Tweco SC-3000 - Manual (Page 56)

SC-3000
OPERATION 4-16 Manual 0-5100
4.10 PROCEDURE WITH GAS PRE-FLOW
Advantage:
The time of gas-pre-flow after reaching the piercing position is eliminated and the cutting cycle is short-
ened significantly.
Preflow during Height Finding
To use Preflow during Height Finding with an Ultracut or Autocut plasma system the 2 wires of the Pre-
flow Control cable from SC3000’s J5 Preflow connector is connected into TB2-3 &4, polarity doesn’t
matter, in the Ultracut or Autocut CCM module.
Using the Operator Terminal from the main menu select the Cut Height parameter Gas Preflow. Set to
a time other than zero, usually 2 sec same as the plasmas preflow time. When the CNC sends Start to
the height control the SC3000 immediately applies the Preflow On starting the plasma’s preflow gas and
preflow timer. Once the SC 3000 has positioned the torch to the initial Pierce Height position Start is
automatically sent to the plasma. If the preflow timer has ended the arc is ignited immediately. It there
is any time remaining on the preflow timer then that has to finish before pilot ignition and arc transfer
occurs but in any case the cycle time is reduced by the time it takes to find height.
Typically you set the Gas Preflow time equal to the preflow time of the plasma supply however, at least
in the case of the Ultracut & Autocut, it doesn’t much matter, you can set it any time longer than zero.
If you don’t want the gases to come on during height finding then set Gas Preflow to zero or don’t con-
nect the Preflow Control cable.