Welding is the process of joining 2 metal components by melting them together. Welding any material is a challenging process requiring experience; welding lightweight metals like aluminum requires the utmost precision to ensure a strong bond. Knowing how to weld aluminum is a matter of assembling the right tools, exercising caution and patience, and gaining experience.
Features offered by welders that are specifically designed for aluminum and advanced steel applications, like Chief Elektron Fusion Technologies new MIG/MAG welders, give technicians who are equipped with these modern tools more confidence about repairing the newest vehicles.
The melting temperature of the aluminum is about 660 °C while for steel is about 1500 °C. However, the melting temperature of the surface oxides (alumina, Al203) is about 2000 °C, which means that surface preparation, and special care of the aluminum wire, is essential for proper welding.
Compared to steel, the aluminum thermal conductivity and thermal expansion change significantly.
- Heat dissipation is faster; consequently, the risk of sticking (lack of fusion) is greater.
- Dilations are higher and cause more significant residual deformations.
- Metallurgical defects, such as “hot cracking”, are possible.
- Operational defects, such as the presence of “porosity” and “lack of fusion, are possible.”
- Problems of joint breakthrough depend on the high fluidity of the weld pool: lap joints, or a flat supporting element, are often used.
The transfer of the filler material by pulsed arc limits the heat input to the workpiece without decreasing the penetration of the fusion. When using the pulse, you work with a current which is on average lower than the transition value, which has the following advantages over not-inverter welders:
- Reduced heat input on the workpiece
- Welding of thin pieces (without changing the diameter of the wire used)
- Better penetration
- Reduced splatters
- Aesthetic welds (flatter on materials such as aluminum and stainless steel)
- Better arc control by the operator
Most OEMs today require synergic pulse technology for welding aluminum.
Double pulse technology outputs high and low frequency pulses, which provides a unique welding feature over most competitors. The double pulse feature allows the weld to cool slightly during the low frequency operation. This is an important feature when trying to weld in the vertical or overhead, horizontal positions, when the welding process may be prone to drip. In addition, the current intensity that varies between two different pulse levels, generating a bead aesthetically similar to the one obtained in TIG welding. Finally, thin pieces are deformed less due to the reduced heat transfer.
Chief offers a Push-Pull torch. This small and very light weight torch has a roller built in the head of the torch which “pulls” the aluminum wire in tight control with the “push” action from the power unit. It is very difficult to feed small diameter, soft aluminum wire through a standard torch without running into many feed and control problems. Although it is possible to feed larger diameter aluminum wire through a standard torch (as long as it has the proper line), but the length of the torch cable must be restricted. The 4-meter cable length of the Push-Pull torch enables the Chief welder to easily reach the areas to be welded. A spool gun can also be used for aluminum welding, but it is bulky and is not typically tied back to the power unit for synergic control. The Push-Pull torch also comes with an up/down button for finder-tip control of wire-feed speed and current levels while welding, real-time, to adjust for the weld conditions and for personal preferences. When working with aluminum, the ability to adjust the wire feed speed and current levels is important due to the fast heat conduction of the base material, especially with the large diameter wire and the high amount of input energy.