Fiber vs. CO₂ Lasers: Which One Should You Buy And Why?

What is the difference between CO2 and Fiber Laser?

The main difference between a CO2 and a fiber laser is the wavelength of the beam. This determines the type of material each laser can process (see Table 3 for a summary). The wavelength of the two lasers is shown below: 

Table 2: wavelength of the fiber laser vs. CO₂ laser

The smaller wavelength of a fiber laser means it is much better suited in general to cutting metals as more of the beam’s energy is absorbed into the material and less is reflected. This leads to more efficient cutting.

The spot size of a laser is one of the factors that determines the kerf width. A smaller spot size results in higher precision during cutting and higher optical densities (the laser power per unit area). CO2 laser spot sizes can be up to 90% larger than a fiber laser equivalent. 

Fiber lasers have the option of either zoom or non-zoom cutting heads. Zoom heads allow you to adjust the focus spot diameter and hence the kerf. This means for the same power laser; thicker sheets can be cut. CO2 machines use different heads and lenses to achieve different spot sizes. 

Evolution of Laser Cutting Technology

CO₂ lasers have been used for sheet metal cutting since the 1970’s and have developed greatly over the years, dominating the industry. However, the rapid development of fiber lasers has dramatically changed the process of sheet metal cutting. 

We strongly believe that the advantages of fiber lasers will continue their rapid development over the next few years and become increasingly popular for industrial applications.

What applications can be cut with a fiber and CO2 laser?

As mentioned previously, CO₂ lasers have been around longer than fiber lasers and hence have dominated the market. However, as fiber lasers have developed, an increasing number of companies are choosing to switch out their CO₂ machines for a fiber laser.

Previously, CO2 lasers have been used in the pharmaceutical industry, food production, the manufacturing of electronic components, fabric cutting and cutting building materials. However, there has been a rapid uptake of fiber lasers being used in the medical, aerospace, automotive and electronics industries due to their rapid cutting speeds, excellent cut quality and high precision. 

Material Selection

Both CO₂ and fiber lasers can cut stainless and mild steel producing a good cut quality. When cutting metals, a continuous wave (CW) fiber laser is recommended for best results in terms of cut quality and cutting speeds because of the higher average power. 

Fiber lasers are significantly better at cutting highly reflective metals such as copper and brass. With CO₂ lasers, the majority of the laser beam is reflected (due to the wavelength) back off the material which can cause significant damage to the optical components in the cutting head therefore, while it is possible to cut aluminium on a CO₂ laser, it will significantly decrease the lifetime of the consumables.

Plastic coated stainless steel can be cut by both laser types. A CO₂ laser beam is absorbed by the plastic coating therefore only one cut pass is required. While a fiber laser can cut through the plastic coating and metal in one pass, the absorption into the plastic is poor, producing dross on the underside of the cut which depending on the application may or may not be acceptable. For the best cut results, two passes are required: the first to melt the plastic coating and a second to complete the cut. This obviously increases the overall cut time.

However, even with CO₂ lasers, particularly for thicker sheets, two cut paths are required as with a fiber laser. This is because during the pierce, the assist gas can get trapped below the coating causing a bubble to form around the head. 

The smaller wavelength of a fiber laser means it is not within the absorption range of non-metallic materials (i.e. textiles, wood, stone etc.). If you need to cut non-metals, a CO₂ laser is advisable.

Table 3: What materials can each laser type cut?

Marking

When it comes to marking metal, a fiber laser is the best option. The extremely small spot diameter increases the intensity of the laser; hence it is able to mark extremely fine details onto parts with excellent precision.

This means it is an excellent choice for product traceability and identification purposes with the marking of serial numbers, barcodes and data matrices onto metal parts.  

When it comes to marking non-metallic materials such as wood, glass, textiles and plastics, CO2 lasers are a better option.

Cutting Range

The cutting range of a laser is dependent on the power source: the higher the power, the thicker the sheet that can be cut. Table 4 shows the standard cutting range for different laser powers for both fiber and CO₂ lasers.

The main difference between the two technologies is cutting aluminium. For the same laser power, the maximum sheet thickness for a CO₂ laser is approximately a third less than that for a fiber laser (note, CO₂ lasers above 6 kW are rare). It is possible to cut thicker sheets than those stated below, however repeatability and cut quality are significantly reduced.

Table 4: Cutting Ranges

If you need to cut thinner materials (< 8 mm), a fiber laser is the ideal choice as they can offer significantly higher cutting speeds than a CO₂ laser and excellent cut quality (minimal dross and regular striations on the cut edge).

If you only need to cut thicker materials, a CO₂ laser may be a better option due to faster piercing and faster cutting speeds while producing a smoother surface finish.   

Although, fiber lasers should not be completely ruled out for cutting thick plates, as with careful balancing of the cutting parameters (speed, focal position, gas pressure etc.), a good quality cut can be achieved with minimal dross and regular striations on the cut edge.

It is possible that for a sheet thickness above 10 mm, a HD plasma machine may be preferable to a CO₂ laser. A plasma machine will be able to cut 10 mm mild steel quicker and produce a smoother cut edge.

However, if small holes/fine features are required, a laser is preferable. Also, when cutting stainless steel or aluminium, a laser machine will always produce better results.

This being said, in some cases Plasma could be an excellent alternative on stainless steel.  For more information on what quality you can expect with plasma we would like to refer to our article on plasma cutting for stainless steel or to the pictures comparing fiber, CO₂ and plasma.

Edge Quality: How do both laser cutters stack up?

In general, the wider spot size of CO₂ lasers means for all sheet thicknesses they are able to achieve a smoother cut edge than a fiber, and the difference can become more pronounced as the sheet thickness increases.

For thinner sheets, the smaller spot size of the fiber laser results in higher cutting speeds and smaller kerfs. The geometry of the resulting cut front enhances the absorption of the fiber laser beam. As the material thickness increases, the geometry of the cut front starts to favour the wavelength of the CO₂ laser.

When the fiber laser beam is directed at thicker materials, it is only able to interact with the top part of the cut. The beam is then reflected multiple times to reach the lower surface causing a rougher surface with fine striations. Further, the small kerf size means higher assist gas pressures are required to ensure the melt is ejected efficiently, contributing to the slightly rougher edge.

The following images compare the cut edge of samples cut on a 6 kW CO₂ laser, a 6 kW fiber laser and a 170 A plasma machine. For details on the cutting parameters used see Table 5 for cut speeds and Table 6 for auxiliary gas usage.

5 mm Stainless Steel

5 mm stainless steel cutting sample – HD Plasma

10 mm Stainless Steel

10 mm stainless steel cutting sample – HD Plasma

15 mm Stainless Steel

15 mm stainless steel cutting sample – HD Plasma

5 mm Mild Steel

5 mm mild steel cutting sample – HD Plasma

10 mm Mild Steel

10 mm mild steel cutting sample – HD Plasma

15 mm mild Steel

15 mm mild steel cutting sample – HD Plasma

Cutting Speed: Which technology cuts faster?

Fiber lasers are significantly faster at cutting thin sheets (< 8 mm) than CO₂ lasers, particularly when cutting stainless steel. For 1 mm, a fiber laser can cut at speeds up to 6 times higher than that of a CO₂ laser. The difference decreases to approximately 2 times faster for a 5 mm sheet.

Increasing the power of the laser source by just 2kW can increase cutting speeds by 2-3 times for thin sheets. As the sheet thickness increases (for the same laser power), CO₂ lasers are able to match and surpass fiber laser cutting speeds. However, the speed advantage is tiny in comparison to thinner sheets. 

High power CO₂ lasers (above 6kW) are less common than higher powered fiber lasers. This means for high powered machines, fiber lasers are able to achieve faster cutting speeds for all sheet thicknesses. 

The optimum cutting speed may not always be the fastest, as it may be more efficient and cost effective to prioritise consumable lifetimes and gas usage. 

Table 5 shows a comparison of the cut speeds used to cut the samples shown above. The following data is for 6 kW lasers and a 170A plasma.

Table 5: Cutting Speed

When comparing cutting speeds, it is important to remember that the cutting speeds quoted are often those when cutting in a straight line, therefore for intricate profiles, the cutting speed will be lower.

Additionally, when cutting nests, a machine will spend more time completing the traverse movements between profiles rather than actual cutting therefore the acceleration and deceleration of the machine must also be factored in when purchasing either type of machine. 

Investment Costs: Which machine has the highest acquisition cost?

 The acquisition cost of any laser machine depends on a wide range of factors such as:

• Laser power 
• Cutting area
• Automation levels

An industrial, second hand CO₂ laser system can cost around £150,000 upwards. 

A new industrial fiber laser machine can cost £275,000 – £550,000 and sometimes up to a million pounds. However, solid state laser technology is becoming increasingly popular and hence the cost of laser systems is decreasing.

A new CO₂ laser will also cost around the same however, the CO₂ laser source prices are stagnant. 

What maintenance & Operating Costs should you expect?

Maintenance

Fiber lasers have significantly lower maintenance requirements than their CO₂ counterparts.  The main difference comes from the laser beam delivery system.

Fiber lasers have a monolithic configuration whereby the laser beam is delivered to the cutting head via a fiber optic cable.

This means that the optics path is completely protected from contaminants. The two main consumables of a fiber laser are the nozzle (the same applies for CO₂ lasers) and the protective window.

CO₂ lasers use bend mirrors contained within bellows (sometimes filled with nitrogen) to deliver the beam to the cutting head.

The mirrors and bellows will get dirty over time and will need cleaning/replacing regularly to prevent a decrease in the cutting performance. The repetitive movement of the machine produces holes in the bellows over time. 

Given the beam delivery system is more exposed to the environment (temperature, moisture etc.) than fiber lasers, CO₂ lasers experience higher levels of variation in the quality and output of the laser.

The heat of the laser often causes the mirrors to distort, reducing the power supplied to the cutting head leading to the misalignment of the laser beam. This may require changes to the cutting parameters to counter this variation which can be a timely process.

The main and most costly issue with CO₂ lasers occurs when the laser beam is reflected back down the beam delivery system causing damage to the expensive oscillator.

Maintenance of a CO₂ laser cutting head can take between 4-5 hours a week compared to less than half an hour a week for a fiber laser. 

The alignment of a laser beam is important to ensure an even cut finish on all sides of a profile (Image below demonstrates the effect of a misaligned beam).

The most common cause of misalignment is a collision between the cutting head and a tipped part and can happen for both CO₂ and fiber laser systems.

Misalignment is both more complicated and time consuming to correct on CO₂ lasers due to the nature of the beam delivery system which normally contains at least three mirrors.

For fiber lasers, only a single lens needs adjusting.

Auxiliary Gas

The smaller spot size and consequent narrow kerf width means that in order to effectively eject the melt from the cut high gas pressures are needed for a fiber laser.

However, careful balancing of the cutting parameters (i.e. cutting speed and focal position) along with the gas pressure and nozzle size, gas consumption can be minimised.

Table 6 shows the gas pressure and nozzle size used to cut the samples shown above and the cost using a 6 kW fiber and CO₂ laser. 

*values for reference only

Table 6: Auxiliary Gas Consumption for different laser cutting technologies

In conclusion, on average a fiber laser will use approximately 40% more nitrogen per hour than a CO₂ laser when cutting stainless steel and approximately 20% more oxygen when cutting mild steel.

If you are mainly cutting stainless steel, and you are looking for more information on fiber laser cutting machines, we could recommend this helpful guide on how to find the best stainless steel fiber laser.

Electricity Costs

When it comes to electricity costs, fiber lasers are significantly cheaper and more environmentally friendly than CO₂ lasers.

CO₂ lasers have an efficiency of approximately 10%, therefore to power a 6kW laser, a 60kW power supply is needed whereas, a fiber laser cutter is approximately 45% (can be up to 50%) efficient so only a 13kW supply is needed.

Clearly, as the laser power increases so will the electricity costs of the machine due to the need for a larger chiller. However, for the same power, a chiller for a CO₂ laser will have higher electricity costs.  

The electrical requirements of the extraction system will depend on the size required: as laser power increases so does the extraction system required. Additionally, as the cutting table area increases so will the power requirements of the filtration system.

Overall, the significantly reduced electricity costs of a fiber laser machine can result in huge cost savings for cutting applications.

Which machine is easier to Set Up and has more Idle Time?

CO₂ lasers have a warm-up time of around 10-20 minute. The lack of moving parts in a fiber laser system means it is ready to go instantly, minimising unnecessary machine downtime.

Regular maintenance of all machine components (laser system, chiller, extraction unit and machine) is essential to prevent costly servicing and also to prevent machine downtime.

What is the Total Cost of Ownership for both technologies?

The total cost of ownership brings together all the direct and indirect costs of owning a laser machine.

While the acquisition costs of a fiber laser cutting machine, the significantly faster cutting speeds (for thinner materials) will increase productivity which combined with the energy savings results in a low cost per part.

Productivity can be further improved with greater levels of automation.

Automation for both CO₂ and fiber lasers can come in the form of a ‘full lights out operation’ and also in the form of automatic nozzle changing and lens autofocus which eliminates the need for manual interventions as well as reducing machine idle time.

While increased automation will significantly increase the acquisition cost of a laser system, the increase in productivity, combined with a reduction in unwanted machine downtime caused by human error can reduce the total cost of ownership.

Which machine will occupy less shop floor space?

The footprint of the machine will largely depend on the size of the cutting bed and shuttle tables used. However, when comparing the laser systems, fiber lasers take up less space than CO₂ lasers.

For the same laser power, the cross-sectional area of a CO₂ laser can be approximately 3 times larger and 4 times the volume requirements.

Additionally, because of the reduced electrical efficiency of CO₂ lasers, the corresponding chiller also has a larger footprint than a fiber laser counterpart.

Safety: which technology is safer to use?

Laser Light

Laser light (both direct and reflected) has the potential to cause significant damage to both the skin and eyes.

Laser types are classified into different categories based on their potential for causing injury to human eyes and skin. All laser machines by law will be required to have a label clearly stating its class. Refer to BS EN 60825-1 (IEC 60825-1) for precise definitions of laser classes and indications on the limits of accessible radiation. These can briefly be defined as:

Class 1 – “Laser systems that are safe in normal operation even with prolonged direct observation of the laser beam and even if the exposure occurs in connection with optical instruments (magnifying glasses or telescopes).”

Class 2M – “Laser systems that emit visible radiation that is safe for the naked eye only in event of brief exposure. An eye injury can be caused by exposure through focusing optical instruments (magnifying glasses, telescopes, microscope, etc.).”

Class 4 – “Laser systems for which direct viewing of the beam and skin exposure are dangers and for which even the viewing of diffused reflections can be dangerous. These lasers also frequently pose a fire risk.”

Fiber lasers, because of their wavelength, on their own are a Class 4. However, most laser cutting systems will be Class 1. This is because the laser source is fully enclosed with a range of safety measures incorporated to prevent any potential injury to the skin and eyes. These safety measures include:

• Interlocks – stop the laser from firing if the laser is no longer fully enclosed i.e. a door is open
• Safety Glass – this is used to allow the operator to view the cutting area while protecting them from the laser beam. Plastic is most commonly used; however, the optical density must be suited to the laser source. The exact requirements of the glass will depend on the power, focal length, beam diameter at the lens and the distance of observation.

It is important when purchasing a fiber laser machine that both the laser source & the machine are fully CE certified.

Fume Extraction

Both laser types will generate fumes and particulates during the cutting process. These not only can cause damage to machine components and the electronics, decreasing cutting performance, but are also extremely harmful for humans. The exact requirements of the system will depend on a range of factors such as the laser power and the size of the cutting table.

The defining factor on the type and quantity of fumes emitted is not the laser type, but the material being cut. Cutting plastics and other combustible materials will produce highly toxic fumes, while metals will produce fine particulates.

Noise

The majority of noise produced by a laser cutting machine is because of the machine movement and not because of the laser source.

When cutting thicker materials, a reasonable amount of noise is produced by the assist gas, in particular when cutting with nitrogen due to the high pressures. In general however, for EC and UKCA conforming machines, no ear protection is required.

In summary

Despite CO2 lasers being an older and potentially declining technology, it still serves as an excellent choice particularly for cutting non-metals.

However, the speed advantage (up to five times greater) on thin materials (< 8 mm), 50% lower operating costs and higher outputs, the financial gains that can be achieved using fiber lasers can be game changing.

If you have any questions about laser cutting, please don’t hesitate to contact us. 

Our team of expert engineers can help you identify the right CNC cutting machine for you and they’d be delighted to talk you through the specific requirements and how Esprit Automation could help you to meet them.

About the Writer

Saquib Ansari – Managing Director – Esprit Automation Ltd

About Esprit Automation

Esprit Automation is a leading manufacturer of CNC laser, plasma and flame cutting machines in the UK. From our base in Nottingham, we supply a range of advanced sheet and plate metal cutting solutions for customers throughout the world.

About Photon 5G Fiber lasers

Ground-breaking axis speeds, an advanced visual nesting system, and a revolutionary CNC interface are just some of the features that make the Photon 5G a new benchmark in laser cutting.