Four Methods for Controlling Welding Deformation

Four Methods for Controlling Welding Deformation

First is the welding sequence. Techniques such as symmetrical welding, back-step welding, and welding from the center outwards all aim to distribute heat evenly and prevent localized, concentrated shrinkage. Long welds must be executed using a segmented, skip-welding approach; welding a 500mm seam in a single continuous pass generates enough shrinkage to deform the entire frame.

Second is the use of jigs and fixtures. Positioning and rigid clamping are the most effective measures; fixtures also act as heat sinks, significantly reducing the heat-affected zone. Jigs are essential for batch production; relying on manual holding makes consistency impossible to achieve. The cost of tooling is typically recouped through savings in rework and correction labor within just a few hundred units.

Third is pre-deformation (or "reverse deformation"). This involves intentionally introducing a counter-deformation before welding so the part returns to the correct shape afterward. There is no universal formula for this; it relies on accumulated structural experience and varies greatly between parts. Our practice is to measure the first article and then incorporate the necessary compensation directly into the fixture design.

Fourth is controlling heat input. Whenever possible, opt for low-current, multi-layer, multi-pass welding rather than high-current, single-pass welding. Pulse welding can lower the average heat input, while minimizing groove angles and assembly gaps reduces the amount of filler material required, thereby limiting shrinkage.