Transcript Metra Mess- und Frequenztechnik Radebeul

Machine Condition Monitoring
Introduction
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Machine Vibration Monitoring
Machine Maintenance
Traditional Maintenance:
• Periodic shutdown and overhaul
schedule
• Production is stopped, off-line
machinery is inspected for wear and
wear-prone components
• Bearings, fans, gear boxes and other
parts are replaced, irrespective of
their potential to operate for a longer
time
• Between these scheduled repairs
unpredicted plant breakdowns cause
production loss
• Unscheduled repairs may be costly
Predictive Maintenance:
• Monitoring techniques include
vibration, acoustic noise,
temperature, oil condition
• Helps to predict machine failure with
sufficient accuracy to enable repair
before breakdown
• Maintenance can be better planned
• Increased plant availability
• Reduced maintenance costs
• Better product quality
• Increased plant safety
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Machine Vibration Monitoring
Advantages of Monitoring Vibration:
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Vibration magnitude is proportional to the magnitude of the problem
Vibration measurement is non-invasive
Most faults show increased vibration in an early stage of the deterioration sequence
Vibration can be measured instantaneously
Vibration can indicate severity and deterioration rate of a fault
Vibration can help to find the location of the fault
Vibration can help to find the cause of the fault
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Machine Vibration Monitoring
How Machine Vibration is Generated:
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Operating machinery produces vibration due to its rotational or linear motion
Increasing trends towards a higher level indicate emerging problems
Typical problems arise through
- misalignment of drive train components
- worn or damaged bearings
- load asymmetry due to debris adhesion on rotary parts like fans etc.
- incorrect assembly
Vibration generally occurs with its major component perpendicular to the rotational
axis of the load transmission shaft
The amount of vibration depends on
- the stiffness and geometry of the machine's structure
- the machine foundation
- the speed of rotation of the shaft
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Machine Vibration Monitoring
Vibration Monitoring
Permanent Monitoring
• Vibration switches
• Vibration severity monitors
• Spectrum monitors
VS6
Regular Patrol
• Hand-Held vibration severity meters
• FFT analyzers
• Data loggers
M12
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VM12
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VM15
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Machine Vibration Monitoring
Vibration Severity Monitoring:
• Widespread and simple method for vibration monitoring
• Measurement of vibration velocity, also called vibration severity in mm/s
• Vibration severity is a measure of energy of the emitted vibration
• Frequency range: 10 to 1000 Hz
ISO 10816:
• The standard gives recommendations for the evaluation of machine vibration by
measurements on non-rotating parts
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Machine Vibration Monitoring
Recommendations for Sensor Locations to ISO 10816-1 :
• Vibration measurements on machines should be made preferably at the housing of
bearings or nearby measuring points
• For routine monitoring it is sufficient in many cases to measure vibration either in
vertical or in horizontal direction
• Rigidly mounted machines with horizontal shafts have their highest vibration levels
mostly in a horizontal direction.
• Flexibly mounted machines may have high vertical components of vibration, too
• For inspections, vibration should be measured in all three directions (vertical,
horizontal and axial) at all bearings.
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Machine Vibration Monitoring
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The following illustrations show some examples for suitable measuring points:
vertical
vertical
horizontal
axial
axial
horizontal
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Machine Vibration Monitoring
vertical
axial
horizontal
vertical
axial
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horizontal
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Machine Vibration Monitoring
vertical 1
vertical 2
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Recommendations for measuring points at different types of machines can also be
found in ISO 13373-1. horizontal
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Machine Vibration Monitoring
Vibration Severity Limits to ISO 10816-1:
• If no reference values of vibration severity
are available on the relevant machine, the
recommendations of ISO 10816-1 can be
used
• Permissible values of the vibration
severity are given for different machine
types
• The basis of the assessment is the
maximum value of all measured points on
the machine
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Machine Vibration Monitoring
Vibration Measurement on Reciprocating Engines to ISO 10816-6:
• Reciprocating engines, like combustion engines and compressors, are characterized
by backward and forward going masses.
• The vibration generated by this motion, is higher than the vibration of rotating
machinery.
• ISO 10816-6 includes recommendations for the assessment of vibrations of
reciprocating machines.
• The measured quantities are the RMS values of acceleration, velocity and
displacement.
• They are measured at the machine block in all three axes of the room. The
recommended frequency range reaches from 2 Hz up to 1000 Hz.
• By means of the measured values of all three vibration quantities, the reciprocating
engine may be classified as belonging to a particular class of assessment.
• The following table allows this classification. At first read the relevant vibration
severity level for all three measured vibration quantities. The decisive class is the
highest of these three determined severity classes. In the right part of the table you
find the degree of machine condition in dependence on the machine class (depending
on size, construction, assembly and speed of the machine).
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Machine Vibration Monitoring
Vibration Measurement on Reciprocating Engines to ISO 10816-6:
A New machines
B Continuous running without restriction possible
C Not suitable for continuous running, reduced operability until the next scheduled maintenance
D Too high vibration, damage to the machine cannot be excluded
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