Cutting metals with precision is a long, tedious process, even more so if you’re dealing with thick lumps. Using saws or angle grinders can only do so much. If you want to speed up the process of metal cutting and want to produce highly accurate metal pieces, then it’s time for you to consider using a plasma cutter.
Plasma cutters are known for their high-precision and efficient cuts. Moreover, unlike other metal cutting tools, plasma cutters aren’t likely to leave “dross,” ensuring that you’re getting a polished product after the work is done.
While having a plasma cutter as your primary cutting tool is highly convenient, you must familiarize yourself with its basic operations before you start using one.
In this blog post, you’re going to learn some basic information on how does a plasma cutter work, how you can hook it up, which gases to use, and the steps you need to take to cut metal pieces with it.
How does plasma cutter work?
A plasma cutter, first and foremost, is a welding tool that is used to cut materials. It does this by producing plasma, which is formed after combining compressed gas with a high-voltage electric arc. By transmitting the electric arc and the compressed gas through a narrow opening (nozzle), the gas reaches a temperature so high that it enters a 4th state of matter. Moreover, this compressed gas runs at very high speeds, allowing it to cut through molten metal.
Awesome, right? You can think of the plasma cutter as a more realistic version of the lightsaber from the Star Wars films. But you don’t have to train like a Jedi Master to wield it. As you’ll soon discover while reading this article, using a plasma cutter isn’t so hard if you know the proper procedures.
Before we go there, let’s talk a bit about why using a plasma cutter is one of the best decisions you can make as a welder.
The advantages of using a plasma cutter
So, why use a plasma cutter? Because it offers many advantages over other cutting tools, that’s why.
Let’s go over these advantages below:
1. It cuts fast
Using a plasma cutter is a great time saver. Did you know that most plasma cutters can generate 40,000°F? With that amount of heat, don’t be surprised if you’re able to cut through metal like a hot knife through butter.
2. Easy to use
When you’re using a plasma cutter, extensive training is not required. Spend a couple of hours using it and it will feel like you’ve been using it for years. You see, the operations of a plasma cutter are pretty straight-forward. Before you know it, you’re making perfect cuts with that thing like a real pro.
3. No warping
There’s no warping because the heat-affected zone is smaller.
4. It’s safer to use
Plasma cutters are relatively safe. Why? Because they don’t have to use any flammable gases to do their thing (unlike with oxy-fuel torches).
5. It’s cost-effective
You might be surprised to know that creating plasma doesn’t require a lot of energy. This saves you a lot of money on energy costs. Most plasma cutters also won’t require any preheating, cutting your energy consumption even further.
6. It’s versatile
The plasma cutter can cut through almost anything, including copper, carbon steel, cast iron, nickel alloys, stainless steel, and more. And it can do so even with various thicknesses and with different types of metals.
7. It’s very precise
Plasma cutting allows you to cut non-ferrous metals as well as thick sheets of steel. This is due to the plasma system’s ability to concentrate its energy in a small area. And by increasing the density of the plasma, a plasma cutter makes it easy for you to make highly precise cuts.
How do you hook up a plasma cutter?
Are you ready to start that thing?
First, connect the compressed air to the air filter that can be found at the rear of the plasma cutting machine. Keep in mind that the compressed air could be bottled, a small air compressor, or a built-in air compressor. Either way, your plasma cutter unit probably has an in-house regulator that can regulate the system’s airflow.
Next, set the amperage of your plasma cutter to the recommended levels. Set the amperage too high and the workpiece will become too hot and will start to gather waste materials. Set it too low and your cutting is bound to get sloppy. You don’t want to do either, so turn up the amperage and make some practice cuts to get a feel of things. Then turn it down slowly and stop once you’re comfortable with the travel speed.
The end goal here is for the plasma to have the right amount of heat and to travel at the correct speed. This way, you can make precise cuts with less dross, which can result in a more refined finish.
What kind of gas do you use with a plasma cutter?
There are several recommended gas for plasma cutting. Let’s go over them one by one. We’re also enumerating their pros and cons to help you decide which one is ideal for your welding project.
Compressed air is the most widely used gas for plasma cutting, especially for lower currents. This gas is ideal for metals that are around 1-inch thick. Many also choose compressed air for plasma cutting because it’s more than enough to create a strong electrical spark that produces a plasma jet.
- Efficient at cutting stainless steel and aluminum
- Minimal chipping during the cutting process.
- Effective at cutting thin metal sheets with smooth surfaces
- Difficult to make incisions deeper than ½”
If you want high-quality cuts on carbon steel that is at least ¼- inch thick, you can’t go wrong with using oxygen. Oxygen also delivers when it comes to precision cutting, not to mention that it has properties that make dross easy to remove. You can still use oxygen on aluminum, though you might end up with a rougher cut face if you aren’t skilled enough to pull it off.
- Requires minimal effort
- Can be used with other fuels
- Can generate extremely hot flames
- Can cut fast
- The intense heat makes cutting soft metals tricky
Oxygen, combined with pure air as a secondary fuel, can create an extremely stable plasma, making it reliable for thick mild steel cuts. Moreover, it cuts metal with stunning precision and leaves little to no debris.
- Oxygen and air are not expensive
- Effective when cutting thick sheets of metal
- Makes highly precise cuts
- Poor results when cutting shiny metals like aluminum
Planning to cut a lot of aluminum and stainless steel? Nitrogen is where it’s at. It’s especially great when cutting metallic pieces that are up to 3-inches thick, especially when you want to create a polished product with a smooth, shiny surface.
Another great thing about hydrogen is that it produces high-precision cuts despite its economical use of plasma. It’s also equally effective when used as secondary gas during the cutting process.
- It’s cheap (nitrogen is abundant in the atmosphere)
- It can be used as a secondary gas.
- Effective when cutting thick sheets of metal
- Can make high-precision cuts
- Cuts slower than most gases
Hydrogen is a great conductor of heat, making it ideal for creating extremely hot plasma flames. Despite this, hydrogen has dissociative elements that speed up the cooling process on smoother metals. This gas is also effective in cutting non-heavy metals like aluminum and stainless steel.
- High thermal conductivity
- Cheap utility and storage
- Can be used with a variety of secondary gases such as carbon dioxide, water, and pure air
- Fast cooling
- Can’t be added to other plasma gases during the plasma cutting process
- Low kinetic energy
Argon is an inert gas, which explains why there are no chemical reactions when metal makes contact with it. This is why cutting metal using argon as the main compound allows for polished, smoother cuts.
- Kinetic energy is high, resulting in high precision cuts
- Low-ionized plasma beam speeds up the cutting process
- Can be paired with a variety of secondary gases, including water, carbon dioxide, and pure air
- Works well with thin metal sheets with shiny and smooth surfaces
- Has poor conductivity
Argon hydrogen is the recommended gas for cutting stainless steel and aluminum pieces that are up to 1/2 -inches thick. The right mixture for argon hydrogen is 35% hydrogen and 65% argon. Thanks to argon hydrogen’s hot plasma gas, this compound helps speed up the cutting process by a great deal. So much so that it can easily cut through 6” of stainless steel plate. This gas compound is also the best choice for plasma gouging on any material.
- Produces a nice big flame
- Generate intense heat that can cut thick sheets of metal efficiently
- Can create clean, refined cuts especially when nitrogen is used as a secondary gas
- Results in shiny surfaces
- Argon can be expensive (it’s a rare gas)
- Causes occasional chipping and cracking
- Effective only in controlled settings
What air pressure is required for plasma cutting?
Getting the air pressure right is an important aspect of plasma cutting. If the air pressure is too high, the plasma is likely to blow up. If it’s too low, then your plasma won’t be strong enough to do any cutting.
There are no hard rules as to how much air pressure is required for plasma cutting given the different requirements between plasma cutting devices. For example, for most Everlast products, the recommended amount is anywhere between 55 to 70 psi. Most manuals, however, recommend anywhere between 70 to 150 psi. For low amperage cuts, the required amount is 45 psi and below. Some plasma cutters have internal regulators, and the recommended amount of air pressure for them is between 60 and 80 psi.
Simply put, if you want to know the recommended amount of air pressure for your plasma cutter, it’s always better to refer to the manual that came with the unit. That doesn’t mean you have to follow it blindly. In the end, it’s up to you to determine how much air it takes to efficiently cut the workpiece. If a certain amount is working for you and you’re getting great results out of it, then why not stick with that?
How to Use a Plasma Cutter
Okay, let’s get to the heart of the matter. How do you use a plasma cutter? Here are the steps to do just that.
1. Choose a work station
Cutting metal can be a hazardous job if you’re not doing it on a safe surface. You need to pick a sturdy table that can support your materials and equipment and keep them in place. Also, pick a location that gives you a lot of wiggle room to move. Make sure the work area is clean. After all, dust and debris may be sucked by the plasma cutter’s cooling fan and may damage the unit as a result.
2. Plug the plasma cutter to a power supply
Make sure that the plasma cutter unit is turned off before plugging it in.
3. Connect the plasma cutter to the air compressor
If your unit doesn’t have a built-in compressor, connect the external air compressor instead.
4. Turn on the air compressor
Most compressors have the power switch at the rear. Turn it on and wait for the tank to fill.
5. Attach the ground clamp
Securing the ground clamp will keep you safe while using a plasma cutter. Plasma cutting, after all, emits potentially harmful electrical charges. Make sure that the ground clamp is attached to the area close to where you’re going to make cuts.
6. Turn the unit on
The switch might be found at the rear of the unit. Turn it on and wait for the interface to light up. You’ll notice the air compressor start to engage by then.
7. Set the amperage
The thicker the material, the higher the amperage should be.
8. Start cutting the workpiece
As you cut through the metal, make sure that the nozzle is on top of the metal’s edge. Turn the trigger on to create an arc and then slowly move the torch back and forth over the metal.
9. Turn off the plasma cutter unit
Once you’re done, turn off the unit.
10. Unplug the ground clamp from the metal
11. Turn off the air compressor
In most plasma cutters, you simply need to rotate the lever 90 degrees to turn it off.
12. Leave the torch to cool
Done with the cutting? Great job. Now it’s time to let the torch cool off. Once the trigger is released, arrange the hoses and make sure the torch, ground line, and airline are all wrapped up.