Cutting metal is always a challenging task. By its very nature, metal is made to be strong and sometimes thick. It’s built to last. This is why two kinds of high-powered cutting tools were devised – flame cutters and CNC plasma cutters. These two are the big guns in cutting, allowing a user to get through metal that cannot be bent or even lifted by a person.
But what’s the difference between the two? And when is it best to use them? Today we will answer these questions and determine which is best for a given project.
What is Flame Cutting?
If you have seen an engineer cutting metal with a blowtorch, you have seen flame cutting. This technique uses a compressed jet of air and flame to cut through thick pieces of metal. The devices consist of two tanks – one of fuel and one of compressed gas, usually oxygen, which earns it the nickname “oxygen cutting.”
It is commonly believed that flame cutting does so due to heat, but that is not entirely true. The flame, heat, and oxygen combination creates a jet that oxidizes the metal on contact. The high pressure makes flame cutting a fast and hot process, doing in seconds what nature would do in years. While the torch will heat a piece of metal to over 1800°F, it is more accurate to say the metal rusts away. The oxygenated metal is blown away as dross from the cut, leaving the once-whole piece in two.
What is Plasma Cutting?
Plasma cutters use a tank of compressed gas as a medium to cut. A jet of this gas is fired against the cutting surface, and an electric current is passed through it simultaneously. This current turns the high-pressure gas into plasma, a state between liquid and gas, reaching temperatures up to 30-40,000°F. However, this gas could be any of several types, including oxygen or nitrogen, but what matters is that it must be conductive.
The combination of high speed and temperature from the plasma jet essentially incinerates whatever is in its way. The metal instantly turns to slag, and a curtain of gas emitted by the cutter protects the cutting area, leaving behind a neat cut.
Flame vs. Plasma
Due to the nature of the two cutting methods, each has a type of cut they are ideal for and a type they aren’t. Here are four questions to ask yourself before you decide which one to use.
What are You Cutting?
The main rule for using a plasma cutter is that the material has to be conductive. This is vital as the electric arc that converts the gas into plasma must first form a circuit with the cutting surface. This means it is great for metals such as aluminum, steel, brass, or copper.
The intended cutting material for flame cutters is mild steel or iron, as these metals oxidize well; however, there are a few exceptions. Due to the heat of a flame torch, it is possible to force your way through thinner pieces of aluminum or stainless steel. This is not ideal, however, as the cut will be ragged and ugly due to the cut being more of a melt. On the other hand, you don’t need to worry about conductivity when using flame cutters, as they work best on metals capable of oxidizing.
Flame cutters are also better suited to cutting through thicker metals than plasma. Thanks to the speed of oxidation the torch causes, it is simple work to cut through metal up to 4-inches thick. Plasma cutters, by comparison, cut well through thinner metals, typically between 3-4 inches thick.
If you work with thin metals for a project, then plasma cutting is the better option. Flame cutters could do the work, but the results will be far neater and more accurate with a plasma cutter. For larger jobs involving thick pieces of metal that don’t need to be laser-precise, flame cutters are a great option.
Where are You Cutting?
Another thing you’ll need to keep in mind is the location of the work. While you can do some jobs from the comfort of a workshop or garage, some projects require you to visit the factory or work in another area on-site.
If you have a task that can be brought to you, then plasma cutters will work fine. Unfortunately, a plasma cutting rig will require much more input, such as a source of electricity, to work. This means they are best for the job if you can use them from your main workshop.
Flame cutters consist of a pair of tanks connected by feed hoses. The only equipment needed to use them is a spark, which usually comes with the tanks. This makes it highly portable and easily maneuverable, so a flame is your go-to choice if you have to go somewhere to cut.
What’s Your Budget?
If you’re the kind of person who has to make many cuts over the long term, a plasma cutter will be much more affordable. Cutting using a plasma cutter is significantly faster than a flame cutter, meaning you will get much more done more efficiently. The initial purchase costs of a plasma cutter are more expensive than flame, but in the long term, it pays out. One plasma cutter can easily accomplish the work of two or three flame cutters.
What Quality of Cut Do You Need?
As mentioned before, a flame cutter can certainly cut through many materials, but if you’re looking for a neat and precise cut, you’ll need plasma. When it comes to thicker materials, a rough cut can be easily compensated for, but precision and neatness are key for thinner materials. If your project requires clean edges and thin materials, you need plasma, but if you’re trying to hack through metal, a flame cutter has your back.
Flame and plasma cutting have greatly improved our ability to cut through previously uncuttable materials. There will never be a day when one or the other becomes obsolete, but they certainly have their niches regarding cuts. Make sure you properly consider what you need for your next project and make the best choice.