Jidoka – What does Line Stop really mean?

By Al Norval

As we look at the House of Lean, we see the roof held up by two pillars – JIT & Jidoka. I’ve written before about Jidoka being the forgotten pillar since most of the buzz is around the other pillar of JIT. Jidoka or autonomation as it is often translated to, really refers to “Built in Quality at the Source” or even more simply – Don’t pass defects on. Many people forget that high quality and Just In Time go hand in hand. There’s no sense reducing lead times just to move defects faster through the value stream.

I like to think of Jidoka as three things:

1. Don’t accept defects
   


2. Don’t make defects
   


3. Don’t pass defects on
   

Today, this post deals with the second bullet - Don’t make Defects. This can be broken down into a process which has four main parts to it:

1. Detect Defects
   


2. Stop
   


3. Call for help
   


4. Problem Solve
   

I see many people jumping on the bandwagon when they hear this but they tend to confuse the Stop step. While Stop accomplishes the goal of not passing defects on to the next operation, the parts of the process must work together. None of the steps works in isolation. I see many operations that wouldn’t run for very long if we kept stopping them every time the line produced a defect.

Machines are better than humans at detecting defects and stopping the line. Humans are better than machines at calling for help and problem solving. For Jidoka to work properly we must have both the machine and human parts of the system working well together. That means we must have a human response system that can respond to defects quickly, problem solve and rapidly get the line back up and running again.

The image I like to use in that when problems occur, the team swarms all over them so the operation can get back up and running again without making defects. Not only do they get the operation back up and running again but they problem solve to root cause so the problem doesn’t occur again.

Too often I see organizations put in the machine system where defects are detected and the operation is stopped but they have a weak human response system which leads to much downtime, delay and frustration on the part of Team Members. Problems aren’t solved to root cause which means they occur again and again.

The key lesson is:

Ensure a rapid human response system is in place and functioning well before line stop is attempted.

If not, it’s an easy way to just trade one type of waste for another.

Cheers