Ive been doing an evening class the local college with a view to learning MIG, stick and TIG. Something which has puzzled me recently is the polarity on stick welders. Some rod type (low hydrogen ?) require the rod to be -ve and others the rods must be +ve. A couple of times Ive made the mistake of setting up the set with the wrong ploarity and struggled to get a decent weld.
This thing is I dont understand why. How can the direction of the current flow make a difference to weld temperature and pentration ?. The current flow is identical independant of direction and surely the heat generated would therefore be the same. The explained that the rod was a restriction and if current flowed from the workpiece to the rod it (ie +ve earth) then it didnt see the rod as a restriction (he used a water analogy). This didnt make sense to me as the current throughout the circuit is the same regardless of direction so the rod always presents the same restriction.
Can anyone throw any light on this ?
This thing is I dont understand why. How can the direction of the current flow make a difference to weld temperature and pentration ?. The current flow is identical independant of direction and surely the heat generated would therefore be the same. The explained that the rod was a restriction and if current flowed from the workpiece to the rod it (ie +ve earth) then it didnt see the rod as a restriction (he used a water analogy). This didnt make sense to me as the current throughout the circuit is the same regardless of direction so the rod always presents the same restriction.
Can anyone throw any light on this ?