Poka-Yoke, or Mistake Proofing, is the Japanese method of reducing errors. Shigeo Shingo first introduced this term to prevent defects from occurring within a process. The method uses a defective function which assists organizations in eliminating defects or errors from occurring in the initial stages. The term poka-yoke (poh-kah-yoh-keh) was invented in the early 1960s, which literally translates to mistake-proofing or avoiding inadvertent errors.
This mistake-proofing mechanism is one of the lean manufacturing tools that entails organizations to eliminate waste, improve efficiency, and employ simpler working methods. Shigeo Shingo invented the method when he discovered that human errors were the root causes of problems/defects. Although initially, the term represented a human, Shingo changed the term to focus on the process. Even our day-to-day activities or routine life can involve mistakes due to various factors.
Purpose of Poka-Yoke in Lean Manufacturing
The lean methodology enables organizations to eliminate waste, improve processes, enhance product value and resolve customer problems. Various lean concepts and tools are implemented in the manufacturing sector as they are easily comprehended. Several companies think of Poka-Yoke as a behavior-shaping constraint that prevents incorrect operation.
Poka-yoke aligns with the “Theory of Constraints” for implementing processes with no constraints from start to end. A simple instance of this mechanism is seen in automatic cars. Unless the gear selection lever is not in ‘Park,’ it is impossible to start the car. This eliminates the possibility of suddenly moving the car resulting in a mistake.
What are the two types of poka-yoke?
Control and Warning are the two types of poka-yoke. The control type focuses on making it impossible for mistakes to occur. On the other hand, Warning type implies that a sound or color indicates operators when they are about to make a mistake. In the end, the main objective of this method is to ensure that no mistakes occur or that there are zero defects.
How does poka-yoke benefit?
Enterprises applying for poka-yoke benefit from the following:
- Reduces common errors that affect operations
- Assists manufacturers in mitigating expensive and time-consuming processes
- Decrease in operational errors as they don’t solely depend on human knowledge
- Employs a culture of continuous improvement among employees
- Focuses on having zero defects or close to zero
- Higher quality products as a result of increased customer satisfaction levels
What are the steps involved in implementing poka-yoke?
This Japanese method of mistake-proofing involves a series of steps for implementation. These steps are easy to understand and assist organizations in assessing the immediate benefits.
Step 1: Identify the problem
As the age-old saying goes, humans are bound to make mistakes. However, a series of mistakes call for attention. The flaw can be from the side of humans or machines. Employees need to examine the entire process to identify such flaws carefully. Using flowcharts can assist such employees in quickly identifying where the flaw is.
Step 2: Find the root cause
To identify the problem, employees must determine the cause of such flaws. An organization performs various processes daily, making it more difficult for employees to find the flaw. Various quality tools, such as 5Whys, can be used to find the root cause of the problems occurring within a process.
Step 3: Determine which type of Poka-Yoke to use
if the flaws identified can be easily prevented, quality employees can use the control type of poka-yoke. This prevents a process from being completed until the operator takes corrective action. Employees can instill the warning type of poka-yoke that can alert the operator to prevent flaws. Using either of the poka-yoke types stops a process from being completed.
Step 4: Choose the right poka-yoke method
Employees can opt for contact, constant number, or sequence methodologies of poka-yoke for identifying the flaws. Contact uses physical attributes to identify errors, while constant number uses specific actions. The sequence method ensures that a proper sequence follows before a process can continue.
Step 5: Test your poka-yoke system
Before an organization implements poka-yoke, quality specialists need to ensure that the employed system will work. This entitles them to test whether errors can be prevented and to check if there are delays in the process due to the system.
Step 6: Train employees
Although implementing poka-yoke is quite simple, employees need adequate training for the method to be successful. Training the employees on poka-yoke allows them to see that their job is easier with the system, thereby making it easier for adoption.
Step 7: Review performance and measure success
Examining the operation again and assessing the success of the poka-yoke system is a vital step. Looking for ways to continually improve allows employees to measure and assess if it is truly beneficial for the organization.
With this, we can easily conclude that the Poka-Yoke mechanism is the most important lean manufacturing tool that organizations can utilize. The Japanese mechanism has gained popularity among various manufacturing companies, entitling quality professionals to understand it comprehensively. Individuals pursuing a career in quality management can enroll in Poka-Yoke Training sessions to understand the function comprehensively and gain a competitive advantage.