subject: Procedure For Safe Aluminum Welding [print this page] Aluminum welding is no doubt a lot trickier than steel welding. Before commencing aluminum welding work, it is advisable to follow the steps outlined below to ensure that the entire welding procedure is both right and safe.
Choose the correct welding process. The widely used processes are Gas Metal Arc Welding (GMAW), sometimes referred to as MIG welding and Gas Tungsten Arc Welding (GTAW) sometimes referred to as TIG welding. Yet another process, Shielded Metal Arc Welding (SMAW) or stick welding, has restricted use for aluminum welding.
Please know that aluminum demands perfect fit up. Joint gaps are extremely difficult to fill when it comes to aluminum welding. Generally speaking, a gap of 1 - 1,5 mm should be the maximum for quality welding. Make it a point to correct any linear misalignment before attempting to weld aluminum.
Molten aluminum has a high solubility for hydrogen and this may lead to spherical porosity and thereby reducing the ductility. Joints should be fully protected from moisture, but where humidity cannot be avoided, local preheat of about 100 C can be applied.
Preheat is generally is not required in aluminum welding. In select cases it can be helpful when welding casting to reduce cracking tendency. It is essential that the welder strictly adheres to the welding procedure - particularly with regard to voltage, current, travel speed and welding sequence.
The gas shield used in the MIG or TIG welding process is delicate and easily disturbed by wind. Use the normal welding screens to prevent passersby being exposed to the arc. It is preferable that the welder knows the specifications of the material to be used on a specific job. He should check the filler wire or rods as well as the material to be welded.
Before commencing welding it is good practice to check the equipment condition. Check the torch, nozzle and cable for any damage. Correct weld preparation is crucial if quality welds are to be obtained. The weld operator must always check that the weld preparation matches the drawing. The weld operator should be familiar with the design of the fabrication.
It is also critically important that the welding process specified in the welding procedure is faithfully followed to carry out the weld. Make sure that the welding machine is capable of being set to the welding parameters needed for the job.
In any type of aluminum welding cleanliness is of paramount importance. Avoid handling clean plate or filler rods with dirty or greasy gloves. The use of contaminated cleaning equipment such as greasy wire brushes must also be avoided. Gloves should be worn to prevent hand oil or dirt from getting on the joining surface.
Allow the joint to cool gradually and if AL-43 coated electrodes are used, you must remove slag after welding.
The type of gas to be used is specified in the welding procedure and the welder must make sure that he is using the correct gas. Argon or argon helium mixtures are usually used for welding aluminum.
Please be aware that aluminum is a very reactive metal, and bare aluminum will form an oxide layer in minutes. Aluminum dust and shavings can catch fire especially if mixed with steel dust.
