Poka Yoke System: Benefits, Explanation, Need, Use, Types, Improvement Alternatives

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Nowadays each and the every company wants profit high productivity value in the market. There are slogans in the most factories stating defect reduction targets but the ultimate aim should always be zero the defects. POKA-YOKE is a vital factor in the eliminating defects. Poka-yoke is a concept in the total quality management which is related to the restricting errors at source itself. It deals with the fool-proofing or mistake-proofing. A poka-yoke is any idea generation or the mechanism development in a total productive the management process that helps operator to the avoid yoke mistakes poka.

Main aim of the Poka Yoke concept is to make whole system error proof that means no one can be the make mistake although some one wants to make mistakes the intentionally. It eliminates the defects or faults. This term was coined by the Shigeo Shingo in 1960s for the part of Toyota Production the System. The aim of Poka-yoke is to design the process so that mistakes can be detected and the corrected immediately eliminating defects at the source.

Need for Mistake Proofing

When any the organization decides to implement lean manufacturing then one of the objective is to reduce scrap because no one is the interested to compensate extra inventory on account of the scrap. Hence it is better to the find root cause of any problem and avidity which gives a defect free the product. The main objective of this project on the Poka Yoke is to study existing issues in the company and how Poka Yoke is used to eliminate them.

 How Poka Yoke has become an important part in the working of a company is clearly the explained here. Nowadays it is the even important in day to day life to have error proof the situations. In this project recent rejection in the Barrier Audit stage is taken and the Poka Yoke is given as a solution to the eradicate it. Barrier Audit is the final inspection stage before the dispatch. The term poka-yoke was applied by Shigeo Shingo in the 1960s to industrial processes designed to the prevent human errors.

Shingo redesigned a process in the factory workers Salish Thatavarti and the K. Tami Reddy 2017 while assembling a small switch would often forget to the insert the required spring under one of the switch buttons. In the redesigned process worker would perform the task in two steps first preparing the two required springs and placing them in the placeholder then inserting springs from placeholder into the switch. When a spring remained in the placeholder workers knew that they had forgotten to the insert it and could correct the mistake effortlessly.

Mistake Proofing

What is Poka Yoke

Poka-yoke means mistake-proofing. A poka-yoke is any mechanism in the lean manufacturing process that helps an equipment operator avoid the yoke mistakes poka. Its purpose is to the eliminate product defects by preventing correcting or the drawing attention to human errors as the occur. The concept was formalized and the term adopted by Shigeo Shingo as part of the Toyota Production the System.

It was the originally described as paka-yoke but as this means fool-proofing or the idiot proofing name was changed to the milder poka-yoke. Each process is done on basis of the Poka Yoke to make sure that mistake is eliminate from the starting itself. Therefore reworks can be the avoided. Poka-yoke gives a strategy and the policy for preventing defects at the source. These solutions are not the only cost-effective but also easy to understand and the apply.

Poka Yoke

Need of Poka Yoke

Manufacturing defects or errors are always the key concerns of any manufacturing the industry. The success of any organization depends on the quality of product especially right product the produced. Poka- yoke refers to the techniques that make it impossible to the make mistakes. When the any organization decides to implement the lean manufacturing then one of the objective is to reduce scrap because no one it is the  interested to compensate extra inventory on account of the scrap.

To the increase profit percentage the cost pressures always become headache for the top management so they never accept continued mistakes like scrap rework out of the tolerance etc. instead they are aiming to the achieve value of zero in this segment. When customers of the any company buys product they rightfully expect defect free products and the conventional 100% inspection or statistical process control do not insure 100% defect-free the products.

History of Poka Yoke

Poka-Yoke method was the introduced by ShigeoShingo in the 1961 when he was one of engineers at Toyota Motor the Corporation. This method in the other words is to prevent defects and the errors originating in the mistake. Shigeo Shingo Born in the Saga City Japan the Japanese industrial engineer who distinguished himself as one of the world’s leading experts on manufacturing practices and the Toyota Production System. It is therefore started in Japanese organizations to the implement a Zero Quality Control (ZQC).

One of its elements implementing the principle Zero Quality Control (ZQC) is Poka-Yoke the method. The name Poka-Yoke was established by Shigeo Shingo in the 1963 it is translated as resistance to the errors avoid yoke errors resulting from absence of the mind Poka. The initial term was paka-yoke which means the fool-proofing. This term paka-yoke was the dishonorable connotation. Hence the term was changed to poka-yoke which means the mistake- proofing.

When to Use It

  • It is the technique a tool that can be applied to any type of the process be it in manufacturing or the service industry.
  •  Poka-yoke can be the used wherever something can go wrong or an error can be the made.
  • Errors can be of the any type
  1. Processing Error the Process operation missed or not performed per the SOP.
  2.  Setup Error Using the wrong tooling or setting machine adjustments the incorrectly.
  3. Missing Part Not all parts included in the assembly welding or other the processes.
  4. Improper the part item Wrong part used in the process.
  5. Operations Error carrying out and the operation incorrectly having the incorrect version of the specification.
  6. Measurement Errors in the machine adjustment test measurement or dimensions of a part coming in from the supplier.

How to Use It

Step by step process in the applying poka-yoke:-

  • Identify the operation or process
  • Analyses and understand the ways in which a process can be the fail.
  • Decide the right Poka-yoke approach such as the using a,
    1.Shut out Type: Preventing the error being made or a
    2.Attention Type: Highlighting that an error has the been made.
  •  Determine the whether a
    1.Contact the Method
    2.Constant Number or the Counting Method
    3.Motion Sequence the Method
  • Trial the method and see if it is the works.
  • Train the operator review performance and the measure success.

Types of Poka Yoke

1] Contact Method

Do not have to be high tech!

Passive devices are sometimes the best method. These can be the simple as guide pins or blocks that do not allow parts to be seated in the wrong position prior to the processing.

Take advantage of parts designed with an uneven shape!

A work piece with the hole a bump or an uneven end is the perfect candidate for a passive the jig. This method signals to the operator right away that part is not in the proper position.

2] Counting Method

Used when a fixed number of the operations are required within a process or the when a product has a fixed number of parts that are the attached to it. A sensor counts the number of times a part is the used or a process is completed and releases the part only when right time is the reached.

3] Motion-Sequence Method

The third Poka-yoke method uses sensors to the determine if a motion or a step in a process has the occurred. If the step has not occurred or has occurred out of sequence the sensor signals the timer or other device to stop machine and the signal.

Reasons Why We Don’t Need Poka Yoke

  • Workers Possess Divine the Infallibility
  • Implementation Costs are the High.
  • The World is not a Dynamic the Environment.
  • It is Cheaper to the Hirer Sorters.
  • Quality Control & the Production.
  • Would Have Nothing To Do.
  • We are All Too the Busy.
  • We use SPC for the Improvements.

Poka Yoke Devices, Systems & Inspection

Inspection with Poka Yoke

1.Source Inspection Zero Quality Control (ZQC)

  • built into the process
  • leads to the zero defect Systems

2. Self-Check Informative the Inspections (SQC)

  • Built inside or the outside immediate process
  • reduces defects to the minimum

3. Successive Check the Informative Inspection (SQC)

  • built inside or the outside sequential process
  • reduces defects to the minimum

Proposed Improvement Alternatives

From observations and the detailed interviews with operators it is the believed that human error is a major issue in this production the line. Since human cause is the major factor in this problem as well as method and the machine factor attempt will be made to the employ Poka Yoke or a mistake proofing the technique. Some proposed Poka Yoke solutions will be the developed and proposed at the end of this study.

Alternative 1: Poka Yoke Device

Rather than warning workers to the pay more attention or to ensure not to forget anything and the appropriate device may be employed since workers will be the eventually or occasionally forget and tend to make the mistakes. The first alternative suggested is to the install a Poke Yoke device into the operation so that if a worker forgets something the device will emit a signal thereby preventing defects from the occurring. This is the quickest way leading to the attainment of zero the defect.

Having developed the concept design for mechanism of the Poka Yoke device the next step is the construction of a prototype hardware. The hardware consists of four parts which are the power supply input sensor processor and the output indicator and motor. Having reviewed the characteristic and comparison of the component final selection for the hardware is as follows.

Concept design for Poka Yoke using automated sensor mechanisms
  • The power supply task is to connect a 9 volt power source from battery into the 5 volt regulated supply available to all microchips in the device.
  • The input is the limit switch sensor which is used to the detect correct position of the part and to send signal to microcontroller and a starting the switch.
  • A unit of microcontroller PIC16F877A is used to process all the inputs. This microcontroller is used to control the automated mechanism opening of the lid buzzer alarming LED flashing based on the signal received from sensor.

Alternative 2: Successive Inspection

In the existing process approach self-check is applied and the detection of abnormalities is performed selectively and the corrective action takes place slowly. If the worker performs his/her own inspections he or she the might compromise on quality or might inadvertently let defects the slip by. Hence a concept is the recommended where it uses the closest person that is the operator at next process to take on the job of inspector. This would have the benefit that information about any abnormality the discovered could be relayed immediately to the worker of the previous process. Figure 3 shows the application of the method. The Successive Check System was devised as the follows:

  • When operator A finishes processing and the item he or she passes it on to operator B at the next process.
  • Operator B first inspects the item processed by operator A and then carries out the processing assigned to him or the her.
  • Operator C first inspects the item processed by operator B and then carries out the processing assigned to him or the her. When the work is completed operator C passes the item on to the operator D.
The sequence of successive inspection system

Problem Identification

The next step in this project involved identifying problems that occur in the selected production line. Selected tools and the techniques such as Pareto diagram Cause and the Effect diagram together with the basic problem identification methodology were employed to identify major the problems. The problem identification methodology employed in this study is shown in the Table 1. The main types of defects found were mis-location missing component and the half insert. Some possible causes for these three problems are the workers not able to follow or are not following the standard operation procedure (SOP) inadvertent error carelessness and the no sensing device.


This paper has presented the findings of quality improvement using the Poka Yoke technique for a selected automotive part assembly the process. This study has identified the problems affecting quality in model the D73A line. The problem can be overcome by using a sensing device where the mistake proofing device has been proposed and the tested.

Categories: Mechanical


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