Summary of Welding:
Everyone can recognize the iconic welding mask and sparks flying everywhere. But, some people have no idea what is going on and why this process is so important. Welding is when two or more parts (usually metal or thermoplastics) are joined together by heating the surfaces to the point where they melt together. This is usually done with a electric arc or a blowtorch. Some materials need a specific method done to be welded while are other materials are deemed “unweldable” (some aluminum based alloys). This complete welding guide will walk you through what you can expect from a welding career or how you can pick it up as a useful hobby.
Welding is different from brazing and soldering because those processes don’t melt the base metal. Welding accomplishes this and adds in filler material as well. When you weld you’ll see a “weld pool” that is made out of molten material, when this cools it forms the join that brings both materials together.
Welding pay in America is generally around $43,000 per year. However, those in unions or working in the distribution of natural gas atmosphere make a quite a bit more. For example, these workers, as well as electric power distribution welders make around $73,000. Overtime is also extremely common within this trade so these workers can potentially earn a lot more than is calculated with just 40 hours per week.
There is a large demand for welders and the demand is only going to increase so the wages may see an increase in coming years. Welders are desperately needed to replace deteriorating utility plants, roads, gas, water, and sewer lines
While welding certifications and licensing can definitely help you find a job easier and with better pay it isn’t always necessary. However, most welders get certified to end up in a certain line of work. This is because a lot of certification simply demonstrate that the welder can perform specific types of welds.
The American Welding Society (AWS) has a few different certifications:
- Certified Welder
- Certified Welding Inspector
- Certified Robotic Arc Welder
The AWS isn’t the only place to go to however, some industries offer certification specficialy for the type of work you’ll be doing for them. For example, The American Petroleum Institute and The American Society of Mechanical Engineers will do this.
What is required in a these certifications?
Some of the most basic things you should be able to do are
- Weld the materials given to you in the position required by the test
- Cut the materials in the way required by the instructor and have them prepared for weld quality testing such as the bend test (bending the weld to see if it tears).
- More tests such as radio graphic (X-ray) or a simple visual examination. You’d be surprised how much welding instructors can figure out just by looking at a weld.
There is a coding system that lets you specify the welding position:
- Flat position
- Horizontal position
- Vertical position
- Overhead position
There are also two joints generally used in welding certifications:
- Fillet weld indicated by F
- Groove weld indicated by G
By using a combination of these codes (IE: 1G, 4F) the right kinds of welds can be specified. However, the exact process and certification will be different for all the different types of welding. Many welding schools also offer welding certifications but a certified welding inspector can also come out to businesses as well.
This image from TWI Global shows how a correct welding bead should look and how you should recognize the different aspects of your work.
Different types of Welding
MIG or Metal Inert Gas welding is an gas metal arc welding process. An arc is used to heat up the metals being joined. The arc comes from a continuously fed filler electrode and the surface that is being welded this is why it is important to distance correctly while you’re welding or the arc will be choppy and sloppy. This form of welding also protects the molten pool from atmospheric elements by using a shielding gas. Lastly, MIG welding requires a Direct Current Positive Electrode (DCPE) or Reverse Polarity.
Now onto the actual welding, many people refer to MIG welding as wire welding because a wire electrode is involved. This electrode is actually a thin wire that is attached to a wire reel that is being continuously fed into the welder while you weld. As soon as you pull the trigger an arc appears between the work material and welder. This arc melts the wire and workpiece making a pool of material, conveniently the wire is a filler source of material as well as a heat source. The wire goes through a tube made of copper that then conducts current into the wire. The nozzle that surrounds the wire also provides the shielding gas.
With MIG welding you can weld just about any material, this is one of the reasons its so popular. Some of the main industries you’ll find MIG welding in are automotive, sheet metal, and pipe welding.
Pros of MIG Welding:
- It can weld materials that have different thicknesses
- Simple and affordable equipment components
- Requires a lower heat input
- Weld and slag spatter is a lot lower than other welding methods
- Welding fumes are kept to a minimum which is safer for welders
- The skill required to do MIG welding is relatively low
- MIG welding is a great option for spot and tack welds
- MIG weld beads look visually appealing
Cons of MIG Welding:
- Welder must stay close to the MIG machine
- MIG is limited to staying indoors because wind will influence the welds too much
- A canister of gas is needed all the time
- Hard to diagnose the machine and get perfect welds if there is something wrong
TIG (Tungsten Inert Gas) welding is very distinct from the other types of welding. It involves holding a torch in one hand while holding the filler material in the other hand, the torch produces the arc while the filler metal generates the weld joint. Due to this simultaneous action by both hands it requires a great amount of skill, but, it is also very versatile. The process can also take some time but the welds are of the highest quality. Because of this you’ll usually see TIG welds done for critical weld joints as well as precise and small welds.
Tungsten is extremely significant in this welding method because of its high melting point and ability to conduct electricity at a high temperature (11,000 degrees Fahrenheit). This makes it a non-consumable electrode that makes the arc for TIG welding, other materials would simply burn up and become ineffective.
Just like with MIG welding, heat is made as electricity passes through the electrode and an arc is made. A canister of compressed gas is released to shield the weld area from the air, it also has a very distinct smell that you’ll recognize immediately when around it. The filler material is dipped into the arc to make the puddle.
To start, the gas flow is initiated by the welder, often times this is a valve on the torch itself. The the welder holds the torch an appropriate distance away so it doesn’t touch the material. Using a foot pedal, the arc is made and the two pieces of metal melt to form a puddle, at this point you dip the filler material into the puddle to start filling up the joint. By the end you’re left with one solid piece of metal.
Pros of TIG Welding
- TIG welding is extremely precise
- TIG welding is cleaner and has less imperfections
- TIG welders can be used in just about every position, sideward, downwards, upwards
- You can choose the exact amperage for your job
- You have a lot more control over the heat used by the welder
- You can weld a lot of different metals and alloys with TIG
- Less smoke and fumes from TIG welding
- You only need argon gas as shielding as opposed to many different types
- TIG welders are affordable
Cons of TIG Welding:
- The TIG welding process is more expensive than other methods.
- Contamination issues are easily made when there is poor gas coverage.
- The correct weld polarities need to be remembered.
- Manufacturers follow their own set of rules and standards
- Craters are easily produced in TIG welding
- Overheating can be a big problem
- Oxidation will easily form around the weld
Flux Cored Welding
This process is newer and very similar to MIG welding except instead of high amounts of argon or carbon gases, the flux cored shields are automatic. This is because the wire used in the process has a flux filled interior and a metal surface. The flux then reacts to the electrical current and melts, resulting in shielding gas. Of course this means that this method can be used outside since it doesn’t need to have gas.
Flux cored welders can handle thicker metals than MIG welders because you’re able to pinpoint where you’re going to put your welds and the arc from this will sink much deeper. However, when it comes to thinner materials it would be a good idea to opt for MIG welder because the welds themselves will be neater and will cause less spatter.
Pros of Flux Cored Welding
- Reduced costs due to higher weld deposition rates in shorter time
- Can use a faster travel speed
- Welding can be done in all positions as well as outside
- Some flux-cored wires don’t need an external gas supply
- Better penetration in Flux Cored Welding
- Able to weld rusty materials
Cons of Flux-Cored Welding
- A constant electrode feeder and potential power source are needed to keep a constant arc voltage.
- Weld beads may not be visually aesthetic.
- Not very good with thin metal.
- Slag inclusions may occur
Stick Welding (SMAW or Shielded Metal Arc Welding)
Stick welding makes use of an electrode often called a stick or filler rod to weld metals together and fill a joint in. The core of the electrode is made of solid metal, within this metal casing there is binding agent along with powdered metal and mineral compounds. This allows an electric current to conduct to the arc and the proper amount of filler is released to fill in the joint. The electrode that you choose to weld with makes all the difference, it will specify the amperage and voltage requirements you need.
The negative cable of the welder uses a clamp to connect to your work piece. This is critical because it is what allows the the power to travel through and make an arc when the electrode attaches. To begin the welder taps the electrode on the workpiece and raises it slightly to form the arc. The electrode will then start to melt and you’ll see the welding pool. After the welding is done and everything cools down you’ll see a sturdy joint
Pros of Stick Welding
- Requires less equipment and the equipment is cheaper
- Cheaper than MIG and TIG
- Effective even in the rain and wind
- Doesn’t need any external shielding gas
- Saves time on pre-weld clean up because its less sensitive to dirt, corrosion and paint
Cons of Stick Welding
- Stick welding is slow in comparison
- A good amount of slag is produced that must be chipped away
- Harder to weld thin metals
- Welding rods must be replaced often
- Possibility of high porosity, rough surfaces, and spatter.
Submerged Arc Welding (SAW)
The arc of this welding method is submerged underneath flux which also means shielding gas is not required because the powdered flux generates this. Electrodes in SAW can either be a strip of sheet or sintered metal, or cored/solid wire. Because the arc is submerged it can’t be seen by the welder, this is why it is mainly a mechanized process. The parameters and filler positioning must be correct on the machine otherwise the weld will be completely wrong.
Pros of SAW Welding
- Splatter won’t get on the workers
- High levels of radiation won’t get into the air because of the flux
- Low levels of welding smoke
- Doesn’t need additional pressure to weld because it is already provided by the elctrode
- Welds very quickly resulting in high productivity (Deposit rate of 45kg/h)
- Can be used indoors and outdoors
Cons of Saw Welding
- Materials are limited to some nickel, steel, and stainless steel.
- Materials also need to be rotated pipes or be long and straight.
- Risk of flux residue being left behind as a health hazard
- Needs a lot of slag removed after weld.
Electro Slag Welding (ESW)
This process uses a molten slag to melt the filler material as well as the surfaces on the piece that is being welded to form a joint. The slag itself shields the weld pool so no shielding gas is needed in this method. The arc heats up the granulated flux which then forms the slag. When enough of the slag is produced the conducive element starts to extinguish the arc. The slag is only kept molten by the its resistance as the electric current passes between the work piece and the electrode.
This process can only be done on low-carbon steels along with carbon steel that are at least 3/4 of an inch thick. It must also be welded while in the vertical position, the weld has to also be continuous with no interruptions.
Pros of Electro Slag Welding
- Joint preparation is very simple
- Thick steels can be welded more affordably
- Extremely high deposition rates
- Distortion and residual stress in the welds is very low
- No blinding arc flashing or spattering
- Cold cracking is avoided due to a slow rate of cooling
- Remaining slag is removed
Cons of Electro Slag Welding
- Not as economical when welding smaller joints
- Risk of notch sensitivity and hot cracking
- Base metal heat is extremely high
- Can only weld vertically
- Weld toughness is fairly low
- A columnar grain is applied to the weld because of the slow cooling rate.
This is one of the simpler welding methods and is commonly used when making car parts to weld two parts together in many different places. This process first uses pressure from two different points that snap down on the metal piece, it then sends heat through through the electric current to this area.
The two electrodes that are being snapped together to put pressure on the part are made of copper. Copper is of course used as an electrode because of its high thermal conductivity. When the material melts the parts become joined in the form of a “nugget”. A nugget is what forms the joint and it looks like a circle with a little depth and gold to brown color.
Pros of Spot Welding
- Quick welds
- Low energy cost
- Low level of skill required
- Able to be automated
- Can weld through more than 2 work pieces at once
Cons of Spot Welding
- Bond is fairly weak
- Looks bad
- Welding guns take up a lot of space
- Hard to move Spot welding guns around
Welding Wood: This can be accomplished through a process known as linear friction welding. The two pieces of wood are simply rubbed against each other very hard and fast, within a few seconds they become one piece. There are four main variables at play that can affect this weld. The speed at which the wood is rubbed, the force behind the wood rubbing it, the amount of time the process is going on and the distance it travels during the process. This is a fairly new technique but it could become more common in the future as it develops
Welding Plastics: Plastic welding works similarly to metal welding where the rod must be made of the same material. You can burn the plastic as a test to figure out what type it is based on the flame color and smell. Here’s hwo to identify some of the main plastics:
- Polyurethane: The flame will sputter while generating black smoke.
- Polyvinyl Chloride: There will not be a flame and the plastic will extinguish itself.
- Acrylonitrile Butadiene Styrene: First you’ll smell a sweet scent and you’ll see a sooty, black smoke.
- Polypropylene: Orange tinted flame with little to no smoke and a sweet scent.
- Polyethylene: You’ll see a bluish flame and little to no smoke.
There are many different ways to weld plastic such as:
- Friction welding: You use angled oscillations at a fast pace with heat to join two pieces of plastic.
- Extruded bead seal welding (extrusion welding): The bead that you use is made out of the same thermoplastic that is being welded. You then press this bead against the piece you’re welding and the heat from the extruded pellet will join them together.
- High frequency welding: Using the electrodes of an electrical generator that has a high frequency you heat up the plastic pieces until they are joined together.
- Hot plate or hot tool welding: First coat your hot surface with PTFE (Polytetrafluoroethylene) so that your plastic pieces don’t just stick to it. You then hold your pieces onto this heated surface until they start to melt. Then you bring them together while adding some pressure so that they join together.
- Hot gas welding: This involves using a plastic welding gun that features a heated gas chamber. Gas (dry air or nitrogen) gets passed through this chamber where it is then heated up to generate a weld. While you do this you must also use a welding rod of the same material.
- Laser welding: Put two thermoplastic pieces together with some pressure and positioned in a straight line, then you use a laser to weld them together. The beam will hit the first part and the second part will absorb the beam this results in the material becoming softer so a weld can be produced.
- Induction welding: Insert a conductive metal piece where you want the weld to occur and join your plastic pieces. All three pieces should be held together with some pressure, using a high-frequency generator you’ll heat the metallic part. The thermoplastic then softens and turns into a joint when cooled.
- Solvent welding: This method uses a solvent to soften up both plastic parts so all you have to do is press them up together until they become joined as one. This is because the materials are absorbed together as the solvent starts to evaporate.
- Ultrasonic welding: Ultrasonic frequencies are used to make vibratory mechanical pressure which is the heat source.
- Spin welding: For this process you put both plastic parts up to each other and rotate them until the friction causes them to melt and join together, once you stop rotating them they become stable and joined as one piece.
General Welding Duties:
Just about all of a welder’s duties revolve around metal whether they’re cutting, shaping, heating, or fusing, they’re doing it to metal and to ultimately form a final product such as a car part or pipe. A lot of times there will also be problems with parts that need to be fixed like imperfections, indentations or holes. Here are a few general duties to expect should you choose to become a welder:
- Examining and interpreting sketches/blueprints to determine the specifications of a final work piece and how to go about making it.
- Looking for and calculating the dimensions of a work piece that is going to be welded to make sure it is correct
- Inspection of welding materials and other structures being welded and adjusting welding settings appropriately for a nice weld.
- Setting up, maintaining, and operating welding machines
- Diagnosing welding machines when they’re not functioning correctly
Since welders occupy positions in a wide range of industries they can vary quite a bit in their duties but their is a strain of jobs that they follow consistently. There are also a few characteristics that are required to be a good welder and have success in your duties:
- Good hand-eye coordination: You need a stable and precise hand when welding
- Attention to detail and precision: Important so you don’t easily make mistakes that are irreversible and you can detect every little variable that could keep you from making good welds.
- Stamina: Welders do a lot of standing and repeating upper body movements.
- Strength: Welders need to be able to lift and move around heavy pars that need to be welded.
- Spatial IQ: Important so you can easily understand drawings in 2D and 3D.
- Technical skills: Needed to operate different machines and diagnose them when things go wrong which will inevitably happen.
If you are more of a visual learning check out this video which will show you how to MIG weld in real time: