Page 358 - The Toyota Way Fieldbook

Chapter 14. Develop a Thorough Understanding 333

Engineer: Every half hour, but you can’t change that without causing a large
problem with the employees. They all agreed on a half-hour rotation for
ergonomics.
Sensei: My concern in not how often they rotate. I am concerned that when
they do rotate, the line stops for about four to five minutes. That is as much
as 10 minutes every hour, nearly 20 percent lost time!
They watch the line a little longer and again the flow stops. This time it is
because the shipping container is full and waiting for the material handler to
remove it and bring an empty one.

Sensei: Why did the line stop?
Engineer: The container was full and they needed a new one. The only way
you’re going to prevent that is to have a material handler here full-time,
and we don’t have enough material handlers for that.
Sensei: (Sternly) There is always more than one way to solve any problem.
I’m sure we can design a system for exchanging the containers in a way
that does not stop the product flow and does not require a material han-
dler here full-time. Right now, though, I am just trying to understand the
true problem.

Here is how the causal chain appears to the engineer:
Problem: The robot breaks down.
Why? There is a run fault signal in Zone 3.
Why? The nut does not feed.
Why? The equipment is not designed correctly.
Where does this path lead? It leads to a dead end! It is a dead end that can
consume large amounts of time and money attempting to correct a very chal-
lenging issue. In the meantime, the “low hanging fruit” is falling from the tree!

Examining a Problem in Reverse

Now let’s look at the causal chain from the sensei’s point of view. First, he begins
with the problem as pointed out by the engineer, and using the “therefore”
method, he proceeds back up the chain until he’s sure he has found the true prob-
lem, as shown below. Note that we begin at the perceived problem line and con-
tinue to state “therefore” proceeding upward until the true problem is identified.

Therefore: The process can’t meet demand without overtime. This is the true
problem.
Therefore: Process doesn’t make parts.
Therefore: The product flow stops.