Bonding - in particular structural or semi-structural bonding - mechanical joining and hybrid joining - has experienced a great surge in demand and development in recent years. Among other things, this surge has been triggered by the increased interest of the automotive industry due to its compulsion to lightweight construction and the associated necessity to join different materials in a so-called material mix. The interest from the automotive or vehicle industry, which can be regarded as a key industry in Germany, triggered a broad demand in other branches of industry, which led to a noticeable increase in the acceptance of the use of structural bonding in technically oriented industrial companies.
Bonding offers a variety of advantages, such as even stress distribution and power transmission. They bond very different materials with each other and do not influence the parts to be joined. In addition to structural applications, adhesives can also be used as sealing and insulating materials. However, the use of adhesive technology brings with it some special features: A fundamental challenge in the production of adhesives is the handling of a viscous medium. Special equipment is required, which represents a certain amount of expense and can cause start-up and maintenance problems. A further technical processing characteristic is the relatively long time, compared to riveting and welding, until a bond reaches the necessary initial strength and can thus be handled without additional fixing.
In hybrid joining, the mechanical joining processes take over the fixing of the joining partners until the adhesive has cured. The mechanical joining processes - mainly with spot-shaped, but also linear joining geometry - have distinguished themselves in recent years through constant further development and a high application potential. Today, mechanical joining processes can even be used to securely join materials that are difficult or impossible to form, such as metal foams. They are increasingly used as an alternative to resistance spot welding.