Most Common Problems In Tig Welding
Welding is the process used for fusing metals. There are different types of welding like arc welding, gas welding and resistance welding. TIG or Gas Tungsten Arc is a type of gas metal arc welding. In this type of welding there is a continuous and consumable electrodes are fed through a welding gun. There should be constant voltage and AC or DC electric current can be used. The general problems encountered in TIG welding are erratic arc, high electrode consumption and porosity of the weld.
Experienced and inexperienced welders will have some problems that are common in TIG welding. If you can identify the problems, time and money will be saved and the work will get done faster. Some imperfections may occur which will affect the quality of the weld.
1. One such imperfection is porosity. Porosity is actually gas pockets formed in a metal weld. You can see it as small holes. The reason for porosity may be due to improper shielding gas coverage, the use of wrong shielding gas or filler metal, too much heat and a base material that is not cleaned properly. To rectify these problems you should tighten all torch fittings and inspect all the holes for leaks. If you cannot easily find a leak, the best method will be to apply a soap solution to it, till the leak is identified. If a hose has to be replaced, it is best to replace it immediately.
a. The shielding gas flow rate should be 10 to 20 cubic feet per hour for the right coverage. If the rate is more it will lead to weld puddle turbulence and if it is low it will not protect the weld puddle. Both a higher and a lower rate of flow will lead to porosity.
b. The right filter rod should be chosen to suit the base material. Argon gas shielding should be used and not CO2. This will also stop porosity.
c. Too much heat can also cause porosity. So, it is necessary while welding on carbon steel to be within 80 to 120 amperage range for 1/8 to 3/16 thick material.
d. Dirt, grease and moisture should be cleaned from the surface of the material. Use a stainless steel brush to remove surface oxides. This can lead to porosity.
2. Undercutting is another problem that can occur in TIG welding. This happens when a groove is made along the edge of the weld and the place is not filled with weld metal. This occurs when the heat is unevenly distributed and the torch is not held at the correct angle. This will result in a weak joint. To rectify this problem, you should initiate the arc, establish a weld puddle and check if the weld puddle is distributed equally on both sides of the joint being welded. The angle of the torch should be adjusted properly and care should be taken to see if the filler metal is flowing evenly into the weld puddle.
3. Lack of fusion is another problem that can occur in TIG welding.
a. If the weld does not join with the base material then it will result in a weak joint. This might be due to using lesser amperage for the thickness of the material being welded. To have the best TIG weld, you should use 10 amps for every thousandth of an inch of material.
b. When a joint has to be welded, you should create a space between the joints or bevel the pieces that form the joint. This will ensure proper fusion of the joint.
4. Excessive penetration will also cause a problem. In this the weld metal melts through the weld joint. This might be due to too much heat or too slow travel speed. To rectify this, the correct travel speed should be maintained. The travel speed should make a weld puddle that is twice the diameter of tungsten that is used. This requires practice.
Being aware of the common problems in TIG welding and knowing how to rectify them will go a long way in perfecting TIG welding.