Introduction to Welding

Last Updated/Verified: Mar 15, 2024

What is Welding?

Welding is the joining of metals. What welding does is join metals or other materials at their molecular level with the technology we have at the moment. I say "at the moment" because welding technology is always changing, and with so many military forces relying on it to make their defense products, there are welding processes we are yet to hear about.

What we know about modern welding is that there are four components to a weld. The four components are the metals themselves, a heat source, filler material, and some kind of shield from the air. The welding process works like this. The metal gets heated to its melting point, at the same time there is some sort of shielding from the air to protecting it, and then a filler metal is added to the area that needs to be joined ultimately producing a single piece of metal.

Back in the day, when the bronze and iron ages began using metals more productively, they would use a direct casting process. The casting process would be done by making a sand mold of the piece to be added. Once the mold was made you simply put it on top of the metal piece you wanted to add a part to, and fill it with hot molten metal, after which you wait for it to cool. Another way metal was joined was by putting two pieces of metal together and damming any open sides. Once the area was leak free you simply poured molten metal to fill the joint.

The Industrial Revolution and Welding

When the Industrial Revolution began around 1750 AD a process known as forge welding was used. It's a very simple process that takes two or more pieces of metal and the joint areas are heated. When the metal is hot enough you simply hammer them together until they fuse. This all worked well enough until 1886.

In 1886 an inventor who was awarded over 700 patents by the name of Elihu Thomson came up with resistance welding. He was someone whom the modern world should be thankful to! Not only did he make resistance welding possible, but we still benefit from many of his other electrical inventions. This was the start of the modern welding age sparking inventor's minds on how to join metals in different ways. This was the beginning of the end for the mass use of rivets, screws, and bolts to join metals.

What many people don't know is how important these new welding processes were to the military at the time. At the end of the First World War new welding techniques were a closely guarded secret to the ship repair industry. Even today the welding technology used by military contractors and the new alloys produced are a closely guarded secret!

It is a simple process that the industrial revolution needed and without it many of the things we take for granted would not be here! Welding is a major need for most manufacturing industries. Almost any industry that works with metal cannot survive without welding. Welding, in a big way, is the back bone of all metal products. Every industry, from underwater construction to space explorations, relies on welding. Just look around right now how many things around you are made of metal? If it's made of metal there is a good chance it was welded.

The Most Common Welding Processes

Welding today has four popular processes. These processes have not always been the most popular in the past but have risen as the favorite of engineers and welders for cost and practical reasons. In the real world (not a text book) these are the welding processes that have the most demand job wise. Not sure? Pick up any newspaper right now and look at the employment ads. These are the types of welders most employers need!

All of the above processes require electricity to create the heat needed to weld metals. The main difference between all of these processes is the way the filler metal is added and how the weld is shielded from the air.

Shielded Metal Arc Welding / Stick welding / SMAW

Shielded metal arc welding / Stick welding / or SMAW uses a rod or in the technical terms it is called an electrode that has a powder coating (technically a flux) on it that burns or melts to create a shield from oxygen, and some rods have filler metal added to the coating to speed up the welding process.

On a scale of 1 to 3 for difficulty, SMAW is a 2. Stick welding is the most common, but from a visual point of view it is harder to determine how much filler metal is added to the joint because the shielding on the rod produces a slag that does not allow you to see the weld directly while welding. Afterwards, you chip off the slag to see the weld. Stick welding is also the best process to weld out doors with. The flux shields the weld from oxygen and is exceptionally good when it's windy.

MIG / Metal Inert Gas Welding / Gas Metal Arc Welding / GMAW

Metal inert gas welding / MIG is a process that uses a wire spool to feed wire to the joint and has a bottle of gas that flows from the machine to the welding handle to protect the weld from the air around it. The best description in a comparison point of view is a bicycle brake cable that has a wire running through that feeds continuously to the joint. But this cable also has a gas flowing through it that shields that weld from the air.

On a scale of 1 to 3 for difficulty, SMAW is a 2. Stick welding is the most common, but from a visual point of view it is harder to determine how much filler metal is added to the joint because the shielding on the rod produces a slag that does not allow you to see the weld directly while welding. Afterwards, you chip off the slag to see the weld. Stick welding is also the best process to weld out doors with. The flux shields the weld from oxygen and is exceptionally good when it's windy.

Flux Core Arc Welding / FCAW

Flux core arc welding / FCAW is the same machine as the MIG welder
but the difference is it either uses just the wire with a flux in the center of it or a combination of the flux in the center of the wire and a shielded gas from a bottle.

On a scale of 1 to 3 for difficulty FCAW is a 2. Flux core welding is mostly used outside when there are heavy production demands for the amount of weld done per hour. This is commonly used in shipyards where a lot of weld is required and it is windy.

TIG / Tungsten Inert Gas Welding

Tungsten arc welding / TIG is a torch that has a gas flowing through it with a non consumable rod made of tungsten that heats the metal and the filler metal is held in the other hand and manually added when needed. The non-consumable rod is only a rod that creates the arc to heat the metal. It does not add to the welding filler material itself.

On a scale of 1 to 3 for difficulty TIG is a 3. You are heating the joint with one hand and the other needs to add the filler metal. The huge upside is total control of the weld and it is the process of choice for exotic metals and joints that needs the best weld possible.

Differences in These Welding Processes

With all popular welding processes it's pretty much the same basic principle, heat, shielding from the air, and filler metal added to the joint! There are two main differences with today's welding processes.

Difference in electrodes

The first main difference is that some processes feed the filler metal with some sort of wire using a mechanical feed like a wheel or spool of wire. These are considered semi-automatic. The second is an electrode that burns down until it is finished or the processes that filler metal is added manually with the other hand. These are considered manual processes.

The second difference is the way the shielding from oxygen is created. MIG, sometimes Flux Core, and TIG use a bottle of gas usually containing all or a percentage of argon gas. While stick welding uses a chemical powder on the rod or electrode that burns and shields the weld. Also, this same chemical powder may contain filler metal to make a faster weld.

Welding Production Speed

When it comes to welding production, meaning how many pounds of wire is applied in a day, MIG and Flux Core take the prize. Second is Stick welding. Finally, there is TIG for totally precise welds that can be done on any weldable metal

Many manufactures who are metal fabricators choose the proper welding process by weighing the minimum quality of the weld they need, versus how fast a weld can be made. Yeah, money, money, money!

Choosing a Welding Process

With MIG or Flux Core (most common in welding shops and shipyards), welding of the metals is very fast because the metal comes on a spool and they are machine driven as fast as needed. Unfortunately, because the wire is feed through a cable much like the brakes of a bicycle, there is a limit how far you can go with the welder distance wise. The further you go from the wire feed, the more friction the wire passing through the cable has. This causes some unavoidable problems. When it comes down to the most welds per hour, MIG and Flux Core welding take the prize!

Secondly, Stick welding can be a fast-paced welding process if the welding rod is big enough or has filler metal added to the coating. The main attraction of Stick welding is that it works great outdoors and requires no bottles of gasses to shield the weld. Additionally, Stick welding machines have long cords and can weld as long as the cord is long, and short enough to keep the electricity at the proper level. Stick welders are the most cost efficient for someone who just needs to do some metal repairs or enjoys welding is their hobby. Stick welding is the most trouble free and easy to set up.

Finally TIG welding, the most respected and valued of all welding processes, is slow but the best for weld quality wise. TIG has the flexibility to take the TIG torch as far as you can go with it just like a stick welder. The downside is you need a bottle of gas to make it work and wind can cause trouble. Typically, many Stick welding machines are also TIG welders. You can simply add a TIG torch and bottle of gas to use it as a TIG welder. The upside is the best quality weld with any metal.

Welding Polarity and Voltage Type

Understanding welding polarity and voltage type is important since the most popular welding process today use electricity to produce the heat needed. Welding also uses different types of electricity depending on the welding process itself and what the welding filler material manufacturer’s recommendations. There are two types of electricity used in welding D/C (direct current) like your car battery, and A/C (alternating current) like the power in your home. There are three types of welding polarity.

      • D/C electrode positive where the electrode is positive, the electricity flows from the metal to the welding rod.
      • D/C electrode negative (the most common) when the electrode is negative and the electricity flows from the rod to the metal.
      • A/C alternating current where the polarity changes from positive to negative many times in a second. Some welding machines offer A/C current, but it is the least commonly used in the welding field.

Weld ability of metals

Almost any metal can be welded depending on the process and conditions. The people who determine what and how the metals can be welded are called metallurgists or welding engineers depending on whom you ask. The three most commonly welded metals are steel, stainless steel, and aluminum.

      • Steel is the easiest to weld and has the least amount of problems.
      • Stainless steel welds very well, but requires a lot more skill and preparation than steel.
      • Aluminum is on the more difficult side to weld. Aluminum welds easily with the TIG and MIG processes, but can also be welded with the other processes.

Outside of the more common metals that are welded there is an almost endless variety of metals produced that can be welded. The cost of these metals can be very expensive and they are considered exotic, such as Titanium that is used in the aerospace industry, Nickel-based alloys used in nuclear power plants, and endless combinations of different metals specifically engineered for a variety of purposes.

Welding as a Career Choice

If you are thinking about a career in welding there are many types of welding and welding related positions. Welding skills are in high demand and with the world becoming environmentally friendly, it is only going to create more demand.

Welding jobs have so much variety it's almost endless. Some jobs can be very dirty, while others are done in an environment almost like a sterile operating room. Most welders go to work to the same place every day, while others travel around the country doing industrial shut downs earning six figures a year allowing them to take a lot of time off. Actually, there is a nick name for these folks – "Road Warriors". An elite few welders work at the bottom of the ocean and a select few in outer space.

Many welding jobs are more than just welding. Outside of a strictly being a welder, the industry has a strong demand for people who are good at solving problems and who are good at math. Having a welding background opens many more career options and opportunities.

The American Welding Society released a press release and in their words this is what they have to say about welding as a career.

January 18, 2005 — (NAPS)—A growing number of men and women are finding financial freedom by taking up a welding torch and beginning a new career. Here, from the American Welding Society, are ten reasons they are “taking up the torch:”

  1. Welders can make more money than doctors.
  2. Welding is an “excellent job prospect,” says the Occupational Outlook Handbook.
  3. Welders have more career choices. Engineering, computer programming, education, and science involve welding.
  4. Qualified welders are in demand by many U.S. industries.
  5. Welders are like athletes—great hand-eye coordination, physical stamina, and they perform well under pressure.
  6. Welders work underwater, on land, in laboratories or even in outer space.
  7. Welders make a difference in the world. Almost everything we see and touch is a result of welding technology.
  8. Welding skills are in demand all over the world.
  9. Jobs in skilled trades are expected to increase 50 percent in the next ten years.
  10. You or someone you know might be a welder. Visit or call 800-443-WELD, ext. 416 to learn more about welding careers.

Many welding positions are more than just welding. For example, Welder/Fitters need to do mathematical calculations, read blue prints, and make thing fit! Welder/Fabricator needs to do all the above, but the hardest part of the job that many people have trouble with is looking at a blue print and being able to visualize the finished product in your mind. Also, Welder/Fabricators spend a great deal of time drawing out patterns and laying out parts that only exists on paper at that moment. This is the job I love to do because you never know what you will be building next!

Frankly, I get bored working in an office for too long, as I also get bored working with my hands for too long. Welding gives me a chance to do both and balances out my life. If you like to work with both your mind and your hands, then welding may be an excellent career choice for you too.

I do want to sum it up and say that getting an introduction to welding changed my life for the better! Out of all of the training classes I have ever taken, welding has always paid off very quickly. I remember when I took a 900-hour welder-fitter course and was worried about paying off my student loans. In a matter of only six months, this career choice gave me the income I needed to pay off my student loans!