Fiber Laser Welding
Laser Welding is a welding technology used to connect several metal components. A laser produces a light beam with high intensity, concentrated into one spot. This concentrated heat source enables fine, deep welding and high welding speeds. Traditional laser welding technologies, such as continuous wave CO2 welding lasers have their limitations in accuracy and undesired high heat input into the weld. On the other hand, the traditional pulsed Nd:YAG have limitations in the maximum welding speed, the minimal spot size that can be achieved and the electrical to optical energy conversion efficiency that can be achieved. More and more applications demand a higher precision control, a lower heat input and a lower electrical energy consumption, Continuous Wave Fiber Laser Welding is a technology offering those features.
In a fiber laser, the laser light is generated in an active fiber and guided to the work piece by a flexible delivery fiber, a lightguide so to speak. The flexibility of the delivery of this laserbeamis an important feature for many forms of material processing such as laser cutting, laser welding, laser marking and laser engraving.
Continuous Wave versus Pulsed Wave for metal welding.
Fiber lasers are available in both type of energy delivery: Continuous and Pulsed. As the name says, the Continuous Wave (CW) lasers deliver a continuous output, not interrupted. This output can have an upslope (soft-start) when switched on, an energy modulation while being active, and a downslope when switched off (crater-filler). Of course this type of laser can also be switched on- and off to create pulses. But the maximum power level can never exceed the average power.
Opposed to this, the Pulsed Fiber lasers deliver a pulse energy which is typically ten to twenty times higher than their average power. For example a laser can have 300W average power and 6000W peak power. These lasers are often referred to as Quasi Continuous Wave (QCW) Fiber Lasers.
Laser welding of very small parts and fine structures.
Welding of the smallest parts can be done with low power Fiber lasers, typically in the 100 to 200W average power. These are well suited for this type of welding because of their features:
• Very small fiber core diameters. The low power level and high beam quality allow power up to 500W to be fired info 10 or 20 micron cores. This results in very small weld spot sizes
• Excellent power stability. A fiber laser will be stable down to about 10% of its power level. As an example a 200W laser will be stable to 20W power. When combined to a 1ms pulse length, weld pulse energies of 20mJ can be achieved. This is sufficient for the finest welds that can be found in precision metal welding.
Typical application examples are stents, small medical meshes, thin membranes for pressure sensors, etc. Typical materials are 50 micron Nitinol wires, 10 to 50 micron platinum coil wires, 10 micron stainless steel foils, etc.
Medium Power Fine Metal welding at high speed.
Fiber lasers with 500 to 1200W and fiber core diameter of 100 to 300 microns, typically replace Pulsed YAG and Disk lasers for precision metal welding. In this range, the Fiber laser will give more welding speed for the same investment level, sometimes ten times the welding speed. As an indication, a 500W Fiber laser will give a weld of 1 mm deep and 1mm wide at about 1 cm/second in mild steel. Value-for-money, this laser is difficult to beat, if the application is suited for this type of welding.
Medium power Fine metal welding with single mode lasers.
A special type of welding is the welding with lasers in the power range of up to 500W with a very small diameter fiber, 20 microns or below. Due to this small diameter, a very high energy concentration will be reached. This results in keyhole welding.
This type of welding is normally coupled to a scanner head which allows a very high speed of progression of the laser beam. The laser beam can be moved linear or in a circular or wobble pattern to achieve a wider weld beam.
High Power Laser Welding of Metals.
In the power range of 1000 to 5000W, Fiber Lasers can weld heavier metals connections at high speeds. Applications can be as diverse as stainless steel sheets for kitchen tops, galvanized steel back plates for flat screen LCD TV’s, sheet steel for stators for electric motors, structural parts like turbocharger waste gates, stainless steel bellows, copper wires, tabs for batteries, etc. Thicknesses of up to 5mm can be welded and speeds of up to 50cm/second can be achieved. Fiber Lasers in this power range are more- and more replacing other welding processes, like Resistance Welding (spot welding), TIG welding, MIG welding, Electron beam welding, etc. With lasers of these power levels, the weld speed is typically only limited to the speed of moving the system or the parts and feeding the parts to- and from the system. In the coming years, it is expected the power of these lasers will increase 20-30% yearly and more- and more traditional welding processes will be replaced by laser welding.
Fiber Laser Welding Applications
To select the right laser source for your laser welding application, download the "Source Selection for Micro-Welding processes" document. These are some basic guidelines, contact us for qualifying your process by testing it in our laboratory.Our proven technologies enable the Automotive, Electronics & Solar Cells, IT & Multimedia, Medical, Aerospace and Defence industries toto laser weld a variety of applications by using fiber laser welding as a key technology.
Typical fiber laser welding examples are sensors, radar components, battery housing, conductors for thin film cells, pacemaker cases, insulin pump cases, etc. The addition of fiber laser welders to our product range along with our well established range of Nd:YAG welders, means we can offer the best laser source for the welding requirement across automotive, medical, electronic, and aerospace industries.