Poka Yoke Archives - 6sigma

Poka-Yoke: Is Mistake Proofing a Reality?

OpEx Learning Team — Fri, 28 Feb 2025 06:04:02 +0000

Is A Mistake Free Environment Possible?

Wouldn’t it be grand to have a process that runs ‘mistake proof’? For most, the idea of a mistake proof environment is business heaven. The real world tells us that mistakes and errors are all part of life and business. The idea is to have processes and procedures in place that reduce or eliminate mistakes. Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or process that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred. This is a method at the disposal of Lean Six Sigma practitioners to reduce and eliminate errors in process and procedures.

The Elements of Poka-Yoke

Like with any other tool in Lean Six Sigma, there are some steps you need to follow to get the most out of mistake proofing your projects. Here are the 7 steps that are crucial for implementation of mistake proofing:

Create a flowchart. Think about where errors will occur.
Identify the source or origin of each mistake.
Identify ways to prevent the errors from occurring.
Consider mitigation methods for errors that cannot be eliminated.
Identify the best method for mistake-proofing the process or device.
Inspect for errors by setting functions.
Set signals that alert workers for errors with regulatory functions.

Factors to Consider With Poka-Yoke

We sometimes depend on inspections conducted by workers to be fail safe for mistake proofing. While this does have some validity, humans are flawed and naturally prone to errors, even to the smallest degree. We can overcome these inspection defects through automation of the process. Automation will not accept a defect in the process, or create a defect in the process, or allow a defect to be passed to the next process. As with any other process, you must consider the cost of implementing poka-yoke mistake proofing methods. When determining the value of poka-yoke, you then must consider these expenses vs. the financial impact of defects reaching your customers.

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In Other Words, It’s the Language of Six Sigma

admin — Mon, 14 Oct 2019 20:25:14 +0000

Every industry has their special words or expressions that are exclusive to them. Mere mortals usually don’t understand what the industry specific jargon means. Well, Six Sigma wants all industries to be part of the Six Sigma family, so we are reviewing some of the special words, expressions and acronyms to make sure everyone is included.

Process: This is the day-to-day activity that must occur to produce a product or service.

Process Map/Flow Chart: This a chart that visually shows the series of steps, describes the steps and who does them to produce a product or service. This will show the flow of the process(s) or events that has to happen to produce a product or service.

SIPOC: Stands for Suppliers-Inputs-Process-Outputs-Customers. This is used to define a process from beginning to end.

PDCA: Plan-Do-Check-Act. This is an improvement methodology that is quite easy to use and very effective.

Output: This is what is produced by a process step, the result.

Affinity Diagram: This is a tool to organize ideas and data into priorities and categories.

Benchmarking: This is used to set a standard by comparing a set of business processes and performances to the industry’s best practices and seeing if there is a gap that can be fixed.

Defect: Anything that isn’t done right the first time.

Defect Opportunity: Any task or activity that can be measured that does not fulfill the requirement for value.

Poka-yoke: Mistake proofing. This is an action you take in Six Sigma to significantly lower the opportunity for error so much so that the customer never experiences the error.

Input: This is a resource added by a supplier to the process; this can be a product, service, data, even labor.

For more information on our Lean Six Sigma courses and services please visit 6sigma.com.

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The Three Methods of Poka-Yoke

admin — Mon, 01 Jul 2019 21:11:35 +0000

This sounds like a game you play, but the term poka-yoke is really a Japanese term and it means “mistake-proofing.” As a quality tool, the concept behind it is that everyone makes mistakes because we are all human. Poka-yoke either eliminates or at the very least greatly reduces the opportunity for us to make a mistake. This action will instantly reduce defects that stem from mistakes. This action will make the day-to-day processes run smoothly with decreased time, and this alone will make manufacturing cost less money and improve the quality of the product.

Here are the three methods to know:

The Contact Method: This method will physically put a deterrent using the shape, size or color of the item. For example, if one constant mistake is that a part is placed upside down on the product, the design is altered so that the only way to place the part is the correct way because it only fits if placed correctly. This could include a switch that limits or prohibits incorrectly installing parts.
The Constant Number Method: This could also include a fixed number of parts used. If a set number of movements are not made, there is an alert. Another example would be that a certain number of parts are at each step in the process. If you have parts left over, that means something went wrong. All parents have experienced this at one time or another while building a bike or a piece of furniture for their kids.
The Sequence Method: A set amount of prescribed steps are in said process before the next stage is rendered. This could be boxed opening in a certain sequence, color coding, and tagging, and then inspecting to ensure that important steps were completed. The theory behind poka-yoke is if it can’t eliminate the chance of error completely, then there should be an immediate warning.

For more information on our Lean Six Sigma courses or services, please visit 6sigma.com.

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Applying Poka-Yoke in the Manufacturing Industry

OpEx Learning Team — Fri, 16 Feb 2018 13:00:46 +0000

Poka-yoke is a great way to improve the reliability of systems operated by humans, and minimize the error rate in their work. Of course, it’s impossible to prevent all types of mistakes completely, especially when it comes to ones out of malice but putting those aside, there’s actually a lot that can be done to make sure that the work done by everyone is safer and less prone to errors. The types of changes resulting from poka-yoke are typically small, but they stack up together and create a much more streamlined environment where everything simply works.

The manufacturing industry is, unsurprisingly, a major adopter of poka-yoke. There are many reasons for that, and it’s clear that this type of work can be simplified a lot by introducing small safeguards and other similar details, while also making it safer for everyone involved. There are indeed many examples of poka-yoke in various manufacturing plants, and one doesn’t have to look long to find plenty of successful applications.

Operator Safety

Various features in a modern manufacturing plant are designed to keep operators safe, either from themselves or from others. For example, many large-scale machines typically feature a box of keys for accessing their maintenance areas. An operator has to physically remove one of the keys from the box in order to enter, and the machine cannot run unless all keys are in place. This makes it impossible for anyone to accidentally start the machine while someone is inside doing maintenance work on it, as long as everyone follows the standard procedure when entering.

On a smaller scale, some machines make it physically impossible for an operator to hurt themselves by not paying attention or suffering an accident that incapacitates them. A common example of this are switches that have to be periodically triggered in order to identify that the operator is still paying attention. It may also be required to use the machine with both hands in order to ensure that the operator is in full control of it. It’s generally very common to see such safety systems in place at various factories around the world, as they do a great job ensuring that operators don’t cause any harm to themselves or others, and of course that they don’t damage the equipment.

Streamlining Work

Poka-yoke can also be very useful for making everyone’s jobs lighter and less demanding in terms of tiny details. This often comes down to various small details that allow people to shift their attention to more important parts of the job instead of having to mind tiny points all the time. Color coding structural elements and equipment is a common example of this, and it can be often seen in factories where workers are frequently required to use different kinds of tools and equipment, switching between them on a regular basis.

Another example that can be seen often is a standardized approach to equipment, such as containers and other commonly used pieces. This can allow workers to stop worrying about compatibility, and just focus on finding a piece of equipment that fits the current job. The cumulative effects this can have on the overall productivity at the facility can be quite impressive, and it’s one of the best ways to ensure that people don’t have to spend too much time minding unnecessary details about their work.

Last but not least, poka-yoke techniques can be very effective in ensuring that the final product is always error-free and it can significantly reduce the stress on the quality control department. Of course, this assumes that it’s applied correctly and without introducing too many details that workers have to observe. After all, the main goal of poka-yoke is to simplify things, not complicate them.

Conclusion

It should be common sense that the manufacturing industry is a common adopter of poka-yoke, and one doesn’t have to look long to find multiple examples of it in that area. We’re likely going to see that number growing even more in the near future, as companies are only now starting to realize the true importance of streamlining and standardizing their work, and mistake proofing as much as possible on the operator side. The cumulative benefits this can bring to the organization are quite significant over a longer term.

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Six Sigma and Business Analytics: Supply Chain Analytics

admin — Tue, 20 Jun 2017 19:31:51 +0000

Six Sigma is by far the most effective improvement methodology for production. Implementing Six Sigma can improve your production process in a multitude of ways. Six Sigma allows you to isolate and eliminate the variation and defect affecting your processes. It does this by minimizing process variance, driving continuous improvement through a project-based team effort. Numerous organizations use Six Sigma to eliminate process issues and reduce variation in their supply chains. This shows powerful a tool Six Sigma can be. One that you should not underestimate. Learn how you can increase efficiency and improve your supply chain using Six Sigma.

Make Order Fulfillment Times More Efficient

Don’t forget that DMAIC can help you define, measure, analyze, improve, and control problems in your order fulfillment process. Similarly, you can use DMADV to devise completely new processes that build on your Six Sigma improvements. Moreover, Six Sigma is an excellent tool with which to revise your order fulfillment system. Doing so allows you to assist project teams in detecting issues like variation or waste. You can then correct these inadequacies by reducing none-value-adding processes like excessive paperwork, plus time- and travel-based waste. Six Sigma aims to garner the best results by improving quality and efficiency. Furthermore, you can implement automated processes such as shipment planning and verification to improve your organization.

Reducing Error to Zero = Optimum Supply Chain

If you want to increase efficiency for your supply chain, you must first minimize error. Various stages in the supply chain can benefit from particular Six Sigma-compatible techniques. Poka-Yoke, for example, reinforces your processes against mistakes. It prevents human error by allowing no possible margin for error, forcing workers to complete the task per pre-established specifications. Similarly, the 5S strategy can also help you minimize errors by targeting waste and variation as they appear. 5S allows you to Sort, Set, Shine, Standardize, and Sustain your processes to create a streamlined, efficient environment for work.

Improving Order Fulfillment Processes

When a customer makes an order, they expect you to deliver on that order promptly. You should fill orders so that they arrive on time, with complete, accurate documentation, and absolutely no delivery-based damage. Six Sigma will help you optimize your order fulfillment by recognizing system problems like insufficient planning processes or poor execution.

Combine Lean with Six Sigma to Minimize Waste

Use Lean Six Sigma to drive gross market share and maximize your revenue. You can identify and eliminate none-value-adding activities like waste. Lean principles will increase functionality and efficiency of your supply chains to make them more responsive.

There are various types of waste Lean Six Sigma can treat. Firstly, over-processing, where you spend too long processing an item. This also leads to excess costs and wasted time. To solve this issue, you should increase your inventory only per customer demand. Speculative forecasting can lead to significant losses as your predictions don’t always pan out.

Moreover, unnecessary process stages add zero value to a product or service. If the customer wouldn’t pay for it, then get rid of it. Inadequate layout of your production facility will inevitably lead to losses down the line. By simplifying and streamlining your processes with Lean Six Sigma, your supply chain efficiency will reach optimum levels.

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Glossary of Six Sigma Terms: Letters P – R

admin — Wed, 26 Apr 2017 20:22:32 +0000

P

PERT.

Six Sigma Black Belts and Green Belts, when organizing schedules for large projects, will often use PERT to compile and plan their activities. PERT is a graphical method usually completed via computer. It stands for Project Evaluation & Review Technique. To use PERT, it is beneficial to have some experience of CPM (Critical Path Method) as they are similar processes. In PERT, a series of horizontal and diagonal connected lines represent your activities, with numbered nodes at key points standing for milestones. You should number each line differently, to represent the durations for each project task. PERT is used in process improvement to organize and plan timelines for the project. It is highly effective for scoping the duration of your work.

PEST Analysis.

A type of strategic approach, you can use PEST analysis to analyze your organization’s macro-environment. It is an acronym for Political, Economic, Social, and Technological. Using PEST analysis, you should run your company by each of these four areas to glean detailed information about their drivers and influences. Political should include a wide range of data. It should cover concepts like political stability, economic and taxation policies, as well as trading agreements and any other national or international concerns. Economic should shed light on your company’s interest rates, employment levels, economic trends, and GDP. While Social will allow you to analyze the religious influences (if any) affecting your company, as well as any population demographic factors, and other religious and cultural concerns.

Finally, Technology, the most wide-reaching of the four, will cover an array of subjects. Subjects like innovation, manufacturing costs, product quality, and the way technology affects marketing and distribution. The internet is a prime example of how technology has affected the business world. Six Sigma Black Belts and Green Belts may wish to use PEST analysis to learn more about the company on whose project they are working. It is a similar process to the SWOT analysis and Porter’s Five Forces analysis types.

Poka-Yoke.

Use in Lean Production, Poka Yoke is a device used by Lean practitioners to prevent error. When we make mistakes in production, they can often be costly and time-consuming to correct. Poka-Yoke was designed to simplify the correction process by immediately highlighting problems or making mistakes immediately clear. As an example, you could easily forget about a metal nut that requires tightening with a torque spanner. You may not realize you have left it loose. With Poka-Yoke, you could design a fixture that prevents the assembly line from moving until the torque spanner has recorded the correct torque. This could be automatic and relay information directly to a computer that will alert you something is wrong. That way, the error won’t cause further problems down the line and can be quickly.

Q

QS9000/TS16949.

First published in 1994, QS9000 is a type of quality system developed by Daimler-Chrysler, Ford, and General Motors. QS9000 is used most often in the automotive industry and in other types of manufacturing. While its designers reissued QS9000 in 1998, companies have started phasing it out, replacing it with an arguably superior system called TS16949. Although some organizations still use QS9000, it is likely to be completely replaced in the coming years. Large automotive companies like Ford rely on suppliers for their parts, materials, and services. Additionally, these services must comply with the principles of QS9000 if it is to be effective.

QS9000 is based on an older standard, ISO9000:1994, which many automotive companies often used as a baseline. It imposed extra requirements and interpretations in production but designers updated it to ISO9000:2000 at the Millennium. This new standard was significantly different to its predecessor. However, in recent years designers have modified it to create TS16949, as opposed to revamping QS9000. A series of manuals, developed by the AIAG (Automotive Industry Action Group), provided precise information about how organizations should operate by the TS16949 standard. Six Sigma practitioners working in the automotive industry will work alongside QS9000/TS16949 protocols while conducting quality improvement.

R

Randomized Block Design.

This is an approach to Design of Experiments, also known as Experimental Design. If you wanted to compare four cleaning products, you could use Randomized Block Design to make a realistic test to determine the best. In Completely Randomized Design, you would randomly allocate a series of dirty kitchen surfaces to volunteers with each cleaning product. This way, you could choose one product for up to all four surfaces. In a Randomized Block Design, however, you place a block on your surfaces. This means you would allocate only one surface from each volunteer to each product. Six Sigma Black Belts or Green Belts, when involved in Experimental Design or statistical analysis, may wish to use Randomized Block Design.

Robust Design.

A man named Genichi Taguchi pioneered the Robust Design concept, which forms the basis of the Taguchi Approach to Experimental Design. Taguchi stressed that reducing variation in design should be a core principle for process improvement. It was his belief that it’s better to create a product that provides consistently good results. This was in contrast to products that gave better results but were inconsistent. Taguchi called this idea the ‘robustness’ of design, and manufacturing companies utilize its principles all over the world. It is essential for Six Sigma and Lean practitioners to cultivate such robustness in process improvement.

Taguchi also created a quantitative model called the Taguchi Loss Function, which allows you to identify the lowest costing design easily. Building on his previous work, Taguchi came up with an approach for designing products with robustness in mind. His process has three stages. System design (using scientific and engineering principles to build a prototype). Parameter design (identifying the settings that will minimize variation for product and process parameters). Tolerances (setting tolerances that will control parameters and reduce losses).

Run Charts.

Six Sigma Belts use Run charts on process improvement projects. Green Belts, when conducting statistical work may choose to use run charts to plot data values in time order. Similar to a standard line graph, you have an X and Y axis, labeled according to your timescale and the data set with which you are dealing. Once you’ve plotted your data onto the graph and joined, you should draw a center line to show the median value. The run chart defines your run as one or more consecutive points of the same median. When you analyze the patterns, they will indicate a special cause, such as:

Too few or too many runs for a series of points.

Too many data points in your run.

An abnormally long sequence of rising or falling data points.

Too many points that form a zigzag pattern.

It is beneficial to be familiar with control charts, as run charts are similar, though they both possess important differences. While control charts are better at perpetually monitoring processes, run charts provide a better process with which to investigate opportunities for improvement. Six Sigma Black Belts or Green Belts may use run charts to assess their data when prioritizing their process improvement tasks.

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What Should be in a Six Sigma Master Black Belt Curriculum?

admin — Thu, 30 Mar 2017 15:55:39 +0000

Our Master Black Belt training lasts two weeks, going beyond traditional Black Belt skills to incorporate new tools. Training prepares MBBs through intensive study DMAIC letters M, A, I, and C. Master Black Belts encourage and support improvement strategies at all levels of Six Sigma hierarchy, in all areas, of an organization. They also deal with suppliers and customers, in addition to project teams and executives. But how do you design a curriculum to meet these goals?

Master Black Belt Curriculum

We believe Master Black Belt training should build upon already existing Black Belt training, expanding on the concepts delivered in their previous education. Master Black Belts will typically require two or more years of Black Belt experience (plus training), and five or more years of business experience. MBB’s previous work and expertise should inform their MBB training, building on their existing skills and knowledge base. Some areas of responsibility for Master Black Belts are as follows:

Leadership and people skills. MBBs will typically manage and coach Black Belts, Green Belts, Yellow Belts, and entire Six Sigma teams, while on the project floor. Furthermore, leadership and people skills are essential to building strong teams and professional relationships. Additionally, MBBs teach team members to deploy improvement tools and solutions, as well as identify areas that require attention.
Developing and implementing organizational metrics. Classical Six Sigma metrics include timeliness, accuracy, efficiency, workability of business and cost, as well as other measures of quality. Moreover, Master Black Belts should know how to select and implement appropriate metrics.
Creating, maintaining, and reviewing Six Sigma curriculums in classroom-based training. As Master Black Belts, you will be required to assess and deliver Six Sigma training programs, providing coaching and support for other Belts.
Networking is an essential skill for Master Black Belts to master, as it can open many doors for you when it comes to finding employment. Master Black Belts often work as consultants, an independent role that requires seeking out opportunities. Networking with other MBBs and Six Sigma practitioners will enable you to get the lay of the land. Likewise, MBB training should teach critical networking skills to build your network from the ground up. Maintaining strong professional relationships is important as an MBB, and training should support this.

Essential Master Black Belt Skills

DMAIC. MBBs should be able to use and teach DMAIC in the classroom and on projects.

Non-Parametric Analysis. When there are fewer assumptions to deal with, NPA enables MBBs to get a handle on their data.

Multi-Vari and Practical Experiments. MBBs will be expected to address multiple parameters and sources of process variation at any one time. Similarly, experience with practical experimentation is just as important.

Handling Attribute Responses and Optimization Experiments. Our MBB curriculum covers how to use Minitab to handle attribute responses and create optimization experiments.

Advanced Regression and SPC Methods. Regression alone is a difficult tool to use, and SPC can be just as tricky, but advanced methods are often required. Our MBB curriculum teaches several different ARMs and ASPCs.

Handling Multi-Response Experiments. We believe in going above and beyond Freeman-Tukey when it comes to MREs.

Distributional Analysis. We teach our MBBs to understand the far-reaching effects of policy programs and funding decisions.

SIPOC Diagrams. SIPOC diagrams identify key factors of process improvement projects before commencement.

Identifying CTQ (critical-to-quality) factors. Quality MBB training teaches how to draw CTQ trees. This enables MBBs to measure and display improvement efforts and align them with customer demands.

Statistical software training. Reliable, statistical data underpins all Six Sigma work. Our trainers teach MBBs how to use statistical software like Statgraphics, SigmaXL, and SPC XL.

Poka-Yoke. Mistake-proofing improvement measures will ensure the same problems don’t arise in the future. Our course teaches MBBs to recognize opportunities and devise solutions to reoccurring issues.

Contact us if you have additional questions.

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