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This is very principal of Hudson fan blade balancing
technique to help you for understanding the quality
of Hudson products. Hudson does not dynamically balance
even the large fan assemblies in their factory, since
Hudson have never found such balancing is necessary.
Hudson do statically balance
the hub assembly, and each blade is moment balanced
to a master standard. If fan assemblies must be dynamically
balanced as a firm customer requirement, then this step
must be accomplished at the job location. Note that
it is highly likely that the structure surrounding the
fans could also influence the final balance point, thus
dynamic balancing of installed fans may infect, yield
better result.
You have to know that the
cost for dynamic balancing is the cheapest than one
for static balancing, since its procedure is very simple.
However, you have to dynamically balance the fan assemblies
whenever to change the blades. Note that a way of statically
balancing each blade is a best methods to reduce such
inconvenience.
Hudson fans are component
(each blade and hub) balanced as compared to whole fan
assembly balance. This allows individual blades to be
changed at job sites without rebalancing the whole fan
assembly. Picture a hypothetical 2 blades fan from a
side as the figure below.
Where, W1 and
W2 are blade weight.
d1 and d2 are distance to center
of gravity of blade.
Fc1 and Fc2 are centrifugal forces
created by the rotating blades.
Centrifugal forces acting
on a rotating system impels particles radically outward
from the axis of rotation. If the masses of rotating
components are evenly distributed about its shaft axis,
the part is "balanced". To have a balanced
system, there should be an equilibrium in centrifugal
forces as follows:
Fc1 = W1
x d1 x (RPM1) / g
Fc2 = W2 x d2 x (RPM2)
/ g
For equilibrium in centrifugal
force, Fc1 = Fc2.
Thus, it becomes W1
x d1 = W2 x d2, since
RPM1 = RPM2.
From the above analogy, the
equilibrium of centrifugal forces becomes the equilibrium
of moments (weight x distance to center of gravity).
The Hudson computer controlled
electronic balancing machine are used to balance the
blades, and this machine will not print its serial number
if a blade is out of Hudson manufacturing tolerance.
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