Baileigh Industrial PT-105HD, Operator'S Manual, Page: 40 / 48

38
38
Cutting Height
An automatic height control system is invaluable when plasma cutting with a mechanical torch.
Using it can provide the proper cutting height for various material thicknesses when transferring
the arc, piercing, and cutting. Below are some examples of how the torch height can affect the
cut.
Arc Voltage
A DC voltage can be measured between the negative electrode and the positive plate during
cutting. This voltage will vary depending on the length of the arc between the electrode and the
plate. A longer arc will show a higher voltage and a shorter arc will show a lower voltage. This is
an effective way to measure torch to workpiece distance. A plasma system height control has a
reference voltage set by the machine operator. Each plasma torch manufacturer provides these
arc voltages which are dependent upon material, thickness of material, and the plasma process
power level. As soon as the plasma process starts cutting the material, the torch height control
looks at the actual arc voltage. It compares this with the arc voltage that was set on the AHC
controller by the operator. Then the torch height control adjusts the up/dow
n “Z” axis until the
reference arc voltage and the actual arc voltage are the same, thereby controlling the distance
between the torch and the workpiece. Any warping issues of the material will now be adjusted
for automatically.
Listed below are a few things that can also affect the distance between the torch and the
workpiece.
•
Changes in cutting speed.
•
Any fluctuations of the gas or air pressure.
•
Crossing an existing kerf.
•
Timing of the arc voltage.
•
Wearing out of consumables.