Buying a Plasma Cutter
Plasma cut capacity
Thicknesses and material types you plan to cut
What is the thickness and type of material you plan on cutting? We recommend selecting a plasma cutter with a recommended cutting capacity that matches the material thickness you plan to cut at least 80% of the time.
For example, if most of your work will be cutting ½” material, but you occasionally need to cut something a little thicker (like ¾”) then you should look for a ½” cutting system. The power output of a used plasma cutter will determine the thickness and type of material it can cut. For example, 12 amps from a 120V machine may only be able to cut about 1/8”, but 60 amps on a 230V plasma cutter can cut 7/8” thick in most metals. Galvanized surfaces, coated steel, aluminum are harder to cut than mild steel, so make sure you have enough power for your application.
Plasma cut quality requirements
What kind of cut quality do you need? Rough cuts might be OK if you plan secondary operations anyhow, but if you can get a clean, smooth edge without secondary work, then that is ideal. Better plasma cutters offer a narrow kerf (cut width) which saves on material and provides a smoother finish.
In general plasma system with fewer parts, manufactured to ISO standards is going to be the most reliable. You may also look for a centralized fan configuration to bring cool air in through the center of the system for more efficient, consistent cooling. This can enable a higher duty cycle.
How easy is it to use a plasma cutter?
Some used plasma cutters are easier to use than others. Ask about the process controls that comes on the machine. On the more advanced controls you’ll see onboard DXF import capability, onboard irregular nesting (the software selects the best way to arrange the irregular shapes for fast cutting and reduced material waste), and touchscreen interaction for improved speed and functionality.
What are the operating costs of a plasma cutter?
Plasma is a consumable cost and plasma life can vary considerably from one brand of plasma cutting system to another. The longer the plasma consumable life, the quicker the change-outs and lower costs you’ll have long-term. Some used plasma cutters use patented technology to extend plasma consumable life and also deliver high-quality cuts.
Speed of operation
Plasma cutters might list the cutting speed in Inches Per Minute (IPM). Think about the most common type of job you expect to run on a particular machine and how long it might take to cut each piece. Some plasma cutters operate four or five times slower than more powerful counterparts. Some plasma cutters for sale will have ratings for cutting as follows – quality cut, rated cut and sever cut.
Quality Cut: Good quality cutting of thicker material, takes longer to cut
Server Cut: Able to cut very thick material or up to a maximum thickness. Cutting speed is slow but increases as the thickness decreases – may require post-cutting clean-up
Rated Cut: The best high-quality cut, used for cutting mild and less thick steel, maximum cutting speed, smooth clean cutting result
What is "Duty Cycle" in plasma cutting?
Another factor contributing to the speed of operation is the “duty cycle.” This is the amount of time a plasma cutter can operate within a ten-minute span before needing to cool off. A five-minute duty cycle means it can run for five minutes before needing to cool off for five minutes. For long or deep cuts you’ll want a longer duty cycle, and for small short cuts, a shorter duty cycle can be ideal. If a plasma cutter is to be used frequently, but not continuously for a long period then you can purchase based on the maximum amperage output. The more amperage output, the more duty cycle.
Inverter requirements for Plasma Cutters
Is a built-in inverter needed? If you need to provide mobile plasma cutting services, you will need a plasma cutter with a built-in inverter. These take DC power and feed it through a high-frequency transistor. Usually, these are compact, fast, efficient cutters.
What is the air-supply and air quality requirements for plasma cutters?
Do you need a plasma cutter with its own air-supply? Plasma cutters need an air supply for the cutting process. This may be a bottled gas, like bottled nitrogen or bottled air. Some prefer nitrogen for stainless steel cutting. Do you have an air compressor to use with this plasma cutter, or do you need it to be integral with the machine? Does the used plasma cutter have an air filtration system? Dirt, oil, and dust polluting compressed air will impact the quality of the cut. For smoother and faster cutting and increased torch life, consider a plasma cutter with air filtration.
Hand-held torch vs. CNC plasma cutter
A hand-held torch is great for cutting quickly through sheet metal or gouging and removing defective welds or for back-gouging. It’s good for cutting small shapes from steel plate, however, it does not provide good enough edge quality and part accuracy for most metal fabrication applications. For accurate, clean cuts, use a CNC plasma machine.
Durability of CNC plasma cutters
Most plasma cutters are used in a rough environment. They can be temperamental and unstable or highly reliable. The less stable ones are prone to overheating or having circuitry issues. Per the inspection instructions, you’ll want to smell for burnt wire when testing it and look for signs of previous sparking in the wiring and on the circuit board. More expensive models have better cooling systems, better quality control, automatic shut-off features, more efficient torches higher build sturdiness and better engineering for built-in heat protection.
Cheap vs. Premium plasma cutters
Prices on used plasma cutters for sale vary greatly, from a few hundred dollars to a hundred thousand dollars. You can get basic cutting features on the cheaper units but will lack the maneuverability, automatic air, amperage adjustment options, control features, and ergonomic design found or more premium used plasma cutters.
Types of torches for plasma cutters
Cutting torches for plasma cutters come in two common types. The most common are high-frequency starting systems which create a spark with a high-voltage transformer, capacitors, and spark-gap assembly. This kind of torch has the advantage of not having any movable parts and can be reasonably dependable. Just be aware that they do require occasional maintenance and can interfere with computers and other electrical equipment because of the high-frequency electric noise they create.