Page 99 - How To Implement Lean Manufacturing

The Significance of Lead T ime 79

them to work. One operator was the deburring operator who was lightly loaded, while
the other one was the person freed up from the assembly cell. We just divided the
25 minutes equally among the three people and gave them the necessary training to
change out the tools on the punch press. This allowed us to perform the tool change-outs
in three parallel paths and so we reduced the changeover time to just over 8 minutes, on
paper. However, in our planning we used 10 minutes as the time for a changeover. Actu-
ally, when we did the first changeovers, they took about 10 minutes. With three people
all gathered around this punch press, access was an issue. Although we were confident
we could make further reductions, we made no more changes at this time. Notes were
taken on possible time reduction opportunities and saved for future use.

Making the First Run

Starting Production
We were now ready and started the production. It went well and we were able to pro-
duce small lots (per Fig. 5-2, notice the change in scale from Figure 5.1)… almost.
Quality problems surfaced and we could “see” the type of quality problems they
were experiencing. During this initial run, we also learned why these quality problems
had such a large effect on their labor efficiency.

Encountering Quality Problems
When we started up the assembly cell, which was about 2.5 hours into the run, we
found a problem on the topside assembly. One small hole had been made, on the CNC
punch press, with the wrong recess dimensions. Luckily, we found this after only 40 units
had been produced. We were able to rework the 40 units offline without disrupting the
assembly cell. On the next changeover of the CNC punch press, we installed the correct
tool. In addition, we found that one bend had been missed on the bottom-side assembly
at the Press Break. These were returned to the Press Break and finished. The overall loss
of time at the assembly line was about one hour.

The Process Smoothes Out
Other than that, the process proceeded smoothly. About three weeks later, they needed
to make another run of 100 and it went flawlessly. In both cases, they were extremely
pleased.

The Results

Labor Efficiency Skyrockets
In the first run, using smaller batches, their labor efficiency was calculated to be 118 percent,
and in the subsequent run three weeks later, labor efficiency rose to 146 percent. Go
figure. (I did a paper kaizen study and found that with no capital, this labor efficiency
metric could be improved another 40 percent to over 180 percent.) As so often is the case,
we redesign the system, improve it to create a new present case condition, and then
again find further opportunities to improve. The cycle seems endless—and it is!!
Changeovers Are Increased, with No Out-of-Pocket Costs
It is interesting to note that there was some resistance to increasing the number of set-
ups on the CNC punch press since they stated that this tied up labor and did not increase