LASER SYSTEMS OF Coherent | OR Laser AT A GLANCE

Laser welding

Laser welding is well established in the industry as a high-quality, efficient, and economic process for joining of plates, plastic components, jewelry, or even construction parts.

The essential processes are laser deep welding, heat conduction welding, and penetration welding for plastics.

Laser welding is used preferably for the joining of components with little allowable thermal load. The high welding speed with this welding process creates a very slender seam geometry with a large depth-width ratio. When the components to be joined are positioned with a minimum joint gap, the use of filler materials like wire can be waived for the welding process.

Practical experience has shown that a joint gap of max. 20 % of the laser spot diameter can be welded without problems.

If the components can initially be tacked by spot-welding and then are welded tight with a laser weld, elaborate devices are often not required for laser welding. This ensures that even small batch sizes can be processed cost-effectively by laser welding.

Depending on the intensity of the laser radiation, laser welding is essentially divided into the following processes.

Heat conduction welding

• The welding process is done via thermal conduction.
• Used for joining thin-walled components.
• The seam depth is only a few tenths of a millimeter to 1 mm.
• No rework of the weld required

Deep welding

• A high power density of approx. 1 MW per square centimeter is required.
• This is used for large welding depths or if several layers of materials are to be welded in a single step.
• The seam depth can be up to 25 mm.

Depending on the application, laser welding can be divided into

• Hybrid welding
• Plastic welding
• Spot and seam welding
• Pipe welding
• Scanner welding

BENEFITS OF LASER WELDING COMPARED TO CONVENTIONAL LASER PROCESSES

• Different material types and thicknesses can be welded.
• Results with high quality
• High automation and welding speed
• Min. thermal material impact, little or no load
• Very slender seam geometry with large depth-width ratio
• Point-accurate, precise energy input
• Contact-free, force-free processing
• Welding of complicated weld geometries
• Min. spatter
• Shorter time required for rework

LASER SYSTEMS RECOMMENDED FOR THESE APPLICATIONS

• ECO LASER
• HTS MOBILE
• EVO MOBILE
• LRS EVO
• LASER CAB
• ROBOLASER
• PICCO LASER
• IQ LASER

Laser deposition welding

Additive laser processing, wear protection, and repair processes are nowadays essential and are used mostly when expensive, large components cannot be replacer cost-efficiently, for example

• Plastic injection molds
• Aluminum die casting
• Punching and cutting tools
• Drop forging
• Engine parts
• Turbine parts

Laser deposition welding or laser coating uses a laser to deposit material on a base material, where the hardness and the properties of the deposited material correspond exactly to the original state of the component. Here, use of a laser allows very precise work in comparison to conventional deposition welding with minimal heat input and maximal absence of load.

Depending on the material to be deposited, the welding processes are categorised as follows.

Laser deposition welding with wire

Laser deposition welding with filler wire is used widely in the industry and can be done manually or automatically. Whether it is correction of production faults, design changes, or repair of defects: The laser beam welds the filler wire with point accuracy to the workpiece and permits area deposition. With a wire diameter of 0.1 to 0.8 mm as a rule, deposition can be performed manually or automatically by CNC and wire feeder. In special cases, filler wire with a thickness of 1.0 mm and 1.2 mm can also be used. However, this is rather an exception.

The filler wire is melted completely, while the base material is melted for 0.3 to 0.5 mm and combines solidly with the added material. The small dilution results in a very small heat-affected zone of a few tenths of a millimeter.

Deposition welding with powder

In the case of laser deposition welding with powder, the powder is fed automatically to the processing point, it is applied in layers, and it is melted to the base material without any cracks. The traces here are applied with CNC control, allowing high reproducibility and making it possible to deposit even larger quantities quickly. The new material layer created in this way can be processed further after cooling. A multitude of powder types is available for powder deposition welding. Material combinations or alloys serve for building-up or repair, creation of plating, wear protection layers, or corrosion protection, and they can be adapted to the mechanical and tribological requirements.

In the case of powder deposition welding, the coating strategy plays a special role, so that the systems are generally programmed offline and are then transferred to the CNC control. Powder application is performed by a co-axial or off-axis powder nozzle that is combined with the laser optics in a laser processing head. Lasers with a few hundred Watt up to several kW are used, allowing deposition rated up to 10000 mm3/h.

Laser deposition welding with powder is used especially in sectors like toolmaking and mold building, in aviation and astronautics, or automobile manufacture, and it is used for

• Changing of surface geometries
• Creation of new surface properties
• Wear protection
• Production of functional layers

LASER SYSTEMS RECOMMENDED FOR LASER DEPOSITION WELDING

• ECO LASER
• HTS MOBILE
• EVO MOBILE
• LRS EVO
• LASER CAB
• ROBOLASER
• PICCO LASER
• IQ LASER