Kemppi LT 250 - Manual (Page 9)

EN
3. USE
NOTE! Welding fumes may be dangerous to your health. Ensure that there is ample ventilation during
welding! Never look at the arc without a face shield specifically designed for arc welding! Protect
yourself and your surrounding area from the arc and hot welding spatter!
Prepare to weld
NOTE! Always wear protective clothing, gloves, face and eye shields suitable for welding. It is
recommended that you make practice welds before you commence welding your main work piece. If
when igniting the arc or during welding, the electrode stick’s or freezes’ to the work piece, note that it
will quickly heat up, and may start to glow red hot. To release the electrode, twist the electrode holder
away from the work piece and start again. If this fails, switch off the machine at the main switch and
then release the electrode after it has cooled down.
NOTE! The electrode and work piece will be very hot. Protect yourself and others at all times.
You can start welding after you have made the necessary preparation described throughout these
instructions.
3.1 TIG welding
TIG welding electrodes and gas nozzles
In DC TIG welding we recommend the use of the WC20 (grey) type electrode, however other types
are available.
The welding electrode size (diameter) is selected depending on the welding current/power to be
used. An electrode with an insufficient diameter compared to the welding current will melt, while
excessive electrode size will make it more difficult to ignite the arc.
Generally speaking, a 1.6 mm tungsten electrode will cover currents up to 150 A, and 2.4 mm
tungsten electrode up to 250 A DC current.
Before use, grind the tungsten electrode to a sharp point at approximately 1.5 times the diameter
of the electrode. If the electrode touches the work piece during welding, re-sharpen the electrode.
7
© Kemppi Oy / 1422