Laser technology for optimum adhesion

Clean, modified surfaces form the basis for long-term stable bonding and painting. Surface treatment by laser offers many advantages over other processes: Not only are the surfaces cleaned, but in a one-step process, the topography and chemistry are adjusted in parallel according to individual requirements. And the technology is environmentally friendly, resource-efficient and in a compact design that can be easily integrated into existing process chains. 

Challenges in the adhesion of coatings and adhesives

Failure of adhesion strength of a coating or adhesive can often be attributed to an inadequate initial condition of the component surface or to a change in the interface during operation. Due to the manufacturing process, transportation or storage, surfaces can have a variety of contaminants. Depending on the material class - metals, plastics, composites, ceramics, etc. - and manufacturing process, loosely adhering boundary layers or brittle oxides may also be present. During application, bond strength failure can occur at these points, especially if this is promoted by the ingress of aggressive media. In addition, the interface between the component and the coating or adhesive can change as a result of external influencing factors, which also causes adhesion failure. An example is the native oxide surface of titanium alloys, which undergoes structural transformation under warm, humid conditions.

In order to prepare component surfaces for further processing steps and to ensure the long-term stability of coatings and bonding, customized laser processes for surface treatment are being developed at Fraunhofer IFAM.

Cleaning and long-term stable adaptation in one step

The laser is an ablative process in which an intense beam of light is focused on the surface and scans it. Depending on the wavelength and power, various interactions with the component can be set, which can be used both for a gentle cleaning process and for structuring. Contaminations, unstable interfaces or oxides are removed in this way. The laser can also chemically and topographically modify the surface. Thus, depending on the requirements of the adhesive, a denser and thicker oxide can be generated, but also reduced. Furthermore, a targeted structural insertion on a nano- to microscopic level enables mechanical bonding, which ensures a strong bond even under medial load. Depending on the material class, component geometry, application and desired throughput, different laser types are suitable for this.

Laser technology: environmentally friendly and resource-efficient

A major advantage of laser technology is that it requires no abrasives or chemical additives. The removed material can be collected in a gaseous state by local exhaust. The only resource required for operation is electricity. This makes the laser an environmentally friendly alternative to many wet chemical or mechanical pretreatment processes. Its compact design and the possible guidance on a gantry system or robot, depending on the laser type, also allow flexible implementation in an existing process chain.

Your competent partner in the field of laser pretreatment for bonding and painting

The "Laser Technology" working group at Fraunhofer IFAM has more than a decade of experience in the field of laser pretreatment of surfaces. This is complemented at our institute by in-depth know-how in the field of bonding and coating technology. We therefore offer our customers a broad portfolio:

• Commercial laser systems for the treatment of all material classes
• Selection of suitable laser types depending on the requirements profile
• In-depth knowledge of laser-substrate interactions
• Adhesive bonding and coating tests at our premises
• Consultations for developments / process introductions
• Wide range of partner companies for possible implementations

The fields of application range from automotive engineering, aircraft manufacturing, consumer electronics, architecture and wind power to medical technology.