Vibration Analysis

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• Vibration Analysis
• Balancing

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What is Vibration Analysis

• The study of Collected data taken with the
  analyzer, of a machine while it is running.
• Data is collected at each location or point in
  the horizontal, vertical and the axial plans.
• Numerous bearing, motor and condition fault
  frequencies are checked and compared.

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Vibration Analysis

• What is vibration?
• Forces that vary in amplitude or direction over
  time cause repetitive motions called vibration
• When is vibration bad?
• All rotating machinery generates some vibration
• Only vibration that exceeds certain amplitude
  levels is bad.

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Vibration Terminology

• Amplitude
• The measure of energy or movement in a vibrating
  object
• Three common ways of expressing
• Displacement in mils peak to peak
• Velocity in inches/second peak
• Acceleration in gs rms

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Vibration Terminology

• Frequency
• The number of times that a vibrating object
  repeats its motion per unit of time
• The rotational frequency is often called 1X
• Other frequencies are often identified as
  multiples of 1X, such as 2X, 3X, 4X, etc.

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Vibration Measurement

• We analyze vibration profiles from, motors, fans
  and pumps, chillers, bearings and overall machine
  health.
• Were looking for bearing condition, mechanical
  looseness, motor electrical problems, resonance
  issues

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Overall vs. Running speed-1X

• Overall amplitude is a measure of the vibration
  energy over a wide frequency range
• 1 times amplitude usually refers to the vibration
  at operating/running speed
• Overall amplitude includes the effects of all
  sourceseven those external to the fan

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Vibration Terminology

• Vibration Spectrum
• (a display of frequency vs. amplitude)

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Profile Plot

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Dynamic Unbalance

• Dynamic (couple) unbalance requires correction in
  two or more planes

• Heavy spot will not bottom out when rotor is
  placed in bearings

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Achieving Lower Vibration Levels

• Involves better precision of many components
• Better balance of all rotating components
• Fan wheel (balance with fan shaft)
• Sheaves
• Couplings
• Motors
• Straighter shafts with precision diameter
  tolerance and roundness
• Less hop and wobble in fan wheel
• Better fits in attached components

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Achieving Lower Vibration Levels

• Involves better precision of many components
  (continued)
• Reduced internal clearance in bearings
• Bearing mounting surfaces machined flat
• Premium quality v-belt drives
• Precision alignment of v-belt drives or couplings
• Precise tensioning of belts

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Achieving Lower Vibration Levels

• Involves other special design considerations
• Heavier and more rigid components Use Class III
  instead of Class II
• Aluminum fan wheel (reduced rotor weight)
• Use inertia base for flexibly mounted fan
• Select lower speed fans if possible
• Avoid operation at any critical resonance speeds-
  vibration can increase up to 10X amplitude

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Balance

• Balancing
• The process of adding or removing weight on a
  rotor in order to move the center of gravity
  towards the axis of rotation
• The purpose of balancing is to reduce the
  unbalance forces that damage machines, there
  surroundings and reduce noise transmitted to
  tenants

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Balance Tolerances

• Defines the maximum amount of residual unbalance
  remaining after balancing
• Originally defined in international standard ISO
  1940/1
• Many new standards exist today.
• We use the manufactures specifications along with
  years of experience to achieve best balance
  possible

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Balance and Vibration tolerances

• Proper balance
• Provides for long life,
• Higher efficiency and
• Reliable operation without excessive cost

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Static Unbalance

• Static unbalance can be corrected by adding a
  single weight

• Heavy spot will bottom out when the rotor is
  placed in bearings

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Dynamic Unbalance

• Dynamic (couple) unbalance requires correction in
  two or more planes

• Heavy spot will not bottom out when rotor is
  placed in bearings

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503 657-4467
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