Efficient Plant July/August 2020 - 25

department | on the floor

when taking a machine in poor condition,
typically with vibration levels exceeding
0.3 ips (pk) (7.5 mm/sec. (pk)) to a precise
state, the machine life is doubled, at minimum. For example, we have data from 336
machines from several manufacturers, of
various styles and types, with a wide range
of horsepower ratings, to which our Reliable
Manufacturing (essential craft skills and
precision maintenance) techniques and principles were applied. The mean time between
repairs (MTBR) was somewhere between 2.8
and 3.2 yr., before the improvements. After
our techniques were applied, the MTBR on
the same machines improved to 6.8 to 7.2 yr.
Of note here is that the mean time to
repair (MTTR) does not necessarily increase
with the application of precision maintenance, because the techniques are applied
in a disciplined and controlled manner in
which technicians understand what they're
doing and why they're doing it. The extra
time needed to execute and document the
work is more than offset by eliminating generally inefficient existing work processes.
In terms of the cost of maintenance (parts
and labor), reducing the vibration levels by
50% will typically result in a cost reduction
of 30%. We've also seen notable process
improvement. At one company, we were
able to improve OEE (overall equipment
effectiveness) from a peak of 67% to 75%
during 25 years of operation to a sustained
91% today.
Average electrical consumption changes
as we reduce the various frictional loads. The
savings are typically at least 20%. Documenting electrical savings demonstrates
immediate return, which is important as it
bridges the gap before longer term results
are realized. As for reliability performance
(When I push the button it does what I want
it to do for as long as I want it to do it and

JUL/AUG 2020

EP2007onthefloor.indd 25

when I shut it off and start it again, performance will repeat.), we have seen threeto-eight times improvements.
A simple formula is used to generate
these statistics. Load life for most mechanical
parts is equal to the inverse of load to the
third power. On a practical level, this means
that if you remove 20% of a frictional load
that is caused mostly by the way an asset is
assembled and installed on the floor, then
you double the life of the machine.
To improve reliability, we must understand the failures we wish to control,
eliminate them by using precision-maintenance techniques applied in a systematic
and disciplined manner, document the work
accomplished, and broadly communicate
those results. Operational excellence is
accomplished one machine at a time. EP

Based in Knoxville, Klaus M. Blache
is director of the Reliability &
Maintainability Center at the Univ. of
Tennessee, and a research professor
in the College of Engineering. Contact
him at kblache@utk.edu.
Tim Dunton is Director of Product
Development for Reliability Solutions,
Walnut Hill, FL (reliabilitysolutions.
net), a UT-RMC training partner. He
has more than 40 years of experience
in vibration analysis and technical
training related to the reliability of
rotating machinery. Dunton also has
extensive experience in workforce
development, curriculum development,
instructional design, and reliablemanufacturing practices. He holds DTI
Class 1 Certification and CMRP and
CMRT Certifications,

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Efficient Plant July/August 2020

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