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4th Year Millwright > Vibration Analysis Assignment 1-4 > Flashcards

Vibration Analysis Assignment 1-4 Flashcards

1
Q

List 3 benefits of vibrations analysis?

A
  • Down time reduced
  • Machine destruction can be avoided
  • Can be corrected
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2
Q

Identify 4 items of machine information needed to help with vibration analysis;

A
  • Type of machine
  • Machines location
  • Machines speed (most critical)
  • Bearing types and locations
  • The date of data collection
  • Coupling types and location
  • The components (machines) with the line (turbines, generators, pumps, gearboxes)
  • Equipment number
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3
Q

List 5 possible sources of vibration;

A
  • Imbalance
  • Misalignment
  • Bearing damage
  • Gear problems
  • Cracked welds
  • Resonance
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4
Q

What type of machine damage will oil analysis identify?

A

Contamination in the oil/lubricant, from metals in oil, water, oxidization, varnish, dirt, antifreeze, breakdown of oil.

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5
Q

True or False;
Temperature analysis requires direct contact with the machinery to be examined.

A

False - infrared thermometers can be used as its a non contact radiant energy detector. (Infrared Thermography)

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6
Q

What spectrum of light is detected when using thermography?

A

Infrared radiation

-detects the thermal radiation(emissivity) of an object.

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7
Q

Vibration is the movement of a body about its ___________ position,

A

Vibration is the movement of a body about its REFERENCE position.

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8
Q

A _____________ analysis is used to find the direct cause of the vibration.

A

A SIGNATURE analysis is used to find the direct cause of the vibration.

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9
Q

List 3 ways vibrations can transfer from one machine to an adjacent machine.

A
  • Piping
  • Floor
  • Noise
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10
Q

By changing either the ______ or the __________ of an object, you change the vibration signature.

A

By changing either the MASS or the STIFFNESS of an object, you change the vibration signature.

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11
Q

List 3 terms used to describe the vibration sine wave;

A
  • Frequency
  • Amplitude
  • Phase

FAP - haha

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12
Q

What vibration term identifies how often an event occurs in relation to a unit of time?

A

Frequency

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13
Q

If a cycle happens 60 times per minute, what is the CPS or Hertz?

A

1 CPS or 1 Hz

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14
Q

25Hz = ?

A

25 x 60 = 1500 CPM

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15
Q

1500 rpm = ?

A

1500/60 = 25 Hz

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16
Q

Orders are multiples of the __________ _________.

A

Orders are the multiples of the OPERATING SPEED.
*

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17
Q

True or False;
Displacement is the distance of movement from rest to the peak of travel.

A

False

  • total movement above and below axis.
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18
Q

Displacement is measured in _______ for imperial and _________ for metric.

A

Displacement is measured in MILS(Peak to Peak for imperial and MICRONS (Peak to Peak) for metric.

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19
Q

Velocity is a unit of _________ over _________.

A

Velocity is a unit of DISPLACEMENT(how far it moves) over TIME.

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20
Q

When placed on a sine wave, the maximum velocity takes place on the _____________.

A

When placed on a sine wave, the maximum velocity takes place on the NEUTRAL AXIS.

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21
Q

Velocity readings are most consistent between _____ cpm and ___________ cpm.

A

Velocity readings are most consistent between 600 cpm and 60000(60K) cpm.

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22
Q

Acceleration is measured in _-_________.

A

Acceleration is measured in G-FORCES.

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23
Q

True or False;
Acceleration is best for slow frequencies.

A

False
- above 60K

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24
Q

Phase is a relationship between ______ related events and is measured in _________.

A

Phase is a relationship between TWO related events and is measured in DEGREES.

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25
Q

Define Natural Frequency;

A

Natural Frequency - The frequency at which an object or system naturally vibrates when a forcing function has been introduced.

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26
Q

True or False;
Resonant frequency is the desired frequency to run a machine at.

A

False
-destroys machines.

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27
Q

What is the safe distance from a natural frequency at which to run a machine?

A

20%

28
Q

Define Harmonic;

A

A multiple or sub-multiple of the fundamental frequency.

29
Q

Why is the baseline information important?

A

Used as a reference to the normal conditions of the machine.

30
Q

Define Synchronous Vibration;

A

A frequency that is a whole multiple of the rotating speed(velocity) of the machine.

31
Q

What is the purpose of severity charts?

A

A reference graph, indicates how smooth your vibration readings are.

32
Q

Fast Fournier transform turns Amplitude versus time to Amplitude versus ____________.

A

Fast Fournier transform turns Amplitude versus time to Amplitude versus FREQUENCY.

33
Q

What type of vibration measuring tool is permanently installed to watch a specific piece of equipment?

A

Vibration Monitors

34
Q

What is the most important part of any vibration measurement system?

A

Transducer

35
Q

What are the 3 basic categories of transducers?

A
  • Displacement
  • Velocity
  • Acceleration
36
Q

A non-contact eddy current displacement transducer is also called a _________ __________.

A

A non-contact eddy current displacement transducer is also called a PROXIMITY PROBE.

37
Q

Why are proximity probes mounted permanently to the machine?

A
  • missed this one in class, shoot me a message and I’ll fix.
38
Q

For the eddy current transducer to work, the shaft must be a _____________.

A

For the eddy current transducer to work, the shaft must be a CONDUCTOR.

39
Q

What type of transducer is made with a coil of wire and a permanent magnet?

A

Velocity transducer
*

40
Q

What type of transducer is the most common?

A

Acceleration transducers
(Accelerometer)

41
Q

What is produced when the piezoelectric material is squeezed?

A
  • Electrical current proportional to force.

“a piezoelectric material, when strained or compressed by an external force, creates an electrical current proportional to force.

42
Q

What are the 4 ways to mount the transducer?

A
  • Stud (Best)
  • Magnetic Pickup (Good)
  • Hand held probe
  • Shaft rider accessory
43
Q

True or False
- A vertical mounted transducer can also be used to calculate data in the horizontal and axial plane?

A

False
“The transducer is only capable of picking up a vibration that is in line with the transducer. The transducer does not pickup vibrations at 90 degrees to the transducer.”

44
Q

Strobe lights are used when the ________ _________ needs to be measured with the prominent frequency.

A

Strobe lights are used when the SHAFT SPEED(RPM OF MACHINE) needs to be measured with the prominent frequency.

45
Q

What is a major concern when using a strobe light to determine rpm?

A

Errors, because the strobe can be at any multiple of shaft speed.

46
Q

What does it mean to trend the data?

A

If readings are taken at the same locations, you can identify changes from previous data within the machine.

  • a reference for changes in the machinery.
47
Q

What is a very common source of vibration and is identified at 1X rpm?

A

Imbalance

48
Q

When will imbalance produce a high axial reading?

A

Overhung rotor

49
Q

True or false;
An increase in shaft speed will cause imbalance to produce a decrease in vibration amplitude.

A

False;
“The amplitude of the vibration also increases with the speed of the machine”

50
Q

True or False;
Imbalance will have a large variation from a vertical to a horizontal reading.

A

False?
-not sure, if wrong, let me know, ill change.

51
Q

List 5 possible causes of imbalance?

A
  • Incorrect Machine assembly(loose parts)
    -Material worn off one side of rotating parts(impeller)
    -Material build up on rotating parts (fan blades)
    -Sag in shaft or rotor
  • A hollow spot in rotor(porosity) or a spot has a different density than the rest of the material
  • Part is made off centre(Eccentricity)
52
Q

Frequency for misalignment is usually __ x rpm, but if misalignment is severe there can be frequencies at ___ x rpm or ____ x rpm.

A

Frequency for misalignment is usually 1x rpm, but if the misalignment is severe there can be frequencies at 2x rpm, or 3x rpm.

53
Q

Angular misalignment will cause a high Vertical, Horizontal, or Axial reading?

A

Axial?

54
Q

Parallel misalignment will cause a high Vertical, Horizontal or Axial reading?

A

Vertical?

55
Q

How should you check to determine if a vibration problem is caused by an electrical problem?

A

Turn off power to motor, if immediate drop in the amplitude of vibration, there is an electrical problem.

56
Q

Gear vibration is a multiple of the ___________ times the RPM.

A

Gear vibration is a multiple of the NUMBER OF TEETH times the RPM

57
Q

What situation would a gear vibration cause a high vibration of 1x rpm?

A

If one tooth was bad

58
Q

A ball bearing with 18 rolling elements is mounted on a shaft rotating at 1750 rpm and has a damaged inner race, what is the vibration frequency?

A

Frequency = 0.60 x 18 x 1750
Frequency = 18900 cpm?

59
Q

A bearing with 15 rolling elements is mounted on a shaft rotating at 1750rpm and has a damaged outer race, what is the vibration frequency?

A

Frequency = 0.40 x 15 x 1750
Frequency = 10500 cpm?

60
Q

True or False;
Oil whirl will cause vibration frequency below 1x rpm.

A

True
“Usually occurs at frequencies of about 45-50% of shaft rotation”

61
Q

Mechanical looseness is identified by a dominant frequency of __ x rpm?

A

2 x rpm.

62
Q

Looseness between machine foot and baseplate will cause the phase to be the same or different?

A

Different

63
Q

Where is vibration from belts the greatest?

A

In the direction of belt tension

64
Q

How does phase identify a shaft?

A

1x or 2x rpm, phase readings are different at opposite ends of the bearing housings.

65
Q

How can resonance be identified as a problem?

A

Adding/removing weight, standing on a part, clamping or bracing it. If the vibration changes, the machine is resonating.

4th Year Millwright (29 decks)

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