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• This method is referred to as ‘Scratch Arc’.

11. To stop welding, simply remove the torch from the workpiece.

12. Turn off the gas as soon as you finish welding.

Notes:

• To avoid a visible strike mark on the surface of the workpiece it is advisable

to strike the arc in the joint where the mark will be concealed by the weld.

• Thin sheet and stainless steel may be welded with or without filler, similar

to gas welding.

• The filler is fed in at the edge of the pool. The rod must not touch the tip of

the electrode or enter the arc. The end of the rod must always be shielded

by the argon atmosphere to prevent as far as possible the formation of

oxides of its surface. When welding stainless steel and copper, it is often

possible to feed in the filler continuously at the edge of the pool.

• The arc length generally varies between 3 and 6 mm depending on the

type of joint, type and thickness of material and so on.

• The torch is advanced in the direction of welding, without lateral

movement, maintaining the torch angle of 45o to the workpiece.

NOTE: TIG DC welding is used for welding Aluminium and also for welding

very thin material (0.5mm - 4mm max).

It is very important, particularly when DC welding, to ensure that the workpiece is

perfectly clean immediately before proceeding to weld.

Remember that oxidation takes place very quickly with some materials, presenting a

barrier which should be avoided if a high quality weld is required.