Page 67 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Field Balancing
Chapter
Chapter
Chapter
Chapter
Chapter
Field Balancing
Field Balancing
Field Balancing
Field Balancing
Field Balancing

INTRODUCTION

nbalance is present to some extent in all rotating equip-
ment, and has been found to be the most common source
U U U U U of vibration encountered. Field balancing of rotating equip-
equipment depends on identifying the type of unbalance and then
applying the correct balancing procedure. Single plane balancing
is only successful in conditions where the unbalance is pure static.
Other forms of unbalance will require two or more planes of cor-
rection.
Dual plane balancing will be required for the majority of
equipment. A method of dual plane balancing is discussed later in
the chapter.
Typical of the types of equipment that can be balanced by the
single plane method are fin-fans and cooling tower fans. For a part
to be successfully field balanced, two conditions must be met.
First, the rotating part must be out of balance, and second, the
required changes in weight must be able to be made to the rotat-
ing part.
The following single plane method of field balancing as-
sumes the use of a vibration analyzer that has a strobe light to
identify the phase angle. Another single plane balancing method
that only requires amplitude will be discussed later.
Balancing a piece of equipment with it mounted and operat-
ing in its normal position is called in-place or field balancing. For
much equipment, in-place balancing has many advantages over
shop balancing. These include less cost; elimination of possible
damage due to disassembly, transportation and reassembling; and
extensive down time. Some machines, due either to their high