Our ancestors have been sticking pieces of metal together for centuries, using older and much more rudimentary forms of welding. However, it wasn’t until the late nineteenth century, and then the early twentieth century when the coated electrode was invented, that welding really found its stride.
So many different styles and techniques have emerged since then—like resistance welding, gas welding and friction welding—that it’s worth taking a look at each to see which might be right for your needs.
What is welding?
Welding is a kind of fabrication process that mainly uses high temperatures to melt different pieces of metal together, then allows them to cool and fuse. Pressure can also be used to join parts together, such as in cold welding.
Welding doesn’t just place the pieces together however, like soldering or brazing does. Instead, it literally joins the two metal structures into one. To do so, it makes use of extreme heat, and sometimes even uses other metals or gases.
A little bit of welding history
The first evidence of welding can be traced back to the bronze age. Some small, round boxes made out of gold, thought to be over 2,000 years old, likely used welding in their manufacturing process. Archaeologists posit that the lap joints were joined together using pressure welding. During the middle ages welding was used by blacksmiths who hammered iron and steel to produce different items such as armor, tools and weaponry.
The next jump forward came in the nineteenth century. The industrial revolution took much of the world in a new direction. Now, everything was being made on a mass scale never seen before. With the development of arc welding, which used a carbon arc and a metal arc, resistance welding simply became a practical joining process.
Around this time many people across the globe, from places like Sweden and Russia, were making discoveries about the welding process. The coated metal electrode was introduced in Great Britian. Stick electrodes were produced as well, using a method of dipping short lengths of iron wire into a mixture of silicates and carbonates and then leaving the coating to dry.
Resistance welding was getting a makeover too, with new processes being developed, like seam welding, spot welding, projection welding and flash butt welding. In Germany, thermite welding was used on railroads and gas welding and cutting were perfected during this era.
In the early twentieth century, World War I brought with it a huge demand for arms production and welders were put to work. Many large companies across Europe and America turned to manufacturing machines and electrodes to meet the welding needs of the conflict.
Types of welding and what they are used for:
Over 50% of all man-made products require some welding. Our ubiquitous gadgets and tech, the transport links we use, the skyscrapers in our cities—all of them require some form of welding. There are a few different types of welding that have been cultivated over the last century. Below is a list of six of these in particular: MIG, Stick, TIG, Energy Beam, Gas and Plasma arc welding.
1) Stick welding
Stick welding, or arc welding as it’s also known, is an older method. That’s why it’s a simpler process, but it also makes it harder to master than, say, MIG welding. Stick welding uses a source of power that sends out a constant current electric arc. The current flows through the flux coated welding electrode—the coating makes sure the weld zone isn’t exposed to air while the rod is melting. This rod is where “stick” welding gets its name from.
Stick welding is relatively inexpensive and can be used on most metals. This method is used in a number of ways including DIY jobs, on construction sites, for farm repairs and more. MIG and stick welding have a lot of similarities and you don’t have to be a professional welder to use these methods. It’s a good idea to do your research and read blog posts, such as this one titled When to Stick Weld vs. MIG Weld, before getting started.
2) MIG welding
MIG welding is one of the easiest welding methods, which helps explain why it’s used by beginners and is one of the most common professional welding methods as well. There are two approaches to MIG welding:
- Bare wire—Used to join thin pieces of metal.
- Flux core—Usually done outdoors due to the gas supply or flow meter it requires.
Essentially MIG welding is what is referred to as an arc welding process, much like stick welding. This is where an arc forms between the MIG wire and work piece. A shielding gas is sent through the welding gas to protect the area from contamination.
MIG welding is usually the choice for hobby welders and DIY enthusiasts who don’t have the money to buy huge, expensive equipment.
3) TIG welding
This method of welding is very versatile, but quite difficult to master, so professionals in this industry are highly skilled.
TIG welding takes two hands: one to hold the TIG torch, and the other to feed the rod. The torch creates heat in the arc which is used to weld most conventional metals such as:
- Copper alloys
- Nickel alloys
TIG uses a tungsten electrode, which delivers a current to the weld pool. Machines used for this method of welding are very complex, so they’re mostly used for repairs, rather than out in the field on farms or construction sites.
4) Energy beam welding
Energy beam welding, also known as electron beam or laser beam welding, is an extremely precise method using high energy welding techniques. Energy beam welding was developed in the late 1950s.
It quickly rose in popularity in many high-tech industries, such as aerospace, where it was valued for how precise it could be, and how strong the welds it created were. A beam can be very accurately placed and the weld can keep most of its original strength. EB welding is unbeatable in quality and it’s the “big guy” of welding processes.
Energy/electron welding is performed in a vacuum environment, as gas can cause the beam to scatter. Essentially, the process consists of a high-velocity electron beam being applied to the materials that need to be joined. The pieces melt and flow together as the energy of the electrons changes into heat upon impact.
5) Gas welding
Gas welding is not as widely used anymore as it once was with many preferring to use TIG instead. Gas welding uses oxygen and acetylene in its kit which is very portable. Repairs to exhaust systems in cars are sometimes still done using gas welding.
It is, however, a relatively cheap, portable and flexible form of welding. It doesn’t need any large electrical equipment and is still capable of welding, cutting and brazing most metals. Because of this gas welding is a very practical form of welding and is used across many different industries, including the aerospace automotive industry, and for repairs more generally.
However, gas welding still has its drawbacks:
- It is less suitable for thick sections of metal.
- It can’t be used for high strength steel.
- The rate of heating is slow.
- It doesn’t have a dedicated flux shielding system.
- It can’t reach the high temperature of arc welding.
6) Plasma arc welding
Plasma arc welding is very particular and requires a very precise technique. It’s mainly used in aerospace applications where the metals being used are both extremely thick and extremely thin. Plasma arc welding and TIG welding rely on similar techniques, where an arc is formed between a tungsten electrode and the workpiece; however, in plasma arc welding, the electrode is recessed and heat is produced by the gases inside the arc ionizing. Plasma is then forced through a copper nozzle which constricts the arc.
Plasma arc welding can work on most commercial metals and alloys, but also on difficult-to-weld metals such as bronze, lead, magnesium and cast iron.
Is cold welding still welding?
Cold welding, isn’t typically considered when comparing different types of welding, but it’s still an important method. Cold welding, also known as cold pressure or contact welding, uses pressure and plastic deformation to join materials. The more scientific term for this is “solid-state diffusion,” which simply uses pressure to create welds well below the recrystallization temperature of metals.
When two things are pressed together, they typically won’t just weld together, because there is a layer of oxide or a thin barrier on the surface of the materials. The materials that are cold welded though are prepared beforehand to overcome this barrier, by going through intense cleaning or brushing to remove the top oxide or barrier layer.
The practice of welding has been growing and evolving since some of these techniques were first used thousands of years ago. All told, perfecting the methods described above took a few millennia, and there are more advances to come.
Today, MIG and Stick welding are considered the more basic methods and can be used for a wide range of different DIY, construction and mechanical projects. The other methods listed require more skill and training, and as a consequence they have very particular uses and procedures involved. If you do want to get into welding, make sure to start with the basics and follow all safety procedures as you learn new techniques.