How accurate is plasma and what kind of cut and edge quality can I expect?

This question is not a simple one. As a general rule, accuracy will vary based on the capabilities of the plasma system, the cutting process used, and how it is set up. For instance, the accuracy of a hand-held plasma system will be different than the accuracy of a plasma mounted on a CNC cutting table, and within the broad range of automated CNC plasma systems, high-definition plasma will always be more accurate than light-industrial and entry-level plasma systems. Expectations about cut quality need to be realistic and relate specifically to the plasma cutting system being used and the application.   

What is plasma cut quality?

Plasma cut quality can mean different things to different people. Some care most about cut angularity and want as straight a line as possible with little to no kerf. Kerf is the amount of metal removed from the plasma jet- the cut path of metal removal for the workpiece cut out. Some care more about edge finish- this could be the top edge or the bottom of the cut. While others mostly want to ensure they don’t have high-speed dross and low-speed dross (metal spatter) to prevent arduous secondary operations. With so many preferences, it is most important that you understand your needs, and relay this to a cutting expert.

Hand plasma cutters

Hand-cutting with air plasma systems is only as accurate as the operator’s comfort with the plasma torch. Torch motion, cut speed, amps being used, and torch-to-workpiece distance (standoff) are all variables that affect accuracy. When cutting by hand - either using a guide or following a soapstone line - experienced operators can cut within 1.6mm (1/16-inch) tolerance. There are highly skilled people out there with amazing physical control, though the human hand will not be more accurate than a plasma torch guided by a digitally controlled CNC machine and torch height control.  

Automated plasma cutters

Entry-level CNC plasma cutting systems are ideal for serious hobbyists or small business owners. The accuracy of these plasma cutting systems will be impacted by the quality of the plasma table, plasma system, CNC, and drives. Slight variations in cut surface and cut angles are normal and you can expect a plus or minus .77 mm (.030-inch) tolerance. 

Entry-level systems have x – y motion but do not typically come with automatic torch height control (the z-axis). Torch cut height control is significant because it automatically adjusts to the proper torch-to-work distance as the consumables wear and that keeps the squareness and the quality of the cut. In the absence of automatic torch height control, the likelihood of negative or positive cut angles and poor cut quality increases and can add costs when grinding excess molten material scratch is required. Torch cut height control should be installed on every CNC plasma cutter system. It is necessary for good cut quality. 

Light industrial plasma cutting systems come with torch cut height control, yet their accuracy can be about the same as an entry-level system. The advantages are reaped over the life of the light industrial system. They are sturdier and built for low-level to moderate production, maintenance is minimal by comparison, the CNC and drive systems are better, and they just last longer. With the addition of a full-feature torch height control, edge tolerances can get within the .38 to .64 mm (.015" to .025") range. Your cut edges are relatively square, the hole quality is good, and most rework is eliminated.  

In high-production shops, heavy Industrial plasma cutting systems can run for multiple shifts a day. These high-amperage systems are the most complex but are the easiest to operate. That is due to the advanced software and controls used to drive them. These plasma systems can cut close to square edges on steel plate from gauge to 50 mm (2-inch) thick, create bolt-ready holes, and hold tolerances from .25 to .51 mm (.010" to .020") depending on material and thickness. Most of the time, parts do not require rework and are ready to use.   

So, as you can see, plasma accuracy and quality of the cut will relate specifically to the plasma cutting system and how it is set up. When making your decision about which plasma cutting system to purchase the accuracy is important, but also consider the importance of system reliability, consumable life, operating costs, and manufacturer support. You will find that you truly get what you pay for.  

Quick cut quality tips

Check the accuracy of a plasma system before you make a purchase:

Hand plasma:

• Ask to demo the plasma system and cut with it to see quality and if specifications can be met
• Compare system specs

Automated plasma:

• Site visit: either go to the OEM showroom and/or ask the OEM to take you to companies already using the system that you are looking to purchase
• Ask for a cut sample and/or see if the OEM will cut a part from one of your own files on the system you’re considering
• Ask the OEM for references and speak to people who are already using the equipment

In both hand and automated options, be sure to speak to industry experts. Representatives from the plasma cutting manufacturers are a good source for information. Share your needs regarding the thickness and types of materials such as mild steel, stainless steel, and aluminum you want to cut, your productivity, cutting parameters and accuracy requirements, and even your budget. Remember, if you are using plasma cutting to create a bevel, the actual thickness you are cutting is higher than a straight cut, depending on the bevel angle, and this can affect cut quality. That information will help them determine which technology is best suited for you.

Also keep in mind that gas pressure, gas flow, and the type of plasma gas can affect cut quality and consumable life. For example, using argon can improve the stability of the plasma arc and can help with cut quality.

If you need further assistance, we recommend reaching out to one of our authorized partners. For a list of locations near you, visit our website for where to buy, or you can contact us directly with questions. 

Why Hypertherm products offer the best in cut accuracy and cut quality

Quality that instill confidence

Hypertherm Associates delivers the industry’s most innovative and high-quality plasma cutting systems. Hypertherm Manufacturing design is customer-focused and goes through rigorous reliability testing, Our partner network, the best in the world, supports consumables, parts, and delivers system service and technical support, including remote support

Training from the Hypertherm Cutting Institute and a global partner network

The Hypertherm Cutting Institute can help educate you on Hypertherm products and cut quality topics. Log in or create an account to view many online courses, and use the search feature using keyword optimization to find the following courses:

107 – Plasma consumables: Care and Optimization

311 – Cut Optimization: Top Edge Rounding

312 – Cut Optimization: Dross

314 – Cut Optimization: Edge Finish

315 – Cut Optimization: Angularity