“Is that bolt from a production part?” I asked. My colleague said, “No, some maintenance guy must have dropped it.”
The bolt looked common enough, lying there under the conveyor, and the impulse of the group doing the 5S walk was to throw it into the scrap metal hopper. If it had been a production part it would lead to stopping shipments until we found the piece that was missing the bolt, but a non-production part seemed harmless.
However, a 5S system is not a housekeeping program, it is a problem prevention and problem identification system so, when 5S shows us something out of place, the process should be to repeatedly ask why until we find the root cause and take action. Taiichi Ohno said that until you have asked why five times, you probably have not found the root cause. Thus, the 5 Why (aka 5Y) root cause process is to ask, “Why, why, why, why, why” until you have found the source, or root, of the problem. Sometimes five times of asking why is not enough, and you have to ask it several more times.
There should be a very strong connection between 5S and 5 Why. The 5S program (called 5S for the five parts of the system: Sort, Set in order, Shine, Standardize, and Sustain) is often mistaken as housekeeping. A good 5S program produces good housekeeping, but it is just an outcome, not the goal. Five S should be a problem prevention program and a way to identify and fix problems when they are still very small, thus preventing big problems. As the saying goes: “Take care of the small things, and the big things will take care of themselves.”
Investigating the Bolt
We began to investigate where the bolt came from and how it had come to rest on the floor. After speaking to several employees in the area for help, and a couple dead ends, a maintenance technician was able to identify the bolt as the type used on the conveyor system. We began to look carefully under and around the conveyor and found that the section of track where we had found the bolt had only one bolt holding it together, and it was loose. If we had not discovered where the bolt had come from, the entire conveyor would have fallen apart and shut down production for hours or days. Even worse, it could have injured someone when it happened.
We also had to answer why the bolt fell out. Conveyor vibration tends to loosen fasteners, so just replacing and tightening all eight bolts was only a temporary fix while we investigated, experimented, and developed a fastener system that would not fall out (such as using a lock washer, or locking nut, or thread locking cement, or other method), eliminated the source of the vibration, improved the preventive maintenance checks, or some combination of these actions that would ensure this would never happen again. Like all good problem solving, the goal is that the problem never repeats.
Another example from a different factory was when I noticed an electrical cabinet that was closed but not latched. It is a violation of basic safety protocol and OSHA regulations but, unfortunately, not uncommon. The machine was up and running, and the operator was not aware that the cabinet was unlatched. Asking “why” finally revealed that maintenance had been working on something during the night but, “Everything must be OK now because we are running parts.” I was assured that the latch would be secured. Then everything would be neat and clean.
A good housekeeping program will not solve problems and can even defeat problem solving by cleaning up the evidence needed for root cause analysis and permanent corrective action."
I continued my questioning and discovered that maintenance had been working on the machine because it was producing nonconforming parts, and they had scrapped many parts until it was shut down. The maintenance guy that had been working on it had gone off shift and removed his lock from the lock out/tag out disconnect with the expectation that the day shift maintenance would finish the work. The day shift operator powered up the machine and began to run parts. Maintenance was short staffed and assumed that the work was done and was focused on higher priority machines.
The safety interlocks and error proofing devices had been disabled. Test parts run by midnight shift had been left on the table and day shift had packed them for shipping. The operator was in danger of serious injury or death without the safety interlocks and did not even know it. Nonconforming product could be made at any time and not be caught because the automatic checks were not working. Known bad parts had already been packed for shipment. Many procedures and protocols were not followed but a good 5S program should have identified the problem before the operator restarted that machine.
5S Builds Self Discipline
Lean programs often start with 5S because it builds, and demonstrates, a culture of self-discipline. Self-discipline is required to follow the standards. This self-discipline forms the basis for further process improvements such as standard work, kanban and autonomous maintenance.
In the first example we could see the bolt on the floor, an out-of-standard condition, because there were no other parts or trash on the floor. In the second example, a factory with a 5S culture would not start a machine until it had investigated why the electrical panel was not properly closed.
A program focused on mopping, sweeping and dusting is a housekeeping program. A good housekeeping program would have put the bolt into the scrap hopper and would have closed the electrical panel without any other actions. A good housekeeping program will not solve problems and can even defeat problem solving by cleaning up the evidence needed for root cause analysis and permanent corrective action.
A good 5S program displays a facility’s culture and mindset and allows problem prevention. Everything has a place, everything is in its place, and ready for use, and when they are not we start asking why. This is the beginning of a 5S program that forms the foundation of a lean transformation.
Without a 5S program in place, we would not have been able to see the little problems until they had become big, or even fatal, problems.