Rockwell Automation 1441-DYN25-MBAL Balancing Extension Module for the Dynamix 2500 - Manual (Page 16)

16 Rockwell Automation Publication 1441-UM004A-EN-P - May 2011
Chapter 2 Balancing Extension Module
Balancing Measurements Balancing is the technique for determining the amount and location of the heavy
spot on a rotating shaft so that you can balance it with an equal amount of weight
in the opposite direction. These methods go through the technique with
stopping points where you start and stop the machine to perform weight addition
or subtraction.
There are three types of measurements in the balancing process:
• Initial Vibration
The initial vibration measurement is taken without any added weights on
the machine. The initial vibration measurement establishes a reference of
how the machine vibrates at each plane without any extra weight added.
This vibration is what will be corrected by the correction weight.
• Trial Weight
The trial weight measurements are taken with a single trial weight attached
to the machine at one plane or the other. The trial weight measurements
are used to determine how the machine is affected by the added weight.
The ideal trial weight should produce either a 30 % change in amplitude or
a 30
° change in phase.
• Residual Measurements
The residual measurements are taken with the correction weight or the
correction weight and trim weights attached to the machine. The
correction weight should cancel out the initial unbalance. A residual
vibration measurement is taken to measure the remaining unbalance. Trim
weights are added to the machine to cancel out the vibration measured
during a residual measurement.
Plane Balancing Regardless of whether you are performing a single or two-plane balancing
procedure, all balancing procedures progress through basic runs as you start
(spin) and stop the rotor.
For two-plane procedures, you perform some of the runs twice, once with weights
on correction plane one and again with weights on correction plane two. For
simplicity, the following example describes a single-plane procedure.
These are the steps you need to take to take a single-plane balancing
measurement.
1. Set up balancing equipment and the Balancing parameters.
With the machine stopped, set up the balancing equipment and mark your
tachometer reference point on the rotor or shaft.
See Set Up the Balancing Parameters on page 20 to configure balancing
measurement parameters for the balancing run sequence.