Keyhole welding

A big plus of Laserline's diode lasers at keyhole welding is the calm molten pool that minimizes the amount of metal splashes on the workpiece and laser optic which leads to smoother and cleaner welding seams.

Besides the aluminum welding or the joining of tailored blanks, applications for welding thick steel with a laser power of 50 kW are also realized.

Keyhole definition

With keyhole laser welding, the material is processed with very high beam intensities. Different to heat conduction welding, here a metal vapor is created additionally to the metal melt that partially displaces the melt, thereby leading to the creation of a vapor capillary (keyhole). This also applies for welding thick steel. The keyhole welding technique is characterized by a high process speed. The heat-affected zone is always limited, hence material distortion is accordingly low. What remains is a narrow, evenly structured welding seam with a depth-gauge that is often bigger than its width.

The advantages of a diode laser using the keyhole welding technique

A big plus of Laserline's diode lasers is the calm molten pool that minimizes the amount of metal splashes on the workpiece and laser optic which leads to smoother and cleaner welding seams. With a protection class of IP54, the lasers guarantee, even without protecting enclosures, process stability in tough application environments. Their high electrical efficiency of up to 50 percent and the robust technology make Laserline’s systems a reliable and very economical tool for keyhole welding. Designed for more than 30,000 operation hours, they are also very durable with low maintenance effort.

Welding thick sheets with 50 kW laser power

Processes for welding sheets with thicknesses between 10 mm and 25 mm are becoming increasingly popular for different industrial applications. For the laser-based process, the seam preparation currently poses a key challenge in this area. Variable gap dimensions are often unavoidable and must be bridged reliably and efficiently. With 50 kW laser power and spot sizes of up to 4 mm, with its LDF high-power diode lasers, Laserline offers a suitable system solution for these applications.

Aluminum welding

Aluminum claddings that are mounted in a visible area require smooth and optically appealing welding seams. Here, Laserline's diode lasers achieve excellent results, as the created joints are uniform in shape and require no post-processing. Always requiring filler material out of aluminum silicon (ALSi), with which hot cracks can be avoided, these can be applied during the welding process with Laserline's diode lasers in one of two ways: either over a tactile process optic or with triple spot method using a supplementary wire that was developed by Laserline. In this method, there are two side-spots positioned in front of the main spot, which first ablate the coating at the edge of the wire melting zone. Because of this preparatory work, the result is a controlled melting process without material transfer to adjacent areas.

In close collaboration with Audi and other plant suppliers, triennial process investigations were conducted and diode laser requirements for aluminum welding were defined.

Application examples

Welding tailored blanks

At the laser-based tailored blanks welding using several sub sheets, shaped blanks are put together that will later be transformed to car body parts. However, the process is often afflicted with inefficient and easily soiled lasers that furthermore leave unpleasant metal splashes on the sheet and welding optic. Laserline's diode lasers generate an extremely calm molten pool that hardly creates a splash. They also resist dust and moisture-intense process environments.

ArcelorMittal Tailored Blanks has been using CO2 lasers for welding of tailored blanks since more than 15 years now; it also replaces old beam sources with modern Laserline LDF diode lasers, which are significantly more efficient.

 

Source: II-VI Highyag Lasertechnologie GmbH

Laser remote welding

To reach a quicker and more flexible process control when welding vehicle bodies or ships’ sides, laser remote welding is increasingly used. Because the laser beam is here directed from a distance of over one meter onto the workpiece, the application requires the combination of high laser power and high beam quality. Laserline LDF diode lasers with beam converter offer an optimal system solution for this special manner of keyhole welding.