Page 170 - The Toyota Way Fieldbook

Chapter 7. Leveling: Be More Like the Tortoise Than the Hare 147

Standardized
Equipment
Work Materials
Needed
Needed
BASIC
LEVELING

Methods (Lean People
Takt
Tools and Needed
Procedures)

Figure 7-1. Basic leveling is the core for all resource planning

creates the need for higher levels of resources (and cost) to be able to accom-
modate the wide swings.
This creates a condition that makes standardized work difficult, if not impos-
sible, to implement. Remember, in standardized work we’re trying to create a
precise balance of work across operations, based on the takt time, which is based
on the rate of customer demand. If the takt goes up and down with the bullwhip,
the work balancing and standardized work swings wildly every day. How is it
possible to standardize when the takt is continually changing? This is the basis
for the second form of heijunka: a self-imposed leveling for the internal benefit
of the value stream (and cascading outward to suppliers as well). This leveling of
demand creates a standard core onto which all resource needs are attached and
aligned, as depicted in Figure 7-1.

Why Do This to Yourself?

Leveling your production is a self-inflicted choice. We say self-inflicted because
it is a conscious choice, and there is a consequence. Some negative effect comes
with the choice. Leveling means precise timing and being very flexible to cycle
through products in small batches. This flexibility taxes the process. Any prob-
lem that causes delays will reveal itself immediately and result in a missed
schedule.
For example, to level by product type means making small quantities of
each item throughout the day, which means changing over from product to
product. There is often some time associated with changing materials, changing
a fixture, and so on. Changing over is lost production time. If the changeover
process is not standardized and precise, then the large number of changeovers
will lead to lost production, and the schedule will be missed. From a traditional