Arc welding is an old welding process that is still very popular among professionals and hobbyists.
If you are interested in arc welding then our post today will provide you with all the information you need on this form of welding.
To understand more about Arc welding we will begin by answering the very important question: What is Arc Welding?
Arc welding is the process of using heat that is generated by an electric arc to melt metal and join two pieces together.
It relies on electricity to create just the right amount of heat required to melt metal and transform it to different shapes or bind to another piece of metal.
Different Types of Arc Welding
There are 4 most common types of arc welding: Shielded Metal Arc Welding (SMAW), Flux Cored Arc Welding (FCAW), Gas Metal Arc Welding (GMAW/MIG) and lastly Gas Tungsten Arc Gas Welding (GTAW/TIG).
1. Shielded Metal Arc Welding (SMAW)
This is one of the oldest and most versatile arc welding methods that is commonly used in construction and pipeline work.
It is a no-pressure method where a flux coated electrode supplied by AC or DC is used on the work piece to form an arc. The electrode is then withdrawn but the arc generates on the work piece.
The heat generated from the arc causes the metal to melt, enabling it to bind with other metals as the pieces start to cool and solidify.
In this process slag is formed which protects the weld from oxides and nitrides.
2. Flux Cored Arc Welding (FCAW)
This is a semi-automatic and automatic arc welding process which was first developed as an alternative to shielded metal arc welding.
For this method tubular electrodes filled with flux are incorporated and due to its high weld-deposition rate it is often used on heavy work pieces where thick sections of 1 inch or more need to be welded.
3. Gas Metal Arc Welding (GMAW/MIG)
Used mainly for thin sheets as the heat generated is relatively low, this form of arc welding is simple and quite economical.
Electrodes here often have de-oxidizers to prevent oxidation thus allowing multiple layers to be welded at once.
In this process, argon or helium gas is used to shield the arc.
4. Gas Tungsten Arc Gas Welding (GTAW/TIG).
A tungsten electrode is used to produce the weld which can be performed on stainless steel or non-ferrous metals.
The process is rather complex with the use of the tungsten electrode, argon gas cylinder and DC power supply.
An inert gas atmosphere which works as a flux is created using argon gas or helium to prevent oxide while the heat is produced by the arc created from the electrode.
How an Arc Welder Works
An arc welder or an arc welding machine’s work is to obtain fusion or metal melting by heat where the heat is created by an electric arc.
This is done to join two surfaces together.
Things like water pipelines, electric towers and even cars and buses are welded. The process of welding is often carried out in industrial fabrication and construction of steel structure.
Since the process of welding involves the use of multiple components, an arc welder is not a single unit or machine. It is a set-up of several components that all work together to achieve the final result.
Equipment of Arc Welding includes:
Welding Machine- You can make use of both DC and AC in the process depending on the application. Selection of power source are usually influenced by factors such as the type of metal to weld or the electrodes to be used, floor space, how versatile the equipment is and costs involved.
Welding Electrodes- This is usually a piece of wire or a rod made of metal or alloy and is used to supply the filler metal. The Arc is generated between an electrode and work piece. Electrodes can be consumable or non-consumable.
Electrode Holder- Used to hold the electrode and conduct current to it. It is insulated to protect the hands.
Welding Cables or Lead- Insulated copper or aluminum cables are used to transfer current from the power source through to the electrode holder and to the work piece after passing the arc before finally returning to the power source.
Clamp- Attaches one end of a welding cable to the work piece
Chipping Hamper- Included for the removal of slag
Wire Brush- Used for cleaning the area to be welded
Arc Welding Processes:
Depending on the type of arc welding you choose to perform the process will vary somewhat and so will the use of components.
However, an arc welder generally makes use of an electric arc between an electrode and a work piece to melt metals.
Shielding gas may be used to prevent oxidation but sometimes fluxes or coatings are also used instead of gas.
The welding machine is connected to the power supply and two cables are attached to it.
One cable has the earth clamp attached on one end, used to clamp on the work-piece while the other cable goes through the electrode holder that has the electrode in it.
The electrode lead is placed on the metal to be welded and once the lead is dragged away an electric arc is created.
As the arc melts the metal filler must be fed to the welding joint to give the welds their shape and look.
Advantages of Arc Welding
Arc welding has many advantages for which it is such a popular form of welding.
Here are some of the advantages arc welding has over other welding processes:
- Cost Effective- Most welding machines and equipment involved are affordable and easily attainable. The number of components involved in the process is also less, especially as arc welding can be done without using any gas.
- Versatile- You can perform arc welding even on dirty metal.
- Easy to transport- The equipment involved are very portable so you can carry everything you need and perform the procedures almost anywhere
- Can be set-up at home- There are many arc welders that are designed for home use as the materials are portable and affordable
- Arc welding can be completed without the use of gas thus allowing welding to be completed with any kind of weather or environmental conditions
- It is one of the fastest methods of welding
Disadvantages of Arc Welding
Unfortunately there are also a few disadvantages to this kind of welding method.
Here we share some of its downsides:
- Operators need to be highly skilled- Even though Arc welding can be done anywhere and with very minimum equipment, it is not the easiest form of welding out there. The process requires operators to have full knowledge where the procedures can get pretty complex.
- More waste- When compared to other forms of welding, arc welding leaves more waste in general. On one side the equipments are not too expensive but with increased waste ratio the project costs tend to be high.
- Arc welding cannot be used on some materials- mostly thin metals.
How to use an Arc Welder
We are going to explain some basic steps of how to use an arc welder to melt and join two pieces of metal together.
To start off you need to connect the electrode holder to the welding machine for current supply.
Place the electrode, also known as the welding rod in the insulated electrode holder and turn the handle to secure the electrode firmly inside.
Next turn the machine on and select the accurate amount of current to charge the electrode. Make sure the ground clip is connected to the steel table or the work piece.
Make contact between the electrode and the work to complete a circuit using the electricity that is passed through the electrode holder, down thorough the metal piece and back to the welder through the ground clip.
To strike the arc you must use a delicate flicking motion, similar to lighting a match gently.
You will notice molten metal generated between the two pieces that are going to be joined. This happens when arc is formed.
Once the arc has started you must maintain a smooth molten puddle of metal and in order to do so you need to keep a steady distance between the rod’s tip and the metal piece.
The welding rod will get shorter as you weld because the rod gets deposited into the melting alloy center.
Keep moving the rod laterally and at the same time continue a pushing action into the seam that is been welded.
Ensure that both the metal pieces that need to be joined are heated equally.
When the welding is over, take out the electrode holder and switch of the current supply.
Once the arc welded seam is completed a dark residue will be present on top of the weld- this is formed by the burning flux from the electrode coating.
Use a chipping hammer and a wire brush to clean off of this residue.
Arc Welding Electrodes
Types of Arc Welding Electrodes:
Arc welding electrodes can be categorized into 2 types. They are:
- Consumable electrodes
- Non-consumable electrodes
When an electrode is ‘consumed’ in the process of their use it is said to a consumable electrode.
These electrodes change in structure and are usually coated with flux to protect the arc and the weld and prevent oxidation.
Consumable electrode is usually made as anode to produce a deeper weld as anode always has a higher concentration of heat. This way the electrode melts faster and fills the gap in the work piece much quicker.
Metal inert gas welding uses this type of electrodes for the process of arc welding.
With a high melting point, a non-consumable electrode does not fill the gap in a work piece.
Usually in this case the work piece needs to have a low melting point or a filler metal that has a low melting point needs to be incorporated.
Opposite to consumable electrodes, non-consumable electrodes are made cathode while the piece to be welded is made anode.
Gas tungsten arc welding is one type of arc welding method that uses non-consumable electrode made of tungsten or inert and separate filler.
Arc Welding Safety Rules
Although an arc welder is one of the most widely used welding equipment, it can cause serious injury if not use properly.
By following some basic rules, operators can be safe from harm and the risks of accidents can be reduced to a great deal.
- Wear proper protective gear- it is most essential to protect the eyes by wearing a welding mask during the task. Gloves and full sleeved clothes should also be worn at all times to cover exposed skin.
- Read the safety manual- If you have never used an arc welder before then this is a must. Even experienced operators are encouraged to always refer back to the manual to know more about the warning labels and other important information about the equipment.
- Do not touch the electrode or work without an electrode holder and avoid any contact with the internal circuits while the unit is charged.
- Maintain your equipment and check for faulty parts- Over using the machine can cause damage from overheating so know when to give your machine a rest. Also check for frayed cables.
- Ensure that there is proper ventilation in the workspace
- Keep your workplace neat and tidy to prevent clutter. The area you set up your work station must be dry and free from any harmful elements.
To conclude this post we would like to remind our readers that it is important to know everything there is to learn about arc welding before attempting to operate an arc welder because in order to conduct the process safely and successfully one needs to be highly skilled and have maximum knowledge on the works involved.
Starting from purchasing the right arc welder to completing a welding project requires a lot of planning and effort so if you are truly interested in arc welding then be ready to invest in a lot of time and first learn the basic fundamentals of the welding process.