3.1.5 Nozzle selection
A plasma nozzle that is appropriate to the cutting current setting must be
selected. If the nozzle is too big, cutting performance is impeded, while too small
a nozzle will cause thermal overload and hence higher wear and tear.
To make the correct choice of nozzle, the areas of application of the various
nozzle diameters are shown on the cutting current adjustment dial.
Only replace parts with original REHM spare parts (see Chapter 4).
3.2 Cutting operation
3.2.1 General description
To achieve an optimal cutting quality, the choice of cutting current, nozzle and
cutting speed must take into account the type of material to be machined and the
thickness of the work piece.
Where light gauge sheet metal is to be cut, better cutting quality is achieved when
the torch is in contact with the material.
If thick sheets are to be cut, higher cutting performance is needed. Therefore
cutting must be performed with the torch held at a distance. The relevant spacer
elements will be found in the appendix entitled “Torches and accessories”.
In hand cutting operations, the quality of the cut and the amount of wear and
tear sustained by the torch components depends not only on the factors already
mentioned, but also on the skill of the user in handling the plasma torch.
Press torch button and move torch with pilot arc to the point at which the cut is to
start.
Following ignition of the cutting arc, draw the torch across the work piece at a
constant speed. The optimal cutting speed is achieved when the cutting jet is
facing towards the direction of cut and is inclined at approx. 10º from the kerf.
The pilot arc should not be ignited unnecessarily, as this will result in higher wear
and tear of the torch components.
With straight cuts, it is recommended using a stop rail to guide lateral movement
of the torch. To obtain even and stick-slip free movement of the torch, we
recommend using a torch carriage (see Chapter 4).
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