14
CAUTION:
During cutting, the speed of torch movement should correspond to the
thickness of the workpiece.
Moving too quickly causes a return of incandescent scale towards the torch, which
shortens the life span of the parts most subject to wear and tear.
The build up of scale on the nozzle should be removed as soon as possible.
9.
To start cutting, bring the torch with the pilot arc near to the workpiece and the
cutting arc between the torch and the workpiece will immediately light. If piercing
or cutting is to be carried out from the centre of the piece, start cutting with the
torch inclined and then straighten it slowly so that molten metal does not spray onto
the nozzle of the torch. If this operation is to be carried out on thicknesses greater
than 3-4mm, first drill a hole from which the cutting can start.
10. During cutting, rest the nozzle perpendicularly on the surface to be cut without
exerting any force. The wire spacer, mounted on the end of the torch, (except
King 35), should be used in all cutting operations, to maintain the correct gap
between the torch and the workpiece. To move the torch, pull towards you
rather than pushing away from you.
11. To stop cutting remove the torch from the workpiece. To extinguish the pilot
arc release the trigger on the torch.
Note:
When the trigger is released and the arc is extinguished compressed air will
continue to flow for a period of time, in order to cool the torch. DO NOT switch off
the machine until the air has stopped flowing or damage may occur to the torch.
IMPORTANT WARNING:
WHEN YOU LIFT THE TORCH AWAY FROM THE WORKPIECE THE CUTTING ARC
WILL BE LOST BUT THE PILOT ARC WILL REMAIN IGNITED IN THE NOZZLE UNTIL
THE TORCH TRIGGER IS RELEASED.
NEVER TOUCH THE NOZZLE WHILST THE PILOT ARC IS IGNITED AS THIS MAY
RESULT IN SERIOUS INJURY.
DUTY CYCLE
The duty cycle of a plasma cutting unit is determined by the percentage of use in
a repetitive cycle of 10 minutes with a given cutting current “I
2
”.
The duty cycle is indicated by the letter “X” on the table of technical specifications
which is screen-printed on the rear panel of the unit.
For example: X=30%
I
2
=50A
X=100%
I
2
=30A
In the first case the operator can cut for 3 minutes (30%), with a 50A current; in the
second case the operator can cut for 10 minutes (100%) with a 30A current.
Do not overwork the machine, operating above the established duty cycle may
cause serious damage.
