What is metal cutting?
Metal cutting is the controlled separation of sheet, plate, bar, tube or structural section into a usable profile. The phrase covers thermal processes that melt or oxidise a narrow path, erosion processes that remove material, and mechanical processes that shear or form chips. Choosing between them is not simply a contest for the fastest machine. Material grade, thickness, geometry, tolerance, edge condition, heat input, batch size and downstream operations all affect the best answer.
A fabrication shop may laser-cut thin stainless covers, plasma-cut structural steel brackets, waterjet an aluminium tool plate, oxy-fuel a 150 mm carbon-steel blank and bandsaw bar stock on the same day. Each method earns its place because it solves a different production problem. The guide below gives practical starting ranges rather than machine guarantees: modern equipment varies widely, and a supplier should confirm capability against a drawing and material specification.
Metal cutting processes compared
| Process | Practical thickness range | Achievable tolerance | Edge quality | Typical cost | Best-fit materials |
|---|---|---|---|---|---|
| Laser | 0.5–25 mm common; thicker on high-power systems | ±0.1–0.25 mm | Excellent on thin and medium sheet | Medium–high hourly rate; low part cost at volume | Mild steel, stainless, aluminium; copper and brass with suitable fibre laser |
| Plasma | 3–50 mm common; up to about 150 mm | ±0.5–1.5 mm | Good commercial edge; some dross and bevel | Low–medium | Any electrically conductive metal, especially carbon steel |
| Waterjet | 1–150 mm common; thicker cuts possible | ±0.1–0.5 mm | Very good, no heat-affected zone | High | Almost any metal, composites and heat-sensitive materials |
| Oxy-fuel | 6–300 mm; substantially thicker possible | ±1–3 mm | Serviceable, with scale and heat effect | Low equipment cost; economical on thick plate | Carbon and low-alloy steel only |
| Mechanical sawing | Section-dependent; thin tube to 500 mm+ billet | ±0.2–1 mm | Square, consistent straight cut with saw marks | Low–medium | Bar, tube, extrusion and sections in nearly any metal |
Thickness limits in published brochures describe what a machine can sever, not necessarily what it can cut economically or to drawing tolerance. Likewise, quoted tolerance assumes a capable machine, stable sheet, correct consumables and a suitable quality setting. A very thick laser cut or high-speed waterjet cut may be technically possible but commercially unattractive. Always compare the finished requirement, including deburring, machining and distortion correction, rather than the cutting price alone.
Laser cutting
Laser cutting focuses a high-energy beam into a narrow spot and uses assist gas to eject molten material. Fibre lasers dominate new metalworking installations because they transfer energy efficiently into metals and cut thin sheet exceptionally quickly. CO2 machines remain productive in many established shops. Laser produces a narrow kerf, small internal features and repeatable profiles, making it a strong default for sheet-metal enclosures, brackets, signs and production components.
Its advantages are precision, high speed on thin material, automation and clean edges that often go straight to folding or welding. Its disadvantages are a relatively expensive machine-hour, a heat-affected edge and declining speed as plate gets thicker. Reflective copper and brass require appropriate sources and machine protection. The quoted cut quality also depends on focal position, nozzle condition, assist gas and plate surface. For real pricing benchmarks, see laser cutting cost per metre.
Plasma cutting
Plasma sends an electrically conductive, ionised gas arc through the workpiece. It cuts conductive metals rapidly and is particularly competitive on medium and thick mild steel. The machine and consumables cost less than an industrial laser, while high-definition plasma can deliver a much better result than older hand-plasma work might suggest. It suits structural parts, base plates, agricultural equipment and general fabrication where robust throughput matters more than tiny holes or cosmetic edges.
The kerf and heat-affected zone are wider than laser, and cut faces can show a slight bevel. Dross may need removal, particularly when parameters or consumables are not optimal. Plasma cannot cut non-conductive material. On a generous-tolerance 20 mm steel bracket it may be the commercial winner; on a detailed 1 mm stainless fascia it rarely is.
Waterjet cutting
Abrasive waterjet accelerates water and garnet through a small orifice to erode the cutting path. Because it is a cold process, it creates no metallurgical heat-affected zone and introduces little thermal distortion. It can cut hardened steel, aluminium, titanium, copper, composites, stone and many layered materials. That flexibility is valuable for aerospace blanks, architectural work, tool plate and parts whose edge must not be thermally altered.
Waterjet trades speed and operating cost for versatility. Pumps consume significant power, abrasive is a continuous expense and taper control may require a slower quality setting. Piercing laminated or brittle stock needs care. It is often chosen because it prevents a later machining or heat-treatment problem, not because its hourly rate is lowest.
Oxy-fuel cutting
Oxy-fuel preheats carbon steel and then directs oxygen into the cut, sustaining an oxidation reaction that removes the metal. The equipment is simple, portable and able to process plate far thicker than most lasers or plasma tables. On thick carbon steel, its low capital cost and practical cutting speed remain compelling for heavy engineering, demolition, shipbuilding and rough blanks that receive machining afterwards.
The process depends on an exothermic iron-oxygen reaction, so it is not the general answer for stainless steel or aluminium. It produces a broad heat-affected zone, visible scale and looser tolerance. Preheat and slow travel also make it inefficient on thin sheet. Oxy-fuel is best treated as a specialist for carbon-steel thickness rather than an all-purpose profile method.
Mechanical sawing
Bandsaws and circular cold saws remove a narrow stream of chips with a toothed blade. They are limited to straight cuts but excel on bar, tube, extrusion, beams and billets. A saw can bundle-cut repeated lengths, leave a square face and handle metals that are awkward for thermal processes without creating a fusion-cut edge. For stock preparation before turning or milling, sawing is often the simplest and least expensive route.
Blade selection, tooth pitch, coolant and feed determine cut quality. Thin-walled tube can snag if the pitch is too coarse, while a fine blade can clog in soft aluminium. Sawing cannot nest complex profiles from sheet and generally needs clamping allowance and end trim. It belongs in the comparison because many “metal cutting” enquiries need a length cut, not a two-dimensional contour.
Which metal cutting process should I use?
Mild and carbon steel
Below about 6 mm, laser is normally the first quotation for detailed sheet parts because it combines speed, small kerf and a fold-ready edge. From roughly 6 to 25 mm, compare laser and plasma: laser favours tolerance and detail, while plasma favours lower-cost general fabrication. From 25 to 50 mm, plasma becomes increasingly attractive unless the drawing demands laser or cold-cut quality. Above about 50 mm, oxy-fuel is usually the economical choice for ordinary profiles, while waterjet suits precision blanks or parts that cannot tolerate heat. Mechanical sawing is preferable at any thickness when the requirement is simply to shorten bar, beam or tube.
Stainless steel
For thin and medium stainless sheet, nitrogen-assisted laser gives a bright, oxide-free edge and excellent detail. Plasma handles thicker stainless economically where edge colour, bevel and tolerance permit. Oxy-fuel is unsuitable because stainless does not sustain the same oxidation reaction as carbon steel. Waterjet is the choice for heavy stainless plate, heat-sensitive grades or components that need an unaffected edge before critical welding. Sawing remains efficient for stainless bar and tube, provided the blade and feed prevent work hardening.
Aluminium
Fibre laser is productive on thin aluminium, although alloy, reflectivity and available power influence the practical limit. Plasma is fast on medium and thick aluminium but can leave a rougher, nitrided or oxidised edge depending on gas choice. Waterjet is attractive for thick tooling plate, precision blanks and distortion-sensitive parts because it adds no heat. Mechanical sawing is usually best for extrusion, solid bar and rectangular plate blanks. Oxy-fuel does not cut aluminium in the conventional way.
Copper, brass and specialist alloys
Modern fibre lasers can process thin copper and brass, but capability must be checked because reflectivity and thermal conductivity make these materials demanding. Waterjet is the broadly reliable choice across thicknesses and for titanium, nickel alloys or hardened material when thermal change is unacceptable. Plasma can cut conductive alloys where the required edge allows it. For straight stock, a properly selected saw avoids the process complications altogether.
Choose by geometry and finish
- Fine holes, slots and close profiles: start with laser, keeping minimum-feature rules in mind.
- Large structural profiles: compare plasma with oxy-fuel as thickness rises.
- No heat-affected zone: use waterjet, or saw straight stock.
- Repeated straight lengths: use bandsaw or cold saw, potentially bundle cutting.
- Near-net blanks for machining: compare waterjet’s cleaner allowance with cheaper plasma or oxy-fuel plus extra machining.
Metal cutting calculators and practical guides
Use the tools to turn a process choice into a first-pass time, material and cost estimate. Then use the guides to refine assumptions about kerf, nesting, density and piercing. These figures support planning and supplier comparisons; they do not replace a production quote.
Estimate laser time, machine cost, material cost and cost per part.
Model plasma speed and job cost from thickness and cut length.
Estimate abrasive waterjet time, weight and total cost.
Calculate sheet, plate, disc and ring weight from dimensions.
Compare speed, accuracy, material range and operating cost.
Allow for cut width in dimensions, spacing and nesting.
Improve material utilisation and reduce sheet cost per part.
Understand why holes and separate contours affect cycle time.
Reference densities and calculate material weight accurately.
UK and EU rate tables, machine rates and a worked quote.
How the metal cutting calculator works
The calculator above stays deliberately process-neutral. Enter the travel speed supplied for the selected machine and thickness, rather than assuming one universal value. Cutting time contains both movement along the profile and stationary pierces. A part with many holes can take materially longer than a simple outline with the same total path length.
Part weight is area multiplied by thickness and density. The nesting estimate lays rectangular parts in a grid, allows for gaps and sheet margins, and tests both orientations. Real CAM nesting can improve utilisation on irregular parts by rotating and interlocking them, so treat the result as a clear planning baseline.
Frequently asked questions
How do I calculate metal cutting time?
Cut length ÷ cutting speed gives travel time; add pierce time (pierces × seconds per pierce) for the total per part.
How do I calculate the weight of a cut metal part?
Multiply part area by thickness for the volume, then by the density — steel ≈7.85, aluminium ≈2.70, stainless ≈8.00 g/cm³.
How do I work out how many parts fit on a sheet?
Lay them in a grid allowing for the gap and edge margin, trying both orientations. Columns × rows that fit gives parts per sheet.
What cutting speed should I use?
It depends on process, power and thickness — doubling thickness often roughly halves speed. For 12mm mild steel: plasma ≈1500, laser ≈1200, waterjet ≈450 mm/min.
Which metal cutting process is best?
Laser is usually strongest for accurate sheet work, plasma for economical medium and thick conductive plate, waterjet for heat-sensitive or mixed materials, oxy-fuel for very thick carbon steel, and sawing for bar, tube and straight cuts.
What is the most accurate way to cut metal?
Laser and precision waterjet are generally the most accurate profile methods. Laser commonly reaches about ±0.1 mm on suitable sheet; waterjet can achieve roughly ±0.1–0.2 mm at slower quality settings without adding heat.
How do I choose a cutting process by thickness?
Laser usually leads on thin sheet, plasma becomes economical on thicker conductive plate, oxy-fuel suits very thick carbon steel, and waterjet covers thick or heat-sensitive material where quality matters more than speed.