Reggae music has never been big here in Indiana, (it probably has something to do with the climate,) but a couple of songs are dear to our hearts. One is Johnny Nash’s 1972 hit, “There are more questions than answers.” This resonates with us because, when selecting a welding process we invariably ask a lot of them.
Is a new welding technology required?
Probably 80 to 90% of the welding jobs we take on are straightforward MIG applications. The balance cause some serious head-scratching. Sometimes the materials are dissimilar, perhaps there are particular quality requirements, or maybe we just need to minimize distortion, (something we’ve addressed in some recent Tiki Talk posts.)
Challenges like these get us wondering if we should be using one of or more of the advanced welding processes also discussed recently. If you missed that post, the list included:
- Magnetic arc
- Electron beam
When we get a challenging welding job we ask questions to help us choose the right welding technology. Actually we ask a lot of questions, but we can group them under three headings. So here are what we consider three important questions to ask when considering advanced welding processes.
- What’s important in this weld or fabrication?
- What materials are to be welded?
- What conditions must the weld process accommodate?
We’ll go through each, but be warned, we will ask a lot more questions.
What’s important in this weld or fabrication?
Is the priority just getting it made quickly? And how about minimizing spatter and clean-up? If this is the case, magnetic arc might be the right welding technology.
What about minimizing distortion in the fabrication, (which means putting less heat into the weld)? Magnetic arc helps with that too, but laser, or for small parts, ultrasonic, welding might also be appropriate.
Is quality a concern, in terms of the weld needing formal NDE evaluation? Aerospace or nuclear applications would be good examples. Laser welding produces high quality results, although electron beam welding might be even better.
What materials are to be welded?
Are we joining dissimilar materials? Low-carbon steel to stainless for example, or steel to aluminum? If this is the case, solid-state welding processes like friction, ultrasonic or even explosive may be good options.
Is the material in tube form, bar, sheet or plate or is it a casting or forging? Friction welding can a good choice for those last two.
What conditions must the weld process accommodate?
Here we’re considering the quantity required and the variation in the pieces to be welded. To start with, is this a one-off job, high volume or somewhere in between? Solid state processes often need some development to optimize process conditions, and may also need tooling for part location and presentation. This makes them more suited to higher volume jobs.
How much dimensional variability will there be in the pieces being welded, and how much variation should be expected in the fit-up? If the answer is, “a lot,” the improved arc control of magnetic welding will help the welder adapt.
Will all the pieces be uniformly clean and prepped, or might some be rusty or oily? How much will the actual materials vary? (Two pieces of allegedly identical steel from different batches can differ in composition by a surprising amount.) The solid state processes do a better job of handling surface contamination and variation in composition as they’re more mechanical than fusion-based.
Advanced welding processes for difficult welding challenges
It’s rarely obvious which process is best for any given application. That’s why, when presented with a difficult welding job, we’ll ask a lot of questions before striking an arc. And when we’re done we’ll lift the welding visor and say, “I can see clearly now.” (That’s another Johnny Nash song, in case you’re wondering about the connection.)