Page 118 - The Toyota Way Fieldbook

Chapter 5. Create Connected Process Flow 95

A “pull system” is an aggregation of several elements that support the
process of pulling. The kanban “sign” is one of the tools used as part of a pull
system. The kanban is simply the communication method and could be a card,
an empty space, a cart, or any other signaling method for the customer to say,
“I am ready for more.” There are many other elements as well, including visu-
al control and standardized work. If the three elements of pull are properly
installed, a “connection” is formed between the supplier and customer processes.
The three elements dictate the parameters of the connection and its relative
strength and “tightness.”
The case example below illustrates the three distinct requirements for pull.
Single-piece flow is the easiest to explain and understand, but the same princi-
ples apply for any variation whatever the situation. For example, the same
principles apply to high-mix, low-volume operations, and to batching operations
where the quantities between processes may be much larger. This following exam-
ple is the easiest to understand, but the principles can be applied to any situation.

Case Example: Creating One-Piece Flow

Operation A supplies parts to Operation B, which supplies parts to
Operation C.
Is the agreement defined and specified?

Yes. We said it was single-piece flow, so in this case the defined quantity is
implied in the name. (As we will see, implied definition is not sufficient).
What is the specified agreement?

Provide one piece at a time.
When is the piece provided?
When the next operation takes the previous piece (remember the bucket
brigade).
Upon observation, we can determine whether the agreement is
being followed. In this case we see in Figure 5-4 that Operation B
is not following the agreement and has exceeded the defined limit
of one piece.

How do we know this is a violation of the agreement?

Operation Operation Operation
A B C

Figure 5-4. Flow that is not defined