1. How to choose the right tungsten electrodes?
①Base Metal Material- Pure Tungsten electrode (green end tip): suitable for aluminum and aluminum alloy welding with AC current and featured with stable arc
- Cerium-Tungsten Electrode (gray end tip): Suitable for carbon steel/stainless steel/Nickle based metal/Titanium metal welding with DC current, featured with easy arc ignition
- Lanthanum-Tungsten Electrode (blue end tip): suitable for stainless steel welding with DC current, featured with easy arc ignition and longer life span
- Thorium-Tungsten Electrode (red end tip): suitable for cooper/carbon steel/non-ferrrous metals welding with DC current, very good performance in big current welding.
- Zirconium-Tungsten Electrode (brown end tip):suitable for aluminum and aluminum alloy welding with AC current
- Compound tungsten electrodes (purple end tip): it is environmental friendly and universal tungsten electrode.It is a good choice to replace thorium tungsten electrodes. Suitable for welding of carbon steel/stainless steel and other non-ferrous metals. Featured with stable welding arc, 35% less power consumption, 40% longer life span and 50% costs down.
1.6-2.4mm tungsten electrodes are suitable for welding thin plates under 10mm; while 3.2-4.0mm tungsten electrodes are suitable for welding thick plates over 10mm.
Before welding, the tungsten electrodes should be sharpened pointed so that the current will be concentrated and it will be easier to operate. FOX ALLOY Tungsten Electrode has longer life span, good conductivity and no radiation to human body.
2. How to choose the polarity
AC pulse Tig welding is mainly applied in welding of light metals like aluminum/magnesium/cooper and their alloys.
DC pulse Tig welding is mainly applied in welding of steel/mild steel/heat resistant steel,etc. And it's more popular in thin plates stainless steel Tig welding and the shield gas will be Ar (99.99% purity).
3. How to operate a Tig welding
①Arc IgnitionWelding arc was ignited by breaking down air with high voltages, caused by high frequency and high voltage generator in electric welding machine, between tungsten electrodes & work piece. That is, holding the welding torch perpendicular to the work piece, making the distance between tungsten electrodes & work piece 3-5mm, turn on the welding machine, the high frequency pulse and high voltage will ionizate the shielding gas to ignite welding arc. This way of arc ignition ensures the end tip of tungsten electrodes intact with minimum burnt and good arc ignition quality, thus it is most widely used way of arc ignition.
②Molten Pool Control
The control of welding temperature is vital for high welding quality,many of the welding defects are caused by improper welding temperature.Hot cracks, undercut, weldbead cracks, sags, alloy elements burnout, overlap are caused by too high welding temperature; cold cracks, porosity, incomplete penetration,non-fusion are caused by too low temperature. We also need to keep the molten pools in same size and shape and the speed uniform, more practise and careful observation is needed to obtain good welding quality.
③Arcing
Arcing requests special skills and regular pattern: the angles between welding torches and the weld bead surface are called included angles. They directly influence the heat input, gas preventive effect and operational filed of view.The included angles should be between 70-85 degrees.Gas protective effect is best when included angles are 90 degrees, but at this time, the shield gas sparged from the welding torches will deviate backwards as the welding torches moving speed raise and this gives poor protection to the weld bead, thus the welding speed can’t be too high. Forehand welding is generally used in GTAW.
④Handle the Welding Torch
Handle the torches with thumb and index finger of right hand, other 3 fingers as pivot on the weld bead
【Swaying welding】:Press the contact tip at the weld bead with some pressure, and weld with substantial swaying of hand
【Advantages】: Asthe contact tip is pressed against the weld bead, the weld bead will be protected properly and welding will be of high quality with nice weld bead appearance.It is very convenient for overhead welding and very beautiful weld bead colors can be achieved in this way of welding.
【Disadvantages】: Hard to learn and can’t apply to welding where there are obstacle as substantial swaying is requested
⑤Handle the Tig Rods
Middle finger on top and ring finger below to hold the tig rods.Feed the tig rods with thumb & index fingers; loose the thumb and index finger, move them backward to move the tig rods forward;
The rods feeding angles and way of feeding are related to the skill levels of the welders and they greatly influence the shape of weld bead.
For welding beginners, FOX ALLOY Tig Pen can make the rods feeding easier and better quality welding can be achieved.
⑥Stop of arc
Stop of arc is that we stop welding for some reasons and restart welding later; The right way of stop of arc is to speed up welding before stop of arc, this is to avoid arc crater & shrinkage. The speeding up of welding should lasts about 20mm.
When igniting arc again, you’d better move 1-2 ripples backwards after molten pool is formed. Adding no or less tig rods at the beginning point of weld bead before resuming normal welding practice. To avoid porosity and ensure welding quality, welding speed should be slower down at the beginning point.
⑦End of Arc
End of arc is the method of ending the welding. End of arc is very important which you should pay special attention to. Improper end of arc will bring defects like weld bead crack, shrinkage, etc.
Normal method of end of arc is to speed up welding and feed less tig rods gradually until base metal does not melt. Main point is giving less heat input, and ensure overlapping welding for 20-30mm. This method is very suitable for ring weld bead as no weld bead holes and shrinkage will be formed.
