PPT: Balancing | Theory of Machines (TOM) - Mechanical Engineering PDF Download

 Page 1


BALANCING BALANCING BALANCING BALANCING
Page 2


BALANCING BALANCING BALANCING BALANCING
Balancing 

 The process of providing the second mass in order to 
counteract the effect of the centrifugal force of the first mass, 
is called balancing of rotating masses.

 To eliminate all shaking forces and shaking moments

 Any link or member that is in pure rotation can, theoretically, 
 Any link or member that is in pure rotation can, theoretically, 
be perfectly balanced to eliminate all shaking forces and 
shaking moments.

 A rotating member can be balanced either statically or 
dynamically.

 Rotating parts can, and generally should, be designed to be 
inherently balanced by their geometry.
Page 3


BALANCING BALANCING BALANCING BALANCING
Balancing 

 The process of providing the second mass in order to 
counteract the effect of the centrifugal force of the first mass, 
is called balancing of rotating masses.

 To eliminate all shaking forces and shaking moments

 Any link or member that is in pure rotation can, theoretically, 
 Any link or member that is in pure rotation can, theoretically, 
be perfectly balanced to eliminate all shaking forces and 
shaking moments.

 A rotating member can be balanced either statically or 
dynamically.

 Rotating parts can, and generally should, be designed to be 
inherently balanced by their geometry.

 However, the vagaries(unpredictable change or action) 
of production tolerances guarantee that there will 
still be some small unbalance in each part. Thus a 
balancing procedure will have to be applied to each 
part after manufacture

 The amount and location of any imbalance can be 
measured quite accurately and compensated for by 
adding or removing material in the correct 
locations..
Page 4


BALANCING BALANCING BALANCING BALANCING
Balancing 

 The process of providing the second mass in order to 
counteract the effect of the centrifugal force of the first mass, 
is called balancing of rotating masses.

 To eliminate all shaking forces and shaking moments

 Any link or member that is in pure rotation can, theoretically, 
 Any link or member that is in pure rotation can, theoretically, 
be perfectly balanced to eliminate all shaking forces and 
shaking moments.

 A rotating member can be balanced either statically or 
dynamically.

 Rotating parts can, and generally should, be designed to be 
inherently balanced by their geometry.

 However, the vagaries(unpredictable change or action) 
of production tolerances guarantee that there will 
still be some small unbalance in each part. Thus a 
balancing procedure will have to be applied to each 
part after manufacture

 The amount and location of any imbalance can be 
measured quite accurately and compensated for by 
adding or removing material in the correct 
locations..
STATIC BALANCE STATIC BALANCE STATIC BALANCE STATIC BALANCE

 The requirement for static balance is simply that the sum of all 
forces on the moving system (including 
d‘ Alembert inertial forces) must be zero.
• Despite its name, static balance does apply to things in 
motion.
• The unbalanced forces of concern are due to the accelerations 
of masses in the system.
• An other name for static balance is single-plane balance, 
which means that the masses which are generating the inertia 
forces are in, or nearly in, the same plane.
• It is essentially a two-dimensional problem.
Page 5


BALANCING BALANCING BALANCING BALANCING
Balancing 

 The process of providing the second mass in order to 
counteract the effect of the centrifugal force of the first mass, 
is called balancing of rotating masses.

 To eliminate all shaking forces and shaking moments

 Any link or member that is in pure rotation can, theoretically, 
 Any link or member that is in pure rotation can, theoretically, 
be perfectly balanced to eliminate all shaking forces and 
shaking moments.

 A rotating member can be balanced either statically or 
dynamically.

 Rotating parts can, and generally should, be designed to be 
inherently balanced by their geometry.

 However, the vagaries(unpredictable change or action) 
of production tolerances guarantee that there will 
still be some small unbalance in each part. Thus a 
balancing procedure will have to be applied to each 
part after manufacture

 The amount and location of any imbalance can be 
measured quite accurately and compensated for by 
adding or removing material in the correct 
locations..
STATIC BALANCE STATIC BALANCE STATIC BALANCE STATIC BALANCE

 The requirement for static balance is simply that the sum of all 
forces on the moving system (including 
d‘ Alembert inertial forces) must be zero.
• Despite its name, static balance does apply to things in 
motion.
• The unbalanced forces of concern are due to the accelerations 
of masses in the system.
• An other name for static balance is single-plane balance, 
which means that the masses which are generating the inertia 
forces are in, or nearly in, the same plane.
• It is essentially a two-dimensional problem.

 Some examples of common devices which meet this 
criterion, and thus can successfully be statically 
balanced, are:

 a single gear or pulley on a shaft, a single gear or pulley on a shaft,

 a bicycle or motorcycle tire and wheel,

 a thin flywheel,

 an airplane propeller,

 an individual turbine blade-wheel (but not the 
entire turbine)