Laser Cutting vs. Plasma Cutting: A Complete Comparison
Here at Red-D-Arc, we talk a lot about welding, the act of taking two pieces of material and joining them together. Often, though, you aren’t just welding; you’re separating materials, whether to fix a mistake, to disassemble scrap, or to fabricate smaller parts used for later welding purposes.
There are plenty of different ways to cut apart materials, even metals. There are saws, grinding wheels, shears, and other machines that can near-effortlessly slice through all but the strongest metals. With modern technology, though, two techniques stand out: plasma cutting and laser cutting. How do these two work, how do they compare, and which is better for a given purpose? Let’s analyze them and find out.
How Laser and Plasma Cutting are Similar
First, let’s start with the similarities between laser and plasma cutting.
Primarily, the similarity is in the mechanism they use to cut materials. They are both known as “thermal cutting” methods, which means they use high, intense, directed heat to melt/burn through material, leaving a gap that becomes a cut. This is opposed to more mechanical methods, where friction or gouging is used to remove material.
Both plasma and laser cutting are powerful tools and are well-suited to precision applications. They are ideal for computer-controlled guidance, particularly programmed CNC cutting. This is how many complex, bespoke shapes are cut from materials and how vast amounts of repeated fabrication can be performed rapidly.
While both work in similar ways and can serve similar purposes, there are some distinct pros and cons of each method that can make one more ideal than the other in specific circumstances. Let’s dig deeper.
What is Plasma Cutting, and How Does it Work?
Plasma cutting may seem like some futuristic technology, but in truth, it was first invented back in 1957. In the subsequent 60+ years, many advancements have been made to the technology, both in plasma cutting itself and in the surrounding mechanisms like computer and robotic controls.
How does it work? In prosaic terms, it can be described as capturing a tornado in a torch and electrifying it. Essentially, an electric arc is generated by a cutting torch. Meanwhile, a particular kind of gas, usually an inert gas like argon or nitrogen, is pushed through the torch in a spiral. The gas passes the arc and becomes electrified and ionized while also heating it to a temperature as high as 20,000 degrees C. Scientifically speaking, it’s no longer even gas but the fourth high-energy state of matter, plasma.
This superheated ionized gas/plasma is then pushed out of the torch by the pressure of the gas behind it and its own thermal expansion. This gas is directed and focused on the specific narrow area where you want to cut, and it rapidly melts the material in that area. The force of the gas blows away the molten material, leaving a void and cutting through the workpiece.
One of the biggest caveats to plasma cutting is the electrical arc. This arc, much like arc welding, is generated by the connection and short-circuit between the torch and the workpiece. As a consequence, only conductive metals can be cut with plasma torches. It’s excellent for cutting steel, aluminum, brass, or copper but doesn’t work on materials like wood, ceramic, silicon, or plastic.
What is Laser Cutting, and How Does it Work?
Lasers have been part of public consciousness for decades, and while using high-powered lasers for cutting and other purposes has been the realm of science fiction for a very long time, the reality is that they’ve also been usable as tools since 1965. This makes them only slightly newer than plasma cutters.
Laser cutting is, on the face of it, very simple. A laser itself is just light, concentrated, and focused. The way that light is generated, directed, and focused may vary. Common lasers include CO2, Neodymium, and fiber laser systems, with varying power ranges and usability. Simple weak lasers can be the size of a battery and are used to play with cats; meanwhile, the most powerful laser in the world currently is the Vulcan 20-20, which is capable of generating a laser with 20 petawatts of energy. Obviously, this is not for use as a cutting tool but rather as a research device.
Fiber lasers, crystal lasers, and other kinds of laser generation systems have their own kinds of pros and cons, but for the most part, they are used in very specialized use cases or in research and scientific experimentation rather than for simple industrial cutting and fabrication. This is because they tend to be larger, more fragile, much more expensive, more elaborate, and prone to failure, and generally don’t have the benefits to outweigh those drawbacks.
The majority of the time, a laser you get for production cutting will be a CO2 laser. In these lasers, a mixture of gasses, including CO2, helium, and nitrogen, is contained in a vessel. This gas mixture is stimulated with an electrode, which excites the CO2 molecules and causes them to emit photons. With enough CO2, this process generates enough photons to create a high-energy laser capable of cutting.
Unlike plasma cutting, laser cutting can be precisely tuned and can be used for cutting, engraving, surfacing, and other finishing. It can cut conductive materials like steel, brass, and aluminum, but since it doesn’t require an electrical connection with the workpiece, it can also cut nonconductive materials like wood, silicon, ceramic, and more. It can also cut metals that are more difficult to cut using plasma, like tungsten and nickel.
So, how do the two kinds of cutting tools compare?
Comparing Plasma and Laser Cutting Tools
Let’s run down a variety of considerations and compare laser and plasma cutters along each axis.
Laser beams can be very concentrated and precise. This makes them much more accurate in general than plasma cutters, which are comparatively high energy and less focused. Plasma cutters tend to have a larger kerf for the cut, meaning they leave a larger hole in the material and have less precision.
Since they remove more material, they also create more residue and slag than laser cutters. Lasers are better for precise and delicate tasks, as well as non-cutting uses like engraving.
Laser cutters, as a form of directed energy, can cut anything that absorbs photons. Plasma cutters, since they rely on electrical conduction with the workpiece, can only cut conductive materials. The disadvantage of laser cutters here is that some metals are highly reflective; they don’t absorb much, if any, photons, so they are very difficult or impossible to cut using lasers, which are essentially reflected away from the material.
Another area where plasma cutters surpass laser cutters is in cutting thick materials. Most common laser cutters can only cut materials up to about 19mm thick with reasonable speed, accuracy, and efficacy. Meanwhile, plasma cutters can easily cut through materials up to 38mm thick without issues.
That said, more powerful lasers can do much more. Strong lasers exist that can cut through pretty much anything, no matter how thick it is, and can even cut materials from over a mile away. These are, obviously, not practical; they’re more being developed as military weaponry and scientific experiment equipment than manufacturing tools.
Plasma cutters follow the same basic design as welders. In fact, many advanced welding machines can also do plasma cutting with the flip of a switch. In contrast, laser cutting is almost always handled using a robotic CNC machine, and there are virtually no handheld laser devices. Things like this are the closest you can get, and they are designed for engraving, not cutting.
Lasers are faster at cutting most materials and use less energy to cut an equivalent piece of material, which makes them a more energy-efficient option.
Many consider laser cutters to be better for the environment than plasma cutters for this reason.
Cost is one of the biggest differentiators between laser and plasma cutting.
Laser cutters are typically expensive. The most simple, low-powered, hobby-grade machines can range between $500 and $4,000; meanwhile, industrial-use laser cutting systems can be as much as $200,000. The sky is also truly unlimited; as linked above, the massive research laser costs billions.
Plasma cutters are often somewhat cheaper to get started. Introductory-level handheld plasma cutting systems can be as little as $200-$300. Much larger systems, including industrial CNC machines, can be between $5,000 and $20,000. Past a certain point, as well, you’re paying more for the surrounding robotics and other equipment than for the plasma cutter itself.
Operating costs, however, swing back in the favor of lasers. Despite the higher outlay, laser cutters cost less in terms of energy to operate, and they have virtually no consumables compared to plasma cutters. Plasma cutters require more energy for comparable cuts, and they require consumables in the torch and the gasses used to generate the plasma.
As with any application of high energy, safety can be a primary concern. Both laser and plasma cutting use high heat and energy to cut materials, which can lead to molten metal or other materials spattering around, sparks showering the area, and fumes generated by burning material in the air.
Plasma cutting is worse than laser cutting in two regards.
The first is that because it uses a shielding gas to generate plasma, in addition to the usual fumes, your machine is also putting that argon, helium, nitrogen, or whatever else into the atmosphere. This is an additional potential hazard, and while these gasses aren’t directly toxic, they can cause problems with oxygen displacement and other hazards.
The second is radiation. The high-energy generation of plasma sheds a high amount of radiation into the atmosphere surrounding the cutting application. This isn’t an extreme hazard akin to Chornobyl or anything, but it’s still a potential danger, especially to long-term users. It can also damage eyesight and cause surface burns to skin akin to sunburn. On top of that, this radiation can cause interference with electromagnetic signals like radio, WiFi, and other technologies and can damage nearby electronics.
Many of these hazards can be addressed. Proper use of PPE, along with the facility using proper ventilation, fume extractors, downdraft tables, and other equipment, can make it much safer to operate.
Additionally, the use of CNC and robotic machines to perform operations rather than using handheld operations manually improves safety dramatically. Enclosing a workpiece in a machine with ventilation and shielding is always safer than performing the task by hand.
Other Kinds of Cutting
There are, of course, a variety of other cutting methods beyond just plasma and laser cutting. Vaporization cutting, thermal stress cracking, reactive cutting, waterjet cutting, and oxyfuel cutting are all potential options depending on the kind of fabrication you’re doing, the precision and thermal needs you have, and how repetitive the cuts you need to make.
If you have questions about them, feel free to ask in the comments.
Which is Better: Laser or Plasma Cutting?
At the end of the day, both laser and plasma cutting have benefits that make it unclear which one is truly better. Laser cutting excels at precise cuts and the ability to cut materials that aren’t conductive metals. However, the initial expense is higher, the lack of handheld flexibility makes it worse for one-off jobs, and the comparative inability to cut thicker materials can be a significant hindrance.
Plasma cutting, meanwhile, is a cheaper and easier-to-use process, and there’s a perfectly viable option to get welders who can also do plasma cutting quickly and easily. While it can be more hazardous to the safety of the operator, it can also be automated, but the flexibility and relatively inexpensive nature of the machinery make it ideal for smaller and mid-size shops that don’t need large fabrication banks.
When it comes right down to it, though, it depends on what you need to cut, how often you need to cut, and if you need additional features like engraving or welding. You’ll simply need to evaluate your circumstances to determine which is the better investment.
That said, if you need handheld plasma cutting, we’re here for you. Our range of rental equipment includes a variety of plasma cutters at various levels of power and capacity. You can rent and try out plasma cutters and decide from there if they can do what you need or if you should explore laser-cutting options instead.
If you’re not sure which you need, you can always contact one of our experts! We’re standing by to help you out with your next project.
Red-D-Arc Welderentals™ an Airgas company rents and leases welders, welding positioners, welding-related equipment, and electric power generators – anywhere in the world. Our rental welders, positioners and specialty products have been engineered and built to provide Extreme-Duty™ performance and reliability in even the harshest environments, and are available through over 70 Red-D-Arc Service Centers, strategically located throughout the United States, Canada, the United Kingdom, France, and the Netherlands, as well as through strategic alliances in the Middle East, Spain, Italy, Croatia, and the Caribbean. From our rental fleet of over 60,000 welders, 3,700 weld positioners, and 3,700 electric-power generators, we can supply you with the equipment you need – where you need it – when you need it.