Welded Parts Knowledge Of The TIG Welding - xlweld.com
Welded Parts Knowledge Of The TIG Welding
What is TIG welding?
TIG (Tungsten Inert Gas) Inert Gas Tungsten Welding. TIG welding is a gas shielded welding method using tungsten rod as the electrode and using an inert gas such as argon or nitrogen as the shielding gas. The arc is generated between the tungsten and the workpiece, and the argon The airflow forms a tightly closed gas layer in the arc area, isolating the electrode and the metal bath from the air to prevent air ingress. While the use of arc heat to melt the base metal and fill the wire to form the molten pool. Liquid metal pool after the formation of weld solidification.
How to choose the correct TIG gun
TIG gun arc using high-voltage pulse arc, so the gun has a good insulation and pressure, to prevent accidental injury.
(1) According to the actual welding workpiece to select the appropriate current load gun type, and MIG / MAG as the welding gun itself is not self-protection, it is recommended in the choice of welding gun, the Torch load capacity must be greater than the maximum output capacity of the welding machine, High lead to the aging of the insulation layer, shortening the torch life.
⑵ according to the cooling method can be divided into air-cooled and water-cooled. Specific selection needs to be specific to the requirements. Such as cost, welding occasions, current requirements, and welding comfort.
The air-cooled torch has a simple structure and easy maintenance, and the cable length can be lengthened, and it does not require water tank cooling. But because the cable with more copper, resulting in poor flexibility of the welding gun, not suitable for precision welding and other special occasions.
Because the water-cooled gun must use the circulating water tank to cool the torch heat, coupled with the torch itself more common welding gun structure is complex, so the cost will be higher than the air-cooled. Another side of the air cold gun in a period of 10min, must stop 6.5 minutes, so that the gun neck accessories and cables, etc. will not cause too much damage to the temperature, which also resulted in waste of working hours, raising costs.
❷ welding occasions
If it is in the outdoor operation, in order to facilitate the transport and management, preferably air-cooled gun. Because the air-cooled gun is only 35% duty cycle under the rated current, it is suitable for manual operation; if the workplace is indoor is suitable for automatic welding, through the extension of the pipe can be welded without moving the cooling device. Water-cooled gun duty cycle 100%, improve welding efficiency.
In 150A and below the current commonly used air-cooled gun, air-cooled gun current range of 100A ~ 500A.
Air-cooled guns use more copper for cables, and because the fittings do not have good water cooling, so the torch is relatively strong and heavy. The water-cooled gun is the opposite, plus if the skin to use sheepskin, inner tube switch to silicone tube, the torch is more soft and light. So we have to consider the actual needs of the use of the election.
TIG torch use precautions
When welding with argon guns, note the following parameters: welding power supply type and polarity, welding current, arc voltage, tungsten diameter, nozzle diameter, argon flow rate, welding speed and nozzle to weld distance and tungsten Out of length and so on. Must be the right choice and a reasonable match, in order to get a satisfactory welding quality
⑴ welding power supply type and polarity of the power supply type and polarity can be selected according to the welding material type and polarity of the choice of power.
Power supply type and polarity
Welded metal material
DC is connected
Low carbon steel, low alloy steel, stainless steel, copper, titanium and its alloys
Aluminum, magnesium and its alloys
⑵ welding current welding current is mainly based on the workpiece thickness and space to choose, too large or too small welding current will make the weld bad or produce welding defects. Therefore, the welding current must be selected correctly within the permissible welding current range of different tungsten diameters, as shown in the table below.
Permissible Current Range for Different Diameter Tungsten
Tungsten Diameter (mm)
DC is connected (A)
2.0 100-200 85-160
2.5 170-250 120-210
3.2 225-330 150-250
4.0 350-480 240-350
⑶ arc voltage arc voltage determined by the arc length. Through the welding current and arc voltage with the control, can control the weld shape. When the arc voltage is too high, easy to produce non-penetration and the effect of argon protection worse. Therefore, the arcing should be minimized in the case of arc, the arc length is approximately equal to the tungsten pole diameter. TIG welding arc voltage selection range is generally 10-24 volts.
⑷ nozzle diameter increases the nozzle diameter at the same time, should increase the gas flow, this time the protection zone is large, the protection effect is good. However, when the nozzle is too large, not only the consumption of argon is increased, but it is possible to make the torch not reach, or to obstruct the sight of the welder, and it is not easy to observe the operation. It is generally tungsten argon arc welding nozzle to 5-14mm is better.
In addition, the nozzle diameter can also be selected according to empirical formula:
D = 2 * d + 4mm
Where: D - nozzle diameter mm (generally refers to the diameter);
D - tungsten pole diameter (mm).
⑸ air flow flow is appropriate, the pool is stable, the surface bright without residue, no oxidation marks, weld appearance. Flow is not appropriate, the pool surface slag, the surface of the weld black or oxide. The appropriate flow rate of argon is 0.8 to 1.2 times the nozzle diameter.