Industry

Laser Cutting for Sheet Metal Fabrication: Choosing Power and Machine

Updated 2026-10-13 · 4 min read

Sheet metal fabrication is the market fiber lasers were built for, and it is also where buying decisions go wrong most often — usually because the buyer optimises the specification sheet instead of the process. The binding constraint in most shops is not how fast the beam moves.

Quick answer: For general fabrication cutting 1–6 mm sheet, 3 kW is the standard starting point; 6 kW suits shops routinely cutting 6–12 mm or needing more throughput. But on thin sheet the cut is not the bottleneck — handling is. A machine with an exchange table usually beats a faster machine without one.

The thickness bands that decide power

Band	What it covers	Power that suits it
0.5–3 mm	Enclosures, panels, brackets, signage	1.5–3 kW; speed matters more than capacity
3–6 mm	General fabrication, machine guards, frames	3 kW — the most common first machine
6–12 mm	Structural brackets, base plates	6 kW for usable speed and edge quality
12–20 mm	Heavy brackets, plate work	6–12 kW; check plasma economics
Above 20 mm	Plate and structural	Plasma is usually more economical

The mistake to avoid: buying 12 kW because a customer might one day send 20 mm plate, when 90% of your work is 2 mm. You pay for that capacity in purchase price, power draw, chiller load and floor space on every part you cut.

The opposite mistake is just as common: under-buying on thin sheet. If you cut 1–3 mm all day, speed is the entire economic argument, and power buys speed.

Why handling beats cut speed on thin sheet

Consider a 2500 × 1250 mm sheet of 2 mm mild steel. Cutting the nested parts might take two to four minutes. Loading the sheet, unloading the skeleton and separating parts takes longer than that.

That arithmetic has a direct consequence:

A 3 kW machine with an exchange table will usually out-produce a 6 kW machine with a single table on thin-gauge work.
An automated loading system can change the labour equation entirely on multi-shift operation.
A single-table machine running one shift often has more idle time than cutting time.

So the sequence to optimise is: nesting → handling → cut speed. Most shops attack it in the wrong order.

What actually drives cost per part

In rough order of leverage:

Material utilisation. Sheet is usually the largest single cost in a fabricated part. A few percent better nesting beats a faster machine.
Common-line cutting. Sharing cut paths between adjacent parts halves cut length and pierce count on repeated geometry.
Handling time. Exchange tables, or automation for multi-shift.
Scrap and rework. Thin-gauge distortion and dross cause rework; parameter discipline prevents it.
Consumables. Nozzles and lenses are small per part but add up, and worn consumables cause scrap.
Cut speed. Real, but usually the smallest of these levers on thin sheet.

Specifying the machine

Specification	What to choose	Reason
Power	3 kW general; 6 kW for 6–12 mm routinely	Match routine work
Bed size	1300 × 2500 mm covers metric sheet; 1500 × 3000 mm for larger	Bed is a constraint you cannot work around later
Table	Exchange table if producing more than a few hours a day	Biggest throughput lever
Cutting head	Branded auto-focus	Routine material changes without manual setup
Control and nesting	Mainstream controller; confirm nesting is licensed	Nesting drives material cost
Extraction	Sized to your material mix	Health requirement; protects optics
Assist gas	Oxygen for carbon steel; nitrogen for stainless	Determines downstream processing
Chiller	Matched to source heat load	Undersized chillers cause summer shutdowns

Bed size deserves an early decision. If the sheet does not fit, no amount of power helps, and a bed that is too small cannot be upgraded later.

Process notes for a job shop

Build a parameter library and protect it. Tuned parameters per material and thickness are an asset. Back them up; losing them costs days.

Use micro-joints on small parts. Parts that release into the kerf tip and scrap the sheet.

Pierce off the visible face. Pierce marks are permanent.

Separate parameters for mild, galvanised and stainless. They behave differently at the same thickness, and reusing settings produces dross.

Plan for distortion on thin gauge. Higher speed and lower heat input, and check that the sheet is held flat.

Track your scrap rate. It is the fastest-moving number in the shop's economics and the easiest to ignore.

Laser and plasma together

Many fabrication shops run both, and it is a rational combination:

Laser for sheet up to roughly 20 mm where edge quality, tolerance and dross-free cuts matter
Plasma for thicker plate where a rougher edge is acceptable and speed per metre matters more

Trying to cover both with one machine usually means over-buying laser power or accepting poor economics on plate. If thick plate is a real part of your business rather than an occasional favour for a customer, a plasma table alongside a laser is usually the better answer.

Where laser stops being economical

Laser cutting is the right process for a wide band, but not all of it:

Very thick plate — plasma wins on cost per metre
Very thick section, high tolerance — waterjet or machining
Tubes and profiles — a dedicated tube laser, not a flat-bed machine
Parts needing machined bores or flatness — laser is the blanking operation, not the finishing one

Recognising where to send work out is as much a part of shop economics as knowing what to keep in-house.

Frequently asked questions

What laser power does a sheet metal shop need?

For general fabrication cutting 1–6 mm sheet, 3 kW is the usual starting point and covers most work. 6 kW suits shops cutting 6–12 mm routinely or needing higher throughput. Match power to your routine job, not your thickest one.

Is laser cutting or plasma better for sheet metal?

Laser for sheet up to roughly 20 mm where edge quality and tolerance matter. Plasma is more economical for thicker plate and where a rougher edge is acceptable. Many shops run both.

What thickness can a sheet metal laser cut?

A 3 kW fiber laser cuts carbon steel to about 16–20 mm and stainless to 10–12 mm. Production work normally stays two or three millimetres below those limits for edge quality and speed.

Why does material handling matter more than cut speed?

On thin sheet the cut itself is fast; loading, unloading and separating parts take longer. An exchange table or automation addresses the real bottleneck. A faster laser with manual handling often loses to a slower machine with an exchange table.

How do I reduce cost per part?

In order: improve nesting to cut material waste, raise sheet utilisation with common-line cutting, address handling with an exchange table, and only then consider more laser power.

Machines mentioned in this article

Fiber Laser Cutting Machine — PL-1390 with Raycus source
Plasma Cutting Machine — For plate too thick for economical laser cutting
Fiber Laser Price Guide — Indicative ranges by power

Related guides