Welding aluminium is not as simple as it looks. Yes, when you try it, you will realise that it comes with a lot of problems, like metal can form pores, warp, or it may not offer you a clean and finished look. Moreover, you can face burned edges, cracked joints, and inconsistent results. But you don’t worry, in this blog, we have the solution for your problem. Laser welding aluminum? Good catch!
In this blog, we will discuss what laser welding is, how it has helped in aluminum welding, how it works, what its advantages are, its applications, and more. So, just keep reading!
What is Laser Welding and Why is Aluminium Hard to Weld?
A modern technique of welding in which a highly focused laser beam is used to join metals is referred to as laser welding.
In traditional welding, energy is transferred imprecisely, but if we talk about laser welding, it transfers energy so accurately and precisely that it only melts the target part of the metal. As a result, you get clean and strong joints that are minimally affected by heat. Due to this concentration of heat, laser welding is commonly used for welding thin and delicate parts.
Some Unique Challenges in Welding Aluminum
Welding aluminum is not so easy. It presents a lot of challenges. Let’s have a look at what those problems are in fact.
High thermal conductivity
The very first this is that aluminium has high thermal conductivity, which means it can transfer heat easily. So, when you try to heat the target part to melt, it transfers heat to the other parts of the metal. That’s why it becomes difficult to raise the temperature of the area to melt it uniformly.
Aluminum's melting point is about 660 °C, but the oxide layer ( which is present on its surface) melts at about 2,000 °C. So, it creates a problem and causes porosity.
High reflectivity
Another factor is the reflectivity of the aluminium. Aluminum reflects a large portion of the incoming energy. It reduces the efficiency of the process. If you don’t set the metal and aluminum laser welder machine properly, all the energy can bounce off the surface. Ultimately, the metal will weld partially.
Surface preparation
Due to the above-described factors, it is important to prepare the surface of the aluminum carefully, which includes cleaning and removing all contaminants and oil. Moreover, before welding, try to remove the oxide layer (mechanically or chemically).
How Laser Welding Solves these issues?
To the above-described issues, laser welding aluminum offers several solutions. Have a look;
Precise Heat Control: Laser focuses energy on the target area only. It doesn’t spread over a large area, which can transfer heat quickly to the surroundings. Well, that small target area reached its melting point (around 660 °C). A you didn’t overheat, there will be fewer chances of distortion and warping.
Small Heat-Affected Zone: You know, only a narrow region faces heat; there’s no thermal stress. Rest of the rest of the metal stays stable, preserving the shape and strength of the metal part.
Oxide Layer Management: Aluminum forms an oxide layer on the surface naturally. This layer melts at around 2,000°C. When you use laser welding and combine it with shielding gases (e.g., Argon), it will displace the oxide layer. Therefore, it helps prevent porosity and weak spots.
Efficient Energy Absorption: As we discussed, aluminum reflects a lot of energy, which reduces welding efficiency. So, if you use a laser beam of short wavelength (fiber or diode lasers), it will help improve absorption, and the metal will be able to melt properly.
Adjustable Parameters: Laser welding allows you to adjust speed, laser power, and other elements. You can set these parameters based on the thickness of the metal, alloy type, and design of the part. Therefore, it is applicable for a lot of applications.
Minimal Post-Processing: As the weld is already clean and finished, there’s no need for extra post-processing steps, like grinding or finishing. SO, it saves your time and maintains the look of the part.
High-Speed Welding: Laser welding is fast as compared to traditional welding. So, it reduces the time of production, creating more quality parts.
Versatility: Due to its flexibility, it can be used for automotive parts, electronic housings, thin sheets, and aerospace components.
So, we can say that the parts that you feel will bend or crack on welding, you can use laser welding on those parts.
Preparing Aluminum for Welding: Post-Welding Process
Behind a successful ammonium laser welding, there’s proper preparation. Due to high thermal conductivity, oxide layer, and softness, aluminium is more prone to misalignment, contamination, and imprecise heat. Let’s discuss what you can do before the actual welding process.
Pre-Welding Preparation
Surface Cleaning: If the surface is dirty, it will cause porosity and weak welds. Therefore, remove all the dirt, oils, grease, and fingerprints from the metal. For this purpose, you can use a solvent or a degreaser.
Oxide Layer Removal: As we discussed, aluminium has an oxide layer on the surface. Remove that surface mechanically(brushing and sanding) or chemically (acid cleaning).
Joint Design: Make sure the parts have the correct gap, fit-up is tight, and alignment is proper. Even if you do not align the parts properly, it will lead to incomplete fusion or cracking.
Securing Parts: During welding, parts should stay stable. Therefore, use clamps or fixtures to avoid any type of movement.
Step-by-Step Laser Welding Process
The laser welding process is not complex if you have a proper guide. In this section, we will break down the whole process into simple, understandable steps.
Step 1: Surface Preparation
In the post-welding preparation, we have learned how to clean and prepare the surface for welding. For example, removing dust, oil, dirt, and the oxide layer. Moreover, check for join alignment and clamping.
Step 2: Machine Setup
Based on the material thickness and type of application, choose the right type of application. Generally speaking, fiber lasers and diode lasers are preferred, as they bombard beams of short wavelength. Therefore, it improves absorption. Now, set the parameters, like speed and laser power. For the aluminum is thin (0.5-3mm), then 500-1,500W power will be sufficient. And, if the sheet is thicker, 2-4kW power can be used.
Step 3: Shielding Gas Application
To protect the molten metal from oxidation, use inert gases like argon or helium. If we talk about the flow rate of these gases, it ranges between 10-20L/min. Well, the flow rate actually depends on the weld size and the design of the laser welding machine. If you do proper shielding, it will prevent porosity and offer a smooth and clear weld.
Step 4: Welding Execution
Now, the welder positions and holds the part with the tools. Start welding and provide a smooth movement for even heat distribution. You know, laser affects only a small area of the metal, reducing distortion and warping.
Step 5: Post-Welding Process
- Inspection: Check if there are any cracks, porosity, or partial fusion. After that, perform non-destructive testing, like ultrasonic testing and X-ray.
- Cleaning: It is also important to clean the part to remove spatter or residue with the help of a brush or solvent.
- Stress Relief (Optional): To remove the internal stresses of the material, pass the part through heat treatment. It will improve the stability of the part and remove cracking.
- Finishing: After heat treatment, depending on the requirement, apply finishing ( polishing, anodizing, or coating).
Techniques in Laser Welding
Based on the thickness of the material, part geometry, and the application, laser welding can be performed by various techniques. Choosing the right technique is important to ensure clean, precise, and strong welds.
1: Conduction Mode Welding
As the name suggests, in this method laser beam transfers energy, and this energy spreads via conduction through the metal. It forms a shallow weld. This method is suitable for thin sheets of aluminium (up to 3 mm). The common advantage of conduction mode welding is that it offers clean welds with minimum distortion.
2: Keyhole Welding
In this type of welding, a laser creates a small vapor-filled hole in the metal that is called a keyhole. Through this hole, the laser reaches deeper into the metal. This method is widely used to weld sturdy and thicker aluminum, which requires strong welds. This method can be operated at high speed, but precise control is necessary to avoid cracking.
3: Hybrid Laser Welding
Hybrid laser welding combines laser with some other welding processes, like TIG or MIG welding. This combination improves strength, reduces defects, adds heat, and fills the gaps. Well, this type is basically for complex joints and thicker aluminium parts.
4: Pulsed Laser Welding
In pulsed laser welding, laser beams are delivered in short bursts. Each pulse melts only a small portion of the small, allowing control of fusion and heat. So, this type of welding is best for small components and electronic housings.
Troubleshooting in Laser Welding
With proper settings and preparations, aluminum laser welding can cause issues. Understaing these issues will help you figure out them and sort them out. So, let’s discuss;
Focus: Laser welding aluminum at 0 focal length—meaning the focal point is on the material surface—reveals a faint green light, indicating deep penetration welding. This results in greater weld depth, superior weld quality, minimal spatter, and a smooth surface. Notably, when laser welding stainless steel, positive focal length is optimal, with the focal point positioned above the material.
Porosity: If the surface of the aluminium is not clean or shielding gas is not enough, it will cause porosity. Therefore, clean the metal and use argon gas at 10-20L/min.
Cracking: If there’s high internal stress or the weld cools too quickly, it will cause cracking. Therefore, set proper laser powder, speed, and clamping. Therefore, apply multi-pass welding and post-welding treatments. It will relieve stress and make the part stable.
Incomplete Fusion: If the laser doesn’t penetrate the metal completely, it will cause incomplete fusion. It may be due to incorrect focus, high speed, or low power. Therefore, set proper power ( 500-4000W depending on the thickness of the aluminum), focal point, and travel speed. It will offer fused and string welds.
Distortion or Warping: Due to uneven sheets, thin sheets of aluminum can bend. Therefore, use proper clamping, low heat input, and pulsed laser modes. It will keep the parts flat and control warping.
Application of Laser Aluminum Welding
Due to the precision, accuracy, and flexibility of laser aluminum welding, it is being used in a lot of industries. In this section, we will discuss the common applications of laser aluminum welding. Have a look;
Automotive Industry
Laser welding is used to join heat exchangers, structural components, and aluminum panels. You know, it offers precision and distortion; therefore, it is considered best for lightweight frames, thin sheets of metals, and intricate designs. Moreover, fast welding saves your time and offers you consistent results.
Aerospace Industry
Aluminum alloys are also being used for making aerospace components, like wing structures, fuselage panels, and fuel tanks. It will ensure tight and durable joints while keeping thermal distortion low.
Electronics and Electrical Equipment
Pulsed laser welding is very beneficial for aluminum housings, connectors, and circuit enclosures. This method ensures tight joints in thin sheet, without damaging the sensitive components.
Heat Exchangers and HVAC Systems
Laser welding is also being used to join tubes, fins, and plates. Laser welding offers a clean surface and maintains strong joints, improving reliability and thermal performance.
Consumer Goods
If we talk about consumer products, like cookware, laser-engraved glass, sports equipment, and aluminum frames, they also use laser welding. This type of welsing maintains the look of the work without compromising the joint strength.
Medical Devices
In medical instruments, precision nd cleanliness are important. Therefore, laser welding is being used to make strong and corrosion-resistant joints.
Conclusion
In a nutshell, laser aluminum is a combination of strength, speed, and precision. It solves all the issues with aluminum welding, like weak joints, surface defects, and distortion. Well, if you are looking for advanced welding tools and services, XLaserLab is here for you. Our laser welding machines are efficient, versatile, and offer high-quality welds for aluminum and all other metals. So wait for what? Visit XLaserLab now!
