Manual

What Is Predictive Maintenance?
Predictive Maintenance can be defined as collecting information from machines as
they operate to aid in making decisions about their health, repair and possible
improvements in order to reach maximum runability, before any unplanned break-
down. Machinery maintenance has evolved because of the demands to become
more profitable through reduced maintenance costs. Below is the progression of
these maintenance philosophies:
• Break Down Maintenance
• Preventive Maintenance
• Predictive Maintenance
Break Down Maintenance occurs when repair action is not taken on a problem
until the problem results in the machines failure. Run to failure problems often cause
costly secondary damage along with expenses resulting from unplanned downtime
and unplanned maintenance.
Preventive Maintenance occurs when a machine, or parts of a machine, are
overhauled on a regular basis regardless of the condition of the parts. While better
than run to failure, preventive maintenance results in excessive downtime due to
unnecessary overhauls and the excessive costs of replacing good parts along with
worn parts.
Predictive Maintenance is the process of determining the condition of machinery
as it operates, to predict and schedule the most efficient repair of problem components
prior to failure. Predictive Maintenance not only helps plant personnel eliminate
unplanned downtime and the possibility of catastrophic failure, but allows them
effectively order parts, schedule manpower, and plan multiple repairs during
scheduled downtime.
Benefits of Predictive Maintenance
Documented experience proves that plants which establish a predictive maintenance
program are able to:
• Improve Machinery Reliability-reduced “unplanned failures”
• Reduce Maintenance Costs-knowing the exact problem to fix
• Increase Production-optimize machinery capabilities
• Lower Energy Consumption- less vibration usually means less friction
• Extend Bearing Service Life- reduce vibration and lubrication failures
• Improve Product Quality- where less vibration improves finish
The benefits are numerous and will vary depending upon the implementation
of your Predictive Maintenance Program.
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Measurement Techniques
In general, vibration of anti-friction bearings is best monitored in the load zone of the
bearing. Equipment design often limits the ability to collect data in this zone. Simply
select the measurement Point which gives the best signal. Avoid painted surfaces,
unloaded bearing zones, housing splits, and structural gaps. When measuring vibration
with a hand-held sensor, it is very important to collect consistent readings, paying
close attention to the sensor’s position on the machinery, the sensor’s angle to the
machinery, and the contact pressure with which the sensor is held on the machinery.
• Location - always collect at the same point on the machine. Mark
locations.
• Position - Vibration should be measured in three directions:
A axial direction
H horizontal direction
V vertical direction
• Angle - Always perpendicular to the surface (90
o
+10
o
).
• Pressure - Even, consistent hand pressure must be used (firm, but not
so firm as to dampen the vibration signal). For best results
use the magnetic base. If using the stinger/probe is the only
method available to collect data, it is best to use a punch to
mark the location for the probe-tip to ensure a consistent
coupling to the housing.
Optimum Measurement Conditions
Perform measurements with the machine operating under normal conditions. For
example, when the rotor, housing, and main bearings have reached their normal
steady operating temperatures and with the machine running under its normal rated
condition (for example, at rated voltage, flow, pressure and load). On machines
with varying speeds or loads, perform measurements at all extreme rating conditions
in addition to selected conditions within these limits. The maximum measured value
represents the vibration severity.
load zone
Magnetically
Mounted
Vibration Sensor
Stinger Mounted
Vibration Sensor