Stop Sign
Toyota Principle #5 – Build a culture of stopping to fix the problem, to get quality right the first time
One of the better known stories about creating a culture that stops to fix a problem is that of the Toyoda automatic loom. The Toyoda loom was unprecedented as it detected when a thread broke and stopped the loom; thus preventing poor quality cloth.
Of course, one of the most famous illustrations of stopping to fix a problem is the ‘Andon Cord’ on Toyota assembly lines. Most are familiar with the fact that any worker can pull the cord if they detect a problem.
Jidoka, an important part of the Toyota lexicon, and central to Principle #5, can be translated variously as: ‘Quality built in,’ or ‘Quality at the source.’
There are four stages to Jidoka:
- Detect the abnormality
- Stop
- Correct the abnormality
- Find the root cause and create a countermeasure
In both illustrations above (the Loom and the Andon Cord), Jidoka was employed. Many have heard that any worker can STOP the line in a Toyota plant. That’s not correct. Stopping alone doesn’t lead to the 3rd & 4th stages of Jidoka.
It’s true that any worker can pull the Andon cord, but that doesn’t stop the line. It simply illuminates an Andon light, or Andon board. That brings support personnel running. Support personnel have one Takt Time to identify the root cause of the problem and develop a work-around.
If a work-around can’t be found, the supervisor stops the line until a work-around can be developed and implemented. The work-around allows time to develop a more robust countermeasure.
Why is Principle #5 important? I’ve worked in numerous industries in which there was a separate organization whose sole job was to “inspect” the products made by others and find problems in them. The premise was that you couldn’t make it correctly the first time, so you inspected later to find and correct problems, before the product got to the customer.
The problem with this approach is that inspection is not all that effective. In fact, Sakichi Toyoda and Taiichi Ohno felt this approach was wasteful. They believed that those actually performing a task should check arriving material or parts before beginning work. This way, the worker didn’t add value (material & labor) to a product that couldn’t be sold in its current state.
Lean carries on this tradition. When a problem is found in a Lean organization, whether it’s a manufactured part, a typed document, or computer code, the next person in line inspects the previous worker’s work before adding their own. If there is a problem, they stop before doing further work.
Rather than repair the part themselves, or send it to a third party to repair, the person who finds the defect (or their supervisor) returns it to the person who created the defect. This return completes a feedback loop. The person who created the defect is shown the problem, taught how to correct it and given the time to complete the correction. This feedback loop gives the person responsible a chance to understand the root cause and take corrective action, the last two steps of the Jidoka cycle.
The defect is still recorded, and if data show it happens with any frequency, a more formal corrective action is taken. What’s key is that Lean workers continue to STOP and correct problems.
One last: Notice that this principle starts with the enjoinder that one should “build a culture.” Employees can’t do that. In a Lean culture, leaders need to empower this process. Employees can’t stop the line if they are not permitted to. In fact, Principle #5 is more a measure of how one manages than of how your employees behave.
