REHM TIGER 180 AC/DC ULTRA, Operating Instructions Manual

Page: 28 / 68

Function description
28
4.8 High-frequency (HF) ignition
The push button [11] is used to select the HF arc ignition for TIG welding,
whereby the LED display shows whether the high frequency is on or off.
4.8.1 Welding with HF ignition
REHM TIG welding machines are equipped with RF igniter. HF ignition is
automatically switched off in the "electrode" setting.
HF ignition makes contact-free ignition of the arc between the electrode and
workpiece through pre-ionization of the air gap for DC and AC welding possible,
whereby tungsten inclusions and therefore welding defects are prevented. In
either case, the HF ignition unit is automatically switched off again after ignition.
Re-ignition of the arc described in Section 4.6.15 when AC welding is performed
without using the HF ignition unit. This reduces the electrical noise emission and
even enables AC welding without HF ignition, as is already known for DC welding
(see Section 4.8.2).
The RF igniter is operational when set to RF On " ". To ignite the arc, the
electrode is kept approx. 3-5 mm above the workpiece. By actuating the torch
trigger the path is ionized by a high-voltage pulse and arcing occurs. Contactless
ignition enables the prevention of tungsten inclusions in the welded seam. When
welding the HF ignition is automatically switched off after ignition.
4.8.2 Welding without HF ignition
When welding with direct or alternating current contact ignition (lift arc ) can be
used. For this the high frequency is turned off. To ignite the arc, the electrode is
placed on the workpiece and the torch trigger actuated. On lifting the electrode
the arc program-controlled ignition takes place without wear occurring to the
pointed electrode. This option can be used to advantage when working on
sensitive electronic devices (for example, in hospitals, repair welding on CNC
machines), where there is the risk of interference originating from high voltage
pulses.
4.9
“Pulsing
The push button [16] is used to select the welding process without pulses, with
conventional pulses and with high-frequency pulses, whereby the LEDs indicate
the selected pulse type by illuminating.