PREPARED BY:MR. HARDIK A. PATEL

ASST. PROF.MECHANICAL ENGINEERING DEPARTMENT

Atmiya Institute of technology and Science,

Rajkot

POKA YOKE AND JIDOKA

Poka Yoke

Zero Defects through Mistake-Proofing Methods that help to avoid mistakes in work caused by choosing the

wrong part, leaving out a part, installing a part backwards, etc. Also called mistake-proofing, error-proofing and baka-yoke (fool-proofing).

The term poka-yoke was applied by Shigeo Shingo in the 1960s to industrial processes designed to prevent human errors.

Shingo redesigned a process in which factory workers, while assembling a small switch, would often forget to insert the required spring under one of the switch buttons. In the redesigned process, the worker would perform the task in two steps, first preparing the two required springs and placing them in a placeholder, then inserting the springs from the placeholder into the switch.

Defects occur when the mistakes are allowed to reach the customer.

Common examples of error-proofing

Types of poka-yokeContact method where a sensor determines the presence of a

part in a process and if the part is missing, it prevents the process from continuing. The sensors could be physical sensors or energy sensors such infrared.

Fixed-value method is a form of poka-yoke that uses a sensor to determine whether a process is complete by the number of parts that have been used or the number of process steps taken. If the right number of steps or parts have not been used, this indicates an error and the process is stopped. This method is also known as the counting method of mistake proofing.

Motion-step method uses a sensor to determine whether all the prerequisite process steps have been undertaken. If a step in the process has been missed, a signal is sent to the subsequent process to stop. This forces a correction of the problem before the process can continue and is a very effective error-proofing technique.

Benefits of Poka Yoke

Quality processes resulting in quality products. It is very hard for a process that is not of high quality to result in quality products or services. All processes must be capable of achieving value for the customer and this is possible through elimination of waste.

Effective teams who work in a coordinated manner so as to deliver value to the customer. Such teams look at the system as a whole and know their what roles they have to play so as to achieve the overall organization goals

Problem solving culture where there is no blaming when problems occur, but a concerted effort to resolve the real issues. This culture allows constant learning to take place within an organization because there is no finger-pointing when a problem occurs.

Solving the root cause guarantees that it will not recur in the future. This is achieved by conducting a root cause analysis to get to the real reason why a problem occurred.

Benefits of Poka Yoke

First time quality is an important principle because it ensures that every effort is made to achieve quality within process. This is in contrast to a culture that continuously pushes out parts irrespective of the quality because there will be a reworking if bad parts are produced

Waste elimination is at the heart of lean thinking because product quality improves and delivery times and costs are reduced. Waste in lean thinking is defined as an action or activity that consumes resources but does not add value to the customer

Continuous improvement of the solutions. This incremental improvement takes a cyclical pattern of problem identification, problem analysis, solution implementation and improvement.

JIDOKA

Jidoka is about quality at source, or built in quality; no company can survive without excellent quality of product and service and jidoka is the route through which this is achieved.

Jidoka highlights the causes of problems because work stops immediately when a problem first occurs.

Jidoka sometimes is called automation with human intelligence.

JIDOKA

Toyoda's innovation let one operator control many machines. In Japanese, jidoka is a Toyota-created word pronounced exactly the same as the Japanese word for automation, but with the added connotations of humanistic and creating value.

Jidoka is one of the two pillars of the Toyota Production System along with just-in-time.

Development of Jidoka

Initially Jidoka invented by Sakichi Toyoda in 1896.A simple device that could stop the shuttle on an automatic

textile loom if the thread broke.It consist of:

Discover an abnormality in the process STOP alerted the operator to a problem Fix the immediate problem Investigate and correct root cause

This principle became known as automation with a human touch.

The principles that were applied to machines with Automation were applied to the whole process by Taiichi Ohno

The Evolution towards Jidoka

Benefits of JIDOKA

The first benefit is the reduction of repair costs.The second benefit of Jikoda is the reduction of

recall costs, if the products and goods are produced with machines only, there may be inherent defects which may not be detected through sampling.

The third benefit of Jikoda is the minimization of law suits and compensations to the consumers as the goods and products being sold are of high quality hence reducing the company’s liability.

Thank you