1. Improving Uniformity:
Increasing First Pass Yield Through the Tire Building Machine
By Morgan Allis
Uniformity kick outs in department 614 has been an ongoing issue. The percentage of tires that passed uniformity
testing the first time, also known as first pass yield, was an area the business center wanted to improve upon. Reprocessing
tires, while hard on our employees, also costs the plant money; sometimes ticket is missed due to low first pass yield. .
Before our team began investigating this area of opportunity we verified that the machines that test uniformity,
Kokusai #1 and #2, were taking precise and accurate measurements. Through the implementation of new procedures, including
daily repeatability tests and shiftly rim cleanings, the two Kokusais were verified to be both accurate and precise.
As seen in figure 1, out of all the MTR build machines, TBM #14 has the highest number of kickouts (for a sample size
of approximately 1 week). A significant number of kickouts failed for the test metric most commonly associated with vibration
(radial runout and first harmonic). TBM #14’s low performance was the perfect opportunity to strategically design an
experiment to study the varying factors that affect tire uniformity; this was done through isolation of variables. In order to
achieve accurate results, variables such as builder and green tire #, were controlled for. A multifunctional team was organized
which included engineers, PQAMS, BCMs, TTLs, tire builders, FARO mechanics, and PM mechanics.
Figure 1. Pre-Alignment Kickout Results [10/28-11-04]
0
200
400
600
800
1000
TBM Kickouts Before
Improvements

2. The first variable to be studied was machine alignment. With invaluable data from the FARO alignment team it was
obvious that there was room for improvement. In conjunction with each other, the PM mechanics and FARO mechanics
efficiently aligned the build machine. The alignment included shaft-to-transfer-ring alignment, transfer ring to belt drum
alignment, and transfer ring to former alignment.
As seen in figures 2 and 3, the impact on uniformity from the TBM alignment was significant. First pass yield increased
from 72% to 98% (figure 2) and the overall number of kickouts significantly decreased from a weekly average of approximately
550 to 23 (figure 3). That is, our employees went from needing to handle tires 28% of the time to 2% of the time. This equated
to a significant amount of time where operators and PQAMs could work on other tasks.
Figure 2. Post-Alignment First Pass Yield Uniformity Results for TBM 14
Figure 3. TBM 14 kickouts [10/11-11/15]
Moving forward, while closely working with the FARO team, we plan to apply our findings to more build machines,
while at the same time also isolating and studying other variables such as centering capability, splice capability, green tire #,
and any other relevant variables. The study has demonstrated that build machine alignment is a critical component of tire
uniformity. Furthermore, the alignment results demonstrate the value that the FARO alignment team brings to the quality of
our product. Eventually we will use our findings to drive the quality of our product throughout all three business centers.
72%
98.43%
0%
20%
40%
60%
80%
100%
Uniformity First Pass Yield
Week Before
Alignment
Week After
Alignment
0
100
200
300
400
500
600
700
#ofKickouts
TBM 14 Kickouts
Alignment
Completed