Laser cutting aluminum is a manufacturing process that uses a high-powered laser beam to cut through aluminum sheets or plates.
In recent years, laser cutting has become increasingly popular in various industries due to its numerous advantages over traditional cutting methods.
One of the materials that benefit greatly from laser cutting is aluminum.
In this article, we’ll explore everything you need to know about laser cutting aluminum, including aluminum’s characteristics, the types of lasers that can cut it, choosing the right laser cutter, the process of laser cutting aluminum plates, and much more.
Characteristics of Aluminum
Aluminum has high thermal conductivity and can be easily cast into various complex shapes. Although it is a relatively soft metal, laser cutting aluminum can be challenging.
Therefore, it is important to understand the material properties of aluminum to ensure successful and efficient processing.
Aluminum is a non-ferrous metal that is abundant in the Earth’s crust. It is lightweight, soft, and durable, making it easy to cut or shape using a laser cutting machine.
Unlike iron and steel, aluminum is resistant to rust and corrosion.
Its high flexibility results in minimal waste during the laser cutting process, and any remaining waste can be recycled, making it an environmentally friendly choice.
Can a laser cut aluminum?
Yes, a laser can cut aluminum. Laser cutting is indeed a popular and effective method for cutting aluminum due to its speed, quality, and accuracy.
Both CO2 lasers and fiber lasers are capable of cutting thin sheets of non-ferrous metals like aluminum.
However, using a carbon dioxide laser requires coating the material surface to prevent reflected light from damaging the laser device. In contrast, fiber lasers can directly cut non-ferrous metals.
Despite being faster and producing smoother workpieces than traditional cutting machines, processing aluminum with a laser cutting machine can be expensive due to the high reflectivity of aluminum.
What type of laser can cut aluminum?
When it comes to cutting aluminum using lasers, there are three main types of lasers to choose from.
These are carbon dioxide (CO2), fiber, and YAG laser cutting machines.
Out of these three, the CO2 laser is the least ideal for cutting aluminum due to its wavelength of 9.5-10.6 µm, which makes it difficult to perform laser processing on aluminum.
The reason for this is that aluminum strongly reflects rays within the wavelength of a CO2 laser.
As a result, most of the radiation bounces off the reflective aluminum, with only a small part of the energy absorbed. This isn’t sufficient to melt and vaporize aluminum.
However, it’s possible to overcome this problem by using a high-power CO2 laser with a high frequency that can hit the aluminum surface fast enough to overcome the power lost by reflection.
Alternatively, a fiber laser or an Nd YAG laser with a wavelength of 1.06µm is best suited for laser cutting of sheet metal. These wavelengths are readily absorbed by metals, making it easier to cut aluminum.
In particular, a fiber laser offers almost three times faster operation on aluminum compared to a CO2 laser of the same wattage.
This is because a fiber laser cutting machine doesn’t require any mirrors and is, therefore, less susceptible to the reflection of aluminum.
Overall, both CO2 and fiber laser machines offer precise and clean cuts for cutting aluminum, but a fiber laser is the best option due to its ability to overcome the issue of reflection and provide faster operation.
Which type of laser cutter should you choose?
Choosing the right type of laser cutter depends on a few factors.
Firstly, it’s important to consider the grade of aluminum you want to cut as higher grades with more alloying elements(which are mixed with other metals, such as copper and magnesium for example) are easier to cut.
Fiber lasers and YAG lasers are better for cutting reflective materials like aluminum, while CO2 lasers are more susceptible to damage.
When it comes to power, more is better. A powerful fiber laser or YAG laser will give you better results than a CO2 laser with similar parameters.
And to combat aluminum’s reflective nature, you need to focus on the right distance to keep the focus point on the farther end of the material. This also helps reduce the occurrence of dross.
In summary, when choosing a laser cutter for aluminum cutting, it’s best to go for a powerful fiber laser or YAG laser, consider the grade of aluminum you want to cut, and keep the right focusing distances in mind.
How to Laser Cut Aluminum Plates?
The process of laser cutting aluminum plates involves using a high-powered laser beam to melt or vaporize the material, resulting in a clean and precise cut.
Firstly, the laser beam is directed onto the surface of the aluminum plate, causing it to reach its melting or boiling point.
At the same time, high-pressure gas is used to blow away the melted or vaporized material.
This helps to keep the cutting area clear of debris and prevent the cutting head from overheating. This process results in a clean and precise cut.
This gas is called an auxiliary gas, and it helps to keep the cutting area clear of debris and prevent the cutting head from overheating.
What gas is used for laser cutting aluminum?
Nitrogen gas is commonly used for laser cutting aluminum. It is an inert gas that prevents additional heat-producing reactions, resulting in cleaner cuts at a faster rate.
Laser cutters use the heat from the laser to melt the material, and then a jet of nitrogen gas is used to remove excess metal from the cut surfaces.
Other auxiliary gases like oxygen, air, and argon can also be used for laser cutting, but nitrogen is ideal for aluminum and its alloys, as well as stainless steel.
Technical Explanation of Laser Cutting Aluminum Plates
Two types of machines are widely used for cutting aluminum plates: fiber laser cutting machines and YAG laser cutting machines. As for CO2 machines, they are not suitable for working with aluminum on an industrial scale.
Both of these machines have proven to be effective in cutting aluminum, as well as other materials like stainless steel and carbon steel.
However, due to the highly reflective nature of aluminum, neither fiber nor YAG laser cutting machines can process thicker aluminum plates.
The cutting thickness of these machines varies, with a 2000W laser capable of cutting 6-8mm, a 4000W laser cutting 14mm, and a 6000W laser cutting 16mm.
Out of the two, fiber laser cutting machines are more suitable for cutting aluminum plates, as their wavelength absorption of 1064nm is more effective.
When it comes to the difference between YAG and fiber laser cutting machines, there are three categories: cutting quality, cutting speed, and production cost.
For cutting thick aluminum, process control is critical for achieving optimal cutting quality. Too fast a cutting speed can result in burrs, while too slow a speed can cause cracks in aluminum materials, affecting the cutting quality.
Generally, fiber laser cutting machines have a faster cutting speed compared to YAG lasers.
The cost of laser cutting is relatively low compared to other cutting processes, but there is a difference between fiber and YAG laser cutting machines.
The cost of fiber laser cutting is lower due to the frequent replacement of laser lamp accessories in YAG laser cutting machines.
However, in the long run, aluminum material has a detrimental effect on the laser of the fiber laser cutting machine, significantly reducing its service life. From this perspective, YAG laser machines are more cost-effective.
Lastly, it’s important to note that aluminum has high reflectivity and low absorption of laser, making it necessary to wear laser protective glasses during processing to ensure safety.
Laser Cutting Parameters for Aluminum
For aluminum cutting, it’s common to use either air or nitrogen with a flow rate of around 40-50 cubic meters per hour.
The speed at which you can cut the material depends on its thickness, and typically, the maximum thickness you can cut is 12mm with an IPG 6000W laser machine.
A 6000W laser can cut a 4mm aluminum plate at a speed of 10,000 to 13,200 mm/min.
However, if you’re cutting a 12mm plate, the cutting speed will be slower at around 800 to 1,550 mm/min.
Fiber Laser Cutting Thickness & Speed Chart for Aluminum
You can scroll the table horizontally(↔️) if any part gets cut out(specially in mobile)
Role of Process Parameters and Auxiliary Gases in Optimizing Laser Cutting Process
The optimization of this process depends on several factors, including laser power, cutting speed, auxiliary gas, and reflection detector. Let’s explore each of these factors in detail.
The power of the laser beam is one of the most important parameters that affect the aluminum processing ability of a laser machine.
The higher the laser power, the thicker the aluminum it can cut through.
For cutting a 1/8″ (3mm) thick aluminum plate, a fiber laser with a power rating of 1000W or higher is recommended.
Using a multi-pass cutting technique with a lower laser power output improves the quality of the cut at the cost of cutting time.
The cutting speed of a process is another important parameter that defines the smoothness of the edge and the overall surface finish of the cut.
A fast cutting speed is recommended while laser cutting aluminum, and for this reason, a high-powered laser module is generally preferred.
However, choosing an appropriate cutting speed along with good process control is very important to avoid burrs or cracks in the workpiece.
The auxiliary gas used for air assist also plays an important role. Nitrogen is the most suitable gas for aluminum laser cutting because it facilitates a much higher cutting speed with smooth edges and no oxidation effect.
High pressure and high flow rate (40-50m3/h) of nitrogen gas are recommended for best results. Using oxygen might improve the cutting speed, but it will lead to the oxidation of aluminum along the edges of the cut.
Whereas using air as the auxiliary gas can give better results with good cutting speed and is less likely to cause oxidation of aluminum.
The laser light reflected back by the aluminum not only hinders the cutting process but can also cause damage to the laser module.
Therefore, most modern metal laser cutters have a safety feature that detects the amount of laser being reflected into the laser head.
This safety feature immediately turns off the laser if too much laser is being reflected, saving the equipment from serious damage. It is necessary to have this safety feature in the laser cutter used for processing aluminum.
Challenges in Laser Cutting Aluminum
Aluminum laser cutting comes with its own set of challenges. Let’s discuss some of the common challenges of this process. I will also add solutions and best practices for overcoming these challenges.
Highly Reflective Nature
Aluminum has a highly reflective nature. It can cause the laser beam to bounce back from the aluminum surface and damage the laser cutter.
This reflection is partly from the surface of the metal and mostly from the highly reflective molten pool formed during the laser cutting.
A workaround to reduce the reflective properties of aluminum is to add alloying elements such as magnesium, zinc, silicon, etc.
This significantly reduces the reflective properties of aluminum and makes it easier to cut with a laser.
Another solution is to use a fiber laser that has a wavelength of around 1 micron, which is less susceptible to reflection than CO2 lasers.
Aluminum Oxide Film
One of the challenges associated with melting temperature is the thin layer of aluminum oxide (Al2O3) film, which forms on aluminum’s surface as it’s exposed to the atmosphere.
The film prevents further corrosion, but it also complicates the cutting process.
The high melting point of the aluminum oxide film formed on the surface of the molten aluminum droplet causes it to solidify very quickly around the still-molten droplet.
So the assist gas needs to flush out quickly before it resolidifies.
If it is not flushed quickly enough, it forms stalactites on the bottom edge, also known as dross.
Loses Heat Quickly
Aluminum is an excellent conductor of heat and tends to lose heat readily. Due to this, the surface cools off rapidly, making it difficult to reach a suitably high temperature for the laser to melt and vaporize the surface.
This problem can be addressed by using a high-speed laser that offers a very high pulse frequency.
This high-speed pulsating laser hits the aluminum fast enough to melt the surface before it loses heat to the surroundings.
Burrs Need Polishing
Even if you succeed in performing laser cutting on aluminum, the sharp edge and burrs along the cut make the process inefficient.
A secondary machining process is sometimes required to attain a smooth edge with a clean finish.
The use of high-pressure nitrogen gas assist will help eject the molten metal from the cut and achieve a faster cutting rate with a smooth edge.
High Processing Cost
Aluminum requires you to follow certain approaches for good quality laser cutting, and depending on the laser and cutting parameters, it might also require some post-processing to get a smooth finish.
This means there is an increased overall cost of the process, making it less efficient than the process of cutting aluminum with a CNC router.
However, laser cutting is more precise and accurate than a CNC router, making it more suitable for complex designs and high-precision cutting.
Advantages of Laser Cutting Aluminum
It is a popular and important process in modern industries due to its high efficiency. Let’s discuss some of the advantages of using this process.
If you use proper laser cutters to cut aluminum, you will get clean cuts with a smooth surface finish. This eliminates the need for secondary processing, saving time and resources.
It is an automated process that can solve the problems of labor shortage and rising costs.
It provides excellent space and time control, reduces the time required for subsequent processing, and offers superior performance and long service life.
Speed and Precision
Laser cutters provide high cutting speed with an accuracy of ±0.004″ (0.1 mm) and a repeatability index of around ±0.002″ (0.05mm).
This precision and accuracy enable you to closely arrange the cutting design on the workpiece, thereby increasing the efficiency of the process by saving 20% – 30% of the material.
Due to its narrow kerf width and high precision, this process produces very little waste material
This results in reduced material costs and less environmental impact, making it a more sustainable option for manufacturing.
It is a non-contact process that eliminates the chances of inducing any mechanical stresses that could lead to fillet or mechanical blanking of the material.
The process allows for intricate and complex designs to be cut with ease.
This flexibility in design makes it possible to create unique and innovative products, including decorative panels, signs, and architectural elements.
I hope this article has given you the confidence to explore laser cutting as a valuable tool for improving productivity, reducing costs, and enhancing product quality.
Now that you have a clear understanding of how to laser cut aluminum, you can confidently use this technology in your laser cutting business or DIY projects.