Metal fabrication specialists often face a challenge when working with thin sheets of metal that have a reduced degree of stiffness. A thinner (and less stiff) metal sheet has a reduced structural strength. This makes it easier for the metal sheet to suffer distortion (often in the form of warping) after the welding process.
There are various ways to reduce the likelihood of distortion when welding thin sheets of metal. Here are three ways to go about this for the apprentice welder.
Alter The Welding Sequence
The distortion of thin sheets of metal during the welding process often occurs due to the shrinkage of sheet metal. Unfortunately, there is no fool-proof way for a welder to prevent such shrinkage. The best that the welder can do is to ensure that this shrinkage occurs uniformly as the metal is welded.
In order to ensure uniform shrinkage, apprentice welders are advised to have an alternating welding sequence. An alternating sequence means that sheet metal is introduced at different points of the weld assembly. Therefore, any shrinkage that may occur along the sheet metal offsets shrinkage that may have occurred in previously-made welds. This often translates to greater uniformity in the shrinkage of sheet metal during the welding process, thereby limiting the chances of distortion.
Reduce The Number Of Weld Passes
Passes are single progressions that form along welded joints. Apprentice welders are often free to increase and/or reduce the number of weld passes used during sheet metal fabrication so as to meet the design specifications required for the welded metal.
However, it's important for welders to remember that the shrinkage forces that cause weld distortion are transmitted from one weld pass to the other. As such, increasing the number of passes used during the welding process increases the occurrence of shrinkage forces, which in turn increases the chances of distortion on fabricated sheet metal.
For this reason, welders are often advised to use bigger weld passes in a bid to reduce the number of passes required for the fabrication of sheet metal.
Jig It Down
Finally, apprentice welders can keep distortion at bay by using a jig or a similar clamping fixture to provide a firm hold on the metal to be fabricated. The firm hold helps to prevent unwarranted movement of the metal during the welding process, thereby reducing the likelihood of distortion. Using a jig is a relatively inexpensive option for those keen on controlling distortion during the welding process.