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Understanding TIG Welding: How Low Open Circuit Voltage Starts the Arc
Understanding TIG Welding: How Low Open Circuit Voltage Starts the Arc
Are you curious about how a TIG (Tungsten Inert Gas) welder initiates an arc using low open circuit voltage? This article will explore the ins and outs of the process, providing a comprehensive understanding of this aspect of TIG welding.
Introduction to TIG Welding
First, it's important to understand what TIG welding is. TIG welding is a manual arc welding process that uses a non-consumable tungsten electrode to produce the weld. A shielding gas (typically argon or a mixture of argon and helium) is used to protect the weld area from atmospheric contamination.
How TIG Welding Works
TIG welding operates on the principle of an electric arc between the tungsten electrode and the workpiece. The arc is generated when an electric current passes between these two points, melting both the tungsten electrode and the base metal to form a weld.
Open Circuit Voltage vs. Arc Initiation Voltage
One key aspect of TIG welding is understanding the difference between the open circuit voltage (OCV) and the arc initiation voltage. The open circuit voltage is the constant supply voltage set by the welder before any current flows. It is kept constant but does not necessarily facilitate arc formation alone. Instead, it is the arc initiation voltage that is crucial for starting the arc.
In TIG welding, the arc initiation is initiated through a “touch start” method. This method involves first touching the tungsten electrode to the workpiece, allowing a low voltage and low current to flow, and then quickly pulling the electrode away. This initial contact creates the necessary conditions for the arc to form and sustain itself.
Low Open Circuit Voltage and Arc Initiation
The term "low open circuit voltage" refers to the voltage maintained by the welder in its no-load state. While the OCV is necessary to sustain the arc once initiated, the actual starting of the arc requires lower voltages. This is because the arc formation process is a complex interaction of electrical, thermal, and physical forces.
Arc initiation voltage, which is typically much lower than the OCV, is the voltage at which the electric arc can be first started between the tungsten electrode and the workpiece. This low voltage is sufficient to ionize the gas in the gap between the tungsten electrode and the workpiece, allowing the current to flow and initiate the arc.
The Touch Start Method: Initiating the Arc
The “touch start” method is a technique used in TIG welding to initiate the arc:
Position the Tungsten Electrode: Put the tungsten electrode in contact with the surface of the workpiece. This is the crucial step where the low open circuit voltage is utilized. Contact Duration: Keep the tungsten electrode in contact with the workpiece for an extremely brief duration, typically just a few milliseconds. The low voltage and current ensure that the tungsten electrode does not melt or damage the workpiece. Pull-Away: Quickly pull the tungsten electrode away from the workpiece just after contact. This action disrupts the ionized gas path, allowing the electric arc to be sustained and maintained.It is important to note that the exact duration of the contact and the required voltage levels can vary depending on the specific setup, electrode material, and material being welded.
Conclusion: A Comprehensive Understanding of TIG Welding Initiations
Understanding the role of low open circuit voltage in initiating an arc in TIG welding is essential for mastering the technique. By utilizing the “touch start” method, welders can effectively initiate an arc with minimal equipment strain and without risking damage to the tungsten electrode or the workpiece.
Now you have a clear understanding of how TIG welding initiates an arc, and you can appreciate the intricacies of this manual process. Whether you're an experienced welder or a novice, knowing the principles behind arc initiation can enhance your skills and improve your welding outcomes.