Jasic EVO 2.0 ET-200PACDC, Owner'S Manual

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GUIDE TO TIG WELDING
Before starting any welding activity ensure that you have suitable eye protection and
protective clothing. Also take the necessary steps to protect any persons within the welding
area.
AC TIG welding square wave
With the electronic development of inverter power sources, the square wave machine was developed.
Due to these electronic controls the cross over from positive to negative and vice versa can be made
almost in an instant which leads to more effective current in each half cycle due to a longer period at
maximum. The effective use of the magnetic field energy stored creates waveforms which are very
near square.
The ET - 200PACDC square wave machine allows
us control of the positive (cleaning) and negative
(penetration) half cycles.
The balance condition with equal positive and
negative half cycles will give a stable weld condition.
The problems that can be encountered are that once
cleaning has occurred in less than the positive half
cycle time then some of the positive half cycle is not
productive and can also increase potential damage
to the electrode due to overheating.
However, this can be eliminated by the use of balance control which allows the time of the positive half
cycle to be varied within the cycle time.
I0 - Initial current
I1 - Welding current
I2 - Final current
tu - Upslope time
td - Downslope time
tp - AC period
tc - Cleaning time
In AC square wave TIG welding, the pre flow time and post flow time are the same as in DC TIG welding.
Others parameters are described below:
Initial current (I0), welding current (I1) and pilot arc current (I2).
The preset value of the three parameters is approximately the absolute average of the practical welding
current and can be adjusted according to users technical requirements.
Pulse frequency (1/tp): It can be adjusted according to users technical requirements.
Cleaning strength (100%*Tc/Tp): Generally, in AC welding when taking the electrode as the anode, the
current is called the cathode current. Its main function is to break up the oxidized layer of the work piece
and the cleaning strength is the percentage cathode current holding in the AC period.
This parameter is 10 ~ 40% commonly. When the value is smaller the arc is concentrated and the molten
pool is narrow and deep although when the value is larger, the arc is spread, the molten pool is wide and
shallow.