Welding Arc Initiation Methods

Welding: Scratch Start, High-Frequency Start, Tap Start, and Lift Start

Welding is an essential skill in various industries, including construction, automotive, and manufacturing. There are several methods to initiate the welding arc, including scratch start, high-frequency start, tap start, and lift start. In this article, we will discuss these methods and their applications.

Scratch Start

Scratch start is the most basic and rudimentary method used in low-cost inverter welders. The tungsten electrode is scratched on the job to initiate the arc. This process requires lifting the electrode off the job quickly to prevent sticking but not too far to avoid extinguishing the arc. While scratch start machines can be advertised as TIG (or stick/TIG), it is not suitable for TIG use. This method is not user-friendly and can be challenging to master, as the electrode may stick to the job, requiring re-sharpening.

High-Frequency Start

High-frequency start, also known as HF start, allows the operator to position the tungsten electrode near the job and simply press the torch trigger to start the arc. This method is typically found on professional TIG welding machines with AC/DC function, such as the Weldclass 201T or 202T. HF start is a touchless method and is the only true touchless TIG welding technique. It is suitable for applications where any contamination of the weld puddle would result in a structural defect, such as aluminum pipe work.

Tap Start

Tap start is a method where the welder touches the electrode to the workpiece and then taps the workpiece with the torch to initiate the arc. This method is commonly found on entry-level machines and can be smoother than scratch start, but it may not be as user-friendly or controllable as lift start.

Lift Start

Lift start is a popular and user-friendly method. To start the arc, the tungsten electrode is touched on the job and lifted off. The start-up current is very low, and the tungsten barely sticks to the job, minimizing damage to the sharpened point. The machine senses that the contact is broken and begins supplying full welding current. Lift start is very controllable, but manufacturers must carefully calibrate the electronic processes to achieve good results.

Choosing the Right Method

When choosing a TIG welding machine, understanding the arc initiation method is crucial. Scratch start is not user-friendly and can be frustrating for beginners. Lift start is smooth and controllable, while high-frequency start is touchless and suitable for sensitive applications. Tap start is a less common method found on entry-level machines.

In conclusion, understanding the different arc initiation methods in welding can help you choose the best method for your specific application. Whether you need a basic, user-friendly method or a more advanced touchless method, there is a welding technique that suits your needs.