By Amanda Carlson,
Associate Editor
It’s no secret that plasma torch consum- ables play an integral role in achieving a successful cut. What may not be widely
known, however, is the relationship among
the consumable components, and that even
one faulty component can cause the others
to suffer.
Clayton Gould, product marketing manager of torch consumables at Hypertherm
Inc., Hanover, N.H., discusses the role of
the torch consumables in a hand-held plasma
cutting setup, outlines what signs to look for
when a component is failing, and gives
advice on how to maintain your torch
properly to ensure consumables work the
way they should.
For most manual plasma cutting systems,
five different components comprise the
torch consumables—the shield, retaining
cap, nozzle, electrode, and swirl ring.
The shield protects the rest of the consumables. With the plasma cutting process
you tend to get an awful lot of sparks and
molten metal. The shield’s purpose is to
prevent that from reaching the inner consumables. In some cases, the shield is a drag
shield, which means it allows the operator
to put the torch right on the metal without
the need of an additional standoff. That’s
nice, especially for inexperienced cutters.
What are the main consumable
components in a plasma torch,
and how does each contribute to
a successful cut?
20 PRACTICAL WELDING TODAY
July/August 2010
The next is the retaining cap. The
retaining cap’s duty is basically to cover and
hold the consumable stackup together.
The nozzle does one of two things.
First, it focuses the plasma arc. The larger
the orifice, the less defined or wider the arc
is. Nozzles with a wide orifice are used in
gouging applications, while some have very
small orifices that constrict and focus the
arc. These are used for fine-feature, detailed
cutting. Second, the nozzle helps to funnel
gas flow, which also helps to shape and
constrict the arc.
The electrode carries the current from
the torch to the plate. It’s a slender piece
made of copper or silver and contains
hafnium or tungsten. These materials have
been found to be excellent conductors of
electricity. The electricity comes from the
machine out to the torch and goes into a
cathode block, which the electrode is in
contact with, and then focuses that charge
on the end of the electrode through the
hafnium/tungsten insert which then arcs to
the plate. The nozzle takes that arc and
really focuses it in a way that cuts metal,
but the electrode carries the current.
The nozzle tends to get very hot because
it’s right in the midst of the superheated gas.
So the back of the electrode has a cooling
device attached that helps transfer the heat
out of the electrode.
And last, the swirl ring channels the gas
in a couple of different directions as it
comes from the machine and down the
torch. First, the gas goes forward in a spiral
manner around the electrode, around the
arc, down through the nozzle, and out
Always try and change out the electrode and nozzle
at the same time. Switching them out individually
compromises cut quality.
through the torch. The reason the ring
needs to swirl is that it allows the gas, as it’s
going out through the nozzle, to be at different temperatures. The cooler gas travels
along the outside—this gas is in contact
with the nozzle and prevents it from burning up. If you don’t have the swirl in there,
gas mixing is inadequate and you could
burn up your nozzle. The other purpose of
