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SPT or Speedtack: what is it all about?

All Freetech Processor-controlled Tig welding machines are equipped with the Speedtack or SPT function.


Workpieces become very hot during welding. Metal has the property of expanding when exposed to heat. However, this expansion is not uniform because the temperature of the workpiece around the arc will be higher than at the edge of the workpiece. This provides different degrees of expansion and a plate that, for example, starts to wave.

If two plates are to be welded, then these will deform and move away from each other, making it almost impossible to weld.

The solution is to first tack the material with an arc that brings as little heat as possible into the workpiece. The SPT takes care of this! It is an extremely short arc with a variable pulse. This pulse makes small waves in the puddle that collide, causing the material to flow.

Because no material is added during tacking, this tack weld will no longer be visible after finishing the final weld seem.