Cutting Quality - Cebora 334 Betriebsanleitung

8

CUTTING QUALITY

There are several parameters and combinations of them that affect the quality of the cut: This manual shows the opti-
mal settings for cutting a particular material. However, due to the installation differences as well as pantographs and
the variation of the characteristics of the cutting materials, the optimal parameters may require changes with respect
to those indicated in the present cutting tables. The following points may help the user to make the changes neces-
sary to obtain a good cutting quality.
As shown in these cutting tables, for each thickness of a particular material can be used different currents cutting.
If prevail productivity needs, set the maximum allowable current and the speed in the column V production.
Before making any adjustments, verify that:
• the torch is perpendicular to the cutting plane.
• electrode, nozzle and nozzle protection are not worn out and that their combination is responsive to the chosen
work.
• the cutting direction, in function of the shape to be obtained, is correct. Remind that the best side of a cut is always
the right with one respect to the torch motion direction (the plasma used has diffuser holes in a clockwise direc-
tion).
If you need to cut high thicknesses, particular attention should be given during the step of lead-out: in particular,
when trying to remove the accumulation of molten material around the cutting start hole, so as to avoid double arc
phenomena when the torch comes by again to the starting point. Moerover, keep the nozzle protection always clean
from molten slag which sticked.
The following table shows some of the most frequent problems and their solutions.
PROBLEM
Electrode or nozzle worn out
Oblique cutting Stand off too high
Cutting speed too high
Cutting speed too high
Nozzle diameter too large compared to the
current set
Insufficient
Excessive plate thickness in
penetration
processing compared to the current set
Ground wire not in good electrical contact with
the cutting plane
Cutting speed too low
Presence of
"low speed
Cutting speed too high
dross" *
Stand off too low
Presence of Cutting speed too high
"high speed
Cutting speed too low
dross" **
Stand off too high
Cutting speed too high
Rounded cut
edge
Stand off too high
* The low speed dross are thick dross, of globular shape, easy to remove. The kerf is fairly large.
** The high speed dross are thin dross, hard to remove. In case of very high speed, the cut wall is rather rough.
CAUSE SOLUTION
Replace both
Lower stand off
Adjust speed
Adjust speed
Check cutting tables
Increase cutting speed
Check the tightness of the earth terminal to the
CNC
Adjust speed
Reduce cutting current
Raise stand off
Adjust speed
Increase cutting current
Lower stand off
Adjust speed
Lower the stand off
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