Wire feed welding or MIG welding is a common welding process. The welding electrode and filler wire are combined in a spool of wire that is continually fed through the MIG gun and into the welding seam. Learning the process of MIG welding and how to perform a sound MIG are fundamental in fabricating and installing sheet metal. Properly setting the MIG welder, maintaining the proper cup angle, and remaining comfortable during the weld will all have a direct effect on the final results of the MIG weld.
Spool the MIG welder with the spool of E70 welding wire. Each manufacturer has a different method of spooling the welding machine; refer to your owner's manual for the proper steps involved in spooling your particular MIG welder. Attach the welder's air gauges to the bottle of shielding gas.
Attach the ground clamp to the welding table and turn on the MIG welder. Refer to the machine's welding chart to set a starting point for your voltage and wire speed. If you do not have the welding chart that came with your welder, set the voltage at 19.0 and the wire speed at 270. This is a hot setting; adjust the setting after you begin to weld.
Lay one piece of metal flat on the table. Stand another piece of metal vertically, and set the piece on edge near the center of the piece lying flat on the table. Place the wire protruding from the MIG gun cup against the area where the two pieces meet. Pull the trigger for roughly two seconds to tack the pieces together. Place additional tacks every three inches until you reach the other end of the metal.
Place the MIG gun, with 1/2 of an inch of wire protruding from the tip, at the front edge of the area that you tacked in step 3. Hold your gun at a 10 to 15 degree angle from the weld joint. Lower your welding hood. Begin the fillet weld by depressing the trigger of the MIG gun, and working the puddle and then down in a circular pattern. With each down stroke move the wire 1/8th of an inch back from the center of the weld puddle. Continue the circular pattern for the entire length of the weld.
Lay another piece of metal flat on the welding table. Lay the last piece of metal flat on top of the piece resting on the table, with the edge of the top piece of metal 1 inch back from the front edge of the lower piece of metal. Tack the two pieces together.
Place the wire into the seam where the two pieces of metal meet. Lower your welding hood. Depress the trigger of the MIG gun. Pull the MIG gun back 1/8th of an inch. When the puddle comes to your location, move the gun another 1/8th of an inch. This pattern of moving straight back makes a thin weld that has excellent penetration.
When the two pieces that are welded together in a T are cooled, stand the piece up on end. Place the wire protruding from the MIG gun at the top of the T on the side that does not have any weld. Lower your welding hood. Tilt the bottom of the MIG gun 10 degrees lower than the MIG gun tip. Depress the trigger. Roll the MIG gun in a clockwise motion, dropping the MIG gun 1/8th of an inch on each down stroke. If the weld puddle falls toward the ground, increase the angle of your MIG gun and the speed of your clockwise rotation.
Turn off your welding machine. Dispose of the test pieces after they have completely cooled.
