Welding is a process that fuses different metallic objects by applying heat in a localized region.
Using a fiber laser to generate heat and perform welding operations has revolutionized the manufacturing industry.
Fiber laser welding employs a high-energy laser to generate the heat required for welding. An optical fiber cable delivers the laser beam to the laser head, which then focuses it on the surface, resulting in a molten pool along the joining path of the objects, causing fusion upon solidification.
This article discusses fiber laser welding by going through its process, applications, and advantages.
In the end, I've also discussed some of the best fiber laser welding machines.
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What is Fiber Laser Welding?
In Fiber laser welding a high-energy laser is used for heat generation.
Filler metal is optional during this welding process as many fiber laser machines weld autogenously (in the absence of filler).
However, it requires a constant supply of shielding gases like argon or helium to prevent weld contamination from foreign particles or water vapors.
During the process, a significant portion of the incident laser is reflected away, resulting in a loss of laser power.
Fiber laser welding machines come in both CNC fiber laser and hand-held versions, with the latter being cheaper and more easily available.
The laser power in these machines usually varies from 1000 W to 3000 W, with some special industrial machines ranging up to 6000 W.
Using fiber laser welding minimizes the heat-affected region, resulting in minimal material distortion or discoloration of surrounding surfaces.
Components of A Fiber Laser Welding Machine
Various components constitute a fiber laser welding machine.
The laser source consists of a laser lamp (generally a diode laser module) that generates the laser used for the welding operation.
This laser is then amplified by doping with rare earth materials and enhancing its ability to melt the workpiece material.
Optical Fiber Cable
These plastic or glass fiber tubes guide the laser along the desired path through reflection.
The ability of a fiber cable to efficiently deliver the laser depends upon various factors such as the thickness, length, and material of the fiber cable.
Welding gun is a handheld component of a fiber laser welding machine that delivers the laser beam onto the workpiece material.
It generally has an ergonomic design with a convenient trigger to turn the laser on and off.
The lens of the fiber laser welding machine aids in focusing the laser beam onto the weld area.
Their diameter usually varies between 10 mm (0.4 in) to 50 mm (2 in) but can go as high as 70 mm (2.8 mm).
Every focusing lens has a fixed focal length, and depending upon the size of the lens, the focal length generally varies from 20 mm (0.8 in) up to 100 mm (4 in).
The control panel of a fiber laser welding consists of a display and control keys to view and modify the process parameters.
The continuous operation of fiber laser dissipates immense heat, which in turn heats components like the focusing lens.
Therefore, a cooling system is required to keep the temperature under control and prevent the equipment from overheating.
A centrifugal pump is used to circulate water or an oil coolant in a cooling jacket surrounding the laser system, thus regulating its temperature.
Factors That Affect Fiber Laser Welding
The laser frequency is an important factor in the welding process. The complete laser waveform is controlled by varying the frequency of the laser.
At constant laser power, the laser energy decreases with increasing frequency and vice versa. Thus, the laser frequency should be at an optimal value, as instructed in the user manual.
For instance, if the laser frequency is exceedingly high, the laser energy will be very low, causing insufficient welding.
Laser Spot Diameter
The laser spot diameter is controlled by varying the lens's curvature or position to move the converging point.
It is crucial to maintain an optimal spot size because having a larger spot diameter will result in low energy density and insufficient welding.
On the other hand, an extremely tight spot can result in overheating of material, resulting in deformation of the workpiece.
Fiber Optic Cable
The material and diameter of the fiber optic cable indirectly affect the final weld as it guides the laser beam onto the lens.
Its diameter should not be too low as that can cause the laser beam to scatter, whereas a larger diameter can result in excessive reflections and energy losses.
The fiber material should have a high reflectivity so that minimal laser energy gets absorbed in the fiber.
The laser power of a fiber laser welding machine varies from one machine to another, and the higher the power of the laser, the better its ability to generate heat.
Extremely high power can damage the workpiece surface, and the reflected beams of this extremely high-powered laser can cause skin burns or eye damage if comes in contact.
Contrarily, a very low laser power will lead to insufficient heat generation, resulting in a poor-quality weld.
Welding Speed and Wire Feeding Rate
The laser head should have an optimized speed, ensuring thorough welding with uniform weld deposition.
If a filler metal is used, the wire feeding rate should also be carefully monitored, as a higher rate can lead to material wastage. In contrast, a lower rate will lead to insufficient welding.
Flow of Gas
The direction and flow rate of the gas should also be carefully monitored and regulated.
Firstly, the cross-flow of air should not be too intense as that can disrupt the laser direction, ultimately affecting the laser weld.
Secondly, the shielding gas should have a moderate flow.
This is because an extremely high flow rate can interfere with the laser, whereas a lower flow rate provides insufficient shielding which can lead to contamination of the weld.
The workpiece should be in a clean and untreated condition. An oily and dusty surface, a galvanized surface, or an exterior oxide layer can inhibit the welding process.
Advantages of Fiber Laser Welding
Fiber laser welding can be used to weld almost any metal workpiece.
The laser power of the fiber laser can be adjusted according to the metal to be welded and produce a strong welded joint.
Moreover, this fiber laser welding is also applicable for fusing dissimilar metals, e.g., for welding copper workpieces with aluminum plates.
Flexibility and Convenience
A fiber laser welding machine is compact and portable, making it easy to move from one point to another.
Its fiber optic cable is highly efficient in delivering the laser at long distances without any significant loss in laser energy, making it suitable for long-distance welding applications.
Moreover, these lasers are easy-to-use. However, training is required to understand the operation and laser safety protocols.
Variety of Welds
Many different types of joints between two objects are achievable through fiber laser welding, e.g., butt joint, overlap joint, T joint, etc.
Superior Weld Quality
The final weld obtained is mechanically strong and does not easily fracture as its strength is higher than the strength of the base metal itself.
Even complex geometrical components can be welded accurately and precisely through this process.
The final weld does not require any post-processing for protection or aesthetic purpose, as it is durable and possesses a visually appealing pattern.
The laser fiber machines house multiple safety sensors to ensure the operators’ safety.
This includes thermal sensors, alarms, and light bulbs to indicate any possible malfunction.
For instance, if the laser head starts to overheat, the sensor will set off the alarm, and the system will shut down automatically.
The training required for handling these laser machines is simple and short, making it convenient for the operator to start using them after a short training period, consequently saving training costs.
Furthermore, compared to typical welding processes, this type requires no or minimal processing, ultimately saving time and money spent on secondary processes to enhance the quality of the weld.
Although hand-held fiber laser machines are more common, CNC versions are also available. They are easier to use and result in better welds.
Applications of Fiber Laser Welding
The fiber laser welding technique has significant applications across multiple industries.
|Aircraft Industry||Welding aircraft frames|
|Automotive Industry||Welding automotive frames and shafts|
|Defense Industry||Welding frames and armor plates of tanks and armored vehicles|
|Electronics Industry||Welding circuit boards and battery casings|
|Medical Industry||Welding in medical devices like heart stents|
|Construction Industry||Welding table and window frames|
Fiber laser welding is used in various industries for welding similar and dissimilar metals.
The most common metals that can undergo fiber laser welding include brass, aluminum, stainless steel, copper alloys, and even some titanium and nickel alloys.
These metals are extensively used in the industry and often require welding for manufacturing different components.
For instance, aircraft wings are often composed of aluminum sheets that need welding. Fiber laser welding is ideal for this application.
Similarly, this welding process is ideal in applications involving welding two different components in an automobile chassis.
Can We Use a Fiber Laser Cutter for Laser Welding?
A fiber laser cutter cannot be used to perform welding operations.
The gas in a fiber laser cutter is used to blow the molten metal out of the kerf, which increases the cutting speed.
In fiber laser welding machines, the gas flows parallel to the laser to shield it against contamination.
Apart from that, fiber laser welding requires a cross-flow nozzle that delivers air to minimize the spattering of the weld.
Moreover, the lens used in laser cutters produces an extremely tight spot size, resulting in a high energy density to vaporize the material.
As a result, the laser temperature in fiber laser cutters is higher than in the fiber laser welders, causing greater energy to strike the workpiece that causes the cutting action.
Hybrid Fiber Laser Machines
Technological advancements have led to the development of hybrid CNC machines that house both a fiber laser welding head and a cutter head, making it possible to perform both processes by a single machine.
These hybrid CNC machines are ideal for welding complex geometrical components.
Their key feature is the autonomous and symmetrical nozzle that houses the lens and contains cross-jets that protect the laser optics from welding spatter.
The nozzle also ensures a coaxial flow of shielding gases so that the laser and the resulting weld stay safe from contamination.
You need to change the process parameters in the CNC program for switching between welding and cutting.
These multi-tasking machines reduce costs, time, and effort, thus improving production efficiency and weld accuracy.
Best Fiber Laser Welding Machines
JPT LW 100 is a handheld fiber laser welding machine comprising a 1000 W laser operating at a wavelength of 1064 nm and utilizing argon/nitrogen shielding gas.
It has a footprint of 0.034" x 0.022" x 0.041" and comprises a water cooling system, a visual positioning red dot, and an automatic wire feeder. You can vary the welding speed from 0 to 120 mm/s.
The JPT LW 100 model works on a single phase 220 V voltage and uses a 7-meter-long fiber optic cable.
Using this model, you can achieve a weld thickness of 0.5 mm ( 0.02 in) to 5 mm ( 0.2 in).
It can easily weld metals and alloys such as stainless steel, silver, gold, titanium, copper, etc., so it's commonly employed for welding cabinets, shelves, window guardrails, stainless steel doors, steel furniture, etc.
Water cooling with a welding speed of 0-120mm/sec
Excellent portability with 7-Meter Optic Fiber Cable
TR-FLW 1000 W is also a handheld, 1000 W fiber laser welding machine with its laser possessing a wavelength of 1070 nm.
It consists of a red light indicator for positioning the laser, a cooling water system, and a wobble thread provider. You can vary its welding speed from 0 to 120 mm/s.
The TR-FLW 1000 W model works on a single phase 220 V voltage and uses a 10-meter-long fiber optic cable.
It can also easily weld various metals and alloys, making it suitable for different industries.
Red light indicator for accurate positioning
Water-cooled system with a welding speed of 0 to 120 mm/s
10-meter fiber optic cable for portability
HG SMART HW is also a handheld, fiber laser welding machine with a laser wavelength of 1080 nm, using an argon/nitrogen shielding gas at 4 to 6 bar pressure.
It can switch between 1000 W and 2000 W laser power. A 197" (5m) long fiber optic cable is used for a 1000 W laser, whereas a 15 m (591 in) long cable is required for a 2000 W laser.
This model comprises a water-cooling system and requires no consumables during welding.
It has a focal length of up to 120 mm and works on a single-phase 220 V voltage. You can vary the laser frequency from 5 to 20 kHz.
Its applications include welding cabinets, shelves, window guardrails, stainless steel doors, distribution boxes, etc.
Frequently Asked Questions (FAQ)
What are the limitations of fiber laser welding?
The limitations of fiber laser welding include high initial and running costs, extensive equipment training, and process hazards.
What materials can not undergo fiber laser welding?
Materials such as sintered metals, cold-worked steel, and tungsten carbide can not undergo fiber laser welding efficiently.
What is the service life of a typical fiber laser?
The service life of a typical fiber laser is up to 100,000 hours, which translates to several years of usage.