The Welding Processes - A Personal Perspective
Many people have no idea what welding is about and think of a welder as a dirty old guy with a cigarette hanging out of his mouth, in a blue collar trade who either fixes stuff, or works in a factory. Although there are many welders making great money and bennies in factories (yes, many with cigs hanging out of their mouths) there are all kinds of other jobs and processes. Welders, both male and female are working everywhere in the world from high up on multi-story office towers to deep underwater in the oceans. They are nuclear code welders, plastic welders, explosive welders, welders who work on LIVE armed missiles, space station component welders, robotic welders and that’s just a few right off the top of my head!
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Welding is a much diversified trade involved in at least half of our Gross National Product and a huge part of our everyday lives. Think about it, we use products or work or live in structures that are welded just about every day of our lives. Pipes bring us gas and water, we travel over roads with bridges that are welded, ride in cars/trucks/busses that have been welded, and our crumbling Infrastructure is going to require probably the most welding in history!
When I was a kid about seven years old we were at an intersection and I heard my mom and dad talking about how daring some guys were. My dad was a World II and Korean War combat Vet and even at my young age I knew if he called someone daring they were the real deal. I looked up and saw Iron Workers WAY up on a high-rise with sparks dropping down like and orange waterfall. I didn’t have a clue what the sparks were, nor did I realize I had just seen my first welders in action.
A couple of years later it happened again but this time it was my mom and her friend gasping as they saw some Iron Workers welding on the Rio Grande Gorge bridge. There were those crazy-brave guys and again the sparks were falling. I still didn’t really know why, but it intrigued me enough that I mentioned it in one of the first articles I ever wrote. It didn’t make me decide on a career in welding, but it did catch my interest. Little did I know that I’d end up making a career starting in an oilfield/agriculture equipment repair shop, become lead welder at a black iron plant, become a member of the International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers, and then teach Structural Welding for twenty years!
I started out at a Vocational College that was run by my great mentors, Phil Newell and Mike Waldrop. Google “Phil Newell Mike Waldrop welding” and you can check out what I’ve said about them in prior articles. They were my foundation and I’ll always remember them fondly. It was old school welding back then and we started out Oxy/Acetylene welding and had to pass 2G, 3G and 4G plate tests. It separated the men from the boys and caused a lot of people to change their minds about getting into the welding trade.
Oxy/Acetylene welding, used to be one of the major processes but now is outdated and pretty much obsolete as far as being used in the shop and field. There were several reasons for its demise, with the main two being:
- A high amount of heat applied to the base metal (metal to be welded, also s referred to as “parent metal”) creates a large Heat Affected Zone (HAZ). The HAZ is the base metal area on both sides of the weld affected by the heat. It can be changed by becoming soft (strength of base metal weakened) or brittle (weakened because it would then be prone to cracking). Softening or embrittlement can happen because of the change to the atomic structure. You don’t want a column which is carrying a building’s weight to the ground, or a car/motorcycle frame to be weakened for obvious reasons, so the smaller the HAZ, the better.
- It is a very slow process and in the field TIME IS MONEY!!!
That said, there is still oxy/acetylene welding done, and it’s still taught in a lot of welding schools because it’s an excellent way to learn how to watch and control the weld pool, and a good introduction for learning Tig. It’s primarily used on a lot of farms, ranches, and a lot of odd jobs also. It’s easy to transport an oxy/acetylene cart just about anywhere, and is cheaper than most electric arc machines, plus has the benefit of using it to cut with. (At the time of this writing (2012) you can get a small set up for around $200 to $300 bucks.) Like electric arc welding, you can buy different diameters of welding rods and also brazing rods. Brazing will be covered under the Gas Tungsten Arc Welding (GTAW, referred to as “Heliarc” by older hands because it used to have helium as it’s shielding gas, and now more commonly called “Tig” for Tungsten Inert Gas.) Most oxy/acetylene rigs are used primarily for cutting steel nowadays though.
After I made it through that brutal first semester I started Stick Welding (Shielded Metal Arc Welding or SMAW) for the summer semester. We took a field trip to Lone Star Steel which at the time was one of the largest steel factories in the world. It was a fun and crazy trip. The van’s air conditioner went out about the time we hit the humid part of Northeast Texas and it was HOT! When we got to the hotel we drank a lot of beer until the wee hours of the morning.
This was a very dumb and stupid thing to do before going to a steel factory on a 105 degree summer day. (Being young back then, dumb and stupid things were a normal activity). Inside the factory temperatures ranged from one hundred ten degrees to no telling how hot by the blast furnaces. Even though we were suffering with headaches, upset guts and were about to keel over from heat prostration, it still was one of the most interesting places I had ever seen. I saw some of the major electric arc welding processes there because that steel plant pretty much used them all.
As we were taking a break I noticed a guy sitting by some controls and wondered what he was doing. There was a lot of grayish powder surrounding what looked like a robot arm with a copper cone at the bottom with a faint light I could barely make out on a bright day. Every now and then he’d take a chipping hammer and knock off some of the powder behind the traveling arm. I asked what he was doing and he took a drag off of his cigarette and asked what the hell I wanted to know for? That was when I learned that not all welders were friendly! However, I would also later learn that a lot of the old hands that seemed grouchy and mean would turn out to be some of my best mentors with kind hearts under their gruff exterior.
I told him I was learning to weld and he told me that’s exactly what he was doing…welding. I asked him what kind of welding it was and he told me “subarc.” I nodded my head like I knew what he was talking about and decided to refrain from asking why he wasn’t wearing a hood. (I would later learn that he was talking about submerged arc welding.) Although the guy wasn’t too interested in helping me to advance my knowledge of the trade, he had opened up a new door to me and showed me the diversity of the welding trade and processes used.
There are more than eighty processes used in welding and you can look them up in the American Welding Society’s free downloadable booklet, Safety in Welding, Cutting and Allied Processes at this link. http://www.aws.org/technical/facts/Z49.1-2005-all.pdf
The four main processes are Stick (Shielded Metal Arc Welding or SMAW), Mig (Gas Metal Arc Welding or GMAW), Tig (GTAW discussed above) and Flux Core (Flux Cored Arc Welding or FCAW.)
I give my high school students a funny way of remembering the latest acronyms. I’ll look at one of them and tell the class that he or she will ask for SMAW potatoes at the dinner table.
Another will ask his/her dad if he will buy them a 12 string GTAW.
Another can’t wait for their Grandpa and “GMAW” to come visit. (I learned the hard way to make sure the student’s grandmother is still alive before using this one!
And I will tell them that FCAW is a rude way of telling someone, well, I’ll stop right there on that one!
Next article will continue with the applications of the main processes…