Though the two lines produced pistons for different product families,
the process used to create them was similar on paper.
Machine builders had already been selected for both the A1 and X10
lines. For the X10 line, the current plant manager’s preference won
out and the same types of machines that were already producing X10
pistons were selected for the sake of consistency. For the A1 line,
Yoshina’s recommendation prevailed and Toyoda Machinery Works
(TMW), a relatively new player in the U.S. market for machining cen-
ters—though an established player in grinders—was selected with the
hopes of initiating a long-term and more far-reaching relationship
with Acme.
We will discuss some of the detailed technical decisions made by each
of the two teams. This is not intended to teach a course in machining,
but to illustrate some of the detailed thinking required to develop truly
lean production lines.
Yoshina Meets with the A1 TeamYoshina’s approach was to provide guidance without dictating how to
make all the engineering decisions required. He gave general advice
and then commented on the ideas of the teams. The A1 team listened
carefully to learn all they possibly could, then translated the lean
concepts into decisions. One issue was how to make the material
flow, given the desire to achieve one-piece flow, while considering
the practical constraints they faced. The team decided that instead
of one-piece flow, they would machine four pistons at a time. There
were two main reasons. First, work would be balanced nicely, since
four pistons would be loaded into one machine (two pistons in each
of the operator’s hands), a whisker switch would be activated, and then
the operator would go to the adjacent machine to pick up the auto-
ejected group of four pistons to place in the next process. Second, based
on machining cycle times, four would be the number of pistons required
per cycle to ensure that the A1 assembly area was not starved for parts;
that is, to achieve the takt time required to make four pistons at a time.
However, with the amount of chips produced if four parts were
machined simultaneously, they were not sure how to keep the jigs that
TMW was providing with their equipment clean—and without clean jigs
for every part, First Time Through Quality levels would be negatively
impacted. The team’s current idea, brought to the table by TMW based
on their process database, was to machine the pistons horizontally so
centrifugal force and gravity would throw the chips away from the parts
and jigs. They were not sure if this would work, and looked to Yoshina
for some sort of reaction. Upon hearing this, Yoshina nodded in
agreement.
Chapter 20. Leading the Change 441