By -
Date 07-18-2001 18:42
Ouch - Why do I feel like I asked a moronic question?
Just to clarify:
In my experience, the "slang" term "stitch welding" is applied to:
1) Intermittent welding as you describe it.
2) "Back step" welding to reduce distortion.
3) A low heat input welding technique used when welding some cast irons. (Random welding)
As I now also understand what you mean, my next question becomes relevant. Why are you stitch welding? I understand that the drawing may ask for it, but why did the designer ask for it on the drawing? Often it is merely a means of reducing welding costs, when full length welds are not required. Often it is of primary importance to reduce distortion of the weldment by balancing the welding around the neutral axis, or to maintain some sort of a "root gap" in the joint. If for some or other reason you need to maintain a 1mm gap in the root of the weld, then starting on one side and "just going" will pull this gap closed. By doing "space welding" (The South African slang term.) and choosing your welding sequence correctly, you will minimize this problem.
If distortion is not a problem, then it does not matter where you begin and end. Make sure how long the welded portions must be and the unwelded portion, mark this out and "let the welder experience freedom of expression". (No, South African welders are not frustrated artists, I am just feeling a bit dramatic this evening.)
If distortion is the issue, then as Prof. Crisi indicated, it must be handled on a job by job basis. It would be very difficult to really comment in this case, unless you VERY CLEARLY describe your particular situation.
Hope this helps
Regards
Niekie Jooste