Laser cutters are versatile tools used for various applications and are available in different power outputs.
Every material has a minimum laser power required to cut or engrave.
But what exactly is laser power, and how does it affect the laser-cutting operation?
A laser power between 5W-50W is optimal for most non-industrial laser cutting and engraving applications. Laser power of 80W or higher is recommended for industrial applications that require fast cutting speed. Using low-powered lasers to cut thick materials requires multiple passes.
This article discusses laser-cutting power in detail and provides insights into optimal power settings for different materials.
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Laser Cutting Power: Why is it Important?
Depending upon the type of material, depth of cut, and the type of laser being used, the optimal laser power varies from one application to another.
A laser cutter works by focusing a high-energy laser beam in a small spot to vaporize the material and produce the desired cut, and the energy of the laser depends upon its power.
As a result, hard materials like aluminum and brass require comparatively more laser cutting power than soft materials like wood, paper, etc.
Similarly, performing a deeper cut requires more energy than a shallow cut, thus requiring more laser power.
Furthermore, the optimal laser cutting power also depends upon the wavelength of the laser and the ability of the material to absorb the energy at that wavelength.
This can be understood from the fact that a 100W CO2 laser can make clean cuts in materials like paper, wood, leather, etc. but cannot be used for cutting metal.
This is because CO2 lasers have a longer wavelength, and metals do not readily absorb energy at this wavelength. As a result, most of the laser energy is lost in reflection.
However, using a high-power CO2 laser (over 500W) overcomes the energy lost in reflected lasers and heats the metal to produce the desired cut.
Therefore, laser power is an important parameter that determines the ability of a laser to produce quality cuts in the workpiece.
How Does Laser Power Affect the Cutting Process?
Laser power is one of the most important parameters in the laser cutting process because it directly affects various other factors like cutting speed, depth of cut, quality of cut, efficiency, and productivity.
Cutting Speed Increases with Power Increase
The cutting speed is the speed at which the laser moves over the workpiece.
As the laser strikes the surface of the workpiece, the laser energy is absorbed by the workpiece and transformed into heat.
The slower the cutting speed of the laser, the higher the energy supplied, and the higher will be the temperature at the cutting area.
Therefore, when using a laser cutter, the power of the laser determines the optimal dwell time to get the desired output.
For example, a 10W diode laser, such as the Comgrow Z1 and TwoTrees TS2, can perform through cuts in 2mm thick plywood at a cutting speed of around 400mm/min.
In contrast, a 5W diode laser, such as the Atomstack X7, will perform a similar operation at a much lower cutting speed of around 200mm/min.
This is because the higher cutting power of a 10W laser provides more energy per second to heat the material and vaporize it.
On the other hand, the 5W laser requires a longer dwell time to supply a similar amount of energy.
This implies that the higher the power of the laser, the faster the cutting speed can be.
However, using high laser cutting power with an extremely slow cutting speed can result in over-burning of the workpiece.
Therefore, it is important to identify the optimal configuration of the laser cutting power and cutting speed that produces the best results.
Depth of Cut Increases with Power Increase
Another laser cutting parameter that depends upon laser power is the maximum depth of cut a laser can perform in the workpiece.
Low-powered lasers cannot produce deep cuts because the amount of laser energy required to vaporize the material increases with the increase in the depth of cut.
Although increasing the dwell time will increase the laser energy supplied to the cutting area, it will also result in a large heat-affected zone, damaging the workpiece.
However, you can use multiple passes to achieve a greater depth of cut without damaging the workpiece, but at the cost of cycle time.
Therefore, higher-powered lasers are ideal for industrial applications where deep cuts are to be made with quick cycle time.
Quality
Laser-cutting power affects the quality of the cut in terms of its accuracy and appearance.
Using a high-powered laser can result in overheating of material, thereby melting the workpiece and increasing the width of the cut.
For example, laser cutting polypropylene (a type of plastic) produces clean cuts with a smooth surface finish, but it is a heat-sensitive material that can easily undergo melting and leave a gooey mess on the cutting table.
Similarly, laser cutting flammable materials like paper and wood can produce clean cuts with slight charring along their edges, but using an extremely high laser power can result in overburning of material.
This overburning of flammable workpieces can affect the quality of the cut by producing heavy charring and even risk fire hazards.
Therefore, it is important to regulate the laser power to prevent overheating of the material and ensure high-quality cuts with good accuracy.
Productivity
The laser power also affects the productivity of the process by affecting its cycle time.
Although a 20W laser can perform clean cuts in acrylic, it cannot be used for applications requiring large-scale acrylic cutting.
This is because, when compared to a 60W laser, a 20W laser will be comparatively much slower at producing the same cut, thereby increasing the lead time of production.
Apart from that, a higher-power laser also provides greater material flexibility, and regulating its laser power enables using a single laser cutter to cut and engrave different materials.
Therefore, a higher-power laser is recommended for industrial applications for quicker cycle time and greater material flexibility.
Cost
A high-power laser cutter requires a powerful laser module capable of producing high-energy laser output. But as the power rating of the laser increases, the cost of the equipment also increases.
Apart from that, high-powered lasers generate high heat, making it necessary to use a cooling system to prevent equipment, such as focusing lenses, from overheating.
This further increases the initial cost of purchasing the laser cutter.
Apart from that, the high input power requirement and operation of additional accessories increase the per-hour operational cost of the laser machine.
However, higher laser power increases productivity and makes it possible to produce a higher output, increasing the overall profit.
Therefore, a high-powered laser cutter pays its cost off by providing higher annual throughput and generating more revenue.
How Much Laser Power Does Your Application Need?
| Material | Laser Power | No. of Passes |
|---|---|---|
| Cutting Regular Paper | 100% of 20W Diode laser | 1 |
| Cutting 2mm Plastic | 100% of 20W Diode laser | 5 |
| Cutting 5mm Wood | 100% of 20W Diode laser | 5 |
| Engraving Fabric (Denim) | 65% of 20W Diode laser | 1 |
| Engraving Glass | 75% of 20W Diode laser | 1 |
| Engraving Metal | 100% of 20W Diode laser | Depends on the type of metal |
A high-powered laser cutter provides various advantages over low-powered ones and is therefore preferable for industrial applications.
But how much laser power is enough power? And how can you identify the optimal power requirement for your application?
The optimal power requirement depends upon the type of material you want to work with and the type of operations to be performed.
Laser cutters can be used to perform operations like marking, engraving, etching, and cutting, with each operation requiring different laser power output.
Generally, laser cutting requires more laser power than engraving, which in turn requires more power than etching and marking.
Similarly, materials with high density require more laser power to vaporize their surface compared to softer materials that are easily vaporized.
Although there are various laser cutting power and speed charts, the optimal settings vary from one setup to another, and the values in the charts should be treated as references to get started with your test runs.
Therefore, performing test runs and finding the best configuration for your setup is necessary.
Laser Power Required to Cut Paper
Paper is a flammable material that is generally soft and therefore does not require high laser power for cutting or engraving.
Using extremely high laser power can result in charring along the cut edges and even cause a fire.
Generally, laser cutting paper requires a laser cutter for home-based applications with around 10-15W laser power to make clean cuts with a high cutting speed.
Laser Power Required to Cut Plastics
Plastics are synthetic materials that are available in different types, and each type behaves differently under a laser.
Acrylic is one of the best suitable plastics for laser cutting and engraving applications as it produces clean cuts with a flame-polished finish.
Apart from that, plastics such as polypropylene, Delrin, mylar, etc., are also suitable for laser cutting.
However, these synthetic materials are heat-sensitive and are prone to melt when processed under a laser.
Therefore, it is important to have a high cutting speed to minimize the dwell time and ensure a controlled heat-affected zone.
Generally, a 40-80W laser is recommended for small-scale applications involving laser cutting plastic and 80-100W for industrial applications.
Using high-powered lasers provides the ability to get the desired result with minimal dwell time.
Laser Power Required to Cut Wood
Wood is a natural material that does not undergo melting but is highly flammable if subjected to extremely high laser power.
Although a high-powered laser can make clean cuts in almost any type of wood, soft wood such as alder, balsa, basswood, poplar, cedar, and pinewood are the best options for laser cutting.
Laser cutting wood requires a high-pressure air assist to facilitate the cutting process and reach the desired depth with a minimal heat-affected zone.
You can make an air assist for your laser cutter by using your existing shop compressor.
Generally, industrial applications involving laser cutting of wood require a laser power of above 150W, but you can also use a 20W diode laser such as xTool D1 pro to make DIY projects from softwood by using the multi-pass technique.
Laser Power Required to Cut Fabric
Fabrics are available in different types, and the optimal laser power for laser cutting fabric depends upon the type and thickness of the fabric being used.
Natural fabrics like cotton and denim produce frayed edges when cut by a laser, whereas synthetic fabrics like nylon, felt, fleece, velvet, microfiber, etc., produce sealed edges.
Laser cutting synthetic fabrics require comparatively less laser power than natural fabrics. Using a higher-laser power than the optimal settings can result in melting and solidifying of these fabrics.
Generally, low powered laser, such as a k40 laser cutter, is recommended for small-scale projects, and a laser power of around 80W is recommended for industrial applications.
Laser Power Required to Cut Leather
Laser cutting leather is one of the most popular applications in small-scale as well as large-scale industries for making accessories like wallets, bags, bracelets, etc.
When processed under a laser, leather cuts with a brownish edge that adds contrast to the workpiece, and the optimal laser power depends upon the type of leather being used.
Generally, synthetic leathers are easier to cut and require a laser power of around 40W for small-scale applications, whereas industrial applications involving laser cutting of natural leathers require a laser power of around 80W to make clean cuts with minimal edge burns.
Laser Power Required to Cut Glass
Laser cutting glass can be challenging because of its high reflectivity and toughness.
Low-cost laser cutters like diode lasers are generally suitable for laser engraving glass and cannot be used for cutting operations.
This is because diode lasers are not effective in machining transparent surfaces. However, you can apply black paint to make the surface opaque and perform engraving.
On the other hand, laser cutting involves making deeper cuts rendering the masking technique ineffective.
Generally, a CO2 laser with a power rating of over 80W is recommended for laser cutting glass but requires special techniques like using a damp paper towel to cover the surface and achieve a clean cut.
Laser Power Required to Cut Metal
Metals are one of the most difficult materials to laser cut. Their highly reflective surface bounces the laser beam off and results in a loss of laser energy.
As a result, high-power laser cutters are required for laser cutting metal.
Generally, a fiber laser with a power rating of over 500W is recommended for laser-cutting metals.
Although CO2 lasers cannot be used for engraving metals, higher-powered CO2 lasers (over 1 kW) are suitable for laser-cutting applications.
This is because, as the depth of cut increases, the reflection of the laser beam inside the kerf intensifies the process and produces a clean cut.
Therefore, fiber lasers are recommended for applications involving laser-cutting sheet metals, whereas high-powered pulsed CO2 lasers are used for cutting thicker metal workpieces.
Apart from these, recent developments have produced direct diode lasers with a power rating of over 5kW, which can be used to perform clean cuts in metal workpieces of variable thicknesses.
Final Thoughts
Laser cutting power plays an important role in determining the ability of a laser cutter to make quality cuts in different materials.
However, identifying the optimal laser power for your application can be challenging and requires you to perform test runs with different power and speed configurations.
The maximum power output of a laser cutter directly affects its cost. Therefore, it is advised to identify your requirement and select the best laser cutter that provides the required power output.
Furthermore, lasers can be dangerous if handled carelessly, especially high-powered lasers. Hence it is strongly advised to follow laser safety protocols and wear laser safety glasses.
Frequently Asked Questions (FAQ)
Is it recommended to use a laser cutter at full power?
No, it is not recommended to use a laser cutter at full power because utilizing the maximum potential of the laser on a regular basis can wear out the equipment and reduce its life. Therefore, it is always advised to use only 90% of the total laser cutting power to maximize its life.
Does the laser focus affect the laser power?
Yes, the laser focus directly affects the laser power. Having an extremely focused laser beam results in high energy density, making the laser capable of vaporizing the material faster, whereas a de-focused laser will result in diffusion of laser power over a wider area, making it comparatively less capable of vaporizing the material.
Does laser cutting involve high electricity costs?
Yes, industrial laser cutters that provide high laser power output require high electricity input than most traditional machines. However, the ability of lasers to produce faster and more efficient cuts enables them to produce more products per hour of operation, thereby covering the high operational costs by providing the ability to deliver more products in the same time.
