TIG rules

The Shed - - Welding -

1. Clean the area to be welded thor­oughly. Clean­li­ness can­not be stressed enough. It’s not like MIG or stick weld­ing where you can get away with weld­ing over a bit of rub­bishy or un­clean metal. Try to TIG weld over rust, paint, or heavy ox­ide and you will con­tam­i­nate the tung­sten elec­trode and the weld pool.

2. How much should the tung­sten elec­trode stick out? As a rule of thumb, stick-out should be half the di­am­e­ter of the noz­zle ori­fice. I al­ways add a cou­ple of mil­lime­tres, so I can see more eas­ily.

3. What level of argon gas flow should you use? With low amps and ma­te­rial up to 6mm thick, start at a flow rate of 8-10 litres per minute. Use a higher flow for big­ger amps and heav­ier ma­te­rial.

4. Use argon gas only, not the argon mixes com­monly used in MIG weld­ing.

5. Which tung­sten types should you use for the elec­trode? Tho­ri­ated, ce­ri­ated, or lan­thanated for DC, and zir­co­ni­ated for AC alu­minium

weld­ing.

6. To set up and test that the set­tings of your ma­chine are cor­rect, try weld­ing some scrap metal first. You don’t want to blow a hole in some­thing you want to keep.

7. Feed the filler rod into the weld pool. Many learn­ers will shove it into the arc and hope for the best. Not so! Just dip the wire into the lead­ing edge of the weld pool. That’s where your con­cen­tra­tion should be.

Pre­pare weld

• Clean: Make sure that the weld joint area and also the filler rod are as clean as pos­si­ble. This is an im­por­tant prepa­ra­tion. Re­move all oil, grease, paint, rust, and dirt. Con­tam­i­nants such as these may re­sult in arc in­sta­bil­ity, con­tam­i­nated welds, or con­tam­i­nated tung­sten.

• Clamp­ing: Clamp­ing may be needed if the work piece can­not be held dur­ing tack­ing or weld­ing. Re­mem­ber you need both hands for TIG weld­ing.

• Tack welds: On thin ma­te­ri­als, it is a good idea to make short 2-3mm tack welds close to­gether, as the heat will dis­tort the joint as it is be­ing welded.

Scratch start

Hold the TIG torch in your hand at a 70°or 80° an­gle. Make sure that the tung­sten is off the metal by ap­prox­i­mately 3-6mm. Don’t let the tung­sten touch the work piece at this stage. With a gen­tle back­ward scratch­ing mo­tion, strike the tung­sten onto the earthed ma­te­rial to be welded. A weld pool will start form­ing. From here start mov­ing for­ward at a reg­u­lar speed. You will soon see what speed suits your am­per­age.

Weld­ing

Now you can try us­ing a TIG filler rod. Hold your filler rod lightly in your op­po­site hand so that it rests hor­i­zon­tally at about a 15° an­gle from the ma­te­rial. Wait for the molten pool to form on the base metal and gen­tly dip the filler rod into the weld pool. As you move for­ward, you will see the weld bead start­ing to form. If your ma­chine has a high-fre­quency start, there is no need to touch the par­ent metal.

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