Plasma Cutting — What It Is and Why It Matters
Plasma cutting is a thermal cutting process that uses a constricted arc and high-velocity ionized gas (plasma) to melt and blow away metal. The plasma jet reaches temperatures above 30,000°F, making it one of the fastest and cleanest methods for cutting conductive metals.
A plasma cutter works by forcing compressed air or gas through a small nozzle orifice while an electric arc ionizes the gas into plasma. The extreme heat melts the metal while the high-velocity gas stream blows the molten material through the kerf. Modern inverter-based plasma cutters are compact, portable, and can cleanly cut steel, stainless, aluminum, copper, and brass.
Plasma cutting is significantly faster and more precise than oxy-fuel cutting on material up to about 1" thick, and it works on non-ferrous metals that oxy-fuel cannot touch. The cut edge is cleaner with a smaller heat-affected zone. CNC plasma tables have made automated precision cutting accessible even to small fabrication shops.
Key variables include amperage, air pressure, cutting speed, torch height, and consumable condition. Worn nozzles and electrodes degrade cut quality rapidly, making consumable management an important operational consideration.
Frequently Asked Questions
What thickness can a plasma cutter handle?
Amperage determines cutting capacity. A 40-amp unit typically cuts up to 1/2" steel cleanly, a 60-amp unit handles 3/4", and an 80-amp machine can sever 1" or more. Manufacturer ratings usually list both a clean-cut thickness and a maximum severance thickness.
Is plasma cutting better than oxy-fuel?
For material under 1" thick, plasma is faster, cleaner, and more versatile since it cuts non-ferrous metals too. Oxy-fuel has the advantage on thick steel — it can cut 6"+ plate that would overwhelm most shop plasma units — and it does not require electricity.