How to use tig welding machine safely
TIG is the process of welding tungsten electrode in a protective environment, inert gases, inert gas is protected from air intrusion. Melted metal is due to the heat generated by the arc between the tungsten electrode and the solder. As well as MIG welding and other gas shield welding, TIG welding can use inert gases or inert gas mixtures.
1. Advantages of TIG welding
Electro-tungsten welding in an inert gaseous environment can be used to weld aluminum, magnesium, stainless steel, copper and copper alloys, nickel, and nickel alloys, and low carbon steel of varying thicknesses.
TIG welding can be performed in all spatial positions without the addition of metallic metal splashes in the welding pool rather than in the arc formation.
TIG welding is not throttled because the welding process does not generate wholesale.
TIG welding can be performed easily on both the most difficult-to-iron metals, fill metals and base metals that are easily combined to form a weld. It is possible to use scrap metal to weld, the weld after finishing without further processing because the shape of the protrusion of the weld can be adjusted easily during welding. Metal welding is solid, not porous or sintered and it is important to be able to do so at a very high welding speed, significantly reducing the cost.
2. TIG welding machine and electric current
tig and arc welding machine are both one-way and rotary. Welding machines are designed for different purposes depending on the welding material and arc characteristics.
Asian. DC current: DC current has two types of forward and reverse polarization (conventional in arc welding). However, reverse bias is rarely used in TIG welding due to the disadvantage of unstable arcs, poor depth and electrode wear. The only advantage of this method is the effect of cleaning the oxide on the surface of the material, which is good for welding oxidized metals such as aluminum and magnesium. However, most of the other metals do not need this process so in TIG welding mainly using the polarization method. Positive polarity is to create a more stable arc, better penetration depth than reverse polarity, which leads to less stress and deformation.
B. Alternating currents: Of course, that would be a combination of both positive and negative polarization. Therefore, when it is in the half cycle of reverse polarity, it also has the effect of removing the oxide layer on the surface. So when welding metals like aluminum, magnesium, and beryllium copper. It is often preferable to use AC currents rather than reverse DC currents. With these metals, the removal of surface oxide plays a very important role in obtaining good and clean welds.
DC welding machines usually use a high frequency current to induce an initial arc (called high frequency addition) and for AC welding machines, this current is maintained continuously. Regular TIG welding machines operate in the 3 to 350 A range, with a voltage of 10 to 35 V and a load factor of 60%. High frequency welding machines can be used with conventional AC and DC sources. The AC source must have a maximum no-load voltage of 75V.
3. Gas protection
Metallic and molten metals will be protected in inert gases such as argon or helium, or in a mixture of both argon gas are used more widely for two reasons: First, it is a cheap, easy gas. Modulation. Second, argon is heavier than helium due to its good protection even in low air flow. When adding helium to argon, this mixture increases the arc energy, although the arc current and arc current are the same, for this reason a mixture of two gases is used to weld thick objects.
There are generally five types of gases and gas mixtures used as gases for TIG welding:
– pure argon
– Heli pure
– pure CO2
– Argon + helium mixture
Argon + CO2
4. TIG welding torch
The soldering iron is responsible for the tungsten electrode, porcelain, electrically conductive and protective gas.
How to use tig welding machine
Because TIG welding generates a lot of heat, the TIG torch needs to be cooled, providing safe and comfortable welding for the welder and increasing the life span of the welding torch.
TIGs with low currents can be cooled by air. Large, large-scale TIG grinders must be cooled by water, and the torches can operate with currents up to 500A.
The “soft casing” type is a special type of welding torch with bending angle at the ends, which is used for special purposes.
B. Electrode electrode
The electrode is held inside the welded silver cone welded, silver cone is a kind of snail hole in the middle. The size of the cone depends on the diameter of the electrode. Direction and flow of air is controlled by a gas cup or nozzle mounted at the tip of the torch.
TIG welding electrodes
Unlike manual arc welding, TIG welding electrodes do not melt during welding, so that the electrode metal must have a very high point of flow to withstand welding currents without melting.
Asian. Tungsten electrode pure
The first electrode used in TIG welding, it has a high flow point of 3400 ° C (6170 ° F), making it virtually non-melting during welding. Then people started to use tungsten alloy electrodes because they had more advantages than pure tungsten for different applications. TIG welding electrodes are distinguished by the color of the electrode tip. The pure tungsten electrodes are painted green and have the letters EWP.
Actually, electrodes are made of either of the following tungsten alloys because they have more advantages:
– Zirconcon – Tungsten: mainly used for aluminum welding, Zirconium Electrode – Tungsten is easy to weld as pure Tungsten electrode but higher durability, This electrode is commonly used with AC and gives high quality welds. .
Zirrconium – Tungsten electrode is painted brown at the electrode tip and has EWZr.
Thorium – Tungsten: This type is used to weld low alloy steels with lower currents than the upper ones and mainly uses direct bipolar DC. Because of its lower current, it is less distorted and less prone to solder quality when it is disconnected from the unwanted solder. There are two types of thorium-tungsten electrodes with a corresponding thorium content of 1% and 2%.
The 1% thorium type is yellowed at the electrode tip and has the letter EWTh1.
The 2% thorium is painted red at the electrode tip and has the letter EWTh2.
For TIG welding, precise control of flow and gas pressure is important, so use only equipment specifically designed for TIG gases.
6. Pressure reducing valves and flowmeters used in TIG welding
In the pressure reducing valve used for TIG welding is generally slightly different than for gas welding (oxy-acetylene welding). In gas welding, the pressure of the nozzle (supply pressure) is indicated on the meter in “psi” (pound square inches – pound in US) Or MPa (1psi = 7.10-3MPa). In TIG welding, the protective gas to the nozzle is measured in units of pressure measured in units of measurement “cfh” (cubic feed per hour – cubic meter per hour) Or m3 / h (1cfh = 28.3.10-3m3 / h). Cfh is measured by the flowmeter, as the air flow increases, the indicator marbles are pushed higher on the scale, so that we know how much air is flowing through the meter. Another clock is used. To measure the amount of gas left in the bottle just like in gas welding.
7. Sub-metals in TIG welding
As in gas welding, TIG welding may or may not be metal dependent depending on the weld. In general, secondary metals are used only for large welds and small welds are not needed. Although the weld metal can be supplied in the form of wires automatically but usually it is hand-operated under Metal rods. The size of the secondary metal rod into the welding current and the thickness of the weld.