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Why a “Wattage” Based Torque
Controller is Right and a “Current” Based Torque
Controller is Wrong.
A) Tube expansion can best be
done by expanding tubes at a set torque value. Torque is
nothing but a rotary force acting on the tubes. For a
given drive, the 'RPM' being constant, torque becomes
proportional to the drive power.
Hence, if the drive power is controlled for tube
expansion, the results will be excellent. All tubes will
be expanded equally. Supply voltage fluctuations which
are very common, do not affect the performance of a
wattage based controller as the controller will trip at
a set wattage irrespective of the supply voltage.
B) In case of a current based
or electric tube expansion systems torque controller, the drive current can
become proportional to the torque if & only if the
supply voltage is absolutely constant. This is never the
case. Practically, the supply voltages vary as much as
20% to 25%. This directly affects the expansion results
as the drive trips at a set current. That means for a
20% higher supply voltage, the tubes will be effectively
expanded by 20% more torque than the required one using the electric tube expansion systems. Hence
tubes will be over-expanded. For supply voltages less
than normal, tubes will be under expanded
proportionately.
Since, the supply voltages fluctuate quite often, the
expansion results of current based controllers will be
unpredictable. They will have no consistency.
It is our experience that a seasoned operator will more
consistently expand tubes with just a drive than if he
is to use a current based Torque Controller. Of course
if he were to use a Wattage based torque controller, he
would achieve near perfect tube expansions all the time.
POWERMASTER is the only company in
the world to offer you a choice of 2 Wattage based
Torque Controllers.
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