Lincoln Electric 205-TAC/DCTIG manual Tips for Improved TIG Starting, Protective GAS

B-10 OPERATION B-10

PROTECTIVE GAS

Both argon and helium work when welding aluminum. Argon is preferred, due to its lower cost and consump- tion rate. This gas also tends to stabilize the arc, thus making it easy to operate. For some applications, however, the use of helium, or argon-helium blends, is recommended due to better weld penetration and faster travel speed. Helium is especially suitable for welding thick workpieces. The recommended gas flow rates are shown in table 5.

	TABLE 5
Current (A)		Helium cfh-(l/min)
50		29 - (14)
100		29 - (14)
150		42 - (20)
200		42 - (20)
250		53 - (25)
300		53 - (25)

TIPS FOR IMPROVED TIG STARTING

1. Start Current:

For the best AC or DC TIG starting characteristics it may be necessary to adjust the start current on the front panel depending on the tungsten size. In gener- al, larger tungsten requires more energy to establish an arc than smaller tungsten. As an initial guideline, set the start current according to the following recom- mendations:

Tungsten Size (in.)	Start Current (Amps)
0.020, 0.040 1/16th	6-10 Amps
3/32 th	10-12 Amps
1/8th	12-15 Amps
2. DC Strike Current:

Aside from start current, DC strike current can also be adjusted from the set-up menu to get a hotter or softer start when DC TIG welding. Strike current is an initial spike of current that lasts a few milliseconds before the machine goes to start current. In general, the fac- tory default of 40 amps works for most applications. If welding on very thin materials with small diameter tungsten, strike current can be turned down to mini- mize burning through the weld material. Like wise for larger diameter tungsten strike current can be turned up to put more energy in the tungsten.

3. AC TIG Start Power:

For AC TIG welding AC start power can be adjusted from the set-up menu to aid starting if required. The V205-T AC/DC when set to AC TIG will try to initiate the arc with positive polarity until the arc is estab- lished. Positive polarity puts more energy into heating the tungsten but the drawback is that is can cause the tungsten to ball excessively or to super heat. Note super heating of the tungsten can be noticed if the tungsten is glowing red or orange during starting. Start Power can be adjusted within two ranges:

Range Mode

0.5to 1 Manual Setting

1.2to 5.0 Incremental setting

If start power is set within the incremental range mode, the machine tries to start electrode positive at a relative setting of 1. If the arc fails to establish it will repeat the start sequence each time by incrementing the amount of electrode positive energy by 10% more (0.1) up to the start power limit setting or until the arc establishes. For comparison a start power limit of 2 if reached will have twice the energy of the starting point of 1. If the tungsten has too much of a ball on it or appears to be super heating during starts the start power limit can be turned down. In the manual setting range, the start power will not keep incrementing up to a limit. Instead the start power stays at whatever level is set. For example a setting of 0.5 will start the machine with half the normal starting energy of 1.

V205-T DC & V205-T AC/DC TIG