Poka Yoke sounds like words from a "incantation by Hermione Granger… Harry Potter's apprentice witch friend" - but it is not. Poka Yoke is a technique developed in the late 50's by Dr. Shigeo Shingo to prevent human errors that can occur in the manufacturing area.
poka-yoke-techniques-prevent-errors-defectsPopularized until the 60's in the Toyota production line.
However, it has been seen that its principles and bases can be applied in any area of daily life, be it commercial, industrial or family. We can see this on a daily basis, and just to cite a few examples:
• Public bathrooms in which the sinks only supply the essential standard amount of water and soap solution if “the proximity detector” detects us. The same happens with the urinal and WC's, an action that is carried out to prevent the user from forgetting to close the water-soap stopcock and waste it unnecessarily or keep it open, wasting more than is really necessary.
• Cars that do not start the march if the seat belt is not on, since it does not “close a circuit”, preventing the user from being unprotected by not fastening the seat belt, forgetting to protect their life and violating traffic regulations in many countries. The alarm will sound if you leave the key in the gear and one gets out of the car, avoiding the mistake of forgetting the key inside the car, etc.
• Computers with differently shaped connectors to prevent the user from mistakenly connecting cables to inappropriate places on the computer and accidentally damaging it.
• ATMs that do not continue any operation if we do not remove our card, to avoid the mistake of leaving it forgotten inside the ATM itself. Error indication if we introduce it with the chip in inverted position, warning that it cannot be read.
• A basic approach to this technique is educational toys. Which have been conditioning us since our early childhood to understand Poka Yoke of contact detection. As is the case of the cube with grooves of different geometric figures, which only allow the solids that accompany the cube to be introduced, only if the infant selects the appropriate piece for the correct groove shape. The teaching would be complemented if the edges of the grooves had the color corresponding to each piece and each piece had a different color - use of an additional color code.
The name Poka Yoke comes from two kanji - character "han" - or sinograms used in the writing of the Japanese language "Yokeru" which means AVOID and Poka "UNKNOWN ERROR".
English-speaking groups have translated it as “Fool-Proofing” –foolproof- because initially the term used in Japan was “Baka Yoke”, however, Japanese operators rejected it as denigrating and dishonorable. On his first visit to the USA, Dr. S. Shingo preferred to use the term "Error avoidance" -avoiding error-, other terms that are used in Anglo-Saxon countries -because of how difficult it is to pronounce it- are: "mistake proofing" or “Fail-safe operation”, however every day the use of the term Poka Yoke is imposed around the world, at least in the industrial environment. The essential difference between one term and the other is ATTITUDE. The healthiest thing is to avoid hurting susceptibilities and knowing how to encourage everyone, showing them the issue as a group challenge to detect and avoid mistakes.People who are susceptible to making a mistake are those who can contribute the most to anticipating and eliminating it, which is only achieved with their positive and imaginative participation in joint work once they know the technique and its bases.
Poka Yoke's main goal is to achieve “zero defects”. In fact, it is one of the components of PhD Shigeo Shingo's Zero Quality Control System (ZQC), whose goal is to eliminate defects in products. It was conceived and is more of a concept than a procedure. Its implementation is focused on what people think can be done to prevent mistakes in the place where they work professionally, and not on a set of step-by-step instructions to follow on how to do their job.
The Zero Quality Control System (ZQC in English and CCC in Spanish) is defined by:
CCC = Poka Yoke Techniques to correct defects + Inspection at the Source of Origin to prevent defects.
The engineering principles on which this system is based are:
• 100% of the inspections made by the operators at the origin of the source instead of inspections to samples.
• Immediate feedback of self-reviews and successive quality verifications.
• Use of Poka Yoke mechanisms.
The emphasis of this system is to go to the root cause of the defect that is to go to the origin of the source where and when the defect occurs, avoiding the need for a statistical control process. It is worth mentioning that Dr. S. Shingo is a specialist in Statistical Control Processes, known as the Japanese Quality Guru.
Poka Yoke was first implemented by using simple objects such as clever little accessories or simple gadgets, preventive mechanisms employed to prevent people from making mistakes, even if they deliberately tried to make them. All these mechanisms are known in the industrial environment as "Poka Yoke mechanisms" and are used to stop a machine, alert the operator to something that is wrong, etc.
Poka Yoke does not imply having to know high or advanced scientific concepts or occult sciences like those learned in "Hogwarts" by "Harry Potter" - although many of our children would be fascinated, at least my daughter Ingrid does - but unfortunately for her, I don't practice magic and I have made some simple little Poka Yoke mechanisms, which means that any simple "muggle" can do it. The basis is to know the process, understand the problem and seek the simplest solution, based on simple logic at the lowest possible cost. Poka Yoke mechanisms must have the following characteristics:
• Easy to use for any logical person {I did not use the famous term “common sense”, because through the years of life that I have, I have realized that it does not mean the same for every person I have met}.
• Simple to install.
• They should not require constant attention from the operator and ideally, they should work properly even if someone wants to "sabotage" or rather test to see if the "device" really works.
• Preferably very inexpensive.
• That provides immediate feedback, prevention or correction and better yet all together.
The first Poka Yoke mechanism registered as such and using that name, emerged during Dr. S. Shingo's visit to the Yamada Electric plant in 1961, and consisted of the following:
Product: The part of the product that had the problem was a small switch with two simple push buttons supported by two springs.
Problem: Sometimes some workers in the assembly section forgot to place one of the springs under each of the two buttons. Often the error was not detected until the product reached the Customers, being expensive and very annoying for the factory.
Dr. S. Shingo's Solution: He suggested that each worker should have a plate in front of him, with two springs so that there would be no chance of forgetting to insert each one under each button. And the simplest logic worked !!! Not magic. No expensive attachments. No complications. Just simplicity, economy and extreme ease understandable by anyone. http://www.businesstrainers.net/pdf/TQM_vs_Poka_Yoke.pdf
S. Shingo commented: "The causes of defects are found in simple errors, and defects are the result of not giving importance to such errors."
From which it follows that, ”… errors should not be allowed to become defects, being achieved if operational errors are discovered, eliminated immediately and reported leaving a record. The defects come from the mistakes that are made, and both have a cause-effect relationship. … However, errors do not become defects if feedback and corrective action takes place at the stage of the error itself. Poka-Yoke tries to find mistakes at a glance and avoid making them.
Defects and Errors is not the same. Defects are results. Errors are the cause that originates the results or defects. Defects are recurring errors.
Poka Yoke's goal is to reduce human error defects through possible simple ways and at the lowest cost. Being its best application when they prevent errors and not when they only detect and catch them, since in the latter case we will have a waste and the objective of lean manufacturing is to eliminate any waste. Human errors are usually caused by distraction from people, fatigue, confusion, demotivation, inadequate training, bad attitude, etc. A good Poka Yoke mechanism is one that does not require any operator attention and prevents the possible error from occurring even though the operator has deliberately contributed to the error arising.
Dr. S. Shingo recognizes three types of inspection:
• Inspection of judgment or criteria,
• Informative
inspection • Inspection of the source of origin or root cause.
Criterion Inspection refers to it as "Quality Inspection" to identify defects that make the product unacceptable. This type of inspection is done to identify product defects before its distribution, it is the traditionally used inspection and it is the most expensive way to maintain the quality of the products, therefore it is not an appropriate approach to a correct administration of management of quality.
Informational inspection, also called “after the event”, uses data from previous inspections to modify the production process and prevent recurring defects. At each stage of the process an inspection by "inspectors" is conducted, achieving that the product is ultimately free of defects. Even though this type tends more towards a better adaptation to quality management, it entails waste of materials, time, movements, etc.
Finally, Inspection at the source of origin or at the root of the problem called "before the event" determines if the conditions exist for a high quality product to be produced. Mechanisms must be in place to ensure that all conditions are adequate before starting production. It is evident that the elimination of the defects of the production process will be more effective if the operating and working conditions are reviewed before starting production, eliminating the root causes at the source of their origin. Consequently, most Poka Yoke devices are designed to ensure the best conditions before the start of production. Foresee is the name of a correct administration of quality management.
However, if this last option is not feasible, the verifications must be made by each worker at the same time and successive verifications will provide feedback to improve the process if it was not possible to carry out Inspections at the source of the possible error prior to the start of the process; or it was not carried out because the process is not sufficiently advanced and known to employ Inspection techniques at the possible source of the error.
The Gurus of Quality and Poka-Yoke:
¨ Shigeo Shingo
¨ Juran and Gryna
¨ Nakajo and Kume
¨ Kiyoshi Suzaki
¨ Mohamed Zari
They are mentioned for the purpose of delving into the valuable books they have written on these topics.
Poka Yoke levels
It has become customary to establish three levels of Poka Yoke:
1. Prevention and Control. Eliminating spills, leaks, losses at the root of the problem or preventing a mistake from being made.
2. Detection of a loss or error when it occurs, allowing its correction before it becomes a serious problem.
3. Detection of a loss or error after it has occurred, just before it becomes a severe problem or catastrophe.
An error occurs when an action is not carried out or is performed incorrectly, or a prohibited action is performed, or the information essential to perform an action is not available or is misinterpreted. However, a high percentage of errors are foreseeable and therefore feasible to eliminate before they occur. Even though there are different techniques to reduce and eliminate errors, the characteristics of Poka Yoke make this particular technique extremely attractive for use in different fields:
• A total error proof technique requires 100% inspection. Unfortunately, it is impossible to detect and control random events that are rare and that with simple statistical sampling inspections guarantee 100% reliability. Even a 100% inspection is not infallible to detect all non-conformities of the product, it is extremely expensive, additionally causing a very high consumption of time that would make deliveries on time unfeasible. Poka Yoke-based foolproof methods are a practical, inexpensive, and fully viable solution for on-time deliveries.
• An error-proof technique should not be onerous. Since errors are events that are not excessively frequent but can be of very varied types that must be controlled. Companies cannot afford to spend large sums of money on every foolproof mechanism.
• However, sometimes several error-proofing mechanisms are required in a small area. Toyota has an average of 12 fail-safe mechanisms at each workstation, and this is achieved because they are usually compact, simple and can sometimes be interconnected, giving great overall results at reasonable costs.
• Being able to interact with the result is one of the best features of Poka Yoke. The best error-proofing technique is one that physically prevents errors or detects when an error is about to occur, thereby blocking undesirable results rather than causal factors controlling the process.
• Prevention is better than detection. Preventing errors is better than just detecting them, which is even better than detecting defects - frequently repeated errors. If an error is not detected until a defect has been generated, rework will be necessary to prevent the end result from becoming scrap or waste.
• Forecast, Stop Control or Warning. Anticipating is best, as resources can be wasted if a process is stopped. If the errors cannot be anticipated, at least control the errors by stopping the process. Stopping provides a better solution to the error than just a warning, which can be ignored and the waste far greater. Poka Yoke mechanisms achieve the desired goal.
• Important quality initiatives are those that add added value. Only error-proof mechanisms that effectively control possible errors during the use of the product by the end customer, which represent quality initiatives that have a high impact on the customer's perception of quality. They are those for which they are willing to pay. With Poka Yoke, countless applications have been achieved that prevent the end customer from making mistakes in the use of the product. See VSM: Value Stream Mapping- Value Chain Analysis. R. Cabrera.
Poka Yoke: Concept little understood.
A large number of people - mainly engineers - when hearing the word Poka Yoke we almost always think of: limit switches - limit switch - or optical inspection systems, guide pins or pins, or the effects of automatic shutdowns and disconnections. It could be said that all of them can be or that they can be part of a Poka Yoke. However, the Poka Yoke concept is much broader. Detect the error, or prevent it and eliminate it to exclude the possibility of recurrence and prevent them from becoming defects; are the attributes that it possesses. Being able to implement not only in a purely engineering or industrial environment. Its application extends to any activity in the life of any person and that is what makes them an excellent tool for everyone.
Poka Yoke: It is a Japanese methodology that provides error-proof mechanisms to avoid Non-Conformities or human errors within a process, allowing the detection and elimination of root errors, being used as a tool for continuous improvement and can be implemented in any area or medium. They ensure that the right conditions exist before a certain process step is carried out, preventing the occurrence of defects in the first place and where it is not possible, developing detection by eliminating defects in the process as early as possible. They can be electrical, mechanical, procedural (administrative, financial, purchasing, sales, etc.), visual, human, or any other way that prevents incorrect execution at a certain stage of a process.
A Poka Yoke in Sales is the procedural establishment of all the written conditions - under which the sales and supply agreement is governed - and that normally appear in some part of the order or contract and that are signed acceptance. Including all those “little things” that some sellers often forget to say to the buyer, but which become the responsibility of the buyer to read and understand. Like this, many other aspects of procedures of any kind. Anticipate where a mistake could be made –by forgetfulness, distraction, etc.- and eliminate it at the root, so as not to have to suffer the consequences later. The best way to ensure quality in a product or service is achieved by using Poka Yoke. It is widely used all over the world as it just takes a little ingenuity,it is cost effective and usually easy to use and adapt to any administrative, commercial, industrial or family process or procedure.
Poka Yoke Rating by: Canada Center for Excellence in Operations
They are grouped into two large sectors, depending on the basic function they perform:
1. Poka Yoke mechanisms based on PREVENTION: They are prevention mechanisms, sensitive to an anomaly that is about to happen, for which they signal or stop the process, before the next occurrence of said anomaly. Action carried out depending on the severity, frequency or consequences after the step of the process under observation. There are two approaches to prevention based on this type of Poka-Yoke:
1.1 Control Method: This method is sensitive to a problem, stopping a line or process so that corrective action can take place immediately, avoiding the generation of serial defects.
1.2 Warning Method: Indicates the existence of a deviation or a trend of deviations by means of an increasing series of alarms, lights or other warning devices, without stopping the process when the error occurs. The Poka Yoke indicates to the operator (with a flashing light or an intermittent audible alarm) that there is a difference –permissible- so that they can eliminate the fault in the line without stopping it and make the necessary adjustments to keep the process under control. If not done immediately, a second stronger alarm will come (constant light or permanent sound) indicating the severity of the problem, but it will not stop the process.
2. Poka Yoke DETECTION System.
In some situations it is not feasible or economically impossible to prevent defects, particularly where the cost of investing the Poka Yoke mechanism (s) required to avoid the problem, far exceeds the cost of preventing the error due. the complexity of the process itself or the economic limitations of the company for that specific situation. In these cases, the aim is to detect the defects as early as possible in the process, preventing them from continuing to flow later –downstream- of the process and multiplying the cost of Non-conformities. The three categories of detection based on Poka Yoke are:
2.1 Contact Method or Physical Method: It is used to test shape, size or any other physical parameter in an entrance, exit or proximity test. It detects any deviation in shape, dimensional characteristics or other specific conditions, through the mechanisms that are kept in direct contact with the part. A sensor is often used. A subdivision of this category is the contactless method, which performs the same function through devices such as photocells. An example of this is a conveyor belt that detects and removes parts that are in the wrong position such as being flipped or inverted and an indicator on the line detects and separates it to avoid downstream problems.
2.2 Fixed Value Method or Counting Method: It is used to test the number of repetitions or parts or weights of an item or article to ensure that the process is complete. It does not allow the product to leave the machine until the correct number of actions have been performed and the quantity of articles is complete. It uses automatic counters or optical devices and controls the number of movements, speeds and duration of the movement, as well as other critical parameters of the operation. The mechanisms are usually installed within a progressive stamping, welding, Manufacturing Technology Systems, and automatic insertion equipment or others. This method includes the detection of the critical condition (pressure, temperature, current, etc.) through electronic monitoring devices.
2.3 Method of the Step in Movement or Sequence Method: (Some Spanish-speaking authors also use the term: Step-Movement Method) It is used to prove that the correct sequence of movements were performed in order. An example of this is the color coding of electronic components in drawings to prevent the use of wrong or mixed parts.
Nakajo Poka Yoke classification based on its application in the industry.
Nakajo and colleagues studied 1,014 fail-safe devices on assembly lines. They divided the fail-safe mechanisms based on what they do:
• Prevention of the occurrence. It is subdivided into:
o Elimination
or Replacement
or Facilitation.
• Minimization of effects. It is subdivided into:
o Detection
or Mitigation.
Each one of them is characterized by: Elimination: They eliminate the possibility of error Replacement: They replace an error-prone process with an error-proof process Facilitation: They carry out the correct actions more easily through mechanisms such as color coding. Detection: They inspect the product according to a standard, successive verifications or self-check Mitigation: They allow the error to occur, but minimize the consequences (Preventing the influence of Tsuda errors).
Most common error-proof industrial mechanisms.
The most common in the industry are:
The information referring to the description of these mechanisms is from “Mistake-Proof it! Companion Reference Guide.
www.qualitytrainingportal.com/pricing/bookpricing.htm). And it is located in detail at:(www.QualityTrainingPortal.com/resources)
• Limit Switches. They are electro-mechanical mechanisms that are activated or deactivated when an object comes into contact with them. They are used to detect the presence or absence of an object..
• Proximity sensors. They emit a high-frequency magnetic field and detect a disturbance in the field when an object is introduced. They are used to detect the presence or absence of an object. Its application is aimed at detecting the level of a tank, confirm the passage of an object, the position of a workpiece. Direct contact is not necessary. They work in severe conditions. Fast response speed. They can be adjusted in tight spaces.
• Laser Displacement Sensors. They focus a semiconductor laser beam on a target and use reflectance to determine the presence of a target and the distance to it. They measure the distance. They detect the presence or absence of a characteristic. They confirm the passage of an object or part. They do not require direct contact. They can work in harsh environments. Some mechanisms can achieve precise measurements down to 0.004 mils.
• Vision Systems. They make use of cameras to observe a surface, comparing it against a standard or reference surface stored in the computer. They can be used to detect the presence or absence of an object, the presence of defects, or make distance measurements. Its application is to detect missing parts in an automated assembly line. Poor quality surfaces or components. Correct orientation of parts or labels.
Ensure the correct relative position. Color detection. Incorrect product detection. Direct contact is not required. Sufficient lighting is required. Extremely flexible (can be programmed for a wide range of applications). They can be compact systems.
• Electromechanical or Electronic Time Mechanisms –Timers- and Counters. The counters are based on the posting of events. They are usually activated by some other type of sensor. They can be programmed to stop the process if a certain number of events do not occur or if more than expected occur. The timers can stop the process if the processing or activity time does not correspond or exceed the established time level. They are used to ensure that an appropriate number of events occur. They prevent equipment or component failure over time. They are very flexible, easy to use and easy to understand.
• Photoelectric Sensors. There are three main types of photoelectric sensors:
o Ray of light passing through the object. It has a light source and a separate receiver
or reflective beam. It has a receiver in the same unit as the light source making the determination by the "bounce of light" off the object.
o Retro reflective ray. Bounce the light beam to a reflector and the determination is made with this. It is applied to register tank levels. Confirmation of the passage of objects or parts. Detection of the presence or absence of an object. Positioning of a workpiece. Measurement of a distance. No direct contact is required. Capable of working in harsh environments. They detect targets of almost any material. They have the ability to discriminate color. Capable of detecting at considerable distances. They can make highly accurate detections.
• Ultrasound sensors. They emit high-frequency radio waves and detect the reflection of the wave when it hits the object. They can detect the presence or absence of an object or make distance measurements. They are used to register tank levels. They confirm the passage of an object or part. They do not require direct contact. They can work in harsh environments.
• Families of Instruments for Measurement of Process characteristics.
o Temperature. Temperature measurements can be made by doing it with contact mechanisms and without direct contact. If the temperature mechanisms are used in conjunction with a controller, the process can be stopped when the temperature begins to rise or fall below a preset point.
o Pressure. A mistake-proof technique is to install a pressure monitor in the air compression system, stopping it when it reaches a certain pressure and restarting it when the pressure drops to a preset pressure. This type of mechanism prevents a malfunction of an air cylinder.
o Electrical Charge. If the amperage or power have variations that exceed the preset limits, the process can be stopped.
o Flow. The flow of liquids and gases can be measured with rotameters, flow switches, and other mechanisms. (pitot tube anemometers, etc.) these mechanisms are often used for fail-safe processes to stop a process when flow is low or not at all.
o Movement. Some motion control mechanisms work on the same principle as ABS brakes. A sensor detects the pulses of a disk rotating on the drive shaft on a conveyor. If there is no movement when there should be, the process stops.
o Speed. The speed can be measured with different mechanisms, which can stop the process if the speeds are too high or too low with respect to a preset speed.
o Viscosity. Viscosity measurements in the process line are used by industries to ensure that the proper ingredients have been added and ensure that the fluid can be processed. These measurements can trigger alarms or in extreme cases, stop the process.
or pH. Plating baths as well as other solutions may require error-proof mechanisms such as pH monitors. Instead of having operators titrating solutions to verify pH, a pH monitor coupled with a controller can stop the process or make automatic pH adjustments creating a solution control.
o Mass / Weight. Weight / mass meters can be used to meter the input feed of materials to a process or stop-start a process.
o Humidity. Some processes can be affected by high humidity, some processes can become unstable when humidity is reduced. Humidity sensors can be used to stop a process if the humidity is high or low with respect to a preset humidity.
• Families of Specialized Sensors.
o Bar Code Reader. They can be used to stop the process when a package or part is detected wrong, they can also be used to divert that package or part.
o Color recognition. Color Detectors can be used to detect the wrong product, poor quality product, or wrong position orientations of some product.
o Impact Sensor. They can be used to detect missing parts, machinery malfunction, improper removal of products or parts of a machine.
o Metal Detector. They are used in the food, pharmaceutical, plastics and other industries to detect undesirable metals in the process. Many of these detectors automatically bypass the product containing the metal. Other systems will stop the line if they detect metals.
o Moisture-mist detector. Normally these detectors work with water, however they can do it with other types of liquids as well. They are often located at remote sites in the process, which are not frequented by the operator or which cannot be easily verified by the operator.
Examples of Poka Yoke in its different classifications:
pokayoke.wikispaces.com/
www.moresteam.com/toolbox/t412.cfm
Poka Yoke example in software: http://www.geocities.com/SiliconValley/Lab/5320/pokasoft.htm
Examples applied to different media and business lines (including service area): http: //www.referenceforbusiness. com / management / Or-Pr / Poka-Yoke.html
An excellent example where you can find numerous Poka Yoke is an electric passenger lift, using them mainly for the safety of users and the lift itself. It can have proximity sensors to prevent the door from closing if a person is nearby and as redundant security photocells to prevent rapid closing, weight sensors to avoid exceeding its weight capacity due to a greater number of passengers preventing it from moving. If the allowed weight is exceeded, speed sensors to prevent them from exceeding a preset speed, oscillatory / trepidation movement sensors to prevent it from being used in the event of an earthquake, and in the event of a power failure with people inside passing the immediate disembarkation so that people can go out avoiding unnecessary risks,temperature sensors to avoid overheating of the machine, a damper in the pit as redundant security, security camera, alarm warning, overlapping closures on the doors and internal insulation inside the walls capable of withstanding high temperatures due to fire if they were requested fireproof, and quite a few more Poka Yoke through its internal structure. However, inadequate training or ignorance of the purpose for which the safety devices were installed by the original manufacturer, make inexperienced personnel "bypass" or eliminate them during their "maintenance", causing risks that can cause real tragedies. In this point,Another Poka Yoke would be to include notices with letters and images "maintenance can only be carried out by highly trained or certified personnel" - preferably by the company that manufactured and installed it - in addition to placing similar notices at critical points. Similarly, numerous Poka Yoke are used in escalators and moving walks or walkways / sliding platforms of world-renowned companies that have the safety of users and their own personnel and equipment as one of their goals.Numerous Poka Yoke are used on escalators and moving walkways or walkways / sliding platforms of world-renowned companies that have the safety of users and their own personnel and equipment as one of their goals.Numerous Poka Yoke are used on escalators and moving walkways or walkways / sliding platforms of world-renowned companies that have the safety of users and their own personnel and equipment as one of their goals.
When to use Poka Yoke and Procedure.
The ASQ (American Society for Quality) establishes as a general guide the following criteria for knowing when to use Poka Yoke and the procedures that this system uses:
asq.org/learn-about-quality/process-analysis-tools/overview/mistake-proofing.html
Its use is recommended:
• When in a stage of a process it has been identified that human error can cause errors or defects to arise. Especially in those processes that cannot be trusted to have the full attention of the worker, or due to possible lack of skill or insufficient experience due to complexity of the process or other cause.
• In a service process. Where you interact with the customer and you can make a mistake affecting or compromising the result.
• In a transfer stage within a process. When the client is transferred to another worker or employee in service processes and an error can be made in the transfer due to not properly passing the “post”.
• When a small error at the beginning of the process can cause serious problems later in the process.
• When the consequences of a mistake are costly or dangerous.
Poka Yoke procedure.
The way to go is usually:
1. Know the process. Obtain or create a flow diagram of the process. Review each step, think about where and when human errors can occur. Seek to understand the possible problems that may arise.
2. For each potential error, it is necessary to look back through the process to find the source that may originate it, determine the root of the possible error.
3. For each error, analyze the possible ways that make it impossible for the error to occur. To consider:
3.1 Elimination. Eliminate the stage causing the error.
3.2 Replacement. Replace the stage with a foolproof medium.
3.3 Facilitation. Making the right action much easier to do than making the mistake.
4. If the error cannot be made impossible to make, analyze the means to detect the error and minimize its effects. Consider: Method of
Inspection, Establish Adjustment Functions or Normative Functions.
Three types of Inspection Methods provide quick feedback:
Successive inspection. It is done in the next step of the process by the next worker.
Self inspection. It means that workers check their own work immediately after doing it.
Inspection at the source. Before proceeding to take the step where the error arises in the process, it is verified that the conditions are correct within the knowledge they have of the process itself, if they already have experience working on it.
Adjustment functions are the methods by which a parameter or attribute of the process or the product is inspected for possible errors, using the methods previously described:
• The Physical or Contact Method, checks a physical characteristic such as diameter, temperature, etc. often via a sensor.
• The Sequence Method checks the sequence of the process to make sure the steps are performed in order.
• The Fixed Value Method or Counting Method, counts the repetitions or parts or weights of an element to ensure that it is complete.
• Sometimes a fourth adjustment function is added: Information Enhancement.
To ensure that the information is available and can be consulted when and where it is required.
Normative functions are signals that alert workers that an error is occurring:
Warning functions: these are bells, buzzers, lights and other sensory signals. Consider using distinctive color codes, shapes, symbols, and sounds.
Control functions: prevent the process from proceeding until the error is corrected (if the error has already occurred); or if the conditions are correct (but the inspection at the Source has not been completed and the error has not yet occurred).
5. Choose the best fail-safe method or device for each failure. Test this and then implement it.
What are the Places that may require a Poka Yoke? -.
Stewart and Grout suggest as conditions that must be met to think about installing a Poca Yoke:
• The result of the process or routine must be known in advance to have a standard for comparison.
• The process must be stable, the results must not be changing.
• There must be the ability to create a separation between cause and effect in the process.
And having satisfied them, initially select as the first places, being in his opinion the most feasible in which Poka Yoke may be needed:
• In environments that require substantial skill on the part of the operators.
• In environments where the cost of training is high or there is high staff turnover,
• In environments with frequent interruptions and distractions.
• In environments with a constant system of product mixes.
• At the beginning of any process where multiple processes are combined that could be started at the same time.
• Any point in the process that requires replacement or orientation of parts to avoid misplacing.
• Any point in the process where constant adjustments are made to the machines or the process.
Poka Yoke Relationship and Analysis of Failure Modes and Effects (FMEA in Spanish and FMEA in English)
Poka Yoke or “fail-safe” system could be considered as an extension of the FMEA Design / Process.
FMEA helps in the prediction and prevention of problems, Poka Yoke emphasizes the detection and correction of errors before recurrence turns them into defects. Defects that may arise while the end customer is in use or at the next stage in the process line, presenting themselves to the internal customer.
Bases for the implementation of the Poca Yoke philosophy.
The Poka Yoke philosophy requires a solid foundation of TQM - Total Quality Management- for which it is required:
First. Organizations must learn to focus on meeting the needs of the Client as the main axis to maintain and increase their market. Second. Organizations must promote quality throughout their internal structure, and ensure adequate investment in training for all their staff. Always encouraging a dignified treatment. Third. A strong emphasis should be placed on the need to always achieve good quality and avoid poor quality by all means. Fourth. Organizations must adopt the philosophy of getting it right the first time, doing more with less, respecting the integrity of people. Fifth. Poka Yoke requires teamwork and constant motivation of all staff, always promoting creativity to achieve the desired results in an expeditious manner.
My Recommendations for those who want to make a Poka Yoke.
1. Don't wait for “tomorrow” to make the perfect Poka Yoke. Do it now. As is the motto of Nike: "Just do it"
2. If your idea to make your Poka Yoke has a greater than 70% chance of success, develop it. Do not stop doing it. Do not be discouraged, remember point 1 above. If it is less than 70%, visualize alternatives, try to better understand the problem and the process, correct your original idea, look for additional economy and consider this 2nd recommendation again. Do not be discouraged, you will achieve it.
3. Make your Poka Yoke now… improve it later.
CONCLUSION
One of the most important points in the implementation of Poka Yoke is the fact that people in general, at all levels, and across all functions and activities, begin to think much more about "PREVENSION MODE" rather than "After the fact" and only use the detection mode when it was not possible to prevent the error in relation to the processes or procedures with which they work.
Foresee is the name of a correct administration of quality management.
I hope that those who have read this article out of curiosity, believing to find new magic words, will know that it is not necessary to be a magician to achieve excellent results in any area of our life.
My personal opinion and conclusion is that Poka Yoke helps anticipate Threats, seeks to eliminate Weaknesses, detect Opportunities and increase Strengths to achieve leadership in our field.
BIBLIOGRAPHY
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Hirano Hiroyuki. Poka Yoke: mistake-proofing for zero defects. PHP Institute. 1994
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Quality Hub. Quality Tools> Poka Yoke / Mistake proofing. http://qhub.hbmeu.ac.ae/q_tools/pokayoke.htm
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Shingo Shigeo. Mistake-proofing for operators: the ZQC. Productivity Press. USES. 1997.
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