At this level the Five-Why chain has developed the first branch. Prior to ask-
ing “Why?” for both branches, it’s important to understand which is the most
significant. This understanding will maintain a narrower focus. For the sake of
this demonstration, we will assume that the data show that scrap is very low
and time is the greater loss, and proceed to show the continuation of the causal
chain from this level. It is imperative to actually confirm the overall impact of
each item, rather than to assume. The scrap quantity data may be available and
fairly easy to quantify; however, the time losses will require a visit to the work-
place (genchi genbutsu) to verify the amount of time loss.
When asking “Why?” do not jump down the chain to the deeper issues.
Carefully consider the loss of time in a production process and try to keep the
focus narrow by answering the direct question. Look for the broad categories
under which the detailed answers will fall. Remember to use the “Therefore”
method if you find yourself answering further down the chain. If the answer
“Setup time is too long” arises, state “Therefore” and find the answer. In this sit-
uation it would be: “Therefore the machine is not running for a long time.” The
following step would be: “Therefore we are losing time.” If the “Therefore”
method was used on some of the other issues, it’s likely that “The machine is
not running” (or “The line is not running”) would be a consistent theme. This
is the common category we are looking for. In addition, our questioning may
lead us to understand that loss of time due to excessive process cycle time is
also a primary category. Now the Five-Why chain will appear as shown in
Figure 15-2.
Again the causal chain is branching. At this time a visit to the workplace is
absolutely necessary. In order to improve your observation ability you must
learn to “look with intention.” Based on the analysis thus far, what is the inten-
tion of your observation? The intention is to look to see whether there are cycle
time losses or situations during which the process is not operating.
The general thinking within Toyota is to consider the cycle losses first. Cycle
time losses are those losses that occur every cycle as the operation is performed;344 THETOYOTAWAYFIELDBOOK
Problem statement: The fabrication units per hour is below goal.
Why?
We are not able to make enough parts each hour
Why?
We are losing production opportunities
Why? Why?
Losing time Losing parts (scrap)
Why? Why? (Not most significant)
Cycle time losses Process not running
Figure 15-2. Second pass Five-Why analysis