9.4 FCAW Operation and Welding Techniques
Cameron Kjeldgaard
FCAW Welding Fundamentals
The fundamentals of FCAW are about the same as those for other arc welding processes:
- Electrical characteristics (current, voltage, and polarity)
- Electrical stickout
- Work and travel angle
- Travel speed
- Electrode manipulation
Electrical characteristics will be recommended by the electrode manufacturer and controlled by the welding procedure specification. The required polarity for an electrode must be used, but welding current and voltage will be recommended as a range and there is room for adjustment. Where you set the machine within this range is really a function of base metal thickness: Thicker base metals will require higher electrical settings, which increase the heat of the welding arc. Remember, there is no direct way to control welding amperage. Rather, amperage is determined by wire feed speed and electrode diameter, with larger electrodes and higher speeds resulting in high welding amperage. At all times you should remain within the range recommended by the manufacturer or required by the welding procedure.
As we’ve already covered, it is critical that the proper stickout is maintained as the electrode is moved down the joint. This takes practice to get used to, so don’t get discouraged. Keeping your head in a good position is helpful in maintaining proper stickout—if your head is positioned directly behind, or nearly behind, the welding gun, it is difficult or impossible to see the amount of stickout. Instead, find a comfortable position where your head can be on one side of the welding gun and you can see, and therefore monitor, the amount of electrical stickout during welding.
The work and travel angles of the electrode influence where the heat of the arc is directed and the shape of the finished weld bead. Electrode angles are not controlled for in welding procedures and are left up to the discretion of the welder. Selecting the proper angle and maintaining it throughout welding is a practiced skill.
Travel angle is the angle of the electrode relative to the length of the weld joint. Guidance for the travel angle in FCAW is rather straightforward: a pulling or dragging angle of 10–30 degrees should be used. A common saying among welders engaged in welding processes that produce slag is “if there’s slag, you drag”, as it speaks to a problem with pushing these types of electrodes. If FCAW electrodes are pushed along the joint, there is a strong chance a ball of slag will be pushed in front of the weld puddle resulting in a slag inclusion at the root of the weld bead. The one notable exception to this rule is when welding in the vertical position with an upward progression—in this case, a slight push angle of 10–15 degrees should be used.
Work angle, the angle of the electrode relative to a cross-section of the joint, is a more complicated matter. The exact work angle used in FCAW is a matter of how the joint is designed and where the welder