Tweco 100 Auto-Cut - Manual (Page 65)

Manual 0-4764 4-5 OPERATION
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.
Dross Build-up and Top Spatter
Dross is molten material which is not blown out of the cut area and re-solidifies on the plate. Top spatter
is dross which accumulates on the top surface of the workpiece. Excessive dross may require secondary
clean-up operations after cutting.
Kerf Width
The width of material removed during the cut.
Nitride Build-up
Nitride deposits which may remain on the cut edge of the carbon steel when nitrogen is present in the
plasma gas stream. Nitride buildups may create difficulties if the steel is welded after the cutting process.
Direction of Cut
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.
Right Side
Cut Angle
Left Side
Cut Angle
A-00512
Scrap
Clockwise
Counter-
Clockwise
Art # A-04182
Workpiece
Scrap
Swirl Effect on Side Characteristics of Cut
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 clock-
wise direction.
Underwater Cutting
Cutting on a water table either underwater or with the water touching the plate or with a water muffler
system is not recommended. If a water table is used the water level must be a minimum of 4 inches from
the bottom of the plate. Failure to follow this recommendation could result in poor cut quality and short
consumable parts life.
Ohmic Sensing
Ohmic height sensing is not recommended with water shield. Water on the plate interferes electrically with
the ohmic sensing circuit.