Precision Aluminium Laser Cutting: Techniques for Flawless Results

Higher reflectivity and thermal conductivity make aluminium laser cutting much more difficult than carbon and stainless steel, but that doesn’t mean perfect results can’t be achieved. By reading this article you will be able to master some of the techniques of aluminum laser cutting.

What is Aluminum?

Aluminum is a metal with high reflectivity and thermal conductivity. It is widely used because of its light weight, corrosion resistance, and lightness.

Although aluminum has been used for a long time, it doesn’t mean that one can cut it perfectly, especially laser cutting aluminum!

So in this article, we will delve into the difficulties faced by aluminium laser cut and how to set the parameters to cut a smooth aluminum cutting surface without burrs.

Why is laser cutting aluminum difficult?

It is well known that laser cutting is characterized by high efficiency and high precision, but in the actual process of cutting aluminum, it still faces many difficulties.

Aluminum is a highly reactive material

Aluminum has a surface reflectivity of 85%-95% to common fiber lasers (1064nm) and CO2 lasers, and most of the laser energy is reflected rather than absorbed, which can damage optical lenses or sensors.

Although aluminum has been criticized for its high reflective properties, it is not difficult to fix. We can reduce the high reflectivity by pre-treating the aluminum sheet, such as laser burring or spraying a temporary coating.

Fast heat conduction

Aluminum’s thermal conductivity is five times that of steel, laser cut aluminium sheet process, the heat quickly spread around, the bottom temperature is not enough, the lower aluminum is not cut, which in turn leads to hanging slag.

Aluminum’s thermal conductivity will also make the size of the melt pool or solidification degree is not controllable, resulting in cut out of the seam width or burr more. When the heat from the laser is conducted around the cutting area, it causes the aluminum in the vicinity to soften and warp, which in turn leads to distortion of the cut part.

In order to avoid the problem of poor cutting results due to the fast heat conduction of aluminum, it can be solved by adjusting the parameters of the aluminum laser cutting machine, preheating the aluminum plate, and choosing the right power equipment.

Low Melt Viscosity

Aluminum has a low viscosity after being melted by heat, which is difficult to be blown away by the auxiliary gas, resulting in slag sticking at the bottom or rough cutting edges. In order to avoid this situation, you can enhance the blowing gas during the cutting process to blow away the melted aluminum on the cutting surface quickly.

Advantages of aluminum laser cutting

Aluminum is used in every aspect of our lives, such as cans, broken aluminum doors and windows, pots and pans, ovens, and metal casings for electronics. There are also many ways to cut aluminum panels, such as saw cutting, CNC cutting, and laser cutting aluminum.

With so many cutting methods, why is aluminum laser cutting widely used? That is definitely because it has many unique advantages.

Non-contact processing

One of the biggest differences between laser cutting and CNC cutting, saw cutting and other methods is that laser cutting is non-contact cutting. This also means that the material does not deform when laser cut aluminium plate or tube, even if it is as thin as less than 1mm.

Laser cutting is non-contact by projecting a focused laser beam onto the surface of the material to be cut, causing the material’s temperature to rise instantaneously and cause it to melt or vaporize. This also means that aluminum laser cutting produces no tool wear, reducing consumables in this area.

Laser cut aluminum with high precision

Compared with waterjet cutting or plasma cutting, the positioning accuracy of aluminum laser cutting can reach ±0.05mm, or even ±0.03mm, and the width of the slit can be controlled at 0.1-0.3mm (equivalent to the width of two hair strands). It is more suitable for industries that require high cutting accuracy, such as iPhone camera aluminum ring cutting such as fine processing.

Fast cutting speed

Cutting the same thickness of aluminum, especially thin aluminum, laser cutting is faster than shearing, sawing, plasma cutting and so on. The speed of cutting 3mm thick aluminum with 6KW laser cutting machine aluminium can reach 15m/min, while the speed of plasma cutting is only 3m/min, which is 1/5 of laser cutting.

Anti-reflective design

Aluminum laser cutting high reflectivity will lead to low energy utilization and risk of damage to the equipment. To solve this problem, many laser cutting machine manufacturers are equipped with a return light isolator, which can block 99% of the reflected light, effectively reducing the damage to the laser from cutting highly reflective materials and improving the cutting effect.

Digitalized Intelligent Production

The automatic loading and unloading system of the laser cutting machine combined with AI visual inspection is revolutionizing the production mode of aluminum processing, which can realize 24-hour unmanned uninterrupted production.

Key methods for high quality aluminum laser cutting

Seeing this, I’m sure you’ve learned about aluminum-related knowledge and the benefits of laser cutting. In this section, effective methods for cutting aluminum with high precision will be introduced.

Equipment power and cutting speed

Due to the fast heat conduction of aluminum and the fact that it is not easy to be blown clean after melting, you need to pay attention to matching the power of the equipment with the cutting speed when laser cutting. Too fast a speed will lead to cut through or slag hanging at the bottom, while too slow will trigger over-burning and too wide a slit.

In the cutting of thin aluminum plate below 3mm can be high-speed cutting (10-25m/min) with high-frequency pulse to avoid heat accumulation. When cutting thicker aluminum than 6mm, reduce the speed appropriately and use progressive power boost to ensure energy penetration.

You can find out the highest efficiency speed point for burr-free cutting by test cut calibration, usually 70-80% of the limiting speed.

Material Pre-treatment

The surface state of aluminum directly affects the laser absorption rate, if the conditions allow, it is recommended to carry out pre-treatment, such as removing the oil film and oxidation layer on the surface of aluminum, spraying matte coating on mirror aluminum and other ways to improve the absorption of aluminum to the laser.

Auxiliary gas

The auxiliary gas is used to blow away the residual slag, protect the lens and increase the cutting speed. When laser cutting aluminum, the use of nitrogen can obtain better cutting results. This is because nitrogen is an inert gas and will not react with aluminum. Moreover, high-pressure nitrogen can effectively blow away molten aluminum, avoiding the formation of burrs from slag condensation and thus improving the quality of the cut surface.

Cutting quality monitoring

Real-time monitoring is the core of cutting quality assurance. Normal melt pool should show stable blue plasma, if there is flying sword or flashing need to adjust the parameters.

The length of the backside spark beam should be 20-40mm, if the spark is too short, it means that the power is not enough, and if it is too long, it is too fast and does not cut through.

Common defects in cutting processing

Defect Phenomenon	Possible Causes	Solutions
Hanging slag at the bottom	Insufficient gas pressure/clogged nozzle	Clean the nozzle and increase the pressure by 0.2MPa
Cutting seam is wide at the top and narrow at the bottom	Focal point position is shifted	Re-calibrate the focal point (±0.05mm)
Cutting surface blackened	Oxygen mixed in / speed too slow	Check gas tightness and increase speed by 10%

FAQs

Can aluminium be cut with laser?

Yes, of course! Laser cutting is by far the most suitable option. It is widely used in the aluminum processing industry because of its high precision, speed, environmental friendliness and cost-effectiveness.

How much does it cost to laser cut aluminum?

Aluminum laser cutting machine price depends on several factors such as laser type, laser power, processing width and so on.

Generally speaking, CO2 laser cutting aluminum has a simple structure and mainly focuses on low power, which is easier to obtain and less expensive.

Fiber laser cutting aluminum has more power and processing width, more suitable for industrial use, and more expensive. The specific aluminium laser cutting price needs to be determined according to the specific configuration.

What thickness of aluminium can be laser cut?

The power of the aluminum laser cutting machine determines the thickness of aluminum that can be cut. The higher the power, the thicker the material can be cut. However, this does not mean that there is no upper limit to the thickness of aluminum that can be cut with a high power laser cutting machine. The relationship between laser power and aluminum thickness is as follows:

Power	Thickness	Cutting Speed (Nitrogen)
1-2KW	1mm	15-25m/min
4-6KW	6mm	3-6m/min
8-12KW	15mm	0.8-1.5m/min

When the thickness of aluminum plate＞25mm, the bottom of the slag will be more serious, need to match with other equipment to clean up the slag.

You may want to know:

Laser cut aluminum VS CNC cut aluminum

See here, perhaps between laser cutting and CNC cutting, you have a lot of questions, the following will be compared from the cutting thickness, efficiency, investment costs and cutting results.

Cutting Thickness

Due to the high thermal conductivity of aluminum, laser is more suitable for cutting medium-thin plates, such as chassis, heat sinks. cnc is suitable for cutting ultra-thick aluminum parts, such as mold blanks.

Cutting efficiency

Due to CNC cutting is layered milling, coupled with CNC is a contact cutting method, tool wear faster, need to change the knife frequently so the cutting speed will be relatively slow.

Laser cutting in the cutting of thin aluminum, the fastest speed up to 20m/min, and non-contact processing, no need to change the tool, in a large number of flat cutting efficiency.

Equipment cost

Laser cutting without expensive consumables, a purchase cost, follow-up maintenance costs are low. CNC cutting machine in the process of processing, tool wear and tear faster, the need for frequent replacement, coupled with the CNC processing of the cut seam is larger, the loss of raw materials is more. In the long run, CNC cutting is not as cost-effective as aluminum laser cutting machine.

Conclusion

Although aluminium laser cutting faces challenges such as high reflectivity and fast thermal conductivity, high quality cutting can be fully realized through scientific parameter setting and advanced process control of material pre-treatment machine.

With the power increase of fiber laser and the development of monitoring technology, aluminium laser cutting is breaking through the limit of thickness and precision, and becoming a key process in aerospace, electronics, automotive and other fields.

Contact us for the best laser aluminum cutting solutions!

XT LASER is committed to providing the most appropriate aluminum laser cutting support to our customers. We have a deep understanding of each customer’s different processing needs, ensuring that each customer receives the most satisfactory solution.

If you have specific needs, please contact our professional team for a free and customized quote.

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