Design for Manufacturing Series: Joining Processes 1

Welcome back to the Design for Manufacturing series! So far, we have covered subtractive and additive processes, which is a good start, but these only scratch the surface of the possible ways you can fabricate your design. In this third installment, we will focus on joining processes, which include technologies such as welding, brazing, and soldering. Because of the vast differences between the various types of joining processes, this article will concentrate specifically on welding. In the future, the Design for Manufacturing series will cover other joining processes in more detail.

Stock image of a welder in a welding mask

History of Welding Processes

Welding is the process of joining two or more parts through heat, pressure, or both. The earliest forms of welding can be traced all the way back to the Bronze Age, where pressure and heat were applied to soft metals to join them together. Later, in the middle ages, blacksmiths developed forge welding, which involved heating metal pieces in a forge and hammering them together. The beginning of modern welding started in 1836 with the discovery of acetylene by Chemist Edmund Davy. In 1881, Auguste De Meritens and Nikolai Bernardos both patented the process for carbon arc welding.

Welding patents from Benardos (left) and Coffin (right) [1]

Nine years later, Nikolay Gavrilovich Slvyanov had the idea to transfer melted metal via an arc. However, that same year, Charles L. Coffin patented the actual arc welding process, known as shielded metal arc welding. From this point, the use of welding grew exponentially from decade to decade. New processes, materials, and applications continually emerged throughout the last 135 years, which has led to a massive network of professional and amateur welders that drives innovation and production world-wide. [2]

Robotic welders in an automobile factory [3]

General Applications

There are so many different types of welding used today. The four most popular are Gas Metal Arc Welding (GMAW or MIG), Gas Tungsten Arc Welding (GTAW or TIG), Shielded Metal Arc Welding (SMAW or Stick), and Friction Stir Welding. GMAW is most often used to join sheets of metal together (even dissimilar ones), such as in automotive and marine vehicles and in pressure vessels. GMAW is also easier to pick up than other welding methods, so successful GMAW welds can be found even in hobbyist welding. GTAW, on the other hand, is much more complicated and requires more training than GMAW. GTAW is most often found in the Aerospace and Automotive industries because of the strength of welds it can produce. Stick welding (SMAW) is one of the more versatile forms of welding because it can be performed in more extreme environments, including wind and rain, which can affect the gas in the previous two types of welding. Stick welding is also the most portable type of welding, since it only requires electricity to function and not gas like GMAW and GTAW. [4] Friction Stir Welding (FSW) is the most industrial application on this list, requiring the most equipment and space to be successful. Friction stir welding is also the quickest and easiest to automate, making it found in large assembly lines, fabricating huge products. [5]

Images clockwise from top left: GTAW, GMAW, SMAW, FSW. Due to the design-centric nature of this article, the specifics of each of these processes cannot be further explained. To learn more, please visit the respective links in the image description.

Design Considerations

The first consideration a designer should make when choosing a joining process, particularly welding, is whether or not the joint must be permanent. A non-permanent joint can be made with adhesives or mechanical fasteners, which are cheaper and easier to implement into a design than welded joints. A permanent joint is necessary when it must withstand high stress and loads over a long period of time. Welding is a costly process in time, money, and expertise. If the capabilities readily available to you do not include welding equipment, your design experience would be better off focusing more on temporary joining processes.

A mechanical vs a welded joint [6]

After determining whether or not you should use welding, the next consideration is joint geometry and location. Because welding involves manually (i.e. with a welder’s own hands) directing energy through a wire or electrode, geometry is an incredibly critical design feature. Any geometry that is not wide enough to allow the welding tool to reach the joint location renders welding useless. Welding tools that hold the electrodes usually have a diameter larger than an inch. The tools also have unwieldy wires and handles that can cause issues when trying to maneuver around the joint geometry. You should also consider the technicians that will be assembling your part and design the geometry for them to complete the welds in the easiest way possible.

Any welds that need to be performed on the bottom side of the pipe with the red circle will be extremely difficult, due to the lack of clearance between the pipe and the ground. Though this image is regarding the repair of the depicted pipe, the concept still applies. [7]

One final consideration for a weld designer is deformation prevention. Welding involves directing immense amounts of heat (you have to melt material to fuse it together, of course) into two pieces of metal, which can warp the metal if you are not careful. Most warping prevention methods are accomplished while welding, but there are a few that can be implemented during design. First, you should ″anticipate the shrinkage forces″ and design the joint so that as you weld, the heat causes the work pieces to warp into the correct place. Second, you can design the joint to need as few welding passes as possible. This means to design a small seam and minimal changes in thickness between the two pieces of the joint. And third, you can design the joint so it only needs to be tacked down in a few locations (called intermittent welding). [8]

Image depicting different methods of presetting joints [8]

Conclusion

Joining processes and welding are an incredibly valuable component of the manufacturing world. Many industries’ modern production capabilities are only possible through welding. In this entry to the Design for Manufacturing series of articles, I have presented three considerations to make when you are designing for a joining process. First, you need to consider the permanence of your joint. Second, you need to consider the geometry and location of the joint. And third, you need to consider how to prevent deformation through design. Welding is a vital component of most industries and has been used for decades to improve the world. As designers, we can take our designs to the next level if we use these considerations to create successful joined parts.

Sources

[1] https://www.researchgate.net/figure/Patents-of-Benardos-left-and-Coffin-right_fig2_313530479

[2] https://www.uti.edu/blog/welding/welding-history-goes-back-farther-than-you-think

[3] https://interestingengineering.com/lists/types-of-welding-their-applications-advantages-and-disadvantages

[4] https://autoprotoway.com/automotive-welding/

[5] https://bondtechnologies.net/applications/friction-stir-welding-applications/

[6] https://www.youtube.com/watch?v=nIz_R0qhUUo

[7] https://weldingweb.com/vbb/threads/716707-How-Should-I-Go-About-This-Pipe-Repair

[8] https://axisfab.com/weld-shrinkage/

To cite this article:

Cousins, Andrew. “Design for Manufacturing Series: Joining Processes 1.” The BYU Design Review, 17 Feb. 2025, https://www.designreview.byu.edu/collections/design-for-manufacturing-series-joining-processes-1.