Firepower FP-78 Operating Manual page 27

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.
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 work-
piece. 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 surface of
the cut when nitrogen is present in the plasma gas stream.
Nitride buildups may create difficulties if the material
is welded after the cutting process.
Kerf Width
Top
Spatter
Dross
Build-Up
Figure 4-7 Cut Quality Characteristics
Cut quality will vary on different types of and material
thicknesses.
The following table shows the cut quality that can be
expected from this equipment for materials with a thick-
ness from gage to 7/8 inch (22.2 mm):
Manual 0-2700
Cut Surface
Bevel Angle
Top Edge
Rounding
A-00007
Cut Surface
Drag Lines
C a r b o n
G a s
S t e e l
G o o d -
A i r
E x c e l l e n t
N i tr o g e n G o o d
Description of Cut Characteristics
Excellent - Minimum bevel (0 - 4°), minimum kerf (2 x
tip orifice diameter), little or no dross,
smooth cut surface.
Good - Slight bevel (0 - 10°), slightly wider kerf (2-1/2 x
tip orifice diameter), some dross (easily re-
moved), medium-smooth cut surface, slight top
edge rounding.
Fair - Excessive bevel (over 10°), wide kerf (over 2-1/2 x
tip orifice diameter), medium to heavy dross,
rough cut surface, top edge rounding.
Cut quality depends heavily on set-up and param-
eters such as torch standoff, alignment with the
workpiece, cutting speed, gas pressures, and op-
erator ability.
21
T y p e o f M a t e r ia l
S t a in le s s
A lu m in u m
S t e e l
G o o d - G o o d -
E x c e l l e n t E x c e l l e n t
G o o d G o o d
NOTES
OPERATION