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Component Identification and Explanation
Explanation of Functions and Plasma Cutting Terms
What Air Pressure do I use to cut?
The unit should maintain between 65 and 72 PSI while actively cutting.
Use the air pressure target LED's to set your pressure while the gas is
flowing. Do not lower the air pressure in an attempt to improve cut at
lower Amps with oversize consumables. Consumable size should always
be matched to the Amp range being used to cut. Lower Amps call for
smaller diameter orifices in the consumables. See the torch page and the
parts information to match consumable size to the Amp range of the con-
sumable. Using too little air pressure will rapidly accelerate wear on all
torch parts and consumables. Using too high of amperage for the con-
sumable will rapidly wear the consumable. For best results, buy a com-
plete range of sizes of consumables to be able to tailor your cut needs.
Bevel. When plasma cutting a certain amount of bevel will be present.
The cut will rarely be a true 90 degree cut. Usually 1 to 7 degrees of
bevel may be present on the "keep" side. Ideally this figure is under 5
degrees of bevel. One side of the cut will have more bevel than the
other. Measure the "keep" side of the bevel. Practice cut with your
torch first before attempting precision requiring cuts to familiarize your-
self with which side of the cut the bevel is being formed on. With the
iPT60 torch the inside swirl ring can be flipped over to change the bevel
side. If circle cutting, be sure you have identified the direction of bevel.
Changing "clock" rotation of the torch in a circle cut will change the side
of the bevel. See the instructions on circle cutting in this manual.
Blow Back Start. There are three common types of start that can be at-
tributed to how the plasma arc is started or maintained. Two of the three
are no longer used in more modern plasma cutting systems. These two
are: Contact start and High Frequency start. Contact start simply means
the torch must be touched to the metal and drug along to maintain an
arc. High Frequency start uses points similar/same as the TIG process
to create a small arc, or spark to start the arc without the torch needing
to maintain contact or touch down to start. HF start with pilot arc opera-
tion causes a lot of electrical interference. The final type of start, is used
in most modern plasma cuttings system. This is the Blow-back Start. In
a Blow-back start torch design, when no gas is flowing and the torch is
not in use, the electrode and tip rest in contact with each other, creating
a closed circuit. When the torch is triggered, either a spring loaded
"piston" or a specially designed spring loaded cartridge uses air pres-
sure to drive the electrode rearward away from being in contact with the
cutting tip, creating a small "Pilot Spark" energizing the pilot arc. This
unit uses the modern "Blow-back" start style. For more information, see
how the arc starts in the illustration located on the torch page.
Dross. Dross is the left-over oxidized metal created by the Plasma cut-
ting arc. In an ideal cut, little or no dross will be left, as it is cleanly
dispersed out the bottom of the cut. Generally, though some slight
dross will be present. Dross is sometimes referred to as "slag" by peo-
ple who are mostly accustomed to stick welding or cutting with oxy-fuel
processes. The amount of and type of dross created is affected by torch
cut height, cut speed, air pressure, consumable size and even torch
angle. Two types of dross are generally present: Hard and Soft. See the
instructions later in the manual to identify the type and cause of different
types of dross.
Edge Start Cut. When the plasma torch reaches the upper limit of the
cut capacity, piercing starts are no longer viable. Usually this is any-
where from 1/2 to 2/3 of the torch rated capacity. Cutting can still be
performed, but starting a cut in the middle of the metal is no longer
an option. If piercing starts are attempted near the maximum capaci-
ty of the machine, wear will greatly accelerate on all torch consuma-
bles and even the torch itself. In fact a poorly performed pierce start
will completely destroy the consumable set in one cut if the pierce is
performed at or near the maximum capacity of the cutter. An edge
start allows the torch to be placed on the very edge of the plate to be
cut to start the arc. The arc actually lights right on the edge of the
metal, and the torch is brought into the metal and the cut begins. A
lead in is usually used to create the cut.
Kerf. Kerf is the width of the cut. Kerf will vary according to the con-
sumable orifice size used, the stand off height, and to a lesser extent,
cut speed. Kerf width is important to maintaining cut accuracy. Test-
ing kerf width first is advised before trying to perform cuts which
need a high level of accuracy. Always remember to adjust for the
kerf width. Smaller kerfs can be achieved by using smaller diameter
cutting tips, but cut thickness will be limited.
Lead-In/Lead Out. Lead ins or Lead Outs are simply cuts that are
made at the beginning or end of the cut that will not be used in the
final part being cut. These are usually tangential to circles or start
outside of the part shape and travel into or out of the cut. This is
done to prevent "blow out" of the kerf width and discontinuities
where the torch starts/stops.
Pierce Start Cut. When the plasma cutter is sized properly and is
used in an average, daily cut, the unit will not be at the all-out maxi-
mum capacity of the machine. In this case, the torch will use the
pilot arc to start the arc and will begin to pierce a hole through the
metal to start the cut. Of course, if desired the pierce can happen
anywhere on the metal. When hand cutting, the piercing limit can be
increased by starting the cut at a slight angle to keep the sparks and
molten metal for bouncing back onto the torch head, and damaging
it. Once the piercing begins and the cut begins to develop, the torch
can then be slowly stood fully vertical to cut as the flame begins to
exit the bottom of the cut.
Problem: I just changed my consumables now my torch
won't light/or the arc is blowing out my tip. What's wrong?
Did you just change your consumables? Or did someone do it for you? All
iPT torches use a swirl ring. This swirl ring is used to help create the torch
arc, and confine it. It is a small brown/orange high temperature plastic
piece shaped like a donut with several pin holes in the side directly under
the cutting tip. Sometimes it'll stick lightly to the old cutting tip, or may
even be dropped, unnoticed during the change. It is lightweight, and the
color may blend in with the color of the copper cutting tip. This swirl ring
is rarely replaced, but must be checked for its presence before reinstalling
the consumables or it can damage the torch head and cause extreme mal-
function. Occasional wild or random starts with poor arc may be present.
Problem: I can touch my torch to the surface and cut, but I
don't get a pilot arc when I pull the trigger.
Check your fuse. The Pilot arc is served by this fuse. The fact you can
touch the torch to the metal and still cut indicates the pilot arc is not func-
tioning, but the cutting arc is still working ok.
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