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Engineers typically learn that the bearing L10 life can be estimated using the so called “C/P method” — or the “basic rating life” of
the bearing, a method rooted in the 1940s. Major developments have since led to the “modified rating life,” released in ISO 281:2007,
which includes the aiso life modification factor. In this paper a succession of equations used for bearing life ratings are reviewed, and
current bearing life rating practices are discussed in detail. It is shown that — despite the introduction more than 30 years ago of
the adjustment factor of the basic rating life, and the standardization in 2007 of the aiso modification factor — use of these improved
calculation methods are not practiced by all engineers. Indeed — many continue referring to the old model as a way of seeking
compliance with existing, established practices.
Engineers are often challenged with the seemingly
impossible task of doing more with less.
Customers want more power transmitted in a smaller space,
they want more efficient designs, and, of course, they want to
spend less money. So engineers are always looking for ways
to squeeze the most out of their mechanical systems. They’re
constantly working to maximize power density, increase
energy efficiency and reduce costs to meet their customers’
needs.
It seems preposterous in the whimsical, wireless world of today, but in 1977 cinema’s greatest visioneers came together and decided the pinnacle of robotic technology in the future would be a motorized trash can.
The use of motor current signature analysis (MCSA) for motor fault detection — such as
a broken rotor bar — is now well established. However, detection of mechanical faults
related to the driven system remains a more challenging task. Recently there has been a growing interest for detection of gear faults by MCSA. Advantages and drawbacks of these
MCSA-type techniques are presented and discussed on a few industrial cases.
When comparing bearing suppliers,
engineers are often left with few options
other than to compare dynamic
load ratings and corresponding life
calculations. Of course, we can look at
steel and manufacturing quality; but
if we are comparing sources of similar
quality, those items may not provide
a large contrast. It often surprises
people to learn that bearing capacities
are calculated values, not tested values.
Lately, however, a trend is emerging
for bearing suppliers to increase their
ratings for higher performance bearings
that have premium features such
as higher quality steel and specilaized
heat treatment. Bearing companies are
under intense competitive pressure to
make every feature add to the dynamic
capacity of their bearings because it is very well understood that an increase in capacity adds to the bottom line.
Bill Walton – a 7 foot tall anomaly
from the annals of basketball history
who wears tie-dye shirts, listens to the
Grateful Dead and, according to his
own outlandish proclamations, hasn’t
taken an indoor shower in 35 years – is
well-known for looking at average accomplishmentsand being overcome
with extreme fits of emotion.