Aluminum Welding - Forney 270 MIG Manual De Instrucciones

Increasing welding voltage leads to a longer arc (without substantially affecting the current).
Conversely, a decreased welding voltage results in a shorter arc (the current again is not substancially
changed). A change in wire diameter results in changed parameters. A smaller diameter wire
requires an increase in wire feed speed to reach the same current. If certain limits are exceeded, a
satisfactory weld cannot be obtained. These are:
A) Feeding wire too fast (too high with regard to the welding voltage) results in pulsing within
the torch. This is because the wire electrode dips into the puddle and cannot be melted off fast
enough.
B) Setting welding voltage to high (too high with regard to the wire feed speed), will result in
excessive and unstable arc. Increase the voltage even higher and the contact tip will burn.
C) Excessive wire speed can be corrected through the arc voltage increase. The limit of this
adjustment depends on the thickness of the material to be welded (a certain limit exceeded
will result in burn through).
Place the torch on the joint you want to weld: the angle between the torch and the nozzle should be
around 45°. The distance between the torch and the work piece should be 5-1/2". Lower the face
shield and press the torch trigger to start the arc. When the arc has struck, move the nozzle slowly
from left to right along the joint. Adjust the wire feed speed until the arc makes a "crisp" sound
(experience will help you to recognize the right sound).
A) Adjust using the trigger "MODE" key for the desired trigger mode. Press the "MODE" key
until the red LED lights up.
- 2T: two time welding (manual). The welding process starts when the torch trigger is pressed
and stops when this is released.
- 4T: four time welding (automatic). The welding process starts when the torch trigger is
pressed (after a pre-gas time), it continues even if torch trigger is released and stops when this
is pressed and released once again after the post-gas time.
- Spot welding with timer: Automatic spot welder with timer. This process allows execution of
repeated welding beads. The duration is set through the adjustment knob #66.
B) Adjust the wire speed knob #5.
The display can show numbers from 1 to 99 (1 being the minimum value and 99 the maximum value).
The display shows the real welding current and the value of the parameter you selected and adjusted
during the regulation phase. After welding, the display will show the welding current value for a
maximum of 5 seconds.

Aluminum Welding

The machine should be set up for mild steel except for the following changes:
• 100% ARGON as welding protective gas.
• Ensure that your torch is set up for aluminum welding:
• The length of the torch cable should not exceed 10' (it is advisable not to use longer torches).
• Install a Teflon wire liner. Follow the instructions for changing the renewing of the wire liner.
• Ensure that drive rolls are suitable for aluminum wire.
• Use contact tips that are suitable for aluminum wire and make sure that the diameter of the
contact tip hole corresponds to the wire diameter that is going to be used.
For aluminium welding or for welding those materials such as CUSI and for applications where the
power source needs to be placed far from the working area the spool gun is particularly suitable. This
torch incorporates a wire feeding motor and the welding wire spool. The potentiometer integrated
on the handle allows constant regulation of wire speed while an internal device in the welder
recognizes and shows the spool gun connection when the green LED on the front of the welder
lights up.
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