Why a “Wattage” Based Torque Controller is Right and a “Current” Based Torque Controller is Wrong.
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.
In case of a current based tube expansion 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. 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.