How to Choose the Best Laser Cutter for Metal Fabrication

Metal fabrication shops and manufacturers are increasingly adopting laser cutting technology for its speed, precision, and flexibility. Laser cutters use a high-power laser beam to melt, burn, or vaporize material to cut intricate patterns and designs.

Compared to conventional machining methods like milling or drilling, laser cutting is contactless and doesn’t wear down cutting tools. This makes lasers ideal for processing sheet metal, plates, tubes, and metal profiles. Laser cutting also yields smooth, clean edges without burrs or other defects.

However, not all laser cutters are created equal when it comes to processing metals. This guide will examine the types of laser cutters available and key factors to consider when selecting the right laser cutting machine for your metal fabrication needs.

How Do Laser Cutters Work?

Laser cutting uses a high-density, focused beam of light to melt, burn, or vaporize material. The laser beam heats the metal to its melting point before a high-pressure assist gas blows the molten material away, leaving an edge with a high-quality surface finish.

The two most common types of lasers used in metal cutting are:

• CO2 lasers: CO2 lasers use an electrically stimulated gas mixture as the lasing medium. The 10.6-micron wavelength beam is highly absorbed by most metals. CO2 lasers can cut thicker and stronger metal materials.
• Fiber lasers: Fiber lasers use a seed laser diode beam that is amplified through an optical fiber lasing medium. The 1-micron wavelength allows for tighter beam focusing and greater precision on thin metal sheets.

The assist gas, typically oxygen or nitrogen, blows away material melted by the laser. Compressed air can also be used as an assist gas. The gas pressure and nozzle design greatly impact the speed and quality of laser cutting.

Key Considerations When Choosing a Metal Laser Cutter

With many laser cutting machine configurations available, here are the most important factors to consider for metal fabrication:

Laser Power and Type

Higher laser power enables faster speeds, thicker capacity, and the ability to cut highly reflective or hardened metals. Industrial laser cutters range from 500 watts to 6 kilowatts, with 1-2 kilowatts suitable for most metal fabrication shops.

Fiber lasers are better suited for thin sheets, while CO2 lasers have advantages cutting thicker metals. Consider the types of metal you will be cutting to choose the right laser technology.

Cutting Area Size

The work area capacity must be large enough for the sheet metal sizes or metal profiles you work with. Laser cutters come in standard 4’x4’, 4’x8’, 5’x10’, or larger custom sizes. Maximize the cut area while allowing safe access for loading and unloading.

Motion Control and Precision

Precision rack and pinion drives or servo motor systems yield higher accuracy and repeatability. Ball screws, linear rails, and precision ground cutting tables also enhance precision on larger machine formats. Customized motion controls can provide very tight tolerances under 0.001”.

Assist Gas Delivery

A higher gas pressure between 80-150 psi produces better quality cuts faster. Multiple gas nozzles around the cutting head provide better coverage. Nozzles should be adjustable and optimized for the materials being cut.

Dust Collection and Fume Extraction

A fume extraction system with HEPA filtration is critical when laser cutting metals which can generate hazardous metallic particulates. Integrated downdraft tables help collect dust and fumes directly at the cutting zone. Robust dust collection improves cut quality and shop air quality.

Safety Features

Laser machines should have safety interlocks on all doors, light-tight covers, and safety mats. Water cooling units prevent laser tube overheating. Fire prevention systems are a must. Additional training may be required to operate industrial lasers safely.

Software and Connectivity

Look for laser controllers with easy-to-use software that allows designing parts directly on the machine or importing DXF, DWG, and other CAD file formats. Connectivity options like Wifi, LAN, and USB simplify transferring cut files.

CO2 vs. Fiber Laser Technology

CO2 lasers have traditionally been used for cutting metals. But with advances in fiber laser technology, fiber lasers have taken over most thin sheet metal cutting. Here’s a look at the pros and cons of each:

CO2 Laser

• Better for cutting over 1⁄4” thick and nonferrous metals like copper or brass
• Can cut stainless steel and aluminum at thicker capacities
• Lower equipment cost for higher power lasers
• Can operate in pulsed mode for cleaner cuts
• Limited beam focusing results in wider kerfs
• Low beam absorption on shiny or reflective surfaces

Fiber Laser

• Ideal for thin sheets below 1⁄4” thick
• Very high beam quality for tight focusing and fine feature detail
• Excellent edge quality and small kerf width
• Higher absorption for cutting aluminum, steel, and reflective metals
• Low maintenance and higher wall-plug efficiency
• Higher equipment costs, especially for higher power machines

Plasma, Waterjet, Punch – Which to Choose?

Laser cutters are not the only option for cutting metal. Here is how laser cutting compares with other major metal fabrication methods:

Plasma Cutting

Plasma uses a constricted arc of ionized gas reaching over 15,000°F to melt metal. Plasma is often cheaper than laser and faster cutting thick plate. But plasma leaves a rougher edge requiring secondary finishing. Precision and detail are limited compared to laser.

Waterjet Cutting

Waterjets turn tap water into an extremely high pressure cutting jet by mixing it with abrasive. Waterjet can cut any material but is slower than laser. It produces no heat effect or HAZ. Liquid mess and high abrasive costs are downsides. Tolerances are ~0.005”.

Punch and Stamping

Punching presses use shaped tooling to punch holes or form features in sheet metal. Extremely fast for high volume production. But punching is limited to simple shapes and holes, while dies are expensive to fabricate. Minimal edge finishing is possible.

Lasers provide the best balance of speed, flexibility, quality, and cost-effectiveness on a wide range of metal materials and thicknesses. Laser cutting enables rapid prototyping and scaling to volume production.

Important Accessories and Options

The versatility and cutting quality of a laser system can be enhanced with additional equipment options:

• Fume extraction: Critical for keeping your shop clean and your workers healthy when cutting metal.
• Downdraft cutting table: Maintains high cut quality by pulling smoke and gases downward through slats.
• Rotary axes: Allow cutting tubing and pipes by rotating the workpiece while laser cutting around the circumference.
• Precision shuttle tables: Let you load and unload sheets faster to maximize cutting time.
• Automated load/unload: Worker safety and cutting productivity are improved by automating the loading and unloading process.
• In-machine tapping: Produce precision threaded holes in your parts without any secondary operations.

Conclusion

Laser cutting provides metal fabricators unmatched speed, flexibility, and quality when working with sheet metal, plate, tubes, or metal profiles.

When selecting a metal laser cutting machine, key factors to consider are laser power and type, work area size, precision, assist gas delivery, dust collection, safety, and software capabilities. Additional options can further improve productivity and capabilities.

Both CO2 and fiber lasers have advantages depending on the material types and thicknesses being cut. Compared to other cutting methods like plasma, waterjet, and punching, lasers give metal fabricators the best overall value for an extremely wide range of applications.

With attention to these details, investing in a laser cutting machine can boost the efficiency, quality, and profitability of your metal fabrication operations.