Fundamental principles
The course starts off by introducing fundamental aspects of adhesive bonding technology. The advantages and limitations of adhesive bonding are covered and a comparison is made with other joining techniques. Participants acquire a fundamental understanding of bonding mechanisms and the properties of adhesives. The key importance of wetting for the bonding process and how this can be influenced by various parameters is highlighted.
Adhesives
In the German market alone there are thousands of different adhesive products. The range of products extends from elastic-soft polyurethanes right through to high-strength epoxy resins. Participants learn which types of adhesives are most important for industry and acquire insight into their distinctive properties and differences. Instruction on the processing and application of adhesives accompanied by practical assignments using different types of adhesives are key aspects of the first week of the course.
Substrates
The course provides the participants with knowledge about the structure and behavior of substrate materials when they are subjected to external forces and environmental influences. This helps participants estimate deformation and property changes in adhesive layers, and so understand the resulting requirements of material-specific surface treatments.
Surface treatment
The importance of the condition of the surface of substrates for the bonding process is another topic covered in the course. Participants acquire theoretical and practical knowledge of the most important methods of surface treatment for a variety of different materials. The topics covered range from cleaning the surfaces of substrates via mechanical, physical, and chemical pretreatment methods right through to the use of primers and adhesion-promoters.
Properties of adhesive films
In order to assess the suitability of an adhesive for a particular application it is necessary to appraise the deformation behavior. Put another way, the factors that determine the deformation behavior set the limitations for the use of a particular adhesive system. Fillers and absorbed moisture can affect the deformation behavior just as significantly as temperature and adhesive film thickness.
Testing bonded joints
The quality of a bonded joint concerns far more than merely high strength after curing. Other factors that are just as important are reproducibility and long-term stability. The necessity to use destructive test methods to determine the quality of bonded joints is demonstrated using specimens which the participants make during the course. The limitations regarding the transferability of results from standardized tests to real components become clear.
Health and safety at work and environmental protection
Ignorance is the main cause of accidents at work. The correct handling of adhesive systems hence requires a sound fundamental knowledge of the specific hazards associated with the products being used. This not only applies to the adhesives but also to the many auxiliary materials that are used.
Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung IFAM