Base metal preparation:
In order to weld aluminum, the welder must carefully clean the base metal, and use oil or solvent to remove any oxides and hydrocarbons from the aluminum surface. The surface of the aluminum has an oxide ablation temperature of 3,700 degrees Fahrenheit, while the underlying aluminum base material ablate at 1200 degrees Fahrenheit. Thus, the appearance of any oxide remaining on the aluminum base material will restrict the penetration of the filler metal into the workpiece.
To remove the oxides on the surface of aluminum, you can use stainless steel wire brush or solvent corrosion. When using a stainless steel brush, it can only be removed in a fixed direction. Be careful not to be too hard and not careful: rough movements will form oxides embedded in the aluminum base metal. Together, use only stainless steel brushes on the exterior of aluminum. Do not use brushes that have been used on stainless steel or carbon steel. When using chemical solvents, be sure to clean the solvent before soldering.
To minimize the adverse effects of hydrocarbons with oil or solvent, use degreaser. Together make sure that the degreaser does not contain any hydrocarbons.
Preheating aluminum workpieces can help avoid weld cracks. The preheating temperature should not exceed 230 degrees Fahrenheit. Use a thermometer to monitor the temperature to avoid overheating. In addition, the placement of continuous welds at the beginning and end of the weld zone can help to enhance preheating. The welder should also preheat a thick piece of aluminum while welding the thin material.
The process of aluminum welding requires “high temperature and high speed” disposal. Unlike steel, the higher thermal conductivity requirements of aluminum use higher current and voltage settings and higher welding speeds. If the welding speed is too slow, there will be too much weld penetration, especially when welding thin materials.
Argon is used as the most common aluminum welding maintenance gas because of its excellent cleaning function. When welding the aluminum alloy of the 5XXX-series, the maintenance gas used is a mixed gas of argon and helium. Up to 75% of the share of helium can reach the optimum effect of reducing the effects of magnesium oxide.
Aluminium welidng wire:
Select and fill the aluminum wire near the melting point of the base metal. The more the welder can constrain the ablation scale of the metal, the easier it is to weld the alloy. Use a 3/64- or perhaps 1/16-inch diameter filler. The larger the diameter of the filler wire, the simpler the wire feed. To weld thin data, use a 0.035-inch diameter wire with a pulsed welding process and a low-speed wire feed (approximately 100 to 300 inches per minute).
Concave material welding:
In aluminum welding, spark splash can cause welding to lose. The crack is the result of a shortening from the high-speed thermal expansion of the aluminum material to the formation of many cooling. The risk of welding cracks is greatest in the time of welding concave data, because the data pits will be shortened, and the data will be torn when cooled. Therefore, the welder should create a pit of convex shape, which will compensate for the shortening formed during welding.
When selecting the voltage of the gas metal arc welder for welding aluminum, the primary requirement is to think about the droplet transition or the pulse.
A welding machine that stabilizes current and stabilizes voltage can be used for ejecting arc welding. The eruption arc is to spray a small molten metal droplet on the electrode through the welding arc onto the base material. In the application of welding thick aluminum, the welding current is required to exceed the stable current of 350 amps, which can reach the best effect.
Pulse transitions are usually carried out with the support of an inverter power supply. The new power supply includes a built-in pulse program. At the time of the gas metal arc welding pulse, there is a drop of filler metal from the electrode to the workpiece during each current pulse. During this process, the droplet transfer of the positive electrode occurs, reaching less splash and higher welding speed. . The pulse gas metal arc welding technology is used to weld the aluminum material, the heat input is also very well controlled, and the misalignment welding can be easily performed, so that the welder can weld the thin material with a lower wire feeding speed and a lower current. .
The preferred method for sending soft aluminum wire over long distances is push-pull wire feeding. This method uses a closed wire feed structure to maintain the aluminum wire from environmental influences. The stabilizing torque and variable speed motor in the wire feeding mechanism act as the wire feeding power, and guide the welding wire through the welding torch to achieve stable output and speed. The high torque motor of the welding torch pulls the wire to ensure that the wire feed speed and the welding arc are coordinated.
Some welders use the same wire feeder to transport steel wire and aluminum wire. Under such conditions, the use of plastic or nylon liners can assist in achieving smooth and coordinated common wire (aluminum) action. In the detailed welding time, try to adhere to the vertical of the torch cable to reduce the wire feed resistance. Carefully check the coaxiality between the automatic roller and the guide tube to avoid scratching the aluminum.
Use automatic rollers designed for aluminum. Set the automatic roller tighter to reach the constant wire feed speed. A too tight setting can cause deformation of the wire and unstable wire feeding: if it is too loose, it will cause unstable wire feeding. Both conditions directly cause instability in the weld arc and weld porosity.
Use different welding torch pads to weld aluminum. To avoid the wire being disrupted, try to tighten the ends of the pad together to eliminate the gap between the pad and the gas diffuser.
Frequent replacement of the liner can reduce the adverse effects of potential oxides on the rough appearance of the aluminum on the wire formation. When the welding current exceeds 200 amps, it is necessary to use a water-cooled welding torch to cool and reduce the difficulty of wire feeding.