Marking lasers as well as short or ultrashort pulse lasers are used for surface cleaning with lasers. The operating principle is always the same: pulse by pulse, the focused laser beam removes impurities such as oxidation or functional layers, which hinder the joining process. The laser evaporates the undesirable layers using very high peak pulse power, in a very gentle, non-contact manner. Compared to CO2 lasers which still leave a thin layer (e.g. 5 µm of paint) behind during cleaning, solid-state lasers are able to process surfaces in an even more targeted manner. The laser pulses have virtually no thermal effect on the workpiece surface; this prevents distortion or damage/changes to the material. The ablated material can be easily and directly removed by means of an optional exhaust system that is integrated into the respective system. Specific laser parameter settings also allow the laser to be used to structure component surfaces, in order to provide better grip for adhesive areas and frictional and form-locking connections, as well as to apply component markings (e.g. tracking codes).
A clean, even surface – this is the basic requirement for successful and durable welding and adhesive connections. That being said, components often become contaminated, oxidise or are covered in protection layers prior to the joining process. The laser provides a remedy for this: the non-contact tool frees components of dirt and oxidation/functional layers within seconds. And it does this only in areas where joining is meant to take place, for example, or where the functional layer is no longer needed. Here's how it works: pulses with high peak pulse power evaporate the wafer-thin layers, without affecting the component. Subsequent processes such as joining can then be carried out faster and more homogenously, and are entirely reproducible. The connections are clean and last longer. Joining preparation work using light as a tool can also integrate seamlessly into industrial series production, due to the fact that data can easily be transferred via interfaces.
While alternative methods to laser cleaning – such as sandblasting – can damage the surface of the component, the laser works in a non-contact, residue-free manner.
The laser allows for controlled ablation of functional layers with micrometer precision – a process that is easily reproducible.
Cleaning with the laser does not require additional abrasives or cleaning agents which would otherwise entail complex and expensive disposal. The ablated layers are removed directly.
Compared to alternative cleaning methods, the laser impresses with a high throughput and fast cycle times.