Flame Straightening with LINDOFLAMM Burners

Correcting Distortions in Metal Parts with an Oxy-acetylene Flame

Welding and other manufacturing processes where significant heat is applied can leave stresses within the workpiece. During the subsequent cooling phase, distortions may develop. The process of flame straightening was developed to overcome distortion created by the heating and cooling cycles of welding and cutting processes or resulting from rolling or other forming processes. Flame straightening is an efficient, well-established method of correcting the weld distortion without impairing the material. An oxy-acetylene flame is the most effective way to rapidly heat a well-defined section of the workpiece and remove these deformations.

Flame straightening is widely used on carbon steel plates in shipbuilding and ship repair yards, large steel fabricators and profile cutters. It is ideally suited to mild steel and carbon steels, but is also widely applied to stainless steel, aluminum, titanium, nickel alloys and copper.

What is the Plastic Deformation Mechanism?

The flame straightening process is based on the physical principle that metals expand when heated and contract when cooled. When heat is applied to a metal, the cold areas surrounding the heat-affected zone (HAZ) restrict expansion, causing upset in the heated zone. These stresses eventually cause the weakest part of the bar or plate, the hottest part, to reach the plastic state and distort. During cooling, the workpiece is shortened (shrinks) around the deformed portion, leading to the desired change in length or shape. This is called the plastic deformation mechanism. The yield limit of the material, which is slightly above the elastic limit, must be reached to achieve plastic deformation, and this controlled deformation process is then irreversible. The target flame straightening temperature required to achieve the plastic deformation effect varies from one material to another.

These stresses created through flame straightening can be used to stiffen component sections, to reduce dimensional deviations, and to produce permanent dimensional changes. 

End-to-end Offering

Widely recognized as a process and application innovator for flame straightening, we support our special LINDOFLAMM burners with a range of complementary services. This includes advice and help - covering everything from adaptation of the burner to your individual flame straightening challenge to more general parameters like the setup of your gas supply system.