Tweco SC-3000 - Manual (Page 62)

SC-3000
OPERATION 4-22 Manual 0-5100
Correct use of THC Pierce Delay and CNC Motion Delay.
As shipped from the factory the SC-3000 Height Control Interface PCB in the SC-3000 Interface Enclo-
sure should have SW2 set to the “B” position. In this case the OK to Move signal from the plasma sup-
ply indicating the cutting are is present (arc has transferred) is sent to both the SC-3000 and the CNC at
the same time.
• The CNC pierce or motion delay should be set to the minimum time necessary for
the arc to fully pierce the metal.
• The THC Pierce Delay should be set at least as long as the CNC motion delay. Often it should be
longer. When you pierce, especially thicker metal, a ridge of slag and partially molten metal is
built up around the pierced hole. If you bring the torch down to cut height at the same time as mo-
tion starts you risk the torch contacting the slag which can damage the torch shield cap and perhaps
the orifice. Best to add more Pierce Delay to the THC to clear the slag.
• If the CNC controller doesn’t have motion delay feature you can use the SC-3000 to delay motion.
• Set SW2 on the Height Control Interface PCB to the “A” then OK to Move to the CNC is also
delayed until end of Height Control Pierce Delay. In this case you will not be able to use the ad-
ditional delay described above. Torch will come to cut height same time as motion starts and may
contact the slag if there is very much there.
Note
This may be a case where Arc Voltage Control Mode would work better. Refer to “Cut Height Mode vs. Arc Voltage
Mode—Advantages and disadvantages” section for explanation.