Six common mistakes in Self Shielding FCAW and their solution
As we know Flux cored arc welding (FCAW) falls in two categories; one is the self-shielding and other one is dual shielding. Many people having trouble with FCAW self-shielding system and they must need practice by keeping an eye on some critical factors. Factors like proper angle, contact to work distance, correct voltage, correct polarity, acceptable travel speed and wire feed speed are imperative for smooth uniform welding with consistent slag coverage in Flux cored self-shielded welds. Below listed are the common factors, how they affect your weld and what are the common mistakes that need to be avoided.
Wire cut
Welding Angles
Wire feed speed
Polarity
Travel speed
Contact tip to Work distance
1. Wire Cut
It’s a recommended practice to cut the wire every time before commencing the weld. So cut the wire before start in order to get good weld results.
2. Wire Feed Speed
a) high WFS b) low WFS
Wire feed speed (in shortened form WFS), has a direct relation with current that is, higher the wire feed speed the higher the welding current. On the other hand, lower the wire feed speed the lower the welding current.
Low wire feed speed results in
Less penetration.
Narrow beam
There may be a lot of spatter.
Too fast wire feed speed results in wire stubbing and you will hear the sound like popping. To avoid this you need to turn your wire speed down a little or to turn the voltage high for compensation.
3. Travel Speed
c) Slow travel speed d) High travel speed
We know travel speed has a vital role in all types of welding. In a like manner, too low travel speed results in convex wider weld bead and also slag wouldn’t cover on the top of the weld. On the other hand if you made your flux cored weld with too fast travel run, no proper size weld bead is obtained that will actually run out of the puddle. So you need to run the weld bead with moderate travel speed to get the proper size weld.
4. Contact tip to work distance
e) Short distance f) long distance
Very important factor in Flux cored self-shielded arc welding. It is the distance of from contact tip to work piece which may be different for different wires. So contact tip to work piece distance must be set according to the recommended settings. Here two points to discuss when the distance is too long or too short what would be the consequences?
1. In case you made the weld bead with too short contact to work distance, no proper slag would cover on the weld. That being the case where flux in core ain’t get enough time for heat. See the figure where slag has no coverage on the convex of the weld, besides the slag is on the sides of weld bead.
2. Too long contact to work distance causes inconsistent feeding of wire owing to the back and forth movement. In this case wire keeps on stubbing and causes ripples in the weld bead.
5. Polarity
Wrong polarity cause a lot of spatter
Making the flux core weld with wrong polarity is one of the major mistake. Working with wrong polarity encourage a lot of spatter. Even more no proper size weld is laid. So before to commence weld make sure your equipment is on correct polarity. For DC electrode negative or also the straight polarity, the feed wire should be plugged on negative terminal and that of work piece with the positive terminal. Similarly in case electrode positive or reverse polarity, the work piece must be plugged on negative terminal and wire feeder with the negative terminal of the power.
6. Welding angle
See What are the angles that can improve your weld.
Like stick welding, flux core self shielding method also involves slagging process. In this case you have to drag the electrode (which is the wire in this case) to ensure the slag before and behind the weld otherwise your weld get slag inclusions. Slag is lighter than the weld puddle and it floats on the top of the weld. For flat plate welding the tilt angle (work angle) must be 90 degrees. In case of T-joints or lap joints tilt angle must be 45 degrees to the joint and the slope angle which the drag angle, must be 5 to 10 degrees in the direction of travel.
