Why do we need High Frequency in a TIG Welding Machine?

Introduction:

In our previous article we learnt in detail about Welding and how to take care of ourselves and the machines while in the process. There are many different methods of welding and each has its specific type of welding machine. There are mainly 4 different types of Welding processes: 

1. Gas Metal Arc Welding / Metal Inert Gas (GMAW/MIG)

2. Gas Tungsten Arc Welding (GTAW/TIG)

3. Shielded Metal Arc Welding (SMAW)

4. Flux Cored Arc Welding (FCAW)

In this article let us focus on one of the most efficient ways of welding process – TIG Welding, its meaning and how it works. TIG welding has played a massively successful role in accepting aluminium for superior quality welding.

How can we define TIG (GTAW) Welding? 

TIG – Tungsten Inert Gas, also known as GTAW is the name classified by American Welding Society (AWS). As the name suggests, TIG creates an arc and joins any kind of metal using a non-consumable Tungsten Electrode. Pure argon or argon mixed with helium is used as shielding gas in the process. The metal is transported from the melting electrode. As a result there’s no need to balance the heat from the arc. Filler Metal is to be added separately in the weld pool. Following this process gives pleasingly precise results due to stable and pure arc. This process must be regulated with constant Alternating Current (AC) or Direct Current (DC). The current flow depends upon the type of metal to be combined.

Understanding different types of TIG Arc Igniting Procedures:

There are majorly 3 different types of ignition processes in TIG:

1. Scratch start TIG Ignition: 

This is the most beginner level process of igniting the arc, where the Tungsten Electrode is scratched on the job to ignite the arc and is pulled away quickly otherwise there are chances of it sticking. But it should not be pulled away so far that the arc blows out. You can think of it like lighting a matchstick. This method of igniting has never been very convenient for any welder.

2. Lift Arc TIG Ignition: 

In this aspect, the Tungsten electrode is just touched on the job to be done and pulled off immediately. The flow of current is very low in such a process and hence tungsten hardly sticks to the job. Welders have to be very careful because if the current flow is not minimised during the start-up, then sharpened points can get damaged and Tungsten can extremely stick to the job. This requires optimum level of attentiveness and accuracy.  

3. HF (High Frequency) TIG Ignition:

In the simplest words, the tungsten electrode is positioned (approximately two millimetre) near the applicable starting position of welding and the welder starts the arc ignition by simply pressing the torch trigger. The gap between the job and Electrode tip is ionized through high voltage once the torch is triggered. Making this ignition process short circuit free and creating ignition specifically at the desired starting point. 

To ensure super seamless welding and to subtract any contact between the job and the electrode, this process has been developed. And it has been the superior one until now. This method has been considered as the best welding practice.

We need HF in a TIG Welding machine because of the following benefits:

• HF creates a very soft start to the ignition and it’s a contactless ignition between Tungsten and the material. 

• It gives maximum level of control to the welder. As there is no need to lift or pull the tungsten electrode. Hence no fear of it sticking to the welding material.

• It adds to the pros that it uses a very low current arc.

• The quality of weld is always seamless and top notch.

• There is a very low level of wear and tear to the electrode because of contactless ignition.

• Since there is no contact with the job, even if the electrode is hot, the welder can reignite instantly. 

There’s also a variation in HF ignition known as “Touch HF”. In this Variation, the tungsten electrode comes in direct contact with the welding part, but ignites only after the pre-set pause time. The fundamentals of this process to ionize the contact gap at high temperature also remain the same as HF Ignition. 

There are certain advantages to TOUCH HF. 

Let’s look into them:

• The position of the welding torch can be determined and applied more precisely. Because after touch down as soon as the contact breaks, there’s no immediate ignition. Hence the welder has the time to steady the position and there’s no shaking of any kind.

• Where there is a requirement of precision ignition, this method can come in handy. As when the tip of the needle touches the job surface, it creates some roughness to the material. This makes it easier to point the needle in the exact same point before the ignition. Examples – welding narrow pipes.

• This process can be paused in between or before the start to reduce the heat input. 

Conclusion:

To get seamless and pure weld results, it’s always advisable to use HF TIG Ignition or Touch HF Ignition. In today’s article we learnt about the different types of ignitions and the best ways to yield the flawless results. Till now, HF TIG is known to be giving the most desirable welds. We would be glad to have feedback from our readers. It helps us to give better output every time, when we get connected to our viewers. Keep viewing and stay connected with us.