case study on poka yoke

February 5, 2021

What is Poka Yoke Manufacturing: Benefits & Examples

Poka-yoke is a technique used in manufacturing to prevent mistakes and defects from occurring. The concept of poka-yoke, as well as the term, come from Japan and translate to “mistake-proofing” or “error-proofing.” Both were developed in the 1960s by Shigeo Shingo, an expert industrial engineer who worked for Toyota.

The objective of poka-yoke is to design processes and systems in such a way that mistakes or defects become nearly impossible to make. This can be accomplished through a variety of methods, such as designing parts or machines that only fit together in one way, adding sensors or alarms to alert operators of potential issues or using visual cues to make it clear how a process should be carried out.

Poka-yoke is often associated with lean manufacturing and Six Sigma methodologies , which aim to reduce waste and improve efficiency in manufacturing processes. By preventing mistakes and defects from occurring, poka-yoke helps to reduce the need for rework, improve product quality and increase customer satisfaction.

The Importance of Poka Yoke

The importance of poka-yoke lies in its ability to significantly reduce costs associated with quality issues such as scrap, rework, and customer returns. It also improves overall process efficiency by minimizing downtime, increasing throughput, and enhancing employee morale.

Poka-yoke is particularly valuable in complex manufacturing processes where a single error can have far-reaching consequences. For example, in the automotive industry, a mistake during assembly could result in a safety issue that puts lives at risk. Poka-yoke helps prevent such errors by using simple and intuitive design features to guide workers and machines, eliminate sources of variability, and catch mistakes before they result in defects.

Another benefit of poka-yoke is that it empowers workers to focus on higher-value tasks instead of wasting time on error correction or quality inspections. This can lead to increased job satisfaction and engagement, which in turn can improve overall performance and reduce turnover.

Ultimately, the importance of poka-yoke lies in its ability to deliver high-quality products to customers while minimizing costs and maximizing efficiency. By reducing the risk of human error and improving overall process control, manufacturers can stay competitive in a rapidly changing marketplace and meet the demands of increasingly discerning customers.

Benefits of This Lean Error-Proofing Process

Reduced Defects: The primary goal of poka-yoke is to prevent errors and defects from occurring in the manufacturing process. This can save time, reduce waste and improve overall product quality. When errors and defects are caught early, they can be corrected before they become major problems that require costly rework or even scrapping of the product.

Increased Efficiency: Poka-yoke can help to improve the efficiency of the manufacturing process by reducing the amount of time and resources that are wasted on correcting mistakes. By minimizing the need for rework and other corrective actions, poka-yoke can help to streamline the manufacturing process and make it more efficient overall.

Improved Safety: Poka-yoke can also help to enhance safety in the manufacturing environment by reducing the risk of accidents and injuries caused by human error. By designing processes and equipment that are inherently safe, poka-yoke can help to prevent accidents and improve worker safety.

Enhanced Customer Satisfaction: By reducing errors and defects, poka-yoke can help to improve customer satisfaction by ensuring that products meet or exceed customer expectations. This can lead to increased customer loyalty and repeat business.

When Should I Use Poka Yoke Manufacturing?

Poka-yoke can be applied to a wide range of manufacturing processes, and can be particularly useful in situations where errors or defects can have serious consequences, such as in the production of medical devices or aerospace components. However, poka-yoke can be applied anywhere errors are a concern. Here are some situations where poka-yoke may be especially useful:

Measurement Errors: Can be prevented with poka-yoke by designing measurement tools that prevent incorrect readings, such as using sensors that only detect specific measurements.

Setup Errors: Can be prevented with poka-yoke by creating systems that automatically detect and correct any setup errors that may occur during the manufacturing process. For example, designing machines that only fit together in one way can help prevent incorrect setups.

Process Errors: Can be prevented with poka-yoke by designing processes that are simple and easy to follow. This can include using visual cues to indicate the correct order of steps or using automated systems that detect errors and correct them in real time.

Operation Errors: Can be prevented with poka-yoke by designing equipment that is difficult to misuse. For example, creating machines with clear and simple controls can help avoid errors caused by operator confusion.

In general, poka-yoke is most effective when it’s applied early in the manufacturing process, as this allows for errors and defects to be caught and corrected before they have a chance to cause serious damage. By implementing poka-yoke, manufacturers can improve efficiency, reduce waste and enhance product quality.

Poka Yoke Examples

Car Seat Belt Buckle

One common poka-yoke example is the seat belt buckle in cars. The buckle is designed in such a way that it can only be inserted one way, preventing users from incorrectly fastening the seatbelt. The seatbelt also includes an alarm that sounds if the buckle is not securely fastened, alerting the driver to take action.

USB Connector

Another poka-yoke example is the USB connector. USB connectors are designed with a specific shape and size that can only be inserted one way. This prevents users from trying to force the connector in the wrong way, which can damage the device or the connector itself.

Coffee Maker

A coffee maker can also be designed with poka-yoke principles in mind. For example, some coffee makers include a mechanism that prevents the user from accidentally brewing coffee without a cup in place. This helps avoid spills and reduce the risk of burns caused by hot coffee.

Poka Yoke & Fluid Applicators

The process of fluid application is a complex one, involving more than just the simple act of applying fluid to a substrate. In fact, there are multiple steps that take place both before and after the fluid is applied, each of which presents an opportunity for errors to occur. These steps can include wetting out the applicator before use, replacing the applicator after the fluid is dispensed, and ensuring the fluid is dispensed at the correct rate and in the correct amount.

Even with a fully automated application system, errors can still occur. For example, an operator might accidentally insert the wrong type of applicator, leading to improper fluid application and potentially damaging the substrate. Or the system might fail to detect when an applicator is worn out and needs to be replaced, leading to inconsistent or inaccurate fluid application.

To prevent these errors and ensure consistent, high-quality fluid application, manufacturers can implement poka-yoke principles and methods. These can include:

• Designing applicators and components with poka-yoke in mind: By designing applicators and components with unique shapes or sizes that only fit together in one way, manufacturers can reduce the likelihood of errors occurring during assembly.
• Implementing visual indicators: Color-coded components or other visual indicators can help operators identify the correct parts to use, reducing opportunities for mistakes.
• Automation: Automated systems can be used to detect and correct errors in real time. For example, sensors can be used to detect when an applicator is inserted incorrectly, triggering a warning or correction mechanism to prevent the error from causing further problems.
• Testing and inspection: Quality control measures can be put in place to ensure that applicators are dispensing the correct amount of fluid, minimizing the risk or over- or under-dispensing.

In today’s manufacturing environment, no process is completely error-proof. That’s why industry leaders around the world have adopted lean manufacturing and Six Sigma tools to help minimize errors and waste, and optimize productivity. At Designetics, we recognize the importance of these principles and have incorporated them into the design of our fluid applicators and automated fluid application systems.

Our focus on poka-yoke, a key principle of Lean and Six Sigma , helps to ensure that errors are prevented before they occur. This can help you to improve quality, reduce scrap and rework, and increase overall productivity. By designing our fluid applicators with unique shapes or sizes that only fit together in one way, we can reduce the likelihood of errors occurring during assembly. Additionally, we can implement visual indicators and automated systems to detect and correct errors in real-time, helping to prevent issues from snowballing into larger problems.

If you’re looking to streamline your fluid application process and minimize the risk of errors, Designetics can help. Our team of experts can work with you to develop customized solutions that meet your unique needs and requirements. Contact us today to learn more about how we can help you achieve error-free fluid application.

Ready to Error-Proof Your Fluid Application Process?

Designetics’ automated fluid application systems supply fluid to a robot’s end-of-arm tooling via an applicator track. However, this seemingly simple process presents several opportunities for error that can result in scape, rework and downtime. To ensure optimal productivity and quality, our applicator track has been designed with poka-yoke principles to keep these errors from occurring.

The applicator track features two poka-yoke design elements: a warning poka-yoke and a control poka-yoke. The warning poka-yoke uses two sensors, a “low applicator” sensor and an “in-position” sensor, to alert the robot’s controller when there is a low supply of applicators or an applicator is not in the correct position, preventing collisions and downtime.

The control poka-yoke ensures that every applicator acquired by the robot is in the correct orientation for proper fluid application. The applicator track’s design allows applicators to be loaded only in the correct orientation, preventing incorrect fluid application and the resulting rework and scrap.

By implementing these poka-yoke design features, Designetics’ applicator track helps ensure error-free fluid application, reducing waste and maximizing productivity.

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Implementation of Poka-Yoke Technique in a Gear Industry a Case Study

Rejection of manufactured parts at various stages of manufacturing cannot be tolerated now days in production scenario due to tough competition worldwide. All manufacturing industries are moving in the direction of zero defect production. To implement this, the first and most important thing which is being done by the manufacturing industries is to prevent the error or completely eliminate the error with the application of some proven techniques. Poka yoke is one of the techniques and this paper focuses on an application of this technique on a drilling fixture of a drilling machine at a cell in gear manufacturing company. As a result of the application of poka yoke on a drilling fixture, possibility of drilling on the opposite face of a gear is eliminated completely.

Related Papers

Yadi Santoso

AXY is one of the component automotive companies that produce electric components for motorcycles. With respect to the increasing sale of motorcycles from a year to a year in Indonesia, this competition will be followed by competition in the automotive component industry. On time delivery and good quality as main requirement in competition among the industry's components of the motorcycle. Basically, in the quality control process, AXY inspects every part since the receipt of material and production processes to anticipation defects product, but in reality there are always defect products that pass to the customer. Therefore the purpose of this research is to improve or apply poka-yoke in the work area to improve the quality of the production process. The application of poka-yoke with sensor installation applying in initial process rotor assembly line(applyresin). Errors that occur can be identified, with a buzzer sound if there is a defect product not same with specifications. ...

International Journal of Industrial Engineering

Lien Herliani Kusumah

XYZ is one of the companies that manufacture automotive spare parts. At present the company should focus on producing high quality, non-handicapped products with the fastest production time to win business competition. The company's strategy is to carry out kaizen which is a continuous improvement with the aim of preventing defective materials from entering the production process in the most effective manner. The method used by the company is to conduct inspection on incoming materials using poka-yoke method. The decision to run poka-yoke has been proven by reducing the amount of dimension defects material on the B8A rotor component of the supplier delivered to the production process up to zero the following month and producing a better cycle time in the 79.77 second. It can be concluded that the poka-yoke method is the right way to prevent the defective material from entering into a production process that can cause a defective.

IJESRT Journal

It is not possible to eliminate all the mistakes people make. People are not mistake proofed by their nature. But organization can avoid these mistakes from reaching the customer, which is known as a defect in this case. Mistakes can be stopped as soon as they happen at least. Poka-yoke is very simple concept in nature. The basic concept of this is avoiding the problems by correcting the process. Poka-yoke is a quality assurance technique developed by Japanese manufacturing engineer Shigeo Shingo. The aim of Poka-yoke is to eliminate defects in a product by preventing or correcting mistakes as early as possible. So what is mistake proofing? The use of process or design features to prevent errors or their negative impact. Also known as Poka yoke, Japanese slang for “avoiding inadvertent errors” which was formalized by Shigeo Shingo. A method that uses sensor or other devices for catching errors that may pass by operators or assemblers. Shigeo Shingo defines Poka Yoke as: Poka – “Inadvertent Mistake That Anyone Can Make” [2] and Yoke – “To Prevent or Proof” [1]. Poka -Yoke performs two key operations of ZDQ (Zero Defect Quality) i.e. identifying the defect immediately ( Point of Origin Inspection) & quick feedback for corrective action. Poka-yoke detects an error, gives a warning, and can shuts down the process.

IRJET Journal

This generation is more conscious about cost reduction, which leads one of the construction equipment industries to come up with a new model of Double drum compactor machine (NDD) for their customers. The project focuses on study of the similar kind of machine in line for NDD and analyzes any potential failures for the assembly of product in line and applies poka-yoke for that process through Process failure mode effect analysis (PFMEA). The aim of the project is to increase the efficiency of workstation, minimizing the failures and thereby increasing the productivity in the assembly line. The data of similar machine in line was collected and analyzed and repeated failures were identified. The critical failures of existing double drum compactor (EDD) was found to be in two places, steering cylinder and drum vibration motor from the data collected. The team was formed for brainstorming session and the project has been addressed with one poka-yoke solution. The techniques of Poka-yoke, Cause and effect diagram, which are elements of Failure Mode Effect Analysis, are applied effectively for new model.

AGUINALDO ALVES DOS SANTOS

This paper discusses the application poka-yoke devices to reduce variability in construction sites. Initially it presents the main pressures for improving production practices in the sector and then it describes the main aspects of reduction of variability. Subsequently, it presents poka-yoke as one of the basic heuristic approaches to implement this principle in practice. The researchers investigated the application of poka-yoke in construction through six case studies carried out in Brazil and England. The pattern-matching approach, supported by quantitative and qualitative data, has confirmed the usefulness of this approach in construction practice. However, the empirical evidences revealed that the sector makes little use of this approach at the present moment. In this sense, there is great scope for developing mechanic and electronic mistake-proof devices to adapt into existing construction machinery. Construction suppliers should reflect on the idea of building poka-yoke devic...

eSAT Journals

The paper represents a case study which focuses on Poka Yoke which is a concept coined by Japanese people. We have studied a system that eliminated the rework and increased productivity of the plant which results in achievement of 0 PPM as well; in the company based in Satpur, Nashik. There was a punching machine there in the plant which was punching a hole on a rear end cap of Mahindra Scorpio's rear bumper. There were 4 metal clips which were fitted on that component before the part gets punched on punching machine. After some of the lots get punched, we observed that component is getting punched unless those clip fittings. At that time, company needs more time to fit metal clips on the component again which was time consuming. So this problem can be avoided by implementing Poka Yoke system to it. So, the aim of the project was avoid the mistake of missing of metal clip on it and make a system which will not allow to punch the hole unless and until all 4 metal clips are arranged on it.

SIGMA TEKNIKA

Arif rokhman Hakim

This article describes a study conducted on the method to prevent error in manufacturing. Two cases in Integrated Circuit manufacturing was observed regarding human error occurred in moulding process. A technical solution was applied to prevent the case to occur. Mechanical approach solution named poka yoke was applied to the location of problem. It is proven that the solution is effective in preventing similar error to occur.

Dr. Shashikantha Karinka

Foundry or casting is an important manufacturing process. Many machine components and mechanisms are manufactured using the casting process. Several automobile and engine components are manufactured through the casting process. There are several types of casting processes and sand casting is one of the preferred methods. The defect free casting is very important in the present day competitive world for survival of industry, which also helps in conserving energy and in reducing the associated environmental pollution, health risks, global warming and climate change effects. In this paper, defects occurring in the manufacturing process of medium to large size automotive brake drums in a mid-size South-Indian foundry have been studied. The study involves segregation of all types of defects and discusses the causes for the variety of defects. It is planned to bring down the present rate of defects from 5% to a lower satisfactory level. Hence it is recommended to create Poka-Yoke for prev...

TRANSSTELLAR JOURNALS

TJPRC Publication

Monitoring the Industrial OEE (Overall Equipment Effectiveness) [3],[4]is now a day's a very essential concern for optimizing the use of the resources and tracking the efficiency of the manufacturing organization. To produce the goods with no errors is really a challenge in this era. Pokayoke [1] is a Japanese term; which means "Mistake Proofing" and most widely used in automotive industries to eliminate defect and possibility of producing the defective parts. "Elimination" is one of the type of the Pokayoke system; which is generally adopted to eliminate the possibility of the chance error during the operation. Thistool is used in Propeller Shaft manufacturing organization; especially in Propeller Shaft assembly; resulting in the productivity optimization which is achieved more than 50%, another breakthrough is 20% saving in "rework" parts and 30% "Not ok" parts are saved out of the total propeller shafts considered for trial.

International Journal of Productivity and Quality Management

Every industry has to ensure a quality check so as to ensure that the products manufactured by them are safe for the consumers. During this process, a lot of wastage occurs due to rejection. Because of this rejection a lot of time, money, resources and manpower are wasted. This research work focuses on minimising this rejection and also to ensure maximum recovery from the rejected material by Poka Yoke. Furthermore, the rejected products from a parent company are smuggled and sold in the market without the parent company's notice, thereby spoiling their reputation. To elude this situation, hallmarking by engraving technique is also suggested. This helps in maintaining accountability of the rejected goods and also in preventing them from reaching the black market.

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A Complete Guide to Poka-Yoke in Six Sigma

March 5th, 2024

Quality management philosophies like Six Sigma and Lean Manufacturing aim to achieve near-perfect processes that have minimal waste, maximum efficiency, and high customer satisfaction.

A key tool for accomplishing these goals is poka-yoke, a concept pioneered by Toyota Production System pioneer Shigeo Shingo in the 1960s.

Poka-yoke, which translates from Japanese as “mistake-proofing”, refers to techniques for preventing defects by designing processes that make errors nearly impossible to commit.

As engineer Shingo realized, rather than blaming workers for inevitable human mistakes, better results come faster from changing systems to guide actions correctly.

Applied as part of continuous improvement initiatives like Six Sigma and Lean, poka-yoke enables identifying root causes of problems and empowers frontline workers to fix issues as they arise.

This mistake-proofing culture increases quality and productivity gains over time across the organization. There are many benefits like a 20% improvement in customer satisfaction with successful implementation.

Origins and History of Poka Yoke

The concept of poka-yoke originated in the manufacturing plants of Toyota in Japan during the 1960s. Industrial engineer Shigeo Shingo, a pioneer of lean production methods at Toyota, first introduced mistake-proofing while observing an assembly process where workers commonly forgot to install a part.

Seeing blame targeted at individuals as an ineffective solution, Shingo developed the countermeasure of using simple mechanisms to guide the process and either prevent errors or make them instantly visible.

This evolved from an earlier term Shingo coined called “baka-yoke” – Japanese for “foolproofing” or “idiot-proofing” – shifting the focus to eliminating defects from the process rather than the person.

As Toyota’s methods attracted global attention, particularly through concepts like Just-In-Time production, Shingo’s approach to error-proofing processes became known as poka-yoke.

Translating as “mistake-proofing” or “avoid inadvertent errors,” poka-yoke formed a key component of the celebrated Toyota Production System (TPS), along with methodologies like 5S workplace organization, quick changeovers, and built-in quality practices.

In addition to TPS, poka-yoke now stands today as a foundational pillar across process excellence frameworks like Lean and Six Sigma.

Applying poka-yoke enables organizations to prevent defects, reduce waste, lower costs, and improve efficiency – all central aims of continuous improvement programs.

It empowers designing systems and work methods that guide proper performance each time.

Implementing Poka Yoke in Six Sigma

Applying poka-yoke entails redesigning processes to reduce variation from human error and make the desired outcome inevitable.

Shigeo Shingo outlined a five-step methodology for instilling mistake-proofing:

Step 1: Identify Critical Defects and Root Causes

The starting point targets pinpointing high-priority defects to eliminate – ones resulting in costly quality issues, rework, delays, or safety risks.

By asking “why” five times (a Lean tool called 5 Whys analysis ), teams uncover root causes and prioritize addressing ones linked to human mistakes. Process mapping provides visualization of each step.

Step 2: Redesign Process to Avoid Identified Errors  

In the improvement phase, redesign the process to remove steps where errors originate and introduce mechanisms that cue proper performance.

This guides operators, equipment, and materials to the correct work sequence and outcome. Consider potential failure modes when developing countermeasures.

Step 3: Incorporate Controls and Alerts

Insert visual indicators, alarms, system logic, hardware mechanisms, operational sequences, or structured procedures that either prevent errors or instantly alert that one occurred.

This makes problems visible for quick intervention versus hidden defects detected only later downstream.

Step 4: Validate Proof of Concept  

Conduct testing to confirm the integrated mistake-proofing features reliably halt or warn of attempts to vary from set parameters across expected conditions.

Refine limits or operations until attaining robustness.

Step 5: Expand Implementation

With confidence in the effectiveness of critical defects, broaden the mistake-proofing controls across applicable processes to widen the impact.

Continual improvement fosters upgrading standards over generations.

When performed diligently, poka-yoke system redesigns significantly increase productivity, reduce waste, lower costs, and sustain gains.

Embedded error prevention empowers people to achieve high quality reliably.

Types of Poka Yoke in Six Sigma

poka-yoke mechanisms fall into two main categories: control types that automatically stop the process when an error occurs, and warning types that detect the error but rely on the operator to initiate correction.

Within these two branches, several methods apply for preventing mistakes.

Control Poka-Yoke

Control poka-yoke automatically interrupts the process when it encounters something wrong, not allowing progress until the defect gets corrected.

This acts as foolproof prevention by making errors impossible within the designed specifications.

Some examples include:

• The assembly line shuts down if a part gets skipped
• Transaction voids if required data fields get omitted  
• System locked if test performed out of sequence

The process cannot proceed until fixing the flagged issue, forcing errors to the surface.

Warning Poka-Yoke

Warning poka-yoke detects an error but relies on the operator to initiate correction before allowing the process to continue. Warning signals commonly use visual or audible alerts.

Examples involve:

• The dashboard light indicates a low fluid level
• Alarm sounds for uncovered manhole
• Email notification of order discrepancy

While less foolproof than control methods, warning poka-yoke still exposes errors that may otherwise go unnoticed until creating downstream defects.

Input Checking

Input checking validates that information entered into a system matches predetermined criteria, preventing entry errors upfront. Common applications include:

• Data field validation for date formats, text lengths, and numeric ranges
• Testing user credentials before system access
• Product codes checked against an approved list
• Automatic prompts for missing entries

Successive Checking

Successive checking performs incremental audits between process steps to verify acceptable outcomes before further work gets based on faulty results.

This regulates quality closer to the source by not allowing deviations to propagate. Examples include:  

• Inspection of welds before assembly
• Code reviews before software release
• Approving batch records before distribution

Applying input checking and successive checking facilitates early detection at critical control points.

Tools and Techniques

Implementing effective poka-yoke integrates well with common Lean and Six Sigma tools for process analysis and improvement. According to the Aberdeen Group, implementing poka-yoke techniques had a 25% increase in productivity.

In particular, the following methods help uncover where and why mistakes occur to guide mistake-proofing:

Process Mapping

Process mapping provides visualization of all actions in their true sequence, forming the backbone for exploring defects and enhancements .

Tracking cycle times, decision points, inputs, and outputs builds in-depth understanding.

Five Whys Analysis

By iteratively asking “why” defects arise, the Five Whys analysis penetrates beyond symptoms to reveal root causes .

Posing the question five times unlocks causal relationships obscured by assumptions. The simplicity yet consistency makes it reliable.

Fishbone Diagram

Fishbone diagrams connect multiple contributing factors visually around the core problem. Brainstorming possible categories with teams enables structured evaluation.

The fishbone provides an analytical tool to target solutions.

Failure Mode Analysis

Failure mode analysis systematically identifies ways an asset, process, or system could potentially fail and assesses the effects.

FMEA delivers an inventory of vulnerabilities for mitigating through poka-yoke methods.

Control Charts

Control charts track process metrics over time to distinguish common cause variation and special cause variation based on statistical probabilities, signaling stability, or instabilities needing correction.

Control limits determine action thresholds.

5S Workplace Organization

5S workplace organization entails sorting, setting in order, systematic cleaning, standardizing, and sustaining production areas for efficiency, visual control, and continuous improvement. The disciplined foundation enables optimal poka-yoke.

Integrating analysis methods with domain experience and stakeholder perspectives arms teams with information to guide optimal poka-yoke mechanisms.

The solutions are tailored to the unique situation.

Benefits of Poka-Yoke

Studies by the Aberdeen Group show a 30% reduction in defects by implementing Poka Yoke techniques.

Applying poka-yoke as part of continuous improvement initiatives like Lean Six Sigma and Kaizen events yields powerful benefits for quality, efficiency, costs, and competitiveness:

Reduces Defects and Waste

By preventing errors from occurring in the first place, poka-yoke effectively reduces process defects and associated waste.

Every defect that reaches customers leads to rework, replacements, or lost business. Poka-yoke makes causes visible sooner to minimize impact.

Lowers Costs

In addition to materials wasted through scrapping defective outputs, costs get driven higher by excess process time, capacity overload, administrative burden, and opportunity costs from diverted resources.

Poka-yoke curtails expenses on multiple fronts.

Improves Quality

Preventing defects upfront with poka-yoke means fewer make it downstream to inspectors or customers, directly improving quality. Well-designed mistake-proofing facilitates right-first-time results.

Increases Efficiency  

Properly implemented poka-yoke woven as standard work enhances process flow, frees up capacity, and boosts productivity.

Smoother operations with minimal control are needed to maximize asset utilization.

Fosters Continuous Improvement  

Poka-yoke inherently takes a continuous view on learning from problems and redesigns systems to steer better outcomes. As processes evolve, so can the application of mistake-proofing mechanisms in a positive feedback loop.

Together this expands capabilities while controlling costs to do more with existing resources. Embedded poka-yoke drives a prevention mindset making true continuous improvement sustainable.

Examples of Poka-Yoke in Six Sigma

Poka-Yoke mechanisms take many forms spanning simple physical adjustments to complex software integrations. The unifying theme centers on guiding correct performance while preventing or instantly detecting errors.

Automated Data Validation

Input fields can be validated against preset criteria to catch deviations for date formats, text lengths, numeric ranges, or incompatible selections. Logging rejected entries helps improve upstream processes.

Process Step Guides

Color coding, visual indicators, checklists, or control plan integration assists in accurately following defined sequences to meet requirements. Skipping necessary actions gets avoided.

Part Orientation

Designing identical parts asymmetrically or using notches/guides forces proper orientation for foolproof assembly. Errors from misalignment get designed out.

Motion Sensors

Movement sensors ensure openings are clear or parts are in place before allowing hazardous motions that could cause injury or machine damage without the right conditions.

Alert Systems

Dashboards with visual or audible signals notify operators of abnormal readings needing intervention per established protocols before producing defects.

Incorporating principles of mistake-proofing align controls to help personnel complete steps properly as designed. Continual learning about failure modes enables strengthening poka-yoke countermeasures over time. No process reaches perfection but sustained incremental efforts pay dividends.

Integrating Poka-Yoke into Six Sigma

While powerful on its own, the poka-yoke goes further when embedded into structured continuous improvement frameworks like Six Sigma. Mistake-proofing steps align well with the define, measure, analyze, improve, and control (DMAIC) phases.

In Define, poka-yoke focuses efforts on critical outputs and defects. Measure gathers metrics on error frequency, impact, and root causes . Analyze evaluates conditions enabling mistakes and potential solutions. Improve and implement preventive redesigns, with Control monitoring performance.

Complementary to Statistical Process Control

Analysts can determine if production varies within expected statistical limits using control charts. By preventing special cause issues originating from human error, poka-yoke sustains stability. Control methods confirm effectiveness.  

Enables Shift Left Quality

Poka-yoke principles integrated early in design shift quality left on the value stream. Building in mistake-proofing during new product development or process creation prevents defects from arising at the outset.

Reduces Control Plan Complexity

The more prevention through poka-yoke eliminates upstream errors, the fewer downstream inspection and reactionary controls remain necessary. Simplified control plans lower administrative costs.

Jointly applying poka-yoke with Six Sigma tools ushers enhanced benchmarking, analysis of variability, process redesign, and monitoring of gains. Mixing managerial and technical tactics produces optimal solutions. Workers gain autonomy in upholding standards through embedded mistake-proofing.

Sustaining a Poka-Yoke Culture

While many organizations rightfully pursue poka-yoke for discrete issues, the real power unfolds across entire systems over long time horizons by fundamentally changing culture. Sustaining mistake-proofing necessitates commitment across managerial levels and frontline teams.

Empowering Workers to Fix Issues

Enabling workers to take ownership of deficits through embedded poka-yoke provokes deeper process knowledge and engagement.

Responsibility for originating solutions creates change agents at all levels.

Leaders should encourage surfacing errors without repercussion, recognizing each as an improvement opportunity. This no-blame culture opens pathways for preventing future occurrences.

Regular Audits

Even world-class poka-yoke controls require regular revalidation to confirm effectiveness, identify any degradation, and spark new ideas.

Scheduling different groups to audit areas outside their purview brings fresh perspectives.

Management demonstrates commitment by participating personally in routine Gemba walks.

Updating with New Technology

As process technology and control automation continue improving, new options become available to reduce manual involvement and take prevention mechanisms to heightened precision.

But upgrading the poka-yoke also demands ensuring personnel possess capabilities to sustain enhancements.

When Poka-Yoke gets woven into operational DNA , it no longer seems an added chore but rather feels integral to daily work. This fusion unlocks the method’s ultimate usefulness.

Leaders must champion the journey toward reliable systems.

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60 Common Examples of Poka Yoke

What is poka yoke.

Poka yoke, ‘mistake-proofing’ in Japanese, prevents avoidable mistakes from occurring. This applies to any environment, be it in manufacturing, hospitals or even in the home.

This article looks at the following:

• Origin and application
• Examples in the automotive industry
• Error-proofing examples in manufacturing
• Mistake-proofing examples in daily life
• Other examples

Definition of Poka Yoke

This is a Japanese word that means mistake proofing of equipment or processes to make them safe and reliable.

These are simple, yet effective design features that make it almost impossible for errors to occur.

In fact, the original term was Baka-Yoke or “fool-proof”. Due to the inappropriateness of the term, “mistake-proofing” became the preferred term.

The aim of mistake-proofing is to remove the need for people to think about the products or processes they are using. This is because the products have a design that makes it impossible to use them in the wrong way.

When someone uses the product the wrong way, it does not function and it becomes obvious to the user that they are doing the wrong thing. The simple yet effective design features make it difficult for errors to occur during usage of the product.

Origin and Application

The concept developed out of the need to achieve quality in production processes. It was Shigeo Shingo, one of the pioneers of the Toyota Production System, who proposed the concept. He was a quality guru who proposed the idea of ‘Zero Defects’ as a quality paradigm.

The thinking was that a process should be able to detect and prevent errors from occurring. This would lead to a final product of high quality.

Poka Yoke Examples in the Automotive Industry

Many people lose their lives or get maimed through vehicular accidents each year. Safety of users of automobiles is of paramount importance and many measures have been taken to make them safe. The following are examples of mistake-proofing in the automotive industry:

• Radar and video cameras  in new vehicle models are able to tell the distance and speed of other road users. This helps them prevent collisions in case of sudden stops. The device here is more of a warning and preventive measure but it does not strictly fit into the concept of behaviour modification. The driver may choose to ignore the warning which will lead to an accident. The device does not stop the accident from happening in the first place.
• Automatic breaking system  stops the vehicle in case the driver fails to brake when an obstacle suddenly appears on the road. If the system above is used with this device, it will be a better preventive measure as the system will note that a warning has been ignored. The sensors will then kick in and stop the vehicle – a key component of poka yoke is at play here.
• Lane-keeping assist  alerts the driver that he is about to deviate from his lane. If the driver is not responsive, the vehicle intervenes and returns to the correct lane on its own. This device also fits well with the automatic intervention philosophy of poka yoke. There is no way the driver will commit an error because the vehicle will stop him from doing so.

• Electronic stability control  helps reduce the possibility of accidents that can occur when a vehicle skids uncontrollably due to over-steering by the driver. The condition being controlled here is the slippery road — when this condition comes into play the system kicks in to prevent an unwanted result from occurring.
• Cross-traffic alerts  warn drivers of impending traffic when they are reversing from a parking position. Like the first example of mistake-proofing in the automotive sector, this device is more of a warning and must be used in-conjunction with other devices to be successful.
• Adaptive headlights  are able to respond to the conditions on the road so as to assist the driver have better visibility. For example, they are able to illuminate curved roads and also during bad weather.
• Airbags  deflate quickly after an accident to prevent injury to the occupants of the vehicle.
• Seat belt pre-tensioners  assist in holding the passenger in place in case of an accident and prevent them from sliding through.

• Blind spot assist  warns the driver when there are objects within the blind-spot range that are not visible.

• EBS  braking distributes power evenly and the discs expand symmetrically when hot. This minimises uneven tear of the discs
• Brakes  that continuously self-monitors and reports any problems to the central control unit. This prevent the likelihood of an accident attributable to the breaking system

Poka Yoke Examples in Everyday Life

Products that we use every day have features that make them safe and convenient. The following are a few examples of how mistake-proofing is used for everyday household products:

• Micro-wave oven  does not work until the door is shut.
• Washing machines  only start when the door is closed and cannot be opened until the cycle is over .

• Electric plugs  have an earth pin that is longer than the other pins and is the first to make contact with the socket. The protective shield of the neutral and earth sockets are then opened safely.
• Electric sockets  are shaped in a manner that only one way of plugging-in is possible. This prevents the possibility of a short-circuit occurring.
• Child resistant tops  for medicines and household chemicals makes it difficult for children to consume the contents.
• Elevator doors  have a sensor that causes them to open when there is an obstruction-this prevents injury to someone trying to enter as the doors are closing.
• Box cutters  have a retractable blade that only pops out when the handle is held.
• Lawn mower s have a safety bar on the handle that when released, switches off the machine.
• Circuit breakers  in the home electrical system prevent electrical overloads.
• Overflow outlets  in bathroom and kitchen sinks prevent flooding of the house when the drain is blocked.
• The Door of a washing machine  or dryer makes the machine stop when it is opened, so as to prevent injury from accidents

Examples of Poka Yoke in Manufacturing

In lean manufacturing systems, poka yoke also includes a philosophy of constantly working to prevent mistakes from occurring in the first place. The internal processes in lean manufacturing systems are supposed to produce quality products the first time. Error-proofing in this case is a quality assurance technique that ensures quality is in-built and results in better products.

For the final product to be of high quality, all the inter-connected process steps have to give first time quality. If an mistake or defect is allowed to move to the next step, the likelihood of it appearing in the finished product is very high. It is therefore necessary to develop ways of preventing a defective product moving to downstream process.

This is important because a finished product is considered to be the most expensive form of inventory due to the accumulated costs along the value chain. If a defect occurs in the finished product, the costs of production increase due to the effort required to correct it.

• Magnets  in a grain packaging plant detect and remove metal pieces before they are packed.
• Interlock switches  which detect the position of a machine guard and switch off the machine when the guard is lifted. The machine will never operate when the guard has been lifted and this prevents accidents to the operator.
• Light curtains  in a factory detect when someone is near very dangerous machines and switches off the machine to prevent injuries.
• Safety mats  near machine areas that pose a danger automatically trigger stoppage when someone steps on them. This prevents injury to personnel (such are technicians) who are trying to access dangerous sections of a machine.
• Power guard s on high inertia machines with moving parts prevent opening until the parts have stopped completely in order to prevent accidents.
• Machines  that must be controlled using both hands ensure that some distance is kept between the operator and dangerous machine parts.
• In the food industry , gloves and other small pieces of personal protective equipment must be blue in colour for ease of detection in case they fall into food. This is because blue foods are rare in nature and the color difference makes it easy to detect that a foreign object has fallen into the food.
• Using standardized containers  at the workstation enables workers to know exact quantities without having to weigh or count the contents.
• Use of colour coded  date labels to mark the production dates of products. This way the different batches are easily identifiable for the purpose of product rotation. The system is especially useful in the food industry where rotation of batches is very important because of hygiene considerations.

Mistake-Proofing of Products

Safety concerns necessitate the use of mistake proofing techniques on the final product in order to prevent harm to the final consumer.

It also provides ease of use to the product so as to enable the final consumers to be able to solve their problems effectively.

Adding user-friendly features to a product aims at solving safety as well as convenience concerns and makes it almost impossible to use the product in the wrong way.

Other Poka Yoke Examples

There are many other examples of products that have fool-proofing ranging from USB cables to child proof sockets. Here are a few examples:

• Glow-in-the-dark strips  around the toilet bowl prevent users from urinating on the sides.
• Mop slippers  save time for the busy person as they prepare to go to work or school.
• Scrap collecting bowl  has a ledge that is attached to the table top to collect vegetable scraps before they fall on the ground.
• Oven rack guard  prevents accidental burns as one is removing food from the oven chamber.
• Locator stickers  that are put on commonly lost items such as keys and can be traced using the phone.
• Upside-down  tomato sauce bottles enable the consumer to use up all the tomato sauce and also lets the water that collects at the bottom come out first.
• Mobile phones  are designed in such a way that when they fall, the cover separates so as to minimise the shock that would damage them.
• Color-coding  of electrical wires is meant to prevent short circuiting that can occur if they are not matched properly.
• Ice blocks   that prevent someone from drinking too much.
• A company invented a  fork that tells you when you have eaten  too much thus preventing you from getting over-weight

Poka Yoke Examples in Nature

Mistake-proofing also occurs in natural systems and the human body system is a good example of how it works to prevent errors from occurring:

• Coughing  is a natural reaction that prevents the error of foreign bodies from entering into the lungs. The sensitive wall linings of the respiratory tract detect and eject minute particles through coughing.
• Veins  have valves that are designed to prevent the error of back-flow of blood as it travels through the system. They also allow some blood to collect within the system without busting as they have a larger internal diameter.
• Arteries  have thick walls that can withstand the high pressure that blood from the heart exerts on the circulatory system.
• Tearing  is a necessary reaction to the entry of foreign bodies into the eye.
• Mucus  membrane traps bacteria and prevents the error of pathogens entering the system.
• The skin  is the first defence against entry of foreign bodies and the oils and enzymes prevent harmful bacteria into the human body.
• Inflammation reaction  of swelling happens when blood vessels leak fluid into the tissues. The chemicals attract white blood cells (phagocytes) that eat germs and dead/ damaged cells. This reaction prevents the spread of harmful toxins and pathogens to the rest of the human body and is a form of natural error-proofing.

Error-Proofing in the Space Industry

The space industry requires accurate procedures to be constantly carried out so as to ensure the successful completion of space missions. Any small error in the implementation of these procedures can lead to a major disaster.

The industry has therefore developed many mistake-proofing devices to prevent errors from occurring and this has resulted in the high success rates of space mission over the years. The following are a few examples of error-proofing in the space industry:

• Escape capsule  is designed to help the astronauts safely return to earth in case if there is an emergency during launch of the spacecraft. An abort motor fires over half a million pounds of thrust to steer the capsule away from the booster rocket. Another motor steers the capsule in the right direction and then a jettison motor separates the escape rocket from the capsule which has parachutes to allow it to safely land on earth. This error proofing device will save lives in case the launch of the rocket fails.
• Checklists  used in the pre-flight preparation are detailed and are designed to ensure all the parameters are within the allowed range before the flight can commence.

Fool-Proofing in Nuclear Power Plants

Nuclear accidents can have devastating effects as was seen in the Chernobyl disaster. Nuclear power plants use the  defense-in-depth   concept of barriers to the prevent fission material from being released from the reactor core to the environment.

The fuel rods have cladding that prevent the release of fission material in the event of a melt-down. The reactor is designed to assist in the cooling of the rods in case there is a decrease in the cooling water in the core. This is very important as the heat released during the decay of radioactive material can start a chain reaction that is unstoppable.

Error Prevention in the Service Industry

The service industry is very important in that there is direct and constant interaction with the customer and any failure on the part of providers of services can result in losing good business.

This failure to serve a customer as per their expectation can be considered an error and many service providers have put in place a number of error-proofing processes to prevent this from happening.

The following are just a few examples of how service providers mitigate against the chances of causing mistakes in their businesses:

• Electronic tags  in airline luggage handling systems ensure that passenger luggage is not lost after check-in. Airline staff are able to locate misplaced luggage anywhere in the world as the tag contains all the necessary passenger and flight information that is used in tracking it.
• Electronic waiter pads  in restaurants ensure that the right order goes to the right table at the shortest possible time. This order matching technology prevents the error of waiters taking the wrong order and also enhances fast delivery to the customer.
• Queue management systems  in banks and other public venues are designed in such a way that customers are served according to the order in which they came in promptly thus preventing customer dissatisfaction.

Examples in Aeroplanes

The fact that air travel is considered to be safer than road travel can be attributed to a number of fool-proofing devices that have been put in place over the years. While air accidents still occur, they have significantly been reduced because of these devices:

• De-icing chemicals  make it difficult for ice to form on the wings of aeroplanes which can cause serious accidents.
• Auto-pilot  keeps the plane flying in case of inclement weather or when the pilot is ill-disposed.
• Captain meals  on planes must be different from the meals served to other passengers so as to prevent cases of food poisoning affecting the pilot, which can be very dangerous especially mid-flight.
• Fuel jettisoning  is an important procedure during emergency landings as it prevents major fires from the fuel held in the tanks.
• Instrument control-panel  is located in such a manner that the pilot and engineer are able to view all readings easily.

Error-Proofing of Medical Devices

• Opportunities for Poka Yoke to Reduce Medical Device Errors in Hospitals and Increase Safety

From the above comprehensive list of examples, it becomes obvious that there are certain characteristics of error-proofing devices that help in achieving the aims of mistake-proofing. These characteristics include:

• Simplicity,  which means that the solutions are not complex and unambiguously resolve the problem of error occurring.
• Automatic Nature:  they do not require any further intervention from the person using the device.
• Safety  is a key characteristic of poka yoke devices in that they also prevent the users from injuries.
• Feedback  is immediate in the case of failure when the conditions go out of specification.
• Quality  is ingrained in the process and the solutions encourage the right methods to be used by operators of the devices. It is a way of standardizing the correct methods of performing a process.
• Location at the source  of a potential problem within a process.
• Reduction in the number of process steps  required to complete a process as the inspection aspect is minimized or completely eliminated.

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Proceedings of the 6th CIRP-Sponsored International Conference on Digital Enterprise Technology pp 1277–1289 Cite as

Wireless Devices Enabled Information System Design Poka-Yokes: A Case Study with a Manufacturing Logistics Process

• Abraham Zhang 4  
• Conference paper

1998 Accesses

Part of the book series: Advances in Intelligent and Soft Computing ((AINSC,volume 66))

The extensive use of Poka-Yoke (Mistake-proofing) devices enables Jidoka (machines with human intelligence) as one of the two pillars of Toyota Production System (TPS). Despite the worldwide adoption of Lean/TPS and the key contribution of Poka-Yoke to the Japanese quality miracle, Poka-Yoke has been largely ignored in academia. This paper narrows the research gap by introducing Information System Design (ISD) as a new way of design for Poka-Yoke and illustrating how wireless communication technologies increase the capacity of ISD Poka-Yoke. A case study is conducted in the paper to explain how wireless devices enabled ISD eliminate three types of human errors in a manufacturing logistics process. In general, ISD Poks-Yoke overcomes the limitation of traditional Engineering Design (ED) Poka-Yoke, by extending the applicability of Poka-Yoke concept to non-production processes. With the integration of wireless devices, ISD can even be used to mistake-proof logistics processes which are often mobile in nature.

• Mistake-proof
• Information System
• Wireless Communication Technology

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Zhang, A. (2010). Wireless Devices Enabled Information System Design Poka-Yokes: A Case Study with a Manufacturing Logistics Process. In: Huang, G.Q., Mak, K.L., Maropoulos, P.G. (eds) Proceedings of the 6th CIRP-Sponsored International Conference on Digital Enterprise Technology. Advances in Intelligent and Soft Computing, vol 66. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-10430-5_98

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Six Sigma Study Guide

Study notes and guides for Six Sigma certification tests

Poka-Yoke Error-proofing

Posted by Ted Hessing

Poka-Yoke Error-proofing is the act of making errors impossible through great design. Defining requirements or ensuring continuous flow are good things but are not entirely part of error-proofing.

A great example for anyone driving in the US is gas pump nozzles’ different shapes and sizes. I can remember one bleary-eyed road trip in college where I was half awake when I tried to fill my 1986 Buick Regal with diesel instead of regular! Fortunately for me, poka-yoke has been used in the design of the gas nozzles; diesel gas is a triangle shape and thus impossible to fit in the cylindrical gas receiver my car had! That was great error-proofing.

History of Poka-Yoke Error-proofing

Coined in the 1960s in Japan, Poka Yoke means “Fool-Proofing” and is a tool used to avoid inadvertent errors. The tool ensures that proper conditions are in place for every step of the process such that there is no room for defects while operating. In other cases, it detects and fixes the defects as early as possible.

Poka-Yoke is a vital tool in lean manufacturing since it helps the people and processes work the first time correctly. It helps to phase out defects during the process and in the products by improving quality and reliability. It is worth noting that it does reduce both machine and human errors in the work processes and products.

When to use Poka-Yoke Error-proofing?

The ideal time to use the technique of Poke-Yoke is when a process or product is likely to have an error or something may go wrong. You can easily introduce the Poke-Yoke technique in both the manufacturing and service industries. Poke-Yoke captures errors like poor process operations, improperly adjusted machines, or incorrectly used tools (setup errors).

Secondly, it flags missing parts on the production line (missing parts errors), incorrectly used parts (improper parts error), processes or products that fall below quality standards (operations errors), and unadjusted machines and parts (measurement errors). Consequently, this last example includes improper dimensions of the supplies or parts used.

How to use Poka-Yoke Error-proofing?

There are several steps that one can follow to use Poke-Yoke in their work operations:

Step 1: The process or operation that needs fixing should be identified using a Pareto chart and analysis.

Step 2: Assess and understand the defects in the process that may lead to failure. Keep in mind the 5-whys during this stage.

Step 3: Decide the strategy to be used for effective Poka-Yoke. Some of the options include

• Shut-out strategy: this is a strategy that prevents the error from being committed
• Attention strategy: which brings attention to the defect when it is being committed
• Comprehensive approach: which is a combination of options

Step 4: First, determine the appropriate strategy needed for the situation. This can be done using a contact, constant number, or sequencing method. A contact is any physical trait that can catch an error. Constant number finds errors in cases where the trigger behind the error is the absence of a certain number of actions. Finally, a sequencing method uses a checklist to tally the completion of steps in the process without error.

Step 5: Run a trial test to ensure the chosen method is appropriate and effective.

Step 6: Once ensured that the method chosen is good, train the operators for the same, review the performance, and measure the success to verify the Poka-Yoke strategy.

Poke Yoke Videos

ASQ Six Sigma Black Belt Certification Poka-yoke Questions:

Question: A company has bought a system that prevents orders with incorrect information from being sent to production schedules. This is an example of which of the following lean tools ? (Taken from ASQ sample Black Belt exam .)

(A) Standard work (B) Kanban (C) Poka-yoke (D) Visual factory

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Asq six sigma green belt certification poka-yoke questions:.

Which of the following is an example of mistake-proofing?

(A) Using an X Bar – R chart to prevent errors (B) Using 100% inspection to detect and contain defects (C) Using color coding as an error signal (D) Having the team that created the errors repair them

Comments (3)

Would I include the Lean Notes under the Control section in DMAIC?

Thank you, Sarah

I mean improve phase?

If you mean for the course, I have Lean spread through out as well as in it’s own section.

If you mean in practical application, yes, you could apply many lean techniques (like Poka Yoke) in the improve phase. However you would likely also use other Lean techniques in multiple areas. For example, Value Stream Mapping, calculating Takt time could both happen in the Measure Phase and then again in the Control Phase.

Does that help?

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