TIG welding (Tungsten Inert Gas) also called Gas tungsten arc welding (GTAW) uses a refractory electrode permitting the transfer of energy towards the workpiece - in the form of an electric arc created between the workpiece and the electrode. This energy melts the materials in order to join them.
How does a GTAW power source work?
A power source enables the user to program and control the parameters of the welding process. If you use a “manual” welding TIG power source, the main parameter will be the consistent amperage of energy and the regulated heat seatings in amperage of the welding energy. Both of which are defined prior to the beginning of the welding cycle and does not change during the cycle.
The energy is dependent on the type of current (constant, pulsed or not), of the arc voltage (distance between the electrode and the tube) and the travel speed of the electrode.
During the manual weld process, the distance between the electrode and the tube, varies according to the movement of the welder’s hand. The travel speed of the electrode is also determined by the welder.
Based on these considerations it is easy to understand that while using a manual welding processes, the energy transmitted to the workpiece is not consistent. The consistency depends on the welder’s dexterity – it is clear that the repeatability of the weld process is difficult to achieve. For the more demanding applications the weld energy must be controlled during the whole process.
Pulsed current can be used for manual welding. In this case the current is pulsed and oscillates between two value sets for the entire cycle. By using pulsed current the average volume of the weld pool is smaller and easier to manage.
GTAW power source: manual versus orbital welding: what’s the difference?
The orbital GTAW power source is designed to work with a welding head, which substitutes the hand of the welder.. But there are some important differences between the two. The orbital welding power source is equipped with a welding head, replacing the hand of the welder. This allows more welding parameters to be controlled compared to a manual welding power source.
- Welding speed: an electronic card controls the power for the motor as well as the speed control. The power sources can also be equipped with additional cards for the control of a wire feeder, the Arc Voltage Control (AVC) which regulates the distance between the electrode and the workpiece, and finally the oscillation which enables the lateral motion of the electrode for applications of beveled tubes with a high wall thickness.
- A more intelligent Man-Machine-Interface, for the control of the welding programs, enables an automatic adjustment of the energy transmitted to the workpiece according to the welding position of the electrode, during the welding.
- Most of the power sources are equipped with a digital control unit, used for the gas flow rate of the weld head, as well as the backgas.
- Data acquisition during the weld
- Some power sources have more complex electronic cards which can control nearly any kind of motor: direct current (DC), stepper motors, brushless motors, with or without coder, with or without tachymeter. AXXAIR generators can also control competitors welding heads.
Why use a GTAW power source?
Manual and orbital power sources are available with different electric power inputs that are generally defined by the maximum welding current (200A, 210A, 300A, 400A or more), as well as, the electrical voltage of 110V or 220V, in the “autoline” version (the power source recognizes automatically the electrical voltage between 110 V and 220 V), 380V or 440V.
The needed current depends on the welding application and in the case of orbital welding of the tubes’ and pipes’ wall thicknesses.
By using an orbital power source the welding current is completely controlled at any given second of the cycle. The only variant that might occur in case of welding without arc voltage control is dependent on the geometry of the workpiece. For this reason, we highly recommend the use of precise workpiece tolerances for tubes and fittings.
A perfect preparation before welding is just as important as the welding process itself, allowing perfect control of the welding energy and thus the repeatability of the process. In this way, orbital welds need less frequent controls as the repetitively rate is at 99 %, or more according to the application.
In short, an orbital power source facilitates control of the parameters and offers a more consistent repeat welds. By using this kind of power source, you have a perfect traceability of your welding process, which is mandatory for certain industry applications.
Download our catalogue to find out more about our orbital GTAW power sources.