Cutting Guide
Plasma vs Laser vs Waterjet Cutting
Three ways to cut a metal sheet, each with a different trade-off between speed, cost, accuracy and the materials they can handle. Here's how to pick.
Every metal cutting job balances the same three things: how fast it cuts, how much it costs to run, and how good the finished edge needs to be. Plasma, laser and waterjet each sit in a different spot on that trade-off, and the right choice usually comes down to material, thickness, and what happens to the part after it's cut.
Cost out all three for your job
Run the same part through the laser, plasma and waterjet cost calculators to compare directly.
Laser, plasma and waterjet comparison
These practical guide ranges repeat the site’s process and kerf guides; they are not guaranteed tolerances or universal maximums. Confirm the drawing and thickness with the supplier. Maximum severance thickness is different from economical cutting to tolerance.
| Factor | Laser | Plasma | Waterjet |
|---|---|---|---|
| Practical thickness / upper range | 0.5–25 mm common; thicker on high-power systems | 3–50 mm common; some systems up to about 150 mm | 1–150 mm common; thicker cuts possible |
| Guide tolerance | ±0.1–0.25 mm | ±0.5–1.5 mm | ±0.1–0.5 mm |
| Guide kerf | 0.1–0.3 mm | 1.0–2.0 mm | 0.8–1.2 mm |
| Heat-affected zone | Small; thermal effects remain | Larger; distortion depends on the job | No thermal heat-affected zone |
| Edge finish | Fine on suitable sheet; gas affects oxidation | May need dross removal and bevel allowance | No thermal discolouration; taper and striations depend on quality setting |
| Relative cost/metre: model at 12 mm mild steel | £1.25/m at £90/hour and 1.2 m/min | £0.72/m at £65/hour and 1.5 m/min | £4.07/m at £110/hour and 0.45 m/min |
| Best uses | Detailed sheet parts and repeat profiles | Structural steel and general plate fabrication | Heat-sensitive parts and thick or mixed materials |
Cost figures use the calculators’ default hourly rates and 12 mm reference speeds. They exclude pierces, setup, material and finishing and are examples, not market tariffs. Relative cost changes with thickness, geometry, equipment and required quality.
Which is best for steel parts?
Start with laser for detailed thin or medium steel sheet where holes, fit and edge finish matter. Compare plasma for heavier structural plate when the drawing permits a wider kerf and more edge finishing. Choose waterjet when thermal effects are unacceptable or the grade and thickness favour a cold process. Specify critical dimensions and compare finished-part prices, including any machining or deburring.
Speed
The calculators model plasma as faster than laser and waterjet on mild steel using their reference speeds below. Actual rankings depend on thickness, power, geometry and quality: a suitable laser can be much faster on thin sheet. Waterjet speed also changes with material and edge-quality settings. All three calculators use the same inverse-thickness rule, so they do not model a crossover between processes.
All three roughly follow the same rule: doubling the thickness roughly halves the speed. Use the laser, plasma and waterjet cost calculators for a speed estimate at your own thickness and material.
Cost
Plasma machines and consumables are the cheapest to buy and run, which combined with its speed on thick steel usually makes it the lowest cost-per-part for structural and heavier fabrication work. Laser costs more per hour to run but its precision reduces secondary finishing, which can offset the higher machine rate on parts with tight tolerances. Waterjet has the highest running cost per hour of the three — abrasive consumable use adds up — and its lower speed compounds that on longer cut paths.
Accuracy and edge quality
Waterjet avoids a thermal heat-affected zone and heat discolouration, but taper and striations depend on speed and quality settings. Laser can give a fine edge on suitable sheet with a small heat-affected zone. Plasma may need more dross removal or bevel allowance. Compare the required edge finish and dimensional tolerance with the supplier rather than assuming one process always gives the best edge.
Material range
Waterjet cuts almost anything — metal, stone, glass, composites, rubber — since it doesn't rely on melting or burning the material. Laser and plasma are both effectively limited to conductive or absorptive materials; laser struggles with highly reflective metals like polished aluminium and copper at lower power, while plasma cuts any conductive metal well regardless of reflectivity.
Which should you use?
As a rough starting point: choose plasma for thicker mild steel structural and general fabrication work where cost and speed matter most; choose laser for thinner material, tighter tolerances and cleaner edges at moderate cost; choose waterjet when the material can't take heat, when edge quality is critical, or when cutting non-metals alongside metal parts.
Frequently asked questions
Which is cheaper, plasma or laser cutting?
Plasma machines and consumables are usually cheaper, and plasma cuts thick mild steel faster, so per-part cost on thick steel often favours plasma. Laser tends to win on thinner material and precision parts where less rework offsets the higher machine cost.
Is waterjet cutting slower than plasma or laser?
Yes — waterjet is typically the slowest of the three on metal, often around a third of plasma's speed on comparable mild steel thickness, because it removes material by abrasive erosion rather than melting or vaporising it.
Which cutting process gives the best edge quality?
Waterjet avoids thermal effects but can leave taper or striations. Laser can give a fine edge on suitable sheet, while plasma may need more dross removal. The best finish depends on material, thickness, machine settings and the drawing.