Balancing Flashcards
What is imbalance?
Imbalance is the unequal distribution of weight of a rotating body about its centreline
What are some causes of imbalance?
11 main ones
Corrosion and Abrasion
Distortion
Eccentricity
Bent shaft
Clearances
Keys and key ways
Non-homogeneous machine parts
Asymmetry
Material buildup
Shifting parts
Temperature
What is static imbalance?
When a shafts weight is evenly distributed along its length, but unevenly from side to side
What is it called if the balance correction is at a single point on the rotor?
Single plane balancing
What is dynamic imbalance?
Vibration caused by extra weight unevenly distributed:
Along the length of the shaft
Across the width of the shaft
At different angles about the radius
If a machine has vibration caused by unevenly distributed weight along the length of its shaft, what kind of imbalance is this?
Dynamic imbalance
If a component or assembly is of significant length requires two weights at opposing ends to balance what is that known as?
Dual plane (two plane) balancing
What is the main result of imbalance?
Vibration
What is the flash angle/phase lag?
What is the angle of delay?
The distance the heavy spot moves past the pickup before the flash occurs
Angle of delay
What is a strobe lights primary purpose when balancing?
To check the phase angle
How often does the strobe light flash when balancing?
Once every revolution of the shaft or rotor
What does imbalance show up as when taking vibration measurements?
1x rpm
When the source of vibration is primarily imbalanced, how do the vertical and horizontal phase readings compare?
The vertical and horizontal readings are relatively similar
How does doubling the rotor speed affect the force cause by imbalance?
Doubling the rpm quadruples the force caused by imbalance
When balancing, does the reference mark change when the trial weight location is changed?
Yes the reference mark changed if the heavy weight changes
