Abstract Scope |
Welding procedures can be designed resulting in large savings of time and money. Currently, procedure parameters are determined by previous experience or trial and error, and their suitability is determined by codes and standards. Welding engineering is different to many other engineering disciplines, in which the distinguishing role of the engineer is their responsibility of design. In welding, the term “weld design” is restricted to the engineering design of a welded joint subject to loads, but says little of how those joints need to be made. When it comes to welding procedures, welding engineers’ activities are closer to those of a scientist, or an engineering technologist.
The current approach to procedure development seldom makes significant use of the knowledge of welding science developed during the last 100 years. This makes sense because trial and error in welding is relatively cheap, while the laws of nature involved are many and diverse. Also, the vast majority of welding is performed in steel, with little incentive to generalize the learnings. Procedures for other common materials systems, such as aluminum are developed around specific knowledge, with little transfer of knowledge between material systems. One shortcoming of this approach is that new materials or welding processes require building a repository of knowledge almost from scratch.
Additive manufacturing is likely to have a radical influence on welding. Both welding and additive manufacturing share the same fundamental principle of moving heat source, almost always also involving melting. People versed on welding often see additive manufacturing as a particular case of welding; however, it might well be that welding is a particular case of additive manufacturing, and that the different way of thinking of additive manufacturing will be of good help to welding.
An obvious difference between additive manufacturing and welding is that the bead size is often of the order of magnitude of the component being made. Also, the “interpass temperature” is more difficult to control, and can grow to levels seldom seen in welding. Automation, sensing, and control are an intrinsic part of additive manufacturing, while for welding they are often not essential.
A less obvious difference is that while a welding operation might exist for its whole life welding steel, in additive manufacturing, the expectation is that the selection of materials is much broader. This expectation is closer to machining operations than to welding.
Because of the needs to deal with a diverse range of materials, more complex heat transfer, and the need for sensing, control, and automation, the additive manufacturing community is active in finding an engineering approach to determine procedure parameters and to predict system behavior based on the physical phenomena involved.
Much of the knowledge needed for additive manufacturing of metals has already been developed for welding, but not generalized. As the additive manufacturing community uses existing welding knowledge to develop an engineering approach, much of this engineering is likely to come back into welding in the form of a different philosophy in which understanding, sensing, and control are expected; and based on the experience of additive manufacturing, can also be delivered.
Even in the long term, metals are expected to be essential to technological progress, and welding, with its atomic-level rapprochement provides as good a joint as science allows. The sources of heat of the future might not be too dissimilar of those known today. The look of future welding equipment might be, however, radically different as automation develops. Manual welding might become something as uncommon as live music, while automated welding might become as ubiquitous as recorded music.
In this talk, current efforts to bring an engineering approach to procedures will be described, including the analysis of heat transfer, residual stresses, and deposition rate. |