document.  It also covers searching for things in a messy environment.  A classic example is sorting through piles of paperwork to find the one form required at that moment to complete the job.

Over Processing

This is work that adds no value for the customer or business.  This usually takes the form of over engineering a product: unnecessary features that the customer does not use, but that increase the cost to the business.  This could be maintaining paint finish or other tolerances, more tightly than is required by the customer.  Another example is building a product that will last for five years when the customer is going to replace it after two.

Excess Inventory

Excess material, work in process or finished goods.  Excess inventory represents cash tied up in the form of material, which is difficult to turn into cash quickly.  Inventory also takes up space.  It has to be managed, stored and can become obsolete leading to scrap.   The quality of inventory can deteriorate over a period of time, especially perishable items such as food or rubber seals.

Transportation

Unlike excess motion which is wasted movement of people, transportation is excess motion of work in process.  This can be at the process level or the value stream level.  At the process level, excess transportation can be having machines too far apart so that parts need to be moved on a fork lift truck.  At the value stream level, excess transport can be moving finished parts or components between facilities and not consolidating the transport.

How to remember the 7 Wastes of Lean Manufacturing

There is a simple way to remember the 7 wastes of lean manufacturing: simply remember the rather silly acronym WORMPIT!

• Waiting
• Over production
• Rejects
• Motion (Excess)
• Processing (Over)
• Inventory
• Transportation

If you can remember WORMPIT, you can easily use each letter to recall the 7 wastes of lean manufacturing.

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The DMAIC Process

Today I want to talk about the DMAIC process which is another process improvement cycle other than PDCA.  The reason for this is to explain some of the differences and hopefully allow you to distinguish between which is the best approach for any given business problem.

The DMAIC process is not really a lean method, it comes from six sigma.  Six sigma is a quality improvement methodology focusing on reducing variation in processes that was made popular by Motorola.  The DMAIC process is an acronym of the five stages:

• Define
• Measure
• Analyse
• Improve
• Control

The DMAIC process is used within six sigma to fix a problem with an existing process.  This is different from DMEDI which is used for a problem where a process does not exist.  DMEDI stands for Define, Measure Explore, Develop, Implement.

To determine if DMAIC or DMEDI is the correct methodology to use, answer the following question for the problem in question: does a process exist currently?  If the answer is yes, then DMAIC should be used.  If no process exists, then a new one should be developed using DMEDI.

So having established that you have a process that is not performing satisfactorily, then you could potentially use the DMAIC process to fix this.  We will now consider each of the five phases in turn.

The Define Phase

The define stage is used to clarify the business opportunity and launch the project. In it the team will create a project charter which details:

• the problem statement,
• the goal or end deliverable,
• the financial impact the project can have by solving the problem,
• the scope of the work (what is included & waht is not),
• the team members and stakeholders,
• a timing plan or Gantt chart.

Another tool used at this stage is the business risk assessment.  The purpose here is to identify and manage any risks that arise by carrying out the project.  This ensures that the project is more likely to be successful.

The Measure Phase

The measure phase is primarily about data collection and process mapping.  In it we develop a measurement plan and operational definitions (eg if we asked ten people to count all the blue cars in a car park, how many answers would match?  It would depend on people’s definition/judgement of the term blue car.)

It is also important to set a baseline before any changes are made.  That way we can later measure the impact the project has made on the process.

However, another purpose of the measure phase is to validate the measurement system.  This is usually done via a Gage R&R experiment.  This basically checks whether the variation being measured is truly as a result of the process being observed, or whether there is significant variation being introduced by the measurement process (eg different people measuring different ways, or inaccurate measurement equipment).

The Analyse Phase

Having established a baseline level of performance for the process in the measure phase, it is now time to try to understand why it is the way it is.  What factors are causing the performance to be the way it is.  The team will try to identify the root cause of the problem – this is the cause that when eliminated will cause the problem to never be repeated.  This can be done using Ishikawa diagrams and/or 5 whys.  It also often takes on a statistical element using regression, Pareto, ANOVA and DOE.  A hypothesis is formed about the cause and tested.  If the test confirms the hypothesis is correct then the project moves to the improve phase.  If however, the hypothesis is rejected then further analysis is required.  It is not uncommon for a project to iterate between the measure and analyse phases while the team get to learn the process.  Often the analysis highlights a gap in the measurement plan so it becomes necessary to go back and make further measurements.

The Improve Phase

By the time they reach the improve phase of the project, the team should have a thorough understanding of the process being studied.  The improve phase is used to tweak the critical few variables that were identified in the analyse phase, with the aim of reaching the desired output.  Often in a six sigma project, this is about reducing variation in a process to give consistently high quality.  It is also about achieving maximum results with minimal resource by adjusting the critical few variables that have the most significant impact.  By the end of the improve phase, the process should be fixed and performing at an improved level over the baseline established during the measure phase.

The Control Phase

Now that the process is performing as expected, it is time for the project team to hand the process back over to the business owner.  However, it is not uncommon for the results achieved by the project to not be sustained by the new owner.  Therefore the control phase becomes one of ensuring that controls are in place to prevent the performance regressing.  These can take various forms, but common approaches include audits, standard work instructions, poka yoke devices and control plans.

What is the major difference between PDCA and DMAIC?

In theory, both the PDCA and DMAIC process can be used to fix existing business problems.  In practice however, they differ in how they are deployed.  A six sigma DMAIC project is usually run by a team of trained employees called black belts and green belts, who then hand it over to the process owners.  A PDCA cycle on the other hand is usually conducted by the team who perform the process concerned.

The DMAIC process also tends to use statistical methods to model a business problem.  The statistical solution to this model is then applied back to the business.  In other words, a lot of the analysis in six sigma tends to be theoretical.  In a lean process however, the approach is much less theoretical and more experimental.  The focus is more on using hypothesis testing to find out what works and to implement quickly.  This does not mean that PDCA is guess work though – the hypothesis are formulated based on employee knowledge and experience.

Another key difference is in the time to deploy.  A lean focused PDCA effort will typically aim for resolution in hours or days, whereas a six sigma project can often run for 3-6 months.

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