Dynamic Balancing Lab Report

Experiment No.1

Objective:

To balance a rotating mass (disturbing mass) with a same mass (balancing mass) rotating at equal radii in the same plane

Related Theory: Balancing of Rotating Masses:

The process of adding the second mass in order to counteract the effect of centrifugal force of first mass is what we call as balancing of rotating masses. Why Balancing is Required

The high speed of engines and other machines and mechanisms are a very common observation today. Hence it is necessary that all the rotating and reciprocating parts should be completely balanced as far as possible. if these pars are not properly balanced, there are the possibilities of developing the dynamic forces which not only cause stress on the bearings but also have

In other words, we can say that when the centers of all the masses (disturbing as well as balancing masses) lie on the axis of rotation i.e. when the line of action of all the centrifugal forces is the same.

Dynamic Balancing (Complete Balancing):

When the net couple acting on the shaft is also made equal to zero along with the net dynamic forces to be zero, this is what we call as dynamic Balancing i.e. when the sum of the moments at any point in the plane is equal to zero.

Basically during the static balancing, we introduce balancing mass (or masses) which generate equal but opposite centrifugal force in order to balance or cancel the effect of already existed centrifugal force. But at the same time opposite and equal forces generate couple which tends to rock the shaft in its bearings. Thus to completely balance, we must have the net centrifugal forces as well as net moment or couple generated equal to zero. Mathematical Approach:

Let’s suppose we have a disturbing mass m1 attached with a shaft rotating at