Mining the Welding World for Information

Gathering Pointers from some Welders on Welding and Weld Fixture Design

If you are serious about learning about weld fixture design, talk with welders.  Visit a shop where welding is happening.  Skim a book on welding and become familiar with the language, the terms, the issues.  You don’t need to be an expert welder to design good weld fixtures, but it helps to understand the issues that welders face, from ergonomics to metal distortion.

A good source of ongoing discussion on welding issues is on some of the Linkedin.com groups about welding, like the Welding Engineering Network.  Below or just a couple pointers that were posted recently.

From Thomas Regarding Clamping in Weld Fixtures:

“Some care needs to be exercised in the use of clamping when welding thin materials. Too much restraint can produce more distortion than no clamping at all. See Mollicone, Camilleri and Gray, 2008,

Procedural influences on non-linear distortions in welded thin-plate fabrication, Thin-Walled Structures, 46, 7-9, pp 1021-1034, Elsevier. The problem, in a few words, is that, if the fabrication is free to move out-of-plane, much of the local movement which takes place as the heat source passes is recovered afterwards, without too much plastic deformation.

If it is severely restrained, this can force plastic deformation and store up elastic stress. This is released when the clamps are released and the structure distorts.”

On Distortion during welding 2m x 3m Mild Steel Sheet Metal. 

Lots of unknowns in the question, such as what it is being welded to, but there were several pointers from welding experts.

From Brandon:

“Assuming they are using GMAW the best solution may be using intermittent welds and alternating the side you are welding on to balance out the heat input.”

From Donald:

“…Also if possible make good tack welds to the inside of the structure, frames, gussets, or what ever you are using for support. stitch welding the inside to the support members prior to welding the exterior seams will also reduce distortion….”

And

“Always clamp work pieces if possible. We have also used a Back bow technique in some of our weldments where we knew distortion was going to control. By placing shim stock under the center of the piece and gradually back bending it to a table with clamps prior to welding….”

And

“Another process that will dramatically reduce distortion is Pulsed Welding, Pulsed Welding can be performed with both the MIG (GMAW-P) welding process and TiG (GTAW-P) as well. ….

Your operators will need to practice with the process on comparable scrap metals but it is a relative easy process to master for experienced skilled welders…

For the MIg welding process, .030 to .035 diameter er70-s6 wire would be recommended, with shielding gas 75/25 Argon/C02 at 30 – 35 CFM. Any other shielding gas with greater Argon Content will create a hotter weld and increase distortion.”

Keep learning!

‘Til next time,

The Queen of Lean Machine Design