General Cutting Information - Impax IM-IPC40 Manual

CUT QUALITY
Nitride Build-Up
Nitride deposits can be left on the surface of the
cut when nitrogen is present in the plasma gas
stream. These buildups may create difficulties if
the material is to be welded after the cutting
process.
Bevel Angle
The angle between the surface of the cut edge
and a plane perpendicular to the surface of the
plate. A perfectly perpendicular cut would result
in a 0° bevel angle.
Top - Edge Rounding
Rounding on the top edge of a cut due to
wearing from the initial contact of the plasma
arc on the workpiece.

GENERAL CUTTING INFORMATION

Warning! Disconnect primary power at the
source before disassembling the power supply,
torch, or torch leads. Frequently review the
Welding Hazards at the front of this manual. Be
sure the operator is equipped with proper
gloves, clothing, eye and ear protection. Make
sure no part of the operator's body comes into
contact with the workpiece while the torch is
activated.
Caution: Sparks from the cutting process can
cause damage to coated, painted, and other
surfaces such as glass, plastic and metal.
Note: Handle torch leads with care and protect
them from damage.
Torch Standoff
Improper standoff (the distance between the
torch tip and workpiece) can adversely affect tip
life as well as shield cup life. Standoff may also
significantly affect the bevel angle. Reducing
standoff will generally result in a more square
cut.
Edge Starting
For edge starts, hold the torch perpendicular to
the workpiece with the front of the tip near (not
touching) the edge of the workpiece at the point
where the cut is to start. When starting at the
edge of the plate, do not pause at the edge and
force the arc to "reach" for the edge of the
metal. Establish the cutting arc as quickly as
possible.
Bottom Dross Buildup
Molten material which is not blown out of the
cut area and resolidifies on the plate. Excessive
dross may require secondary cleanup operations
after cutting.
Kerf Width
The width of the cut (or the width of material
removed during the cut).
Top Spatter (Dross)
Top spatter or dross on the top of the cut
caused by slow travel speed, excess cutting
height, or cutting tip whose orifice has become
elongated.
Cut Surface
The desired or specified condition (smooth or
rough) of the face of the cut.
Direction of Cut
In the torches, the plasma gas stream swirls as
it leaves the torch to maintain a smooth column
of gas. This swirl effect results in one side of a
cut being more square than the other. Viewed
along the direction of travel, the right side of the
cut is more square than the left. To make a
square - edged cut along an inside diameter of
a circle, the torch should move
counterclockwise around the circle. To keep the
square edge along an outside diameter cut, the
torch should travel in a clockwise direction.
Dross
When dross is present on carbon steel, it is
commonly referred to as either "high speed,
slow speed, or top dross". Dross present on top
of the plate is normally caused by too great a
torch to plate distance. "Top dross" is normally
very easy to remove and can often be wiped off
with a welding glove. "Slow speed dross" is
normally present on the bottom edge of the
plate. It can vary from a light to heavy bead, but
does not adhere tightly to the cut edge, and can
be easily scraped off. "High speed dross"
usually forms a narrow bead along the bottom
of the cut edge and is very difficult to remove.
When cutting a troublesome steel, it is
sometimes useful to reduce the cutting speed to
produce "slow speed dross". Any resultant
cleanup can be accomplished by scraping, not
grinding.
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