If two or more metal parts are to be joined together permanently without any addition of material, then in many cases laser joining is the only viable alternative.
The laser's high flexibility allows many application options: from very precise welding points to keyhole-welded seams over many meters with slim seam geometries and minimum warpage. The laser is used by a wide range of very different industries. Whether the application includes precision weld points in the electronics industry, stainless steel bushes for sensors in the automotive industry, membrane welding of highly sensitive pressure sensors in the aerospace industry or super-fine welds in the medical industry - the laser process is quick, precise and flexible.
ACSYS welding systems do not add material to the workpieces during the welding process. The new fiber laser technology uses a large focal depth. As a result, process-tolerant welding is possible even if the materials have different wall thicknesses or are not entirely square during the welding process.
In principle, there are two possible methods of laser welding:
fusion welding (also called melt welding) and keyhole welding.
Fusion welding
The image on the right shows an illustration the of laser fusion welding process.
The material melts only on the surface. During fusion welding, the materials that are to be joined are melted through the absorption of the laser beam on the material surface. The molten sections flow into each other and the combined molten section solidifies, thereby joining the materials. This process is used for joining parts with thin walls. The welding depth is typically less than 1 mm. The laser produces a smooth and well-rounded weld seam that requires no further processing.
Keyhole welding
The principle of keyhole welding is based on producing a vapor capillary in the material. The laser beam produces the required local evaporation temperature. The evaporation pressure that is produced in the material generates a capillary with a diameter of about 1.5 times that of the laser beam focus.
This evaporation capillary (also called a keyhole) is drawn through the workpiece by the movement system of the laser machining center. The molten metal flows around the evaporation capillary and solidifies on the rear. This way, a deep narrow weld seam with a uniform joint is produced.
Keyhole welding is highly efficient and can be performed at high welding speeds. Because of the high speed, the area that is impacted by the heat is small and the warpage of the material is minimal. The process is used if big welding depths are required or if several layers of material are to be welded at the same time.
Types of seams and joints in laser welding
Designation | Example | Property |
---|---|---|
Square (butt) weld, corner joint |
+ Good flow of force - Big positioning effort |
|
Square weld on overlapping joint | + Small positioning effort - Poor flow of force - Small connection cross-section |
|
Fillet weld on overlapping joint | ||
Fillet weld on T-joint | + Good flow of force - Large connection cross-section - Big positioning effort |
|
Square weld on T-joint, corner joint (hidden T-joint, corner joint) |
+ Good flow of force - Big positioning effort |
|
Square weld on flange 1 & 2: Edge weld |
1: Big positioning effort 2: Good for blasting processes (reflection towards the weld) |
|
Single-flare-V-groove weld | For hidden welds of vehicle bodies |