What causes the contact tip burn back in aluminum welding?

Problems encountered: When I process aluminium welding, the welding wire is stuck in the contact tip. After preliminary observation, it is found that the aluminum alloy welding wire sticks to the contact tip.  People say this is contact tip burn back. The diameter of the aluminum welding wire is 1.2mm.

What you describe is contact tip burn back. why does this happen? How do we solve it? Are there any requirements for the material of the contact tip? Is the aluminum alloy welding wire relatively soft that wire scraps fall off? Do scraps stick to the contact tip in the wire feeding process?

Compared with steel wire, aluminum alloy wire has poor strength and wears resistance. The surface roughness of the aluminum alloy welding wire is very large when it reaches the contact tip through the wire feeder and the tube.

The burning contact tip is mainly caused by the clogging of aluminum scraps. The first choice is to choose a suitable wire feeder, not a pair, but a set of 4, which can reduce the pressure and avoid damage to the surface of the welding wire. The guide groove cannot use the I type, it is better to use the V or U type.

Wire feed conduits are also important, good conduits are wear-resistant and smooth. The aperture and length of the contact tip and the processing quality of the inner surface are very important. The aperture is small and the contact is good, but the friction force and the effect of discharging aluminum scraps are poor. Too large it will easily lead to poor contact and poor wire directivity.

Is the 1.2 wire too small? Also, the degree of bending and length of the torch is very important. The cooling effect of the contact tip is also very important, after all, the melting point and thermal strength of aluminum alloys are very poor.

This is a common phenomenon, and it is related to the wire feeding system, the finish of the welding wire, and dust. The sudden elongation of the arc also burn the contact tip.

Use contact tip with AL or A on it, such as 1.2AL or 1.2A.  The inner diameter of the contact tip is larger than regular ones. Another piece of advice is to use Teflon material or graphite liner.

Contact tip burnback is usually caused by poor wire feed, while arc ignition is difficult due to low voltage

1. Use lower voltage setting (if arc is too long)
2. The better the wire feedability, the less problems there will be
3. Use larger diameter wire
4. Check wire feeding system
5. Changing or adjusting the contact tip
6. Clean or replace liner
7. Check drive roll and brake adjustment
8. Recess contact tube (if tube runs too hot)
9. Use a water-cooled torch (if the torch overheats)
10. Shorter feeding systems have fewer problems
11. Fewer problems with small wire guns
12. Do not start arc if the welding wire touches the workpiece
13. If the nozzle is too close to the product, just raise it a little more.