How laser cutting works
A laser cutter focuses a powerful beam of light onto a small spot. The material heats until it melts, burns or vaporizes, and a stream of assist gas blows the molten material out of the cut, called the kerf. A motion system moves either the beam or the sheet along the programmed path. Because there is no tool to wear in the usual sense, and the cut can follow nearly any outline, laser cutting is widely used in sheet metal work, often next to press brakes for bending and other metal fabrication equipment.
The five types below are categories, not products. Capabilities vary by manufacturer, so treat the comments as typical tendencies.
1. Fiber laser cutters
The beam is generated in an optical fiber and delivered to the cutting head. Fiber lasers are widely used for cutting metal sheet, including steel, stainless steel and aluminum. They are usually efficient electrically, need relatively little beam-path maintenance, and are generally well suited to thin and medium thicknesses at high speed. Highly reflective metals such as copper and brass have historically been harder, though modern fiber systems often handle them with suitable settings. Fiber lasers are not normally the first choice for cutting many non-metals.
2. CO2 laser cutters
CO2 lasers use a gas mixture and mirrors or optics to carry the beam. They cut a broad range of materials, including many plastics, wood, acrylic, paper, textiles and some metals. For thicker mild steel, some shops still use them because of the edge quality they can produce. They tend to need more upkeep of mirrors, optics and gas supply than fiber, and they are typically less energy efficient. They remain common where a mixed range of materials is cut.
3. Crystal (solid-state) laser cutters
Neodymium-based crystal lasers deliver a beam well suited to fine work and, in pulsed mode, to small precise cuts in metals, ceramics and some plastics. They are often found in small-part work such as medical device components or electronics, where kerf and heat-affected area need to be small. Power levels are typically lower than fiber or CO2 systems for heavy cutting, so they are not a choice for thick plate.
4. Ultrafast (picosecond and femtosecond) laser systems
Ultrafast lasers emit extremely short pulses. The material is removed with very little heat spreading into the surrounding area, which can produce very clean micro-cuts with minimal burr or discoloration. They are used for delicate parts, thin foils, stents and similar precision work. They are slow for bulk cutting and generally expensive, so they suit specialized jobs rather than general sheet cutting.
5. Tube and profile laser cutters
These machines are built around cutting round, square or structural tubes and profiles, usually with a rotating chuck. They can produce holes, slots, miters and joint features in one setup, which reduces sawing, drilling and fitting work downstream. They may use fiber or CO2 sources. They are a good fit for frames, furniture, and fabricated assemblies.
What sets cut quality
Several variables work together.
- Laser power and beam quality. Higher power generally cuts thicker material or cuts faster, and a good beam produces a narrower, cleaner kerf.
- Focus position and nozzle condition. A dirty or damaged nozzle or lens can quickly degrade edges.
- Assist gas. Oxygen can speed cutting of mild steel but leaves an oxide layer; nitrogen usually gives clean, oxide-free edges on stainless steel and aluminum; compressed air is sometimes used where edge finish is less critical. Gas supply often relies on compressed air systems or bottled or bulk gas.
- Speed and path. Too fast leaves incomplete cuts; too slow adds heat and can burn corners.
- Material condition. Surface rust, coatings, flatness and alloy all affect results.
- Machine mechanics. Rigid frames, accurate drives and a controller that handles acceleration well keep small features accurate. The underlying principles are those of motion control.
Material range and thickness
Each laser type has a window. Thin sheet is generally cut quickly and accurately; as thickness grows, cutting speed drops, the kerf can taper, and edges may become rougher. Maximum thickness depends on the material, laser power and gas, so quoted values should always be confirmed with cutting tests on your actual material. Materials that release harmful fumes when heated, such as some plastics, should not be cut without proper approval and extraction.
Safety and practical points
Laser systems are classified as hazardous: the beam can injure eyes and skin, and cutting can create fire risk, smoke and fumes. Follow the manufacturer’s enclosure, interlock, eyewear and ventilation requirements, and local regulations, and use trained personnel. Fume extraction and dust and fume filtration are normally part of a proper installation.