Welding is an extremely important part of metal fabrication. Without it we’d be stuck using rivets, screws, and bolts, and every joint would probably leak and deform. However, while the mainstream arc welding processes can handle 90% or more of what’s needed, there are niche situations where engineers want welds that are, or have been, impossible to make.
To address these, welding experts and researchers continue to develop innovative new welding processes. In this blog we’ll look at six advanced welding processes, explaining what each one is and why and when you might want to use it. First though, a refresher on the strengths and limitations of mainstream welding technology.
The Widely-Used Welding Processes
In common with most metal fabrication shops, the majority of the welding our AWS-certified welders do is gas-metal arc (GMAW), and in particular, metal inert gas (MIG) rather than tungsten inert gas (TIG). We also do a certain amount of resistance or spot welding, although that is restricted to overlapping sheet metal where the electrodes can access both sides.
GMAW involves striking an electric arc between the workpieces and a welding torch and letting the heat of this form a puddle of molten metal called the weld pool. Usually, we’ll feed in some filler metal to increase the volume of this pool, and that’s where the differences between MIG and TIG arise.
In MIG the electrode doubles as the filler metal and is consumed in the process. In TIG filler wire is added separately. TIG is good for thin materials and where high precision is needed. Most welded fabrications though are served just fine by MIG.
GMAW Strengths and Limitations
Arc welding does a good job of joining metals with similar properties, providing they aren’t too thick to get deep penetration, or so thin that they melt before a weld pool forms. Where these welding processes struggle is with dissimilar metals, especially those with different melting points, and with welding very thick and very thin material. They are also unable to weld over a wide area and are just used for linear and point welds. In addition, it’s hard to focus them down to very small regions.
What we’d all like, as a way of overcoming these problems, are welding processes that work faster while putting less heat into the workpieces and at the same time, can handle thick, thin, and dissimilar materials. So this is where the newer and less widely used welding processes come into play.
Six Advanced Welding Processes
The processes we’ll cover here are:
- Magnetic arc
- Friction/Friction stir welding
- Explosive
- Ultrasonic
- Laser
- Electron beam
There are almost certainly others being explored in research labs, but the ones listed above are those that are actually being used, (including some by us!)
Magnetic arc
This welding process uses a magnetic field to rotate the arc as it heats the workpieces. The process begins with these being clamped together, and they are separated slightly as heat builds. Once hot enough, the two edges are pushed firmly together to make the weld.
Advantages of magnetic arc welding are that it doesn’t need a filler, the weld is made quickly, and there’s lots of control available over the welding parameters. The main application is in welding tubular materials no more than 7/16” thick.
Friction/Friction stir welding
Rub two surfaces together and they’ll get hot. Keep rubbing and their temperature will rise to a point where they’ll fuse together.
This is the basis of all friction welding processes. One of the most common methods is to rotate two cylindrical pieces in opposite directions in a machine like a lathe and bring them together under pressure.
A newer variant is friction stir welding (FSW). In this process, a rotating tool is pushed into the interface between two pieces of material. It’s then moved along the length of the join, stirring the two pieces together.
Friction welding processes can provide deep penetration and join dissimilar materials. They result in high-quality, defect-free welds.
Explosive
This process is used to clad one material – the substrate – with another. The materials are positioned one on the other, and a small explosion set off above them. Heat and pressure together result in fusion.
Ultrasonic
This could be considered a form of friction welding. It uses ultrasound to create microscopic levels of movement between two materials, with the resulting heat fusing them together. Ultrasonic welding is primarily used to join plastics, although usage with thin, lightweight metals is rising. It can join dissimilar metals, within a limited range of melting points.
Laser
Lasers can generate intense heat and are often used in laser-cutting processes like sign-making. That same heat can also be used like an electric arc to create a weld pool that joins two pieces of metal. We use laser welding in many metal fabrication projects and have a number of such systems. Laser welding works quickly and is suitable for robotic automation. It’s good for minimizing heat input and making very small welds.
Electron beam
This uses a device very similar to the cathode ray system used in old TVs to create heat by firing high energy electrons into the materials. The resulting welds are very high quality.
Electron beam welding equipment is hugely expensive, not least because it’s best done in a vacuum. Its niche is welds that need extremely deep penetration, where it’s many times faster than arc welding.
Welding Processes for All Your Metal Fabrication Needs
The overwhelming majority of fabrication work we take on needs some kind of welding. Most of it our AWS-certified welders do to a very high standard using MIG welding, but for specific applications, we also have TIG, resistance, and laser welding capabilities.
In the very rare circumstances that a customer has designed something that can’t be welded, we’ll work with them on some changes to make it weldable. And if that’s not possible we can always look at the welding processes discussed above.
At Wiley, we’ve been in the metal fabrication business four decades and counting and there’s little we haven’t seen and been asked to do. Whatever your next project looks like or what you need to make, we can almost certainly handle it. Contact us for a quote or to discuss your specific requirements.