Welding and bonding preparation for high process reliability

Innovative welding or bonding processes in automobile manufacturing require perfectly pre-treated surfaces. Depending on the task, release agents and oils must be removed or the surface must be prepared with a specific roughness in order to produce a reliable joint.  The use of lasers provides a dry, precise, and wear-free alternative to the conventional wet chemical or abrasive blasting methods. By use of a flexible setup with an adaption of a special beam shaping unit, the surface can be prepared in a defined manner.

Welding Preparation

Welding preparation by selective laser cleaning

Production residues, oxide layers and protective coatings have to be removed from the bonding surfaces of the parts.  The surface of the base material remains unchanged, because the required energy density for removal is significantly below the ablation threshold for metals.

Using a scanning beam deflection, in which the focused beam of a pulsed laser is guided over the surface at a speed of several m/s, the parts can be processed in a defined manner. Typical ablation rates vary between 10 – 100 cm²/s depending on laser power and coating.

Bonding Preparation

Bonding Preparation
Haftverbesserung durch Laservorbehandlung

Adhesion improvement by laser bonding preparation

In addition to the gentle cleaning, the laser can also specifically structure or activate a surface by changing its morphology. Many bonding processes for metals, plastics, and composite materials require improved roughness on the joining surfaces. Owing to the superb focusing capability of the lasers used, high intensities can be generated in the workspace, which cause the material to vaporize locally, and thereby enable the creation of small bowl-shaped cutouts or a grooved structure. A surface modified in this way features improved mechanical adhesion.

New material combinations are also facilitated by laser processing: so, for instance, sealing foams can also be applied to materials such as ABS plastics or die-cast components as well as carbon fibre substrates.

4JET offers its Parts Cleaning Systems (PCS) as well as customized solutions for selective, flexible laser processing .