Jidoka - The Missing Pillar!

Jidoka is one of the main pillars of the TPS. The TPS is presented as a house with two pillars. One pillar represents just-in-time (JIT), and the other pillar the concept of Jidoka. Take away any of the pillars holding up the roof, and the entire system will collapse. Take out quality, and there is no TPS. Jidoka is a principle of building quality for customers—not inspecting quality. Building quality mean making it right the first time. If you are making defective products or using unacceptable quality standards and filtering these defects out through an inspection system, there is no building quality—and no Jidoka. You are just catching the mistakes made in the manufacturing process. This costs a lot of money and resources and puts the business at risk.

Yet many companies focus on the mechanisms of implementation--one-piece flow, pull production, takt time, standard work, kanban--without linking those mechanisms back to the pillars that hold up the entire system. JIT is fairly well understood, but jidoka is key to making the entire system stick. A lot of failed implementations can be traced back to not building this second pillar.

The principle's origin goes back to 1902 when Sakichi Toyoda invented a simple but ingenious mechanism that detected a broken thread and shut off an automatic loom. That invention allowed one operator to oversee the operation of up to a dozen looms while maintaining perfect quality. But the system goes much further. 

Detect and signal abnormalities: To build quality into the process machines have to be designed to detect defects when they occur and automatically stop production so an employee can fix a problem before the defect continues downstream.

"One of Taichi Ohno's famous quotes is "get the factory to work for the business the same way the human body works for the person". This is to say that when your body needs more blood, you don't have to tell the heart to pump. It does so autonomically. Jidoka is the concept that you need to design processes and systems so that when errors occur, people respond immediately in support. So at midnight on a Saturday, how do your systems respond to errors? Do the errors come to light immediately and problem solving begin or does everything wait until Monday? Jidoka would drive you to ensure that abnormalities are made immediately visible at all times and it would drive you to ensure the associates who respond to that abnormality have the capability and  authority to fix it."

Toyota uses an andon cords or pull cords which can bring the entire assembly line to halt. Every team member has the authority to stop the line every time they see something out of standard. As liker explained, “jidoka referred to as automation-equipment endowed with human intelligent to stop itself when it has a problem.”

My first exposure to jidoka was in a manufacturing company in Egypt that tried to apply this principle to improve quality and safety. In this factory, if you didn’t run the production 100% of the shift, you had to explain to the divisions. Quality and preventative maintenance are compromised in favor of quantity. By building a culture of stopping to fix problems, you are encouraging the workforce not to hide their problems that are actually killing profitability and causing inefficiencies. You should be planning for a long-term productivity.

Jidoka is a principle of building in quality not losing production! Unfortunately, and like many other companies there is a wrong misunderstand about the concept and how it operates. As Liker illustrated in The Toyota Way when Toyota competitors started to use the andon system, they made the same mistake of assuming the line-stop system was hardwired to each and every production line. So when the button is pushed, the entire assembly line like comes to a screeching halt. At Toyota, the principle of andon is worked remarkably different. When an operator in a workstation pushes an andon button, that workstation will light up in yellow typically like the traffic light, but the line will continue moving. The team leader has until the product moves into the next workstation zone to respond, before the andon turns red and the line segment automatically stop. As Liker explained, in Toyota this likely is to be a matter of 15-30 seconds on an assembly line making cars at one minute. In that time the team leader might immediately fix the problem or note it can be fixed while the car is moving into other workstations and push the button again, canceling out the line stoppage. Or the team leader might conclude the line should stop.

In that system, that are many considerations and tips:

1. The team leader has to be trained as well on a standardization procedure on how to respond to andon calls.

2. The assembly line should be divided into segments with small buffers of products in between (in Toyota this buffer is typically 7-10 cars). Because of the buffer, when a line segment stops, the next line can keep working for about 10 minutes using the buffer and before the entire plant is shut down and rarely it does shutdown.

3. The purpose of andon is to build in quality, not to lose production. Toyota achieved the purpose of andon without taking needless risks of lost production.

4. Some manufacturers assign a worker to watch the machine for error. This is a waste of the human precise time! Operator that is watching the machine for error is a pure waste and you have to develop a method (like Toyota andon) so problems are surfaced automatically when they occur. 

Two different concepts of Jidoka principle: The first concept is to separate man from machine. It was normal in the original parent company for a single young woman to operate many machines since they were automated. So when Mr. Ohno came to the automotive company after WW II and saw one man operating one machine tool he thought that it was strange and inefficient.

He embarked upon a path of breaking down the notion of one man one machine in the engine shops. Instead of “monitoring” machines the operator was to walk between two machine tools and keep them both up and running. Then three machines and four machines and so on.

The second concept of Jidoka is of course the concept of building in 100% quality every time at the process and not inspecting it in later downstream.

This means you have to have a highly capable process and know how to maintain all the key variables in the process so that a good part is made every time. If a problem occurs the machine should stop right away.

The main purpose of Jidoka principle is to discover quality problems at earlier stages, find the root causes and eliminate the problem from recurring again in the future. By doing so you are saving both your customer and your business. If a defected product is passed to customer so this is a problem and because customers are what keep you in business, you have to build quality for them. This is one of the main lean goals. The goal is to prevent a quality issue that is reducing productivity every day and killing your capacity, decreasing value, increasing costs and reducing safety. Lean encourage you to make it right from first time and this is why surfacing problems is important and can’t be done without a single-piece-flow system. Inspecting defects before they pass to the customer is not really the main goal of lean. But having a system that allow information to flow, problems to surface so they can be fixed immediately is the goal. Root causes should be identified and eliminated through kaizen. With lean, there is no or very little inventory buffer, so when process A stops process B will stop too. This allow problems to be noticed quickly and eliminated. There will be no more underlying costs and hidden wastes.

You can’t compromise quality. Quality problems are one of the greatest wastes in the process. Quality is what adds value for your customer and keeps you in business and defective products that reach the customer can lead to complete business loss.

Analyzing quality failures to eliminate root causes: Basically it is not difficult to know how many defective products are produced, as a simple sheet of paper can record this information. What is not easy to know is what caused the defects. Finding out can require intensive efforts to understand the source of variation that is causing the quality problem. And this is why one-piece flow improves quality. When problems are quickly noticed, they can be solved and eliminated immediately before they become chronic and costly.

Finding problems in quality is an important function of management. When faced with issues, many practitioners go straight to a complex tool like Six Sigma to find the sources of variation. But often, the simple approach of go and see (referred to gemba) could find the real cause easily. Monitoring how the operator is producing, revising the work against the standard, and involving the technical team could clear up many things. Comparing the machine or process with another one that produces the same part with fewer defects can make the analysis even quicker and easier.

At Toyota, managers use very few complex statistical tools for quality. They usually stick with go and see, mistake proofing techniques, a simple analysis tool like Pareto and problem-solving approaches like the five-whys, as Liker reported in his best-selling book The Toyota Way.

Quality improvement techniques: There are many tools to accomplish the quality goals at every aspect of the process. There are many tools that will help prevent quality problems before they occur and allow you to plan for an error-free product. Poka yoka which is a Japanese term, also refers to mistake-proofing is an effective tool to prevent human-errors. I have personally used it many times when conducting a failure mode effect analysis process. This tool can improve quality in many business processes include service, manufacturing, and design. Inventory control is another technique that is usually associated with any mistake proofing device.

There are large number of applications in real world regarding the use of mistake proofing in product design. Examples: Limit switches to assure a part correctly placed or fixtured before process is performed; part features that only allow assembly the correct way, unique connectors to avoid misconnecting wire harnesses or cables, part symmetry that avoids incorrect insertion.

Unfortunately, companies invest on technologies mistakenly thinking that technology can prevent errors. Technology can only support people and systems to prevent errors when there is a good management system and people are trained on problems solving and how to react immediately to abnormalities. 

To assess a product failures and determine failure mechanism that need mistake-proofing you may need the use of a technique like failure mode and effect analysis.

Failure mode effect analysis (FMEA) is a process of assessing the failure risk based on its occurrence, severity, and detectability. The more detectable methods we have in the system to detect and predict failure, the lower the risk of the product failure. FMEA and if used properly, can be a good tool in improving quality. An article that I wrote in the last year in the Industrial Management Magazine “Analyzing Failure to Prevent Problems” can illustrate this as well. Many organizations only use FMEA during the design stage, but FMEA can be really used in manufacturing, design, service and maintenance.

Lean is not a toolkit for manufacturing to lower costs for profitability. Lean is a long term strategy to satisfy customers through better quality and lower costs. Engineering a product that solve your customer’s usage problems is a legitimate lean goal. Lean is about innovation and creativity. If you can manufacture defect-free product or build quality into the design, this will help satisfy customers and increase their confidence.

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So what about you, have you tried to apply the Jidoka principle in your organization? What have you done to build a culture of stopping the process to fix quality problems?How was the success? The results? How was the top management commitment to change? 

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