Many industries have now replaced the use of welding systems such as TIG and MIG welding with laser welding due to ease of operation, accuracy, and other features. However, you should know how it works before choosing the welding process. This article fully discusses the welding process, its types, and applications.
What Is Laser Welding?
Laser welding involves using a laser beam to heat, melt, and merge two materials. It uses cutting gas during the process for the prevention of unwanted reactions which can affect the welded joint quality. Although highly sophisticated, laser welding is compatible with many materials irrespective of their complexity and thinness. Furthermore, it generates low heat, which disallows material distortion and is highly accurate.
Step 1: Pre-Welding Preparation
Before welding, removing surface contaminants such as dirt or grease from the workpiece is important. Having a clean part prevents process errors or flaws while increasing tooling life. One can carry out this process using degreasers, aqueous solutions, and other solvents.
Note: It is important to use a cleaning method that is compatible with the material to ensure better weld quality.
Step 2: Aligning and Fixturing
- After cleaning the workpiece, align them properly before the welding begins. This ensures the laser energy is evenly distributed to the intended joint area.
- Securely clamp the workpiece using a workholding fixture. This workholding fixture accurately positions the part and keeps vibration in check.
Step 3: Welding Process
- Set up and configure the laser welding machine to meet each part’s requirements.
- After that, position the laser beam just above the joint using fiber optics or mirrors afterward. The material gets heated up and melts as heat is passed through.
On cooling, the welded joint forms.
Note: it is important to monitor the beam diameter, focal length, speed and power density during laser beam welding.
Laser Welding: Types
Each type of laser welding process discussed below has its mode of operation, which makes each of them suitable for unique applications.
· Heat Conduction Welding
In heat conduction welding, the transfer of heat is by conduction. As a result, the process is used for joining metals. Furthermore, heat conduction is the method of choice for visible surfaces where aesthetics is a major concern. When used, the weld’s width is greater than the depth. The weld depth is usually 1 millimeter or less. For this reason, there is a reduction in the need for post surface finishing process.
· Keyhole Welding
Keyhole welding creates deeper and narrower welds when compared to heat conduction. With keyhole welding, the molten metal vaporizes. The keyhole welding process generates gas that forces the metal outward. This leaves a hole or tunnel which moves toward the heat. The melted material then fills the keyhole cavity creating a weld bead
Furthermore, this type of welding creates seams up to 8-millimeter depth in a single operation. However, applying minimal heat with a small travel speed is important for the best result. This process is compatible with a wide range of materials, including thick sheets that are hard to penetrate.
Laser Welding: Types of Lasers
Generally, laser source types are based on the lasing medium and generally categorized based on the material state of their material, i.e., solid, liquid, or gas. For laser welding, the solid and gas medium is the most common. Common types include:
· Solid-state Lasers
Solid-state lasers use solid materials such as glass rods or slabs as the active medium. These materials are doped with impurities in the form of ions to alter their electrical and optical properties. The pumping source is light energy from laser diodes, arc lamps, or flash tubes. When these ions interact with light, they get excited to higher energy levels.
Furthermore, the most common materials experts use as the gain medium includes Ruby, Neodymium-doped YAG, and Neodymium-doped glass. Solid-state lasers are robust and compact with a wide range of wavelengths. This laser generates short and high-power pulses. For this reason, one will find solid-state lasers in many applications across different industries.
· Gas Lasers
The laser medium is a gas or mixture of gases that converts electrical energy to light energy. When the gas medium gets excited, the atoms and molecules release photons. These photons collide with other excited molecules in a specific manner leading to amplification and laser beam production. This stimulated emission of light has a greater intensity than normal light.
The quality of the laser beam gas lasers produces is second to none. There are many gas lasers, with the C02 laser being the most widely used.
· Fiber Lasers
The principle of operation is similar to the solid-state lasers. This medium is an optical fiber doped using ions from rare elements, including neodymium and ytterbium. Additionally, you can use fillers to enhance the original properties of the workpiece material.
Fiber lasers such as HeatSign handheld laser welder are highly efficient which improves their application. Furthermore, the long path length of the laser optics gives a higher power output while maintaining the coherence of the laser beam.
This is the combination of laser welding and other traditional welding method such as TIG and MIG welding. As a result, it has the advantages of the combined welding processes. For example, a combination of laser welding and MIG welding will ensure a concentrated heat source and improved suitability for thick materials
Laser Welding: Advantages
You can consider using a laser welding machine over other methods/machines due to the following advantages:
Speed and automation make laser welder the best for industries looking for an increased in efficiency and productivity. Laser beam welding can also complete a joint in a minute, even with thicker materials. This makes this process ideal high volume production.
· Material Compatibility
Depending on the type of laser beam, laser welding machines are compatible with several materials. The laser works perfectly with many metals, plastics, rubbers and composite materials. Furthermore, lasers can join dissimilar materials together. However, you should use the right power density and type of laser to get the best result.
· High Precision
Laser welding’s accuracy makes it a better welding method for parts that requires tight tolerance during welding. As a result, it is commonly applicable in the aerospace and automotive industry.
· Low Heat Input
The laser beam focuses only on a small part of the workpiece. As a result, a small HAZ leads to unwelded parts with no heat-induced damage. The low heat input also means that the cooling rate is faster.
Applications of Laser Beam Welding
Laser welding is applicable in the following industries:
· Automotive Industry
Laser welding is used in welding small, delicate, and complex automotive parts such as connectors and circuit breakers. This process has successfully replaced traditional welding operations, including metal inert gas and resistance welding.
One of the most important contributions of laser welding is manufacturing battery packs in electric vehicles. Laser welding is essential when joining cells and setting up a full battery assembly. Other examples include plastic car components and subcomponents.
· Steel Construction
This process applies to welding steels for wind turbine towers, bridges or container ships. Furthermore, welding high carbon steels using a laser beam saves cost and energy.
· Tool Making
Part manufacturers use the process for welding and making tools such as inserts, cutting edges, mold, and die tooling. Furthermore, it is possible to laser weld the tools without compromising the appearance and structure. One can add material to the damaged region during periodic maintenance instead of total tool replacement. This, in turn, saves cost and time.
· Medical Devices
Laser welding is the safest and the most non-intrusive way to weld medical devices. These devices must be sterile with undistorted dimensions to enhance their functionality. Laser beam welding can meet all these requirements. This welding process can create high-quality seams even in thin materials such as stents and surgical tools.
· Aerospace Industry
Using a laser welding system, the aerospace industry can adhere to the strict requirement for safety. The welding method is highly precise and accurate, suitable for the high tolerance the industry is known for.
Another reason for the increased adoption of the laser welding method in the aerospace industry is the compatibility with dissimilar aerospace materials from titanium to aluminum alloys. Common aerospace parts joined by the welding method include engine parts, fuel tanks and turbine components.
Laser welding is nothing new, as it has taken over the automotive industry for years. Laser beam welding is an accurate way to merge parts without distorting the mechanical properties of the parent material. This article has explained what laser welding is and the advantages of laser welding. Feel free to contact us for all your laser welding services.
What is the maximum speed for laser welding?
The material makeup of the part will determine the maximum speed one uses. However, to obtain an excellent result, experts recommend using the highest laser power and a welding speed of 750 mm/min.
Can plastics be laser welded?
Yes, you can weld plastics using laser beams. It is an additional advantage if plastic contains additives like filler materials. This additive helps to increase heat absorption.
What are laser-hybrid welding applications?
Laser hybrid welding has many applications. However, it is most popular in the oil and gas industries due to the different materials used.