Taiichi Ohno, former
Toyota vice president,
once gave the following example of finding the real cause of a machine
Q1: Why did the machine stop?
A1: Because the fuse blew due to
Q2: Why there was an overload?
A2: Because the bearing
lubrication was inadequate.
Q3: Why was the lubrication
A3: Because the lubrication pump
was not functioning right.
Q4: Why wasn't the lubrication
pump working right?
A4: Because the pump axle was worn
Q5: Why was it worn out?
A5: Because sludge got in.
Turn Problems to Opportunities:
The Key To Japan's Competitive Success," Masaaki Imai
or juggling symptoms?
The Five Whys is a simple but great technique to
It is a
question-asking method used to explore the cause/effect relationships
underlying a particular problem. Ultimately, the goal of applying the 5 Whys
method is to determine a root cause of a defect or
4 WHYs of True Success
In most situations, real problems and root
causes are obscured by apparent problems. The intent of the "Five-Why"
procedure is to assure that the route causes and not merely superficial
symptoms are corrected. The "Five-Why Process" was introduced at
find solution to manufacturing problems, but this approach can be applied to
any other area as well. Ask "Why this problem happened?" to discover its
underlying problem; then ask "Why?" again to go deeper by another level
until you reach the root cause.
Asking "why" repeatedly, possibly more than
five times, directs the focus toward real causes so
problems can be solved
Problem Solving: Switching Perceptions
Origin of the Five-Why Technique
The technique was originally developed by
Sakichi Toyoda and was later used within Toyota Motor Corporation during the
evolution of their manufacturing methodologies. It is a critical component
problem solving training delivered as part of the induction into the
Production System. The
architect of the
System, Taiichi Ohno, described the 5 whys method as "the basis of
Toyota's scientific approach . . . by repeating why five times, the nature
of the problem as well as its solution becomes clear." The tool has seen
widespread use beyond
and is now used within
lean manufacturing, and
Six Sigma. The 5 Whys really gets people involved using their brains and
challenging the ‘status quo.’...
Kaikaku and the Five-Why Technique
Radical Improvement (Kaikaku):
Kore 10 Tips
"Ask "Why" five times," advises Hiroyuki Hirano
in his "10 Kaikaku Commandments“
that provide a roadmap for radical
Norman Bodek, a
guru, writes in his comments to the 10 commandments, "In the mid-nineteen
eighties I took Dr. Shingo to Granville-Phillips a manufacturer of vacuum
testing equipment in Boulder, Colorado. Granville-Phillips had brilliant
engineers, but they took four months to bring a new product to market (and
then the result was 97% defects in final inspection). Dr. Bills, the CEO of
Granville-Phillips, asked Dr. Shingo to please look at their manufacturing
process to see if he could help them become more efficient. Shingo at first
went to where the process originated. We went to watch the design engineers
and then we followed a logical progression through the entire manufacturing
process. At each stage engineers and managers would present problems to Dr.
Shingo and he would carefully think and look and then instead of just giving
the answer, he would ask the engineers some very basic questions. He loved
to use the Five Whys, asking why five times.”