Quality

Chet Marchwinski recently exhumed a 2011 discussion about Poka-Yoke that had been started by the following question:

I’m a manufacturing engineer and since I have started participating in kaizen workshops, I have noticed that production supervisors tend to disconnect some of the poka-yokes we’ve put in place in the machines. When I challenge them about this they argue that operators can’t run production and cope with the complexity of our machines. I am perplexed by this and wondered whether you’d have a comment.

In short, I can think of two reasons for production supervisors to disconnect Poka-Yoke:

1. No production supervisor in his right mind would disconnect devices that make the work easier for operators. If they do disconnect them, the most likely explanation is that the devices described as “Poka-Yoke” actually add work for the operator. If you have to pick a part from one of ten open bins in front of you, you will spend precious seconds finding the right one; if all bins are covered with lids except the right one, not only are you physically prevented from picking the wrong one but you don’t have to look for it. It makes your job easier. On the other hand, if you have to scan a bar code on the part to validate the pick, it adds to your work load and your supervisor will pull the plug on the next production rush.
2. The manufacturing process is not ready for Poka-Yoke. A production supervisor is quoted in the question as saying “operators can’t run production and cope with the complexity of our machines.” This suggests that the line has process capability issues that must be addressed before implementing Poka-Yoke.

The following paragraphs elaborate on these points.