This fourth installment in our multi-part series exploring micro pulse arc welding (micro TIG welding) focuses on “Touch Start” technology, which requires much lower voltage than the standard DC start system. Low voltage operation means no high frequency noise emission.
With the Touch Start system in place, the user applies initial current while the electrode is touching the workpiece. The torch is then moved up, which generates a high electric field between the electrode and the workpiece, causing breakdown and generating the arc. The close proximity of the electrode to the workpiece in this Touch Start process allows the arc to be created at lower than normal voltage. The diagram provides a generalized illustration of how the Touch Start feature works.
The two key advantages to this system are a) low noise eliminates the possibility of damage to electrical devices near the unit and b) the ability to indicate and control the exact welding location. Touch Start also avoids firing of a start arc, which may damage very small parts even before the welding arc fires.
For example, the diagram shows a waveform comparison by arc generation mechanism. With Touch Start (left diagram), there is little noise at the time of start. The high-voltage start, on the other hand (right diagram) generates a noise of a few microsecond duration due to the 10 kilovolt (kV) trigger voltage at the time of start.
Other advantages are listed in the table below, which compares the Touch start feature to other standard high-voltage start systems from the point of view of noise generation, arc discharge, takt time (defined as the measure time, or the average time between the start of production of one unit and next), and difficulty of positioning.
For more information on improving your MicroTIG pulse arc welding results, visit our previous blogs: