Straight welds or circular welds are relatively easy to program. But when a weld has curvature, programming starts becoming more difficult. And harder it becomes when a curve radius is changing constantly and not just relative to one surface but might be double-curved.
Parts like body frames of Sport Utility Vehicles (SUV) include a lot of curved and double curved welds. The welds are also located in such way that collision risk is obvious and the welds are hard to reach.
A modern offline programming software takes the full advantage of the topology of a CAD part and can solve how to create welding program for splines and curves.
Heikki Aalto, 05.04.2015