CARBONE PowerMaster256, Operator'S Manual

B-8                                OPERATION                                      B-8

Increasing the frequency constricts the arc, 
increases stability and improves weld quality.   
                  FIGURE B.6   
 
 
 
 
 
 
 
 
 
 
 
 

 
A.C. (Alternating Current) 

(see Figure B.7)   

 
Alternating Current welding is typically used for Tig 
welding aluminum (and its alloys) or magnesium. 
The polarity alternates between Electrode Positive 
and Electrode Negative (EN). During the positive 
halfwave the oxide is broken. During the negative 
halfwave, the electrode cools, the workpiece melts 
and penetration occurs.   
                                    FIGURE B.7   
 

Greater % EN = MORE PENETRATION 50% (EN) Lesser % 
EN = more CLEANING   

Changing the wave balance alters the ratio between   
the cleaning and the penetrating current.   
 

A.C.-Pulsed TIG   

 
When AC welding, a pulsed current can be used, 
with similar effects to those described in pulsed 
direct current welding.   

                        FIGURE B.8   

STEEL TIG WELDING   

The TIG process is very effective for welding both 
carbon steel and alloy steel, especially in 
applications requiring precision results. DC 
Electrode Negative Polarity is required. Since this 
process does not include the removal of impurities, 
proper cleaning and preparation of the edges is 
required.  

FILLER MATERIAL:   

The filler rods must deposit welds with mechanical 
characteristics appropriate for the application.   
 

COPPER TIG WELDING   

Since the TIG welding is a process characterized by 
high heat concentration, it is particularly suitable for 
welding materials with high thermal conductivity, 
like copper. As with steel, the DC Electrode 
Negative  
Polarity is employed, with argon as protective gas. 
Considering the fluidity of molten copper, the use of 
backup support may prove useful.   
 

FILLER MATERIAL:   

In order to avoid the oxidation of the molten material, 
filler materials containing phosphorus, silicon or 
other deoxidating materials are typically used. The 
mechanical properties can also be improved 
through the use of silver.   
 

TIPS FOR AC TIG WELDING   

AC Inverter TIG power sources offer two significant 
advantages over conventional Silicon Controlled 
Rectifier (SCR) / transformer power sources:   
1. The AC wave balance(SP%) can be set to a 
higher percentage electrode negative which 
minimizes tungsten heating and erosion.   
2. The AC frequency can be varied to "focus" the 
arc. Increasing the AC frequency above 60Hz will 
narrow the cone shape arc from the tungsten’s tip. 
Decreasing the AC frequency below 60Hz will 
broaden the cone shape arc from the tungsten’s tip.   
The two above benefits can be used to maintain a 
tight focus of the arc for precise heat control and 
tight joint access. Because of the AC inverters 
abilities in these areas the following 
recommendations are made as a starting point:   

●

A 2% Thoriated tungsten is recommended instead 

of the Pure tungsten that is normally recommended 
for AC welding. Thoriated tungstens emit electrons 
easier and therefore will improve starting.   

●

. Sharpen the tungsten to a point. Normally it is 

recommended to preball a pure tungsten when AC 
welding with a conventional power source.   
However, the AC inverter with it

’

s extended AC 

balance control minimized tungsten heating thus 
allowing for a pointed tungsten to be used.   

Greater % EN=more penetration 

Lesser % EN=more CLEANING

50 % (EN) 

DC TIG-NOT PULSED 

DC PULSED TIG 

I(A) 

Ip 

I(A) 

Ip 

Im 
Ia 

 t 

t

T

f = 0.5 ~ 25Hz
T =1/f