Welding has been around since time out of mind, and it has come a long way since August De Meritens used arc heat to fuse two metal pieces. Thanks to technological advancements over the last few decades, welding metals has never been more efficient and easy. A big part of that can be attributed to arc welding.
Arc Welding: What is it?
Arc welding is a welding method that uses an electric arc to generate heat. That heat is then used to melt or meld metals. By using a power supply, you can use direct current (DC) or alternating current (AC) to create an electric arc between a base material and an electrode (consumable or non-consumable). Of course, a power supply has to generate enough heat (around 6500° Fahrenheit). to melt two pieces of metal and fuse them.
How does arc welding work?
Arc welding aims to fuse metals, and you need a welding machine to do that. As the power supply creates an electric arc that is hot enough to melt metal, you can guide the electrode holder along the gap line while the electrode continues to generate the current that helps produce the filler metal to the said gap.
When metal undergoes extreme temperatures while in contact with oxygen and nitrogen, chemical reactions occur. This is what the arc is for. But the arc does more than that. To facilitate the welding action, the arc provides a protective gas to reduce contact between the molten metal and the air. Once the molten metals have cooled down, you get a metallurgical bond that fuses the metals.
Different types of Arc Welding
There are many different arc welding methods, and the right one for you depends on your objectives and the materials you’re working with.
Let’s go over them one by one.
Metal inert gas welding (MIG) is a fusion welding method that feeds a consumable electrode to a metal piece. MIG welding can either be a metal inert gas or metal active gas. For metal inert gas, you use a chemically inert gas (i.e., helium, argon, etc.) as a shield that helps maintain the arc.
MIG welding is done by using a spooled wire electrode via a spool gun. The gun releases a shielding gas that protects the shielding area from the atmosphere, which prevents the formation of oxides in metals.
MIG welding has its share of advantages and disadvantages. Let’s break them down to see if MIG welding is the right method for you
Tungsten Inert Gas Welding (TIG)
TIG (Tungsten Inert Gas) welding uses a non-consumable tungsten electrode heated at extreme temperatures to meld parent metals. Once two metals are fused, the tig welder dabs the material onto the weld puddle.
FCAW is a method of arc welding that utilizes flux-filled electrode tubes to create electric arcs. The tubes emit flux shields to create a barrier against the air, helping to maintain the electric arc. This type of arc welding has a high weld-metal deposition rate, making it the ideal method for welding thicker sections of metal (those that are more than an inch thick).
Plasma arc welding (PAW)
This method uses air ion generators to emit hot plasma jets in the direction of the welding area. Jets released via PAW are extremely hot, which creates an ideal environment for welding narrower and deeper welds. PAW is also the recommended method if you want to speed up the welding process.
Shielded metal arc welding (SMAW)
This arc welding technique uses coated electrodes to generate an arc. Once the heat causes the coating and the tip of the electrode to melt, the alloy slowly solidifies, which facilitates the forming of the weld. This method is ideal for construction work.
Submerged arc welding (SAW)
This method uses a granular flux to create a dense layer that covers the molten metal. SAW allows for deeper penetration of heat, not unlike what a thermal insulator does. If you prefer a welding technique that does away with sparks and spatter, SAW is your go-to welding method.
What are the differences between TIG and MIG welding?
The two most popular arc welding methods are TIG and MIG welding. Chances are, you’re stuck trying to decide which method to use. Let’s break down their major differences to help you decide.
One major difference is the method used. As already mentioned earlier, MIG uses a wire electrode to feed the weld while TIG welding uses a filler material. If you want to do it fast, MIG is the way to go. But if you want a refined finish, you’re better off using TIG.
The best method also depends on the thickness of the metal. MIG is the better choice if you’re working with thicker metals while TIG is preferred for thinner metals.
You’d do well to use MIG if you’re not experienced at welding. If your skill is at the professional level, then you can leverage that skill by using TIG. TIG is also much more expensive than MIG.
To help you make an informed decision, let’s break down the pros and cons of each method.
TIG Welding PROS
- Welding work is more precise
- Provides high-quality finishes
- Allows you to weld a wide range of materials
- Requires small amounts of flames
- Works well with thin metals
- Resistant to corrosion
- Weld beads are visually pleasing
TIG Welding CONS
- Takes longer to do than using a MIG welder
- Complicated for most beginners to learn
- Welding surface needs to be kept clean
MIG Welding PROS
- Welding is done faster.
- It can be used on a wide variety of metals and alloys.
- Spatter is minimized.
- Easy to learn
- Not a lot of spatter
MIG Welding CONS
- A little expensive
- Not fit for outdoor welding
- Cools fast
- Positioning is limited
- Doesn’t work well with thicker metals
What are the advantages of arc welding?
Now that you know how arc welding works, you might already have an idea or two about its advantages. However, your mind is probably not made up yet on whether this method is for you. Will it be worth it? Here are the advantages of arc welding you should look forward to:
- Portability. Welding materials and equipment are lightweight and easy to move around.
- Affordability. There’s no need to use expensive machinery. You can carry out the process even on a shoestring budget.
- Refined finish. You get a neat and refined result due to the mechanized nature of the welding process.
- Less spark and spatter. When we think of welding, we see a person, his face covered with a thick welding mask, sparks flying in front of him. That’s not the case with arc welding, where a lot less spark, spatter, and smoke is produced.
- Faster welding process. Because of the concentrated heat it produces, arc welding is much faster.
- Distortion is reduced. Most beginner welders struggle with distortion, which is caused by a disfigured base plate following extreme heat. Weld distortion is troublesome because it can compromise the structural integrity of a weld. The arc welding process, however, reduces much of the distortion because of the faster process and the higher concentration of heat.
- Resistance to corrosion. Arc welding produces a welding joint whose properties are non-corrosive. As a result, you don’t need to employ anti-corrosion methods when doing arc welding.
- Welding joint doesn’t break easily. The welding joint has high tensile strength than normal welding and therefore doesn’t break easily.
How to Arc Weld
Now that you have a basic idea of how the arc welding process works, let’s dive into the procedures on how to do it.
Word of caution: When properly installed, using an arc welder is relatively safe. However, it always pays to be safe. The improper use of an arc welder can expose you to potential hazards such as electric shock, heat stress, noise, noxious fumes, fires, burns, etc. Make sure to wear proper safety gear before you proceed.
Equipment for Arc Welding
- Welding Machine (welding equipment can either be A.C. or D.C.)
- Cables or Leads
- Electrode Holders
- Cable Connectors
- Chipping Hammer
- Wire Brush
- Protective Gear (welding gloves, work boots, welding shield, welding apron)
1. Create a weld
You need to create a serviceable weld to ensure a smooth welding process. First, you need to strike a successful arc between the workpiece and the electrode. Once that’s done, create a bead by guiding the electric arc between the pieces. Then move the arc back and forth along the path of the weld until the metal achieves your desired width for the bead. Next, remove the melted slag from the bead until the molten metal looks refined enough.
2. Make the preparations
Next, you need to gather round all the tools, materials, and equipment you need to perform arc welding. These include your arc welding machine, cables, clamps, electrodes, and metal pieces. Make sure that your work area is secure and safe. The table should be made of non-flammable material or steel.
3. Prep your weld
Grind a sharpened edge to the sides of the metals that are to be joined to give the weld arc more room for melting the sides of the metal pieces. Remove any dust, dirt, grease until you have a clean slab of molten metal.
4. Clamp the metal pieces together
Any clamp (i.e., spring-loaded clamps, lock pliers, or a vice) will do as long as it can hold the metal pieces together firmly.
5. Secure the clamp to the large stock being welded
Ensure that the work piece’s grounding is clean to complete the electrical circuit with the least resistance possible. This allows you to create an electrical arc with minimal effort.
6. Pick the right rod and set the amperage range
Put the electrode in the stinger and see to it that the electrode holder is set firmly at the end of the electrode.
7. Turn on the welding machine
You’ll hear a humming noise from the power supply as soon as you turn your welding machine on. Take the time to examine if the cooling fan is running.
8. Hold the electrode holder and aim the tip of the rod towards the metal plate
Make sure the tip of the rod is within a few inches of the metal workpiece. Give it a few practice taps to ensure that you got the positioning right. Caution: You’d want to protect your eyes when striking an electric arc so make sure that you have your welding mask on.
9. Tap the electrode against the metal piece’s surface
This can get tricky since the recommended distance between the electrode’s piece and the metal piece depends on the diameter of the electrode and the machine’s amperage settings. But you’ll know you got it right once the machine is able to generate a continuous arc. See to it that the arc’s gap does not exceed the electrode’s diameter. Once you’re able to keep the arc steady, gently guide the rod along the area you want to weld. You’ll start to notice the metal melting away. You can begin creating your weld once the pool is filled up.
10. Maintain the electric arc
You need to establish the arc as you move through the weld you’re building. Don’t move the electrode away from the metal piece’s surface or you’ll lose your arc. If you do, stop what you’re doing and remove the slag from the metal piece. You need to do this to protect the weld from contamination.
11. Set your welding machine’s amperage
How many amps do you need? That depends on the type of material you’re welding. Make sure that you reduce the amperage if you see craters starting to form at the edges of the bead. Turn up the amperage if you’re having difficulties maintaining an electric arc.
12. Clean it up
Clear away any slag or dirt once you’re done. Do this not only because it makes the finished product look better, but also because it’s good preparation for paintwork. You can remove any remaining slag or dirt by rubbing at it with a wire brush or a rough file. You can also use an angle grinder if you want to remove a piece of the weld.
13. Put a primer on it
A fresh weld can get corroded if exposed to the elements. To keep the rust away, apply an anti-rust primer along its surface (preferably one in a spray can).