Welding, soldering, and brazing – just like riveting – should be in every metalworker’s arsenal. Whether you need to put a stringer on a lap joint to hold a trailer hitch at a forty-five, or need a motherboard to hold a diode in the right spot, each method has its application.
Here, first, we’ll take a look at three different welding types, two common forms of soldering, and three types of brazing. Then we will take a look at their differences, and finally, we will examine when each of them is appropriate to use.
Welding, Soldering, and Brazing: The Basics
No matter which process you are using, welding, soldering, and brazing all involve heat. They involve varying temperature ranges and methods of reaching higher temperatures, but in essence, they are very similar processes.
Brazing is generally done with some form of direct heat like a torch or some kind of flame and filler metal. The filler metal is melted into a slot or hole and then filled. Once cooled, the metal forms a type of weld.
Soldering is performed by using an electric current, passed through a soldering gun, that creates an arc between the top and the tin filler metal. The filler metal is again superheated to fill a gap or attach two similar material pieces together.
Brazing is a much older technique that is much more large scale and involves the same process of heating a filler metal to join two or more pieces.
Now, let’s look at each of the three in a bit more detail.
What Is Welding?
Welding is defined as the joining of two or more parts together as one by means of heat and/or pressure. It has been around for two thousand years in its basic form of two pieces of iron being joined.
More modern arc welding was developed in roughly 1881 by August De Mertens who used a rapidly moving arc to create heat and join two plates. His student, Nikolai Benardos, used an electric arc with carbon rods. The three main types are stick (SMAW), MIG (GMAW), and Tig (GTAW). Shielded metal arc welding, gas metal arc welding, and gas tungsten arc welding respectively.
What Is Soldering?
Soldering does melt the workpieces the way welding does. In 1921, l invented soldering and mass-produced the first electric soldering iron. The process is generally used for the joining of electronic components.
The filler metal has a much lower melting point than the adjoining metal in the gap it’s being applied to. The old soldering filler metal used to contain lead which is, obviously, bad for health and the environment.
Modern solder is usually comprised of tin and silver. Other materials are sometimes used as well.
What Is Brazing?
Brazing is close to soldering in that it uses a filler metal and doesn’t melt the surrounding material. The filler material, however, has a much higher boiling point than the material being joined.
The history of brazing is a complete guess as many cultures around the world had different methods for joining metals and braising seems to be one of the first. Five thousand-year-old Sumerian swords have been uncovered in the past that showed the pommel and hilt of the sword being joined by heat.
Torch brazing is the most common method and consists of using an acetylene torch and a filler rod. Brazing with skill is an art form of its own and is sought after for brass work and machine work especially.
Welding Vs. Soldering Vs. Brazing: What Are The Differences?
Let’s take a look at the major differences between the three metal joining processes.
Temperature & Equipment
The most involved is welding. Doing welding subjects you to heat in the range of 3,000 to 20,000 degrees Celsius. There is also intense UV radiation. A special helmet, set of gloves, cap to prevent scalp burning and a leather jacket are all standard fare.
For soldering, the tip of the gun is generally in the range of 330 to 350 degrees Celsius. Wire cutters, eye protection, solder, and a soldering gun are really all that’s needed.
For brazing, the temperature ranges between 426 and 1426 degrees Celsius. Eye protection, gloves, and a jacket, in addition to the acetylene torch and desired filler metal, are what you need to get started.
Cost & Set-Up Time
The cost to buy a welding rig, gases required by many types of welding, protective gear, and the filler metal (usually electrodes) is substantially greater than that of soldering.
As for brazing, the only truly expensive part is the required gas. The filler material isn’t very expensive unless you get into more exotic alloys and metals.
The setup time, once you have your work area established, is very similar between the three metal joining processes.
Work Environment & Use
There’s also the matter of welding and brazing not having the best fumes to inhale versus soldering which has very little by-product smoke.
Another difference is the way these three processes are used. Just as an example, while brazing circuit boards isn’t a good idea, neither is welding jewelry.
There’s also the matter of flux. Flux is what removes oxidation from the area being filled increasing its strength. Flux is what removes oxidation from the area being filled increasing its strength.
So What Method of Joining Metals Is the Best?
There’s no ”better” method. Each process is useful in its own right.
If you are securing a twenty-four-ton bridge, welding is probably preferable to soldering. If you are assembling a 30,000-dollar motherboard, brazing it wouldn’t be very good, and soldering an industrial table saw guard would probably just make a giant melted mess.
So as you can see, there’s no real ”winner” or ”best” form when it comes to joining two pieces of metal together. Just different circumstances call for different processes.
Summary
Every form of joining of two metal plates is valid but the main things to consider are the strength of the actual site where the two materials are joined, cost, time, safety and skill.
The strength of the weld, solder, or brazed area is a big factor because choosing the wrong process and filler material can have catastrophic results. Cost is always a factor because, as we have learned, there are very different costs associated with each process.
Now you hopefully know the differences between the three processes, where their strengths and weaknesses lie, and have a better idea of where to apply each. As with anything, read all that you can about each one before starting any project.