Bonding technology as the No. 1 joining technology in the 21st century

The design spaces in industry and handicrafts are subject to a continuous process of change due to constantly changing technical, social and legal conditions. This change particularly affects adhesive bonding technology, as it is an essential joining technology in almost all areas and industries today. »Adhesive bonding technology has great technological, ecological and economic potential as the leading joining technology of the 21^st century and is thus the basis for urgently needed innovations across all industries«, says Professor Dr. Andreas Groß, head of the »Workforce Qualification and Technology Transfer« department at Fraunhofer IFAM (Bremen). This knowledge must finally reach the political decision-making levels, because bureaucracy and regulatory dirigisme are developing into an unnecessary source of tension.

What does adhesive bonding technology need in the 21^st century?

Groß: Good question! Nevertheless, I would like to turn the question around first, because what is much more interesting is: does the 21st century need adhesive bonding technology?

And does the 21^st century need this joining technology?

Groß: Yes – because the key to innovation today and in the future lies in the problem-free jointing of the most diverse materials. Today, we use many materials across all industries that we can no longer meaningfully join using classic technologies such as welding or riveting. The continuous and ever-faster process of change in all decisive areas of the present and the future leads to ever more demanding customer expectations when it comes to product development: better product quality, higher functionality, lower weight, contemporary design, etc. This inevitably leads to new and further developments at a rapid pace, based on materials that have been developed and selected according to specific requirements. Consequently, materials are the decisive factor in the 21^st century for the major future fields of energy, climate and environmental protection, resource conservation, mobility, health, safety and communication, taking into account technological, ecological and economic aspects. Materials and their properties enable continuous progress, without which, for example, the fields of mechanical engineering, transportation, the aviation industry, the chemical industry, medical technology, energy technology or environmental protection would be inconceivable.

So materials technology, along with adhesive bonding technology, is one of the key technologies of the 21^st century. What are the implications of this?

Groß: The two technologies together develop their potential in many areas of application. The variety of materials is increasing to meet the ever more complex requirements in the joint of the same and different materials. Many products, parts or components are or will be compound systems today and tomorrow. The resulting material development and the development of joining technology must be considered equally and in context. Both must fit together while preserving the material properties.

Adhesive bonding technology is just one joining technology among others, such as riveting, welding and soldering. What makes it special?

Groß: Adhesive bonding is much more than »just another joining technology alongside riveting, welding, soldering, etc.«. As already mentioned, in order to meet increasing product requirements, a joining technology must preserve the properties of the respective materials – i.e. material damage caused by drilling holes, as with screwing, riveting, nailing, etc., or the changes in properties caused by heat stress, as with welding or brazing, are limiting factors for many of today's materials.

The preservation of material properties is the essential unique selling point of adhesive bonding technology: adhesive bonding is the only joining technology that makes it possible to join any material to itself or to other materials in a way that is both long-term stable and secure. And then – and this is a decisive factor – to achieve this without changing the material, i.e. while preserving its material properties, and thus to arrive at the desired product properties.

Can you give us an example of this unique selling point?

Groß: Countless examples! Let me take the development of alternative energy sources as an example, because adhesive bonding is an enabler for the desired energy transition. This is unthinkable without adhesive bonding technology according to the current state of the art. For example, the rotor blades of wind turbines are purely adhesively bonded constructions made of the classic lightweight material of glass-fiber-reinforced plastics (GFRP). Point connections of the GFRP rotor blade half shells, such as bolted joints, rivets or nails, are not an option. These would destroy the GFRP lightweight material at the connection points due to the »holes« and generate such high stresses at the connection points under load that the GFRP rotor blade walls would have to be heavily thickened. The actual lightweight rotor blades would then be much too heavy, making wind energy as a form of alternative energy generation no longer an option. Welding is not an option because the GFRP material cannot be welded. In addition, a protective film layer is adhesively bonded to the leading edges of the rotor blades that are subject to particularly high loading. This ensures a permanently smooth and aerodynamically favorable surface for optimized energy yield, even under extreme offshore conditions with rotational speeds of up to 390 km/h.

Is the place value of adhesive bonding technology in Germany already being properly assessed?

Groß: That is in the eye of the beholder, and unfortunately it varies greatly. But first, the term »place value« should be defined more precisely: Germany is the world leader in adhesive bonding technology, both in terms of tonnage and sales. We are the world leader in adhesive bonding research and development, in both the industrial and institutional sectors. We are the world leader in adhesive bonding quality assurance and the founder and world market leader in extra-occupational, personnel-certifying training for adhesive bonding experts. This personnel qualification – an essential quality assurance contribution – has become an international industry standard. Today it is harmonized throughout Europe and implemented worldwide. Germany does not have a leading role in adhesive bonding technology, Germany has the leading role. The importance of this is increasingly being recognized and utilized by the industry. All parties involved – the adhesive industry, the developers and manufacturers of process technology, the R&D sector, etc. – have helped to establish this importance.

Unfortunately, at the political decision-making level and thus in the regulatory environment, adhesive bonding technology has, to put it diplomatically and politically correctly, a rather limited image.

Why is that so?

Groß: Adhesive bonding is complex, which makes a holistic assessment that takes into account all relevant factors quite difficult. In the political and regulatory environment, we often see a preference for the easier way. In doing so, the focus is on seemingly more manageable individual aspects, which are then used as a basis for decision-making and evaluation in a »big picture« without an impact assessment. This approach is reinforced by a now misguided bureaucracy. The result is a long-unmanageable, completely counterproductive bureaucracy, which makes the important overview as a basis for meaningful decisions impossible with its hyper-complexity in the small.

Many companies consider these current obligations and prohibitions to be the biggest obstacle to investment. The next level of bureaucracy and regulatory dirigisme will then be shifted from the national to the European level. One example that also affects adhesive bonding technology is the EU's »chemicals strategy«. Despite the fact that the safety standards in place in Germany are already the highest in the world and serve as a model internationally, there are political efforts to further tighten these standards. I will attempt to explain what this means for adhesive bonding technology in a nutshell: If the same bureaucratic and regulatory approach had been applied at the beginning of the 20^th century as is practiced today, the great success story of welding techniques in the 20^th century would never have happened!

So the success story of adhesive bonding technology is set to continue in the 21st century...

Groß: Theoretically yes, because in contrast to the conventional joining technologies mentioned, the end of the development phase for adhesive bonding technology is not yet in sight – neither in research and development nor in application. As a »technological enabler« for many developments, its market potential in this century is also very high.

And practically?

Groß: We all have to work together on this and make four things clear to the political decision-makers: 1. No one, neither in Brussels nor in Berlin, can stop the success story of adhesive bonding as a joining technology. Adhesive bonding technology and its applications will continue to develop in any case. 2. The continuation of the current European and national bureaucracy and regulatory dirigisme will almost certainly put a stop to the development and success story of adhesive bonding technology in Germany and Europe – but never in a global context. 3. A technology is completely unconcerned about who promotes it and where, i.e. on which continent it is promoted. That is why Brussels and Berlin need to clarify what a national or European leadership role is actually still worth. 4. Issues that need to be considered in a complex and holistic way cannot be treated lightly. Common sense alone demands this. Those who do not take the necessary seriousness here should regulate things that can be easily regulated.

What demands arise from this?

Groß: I expect that we will quickly move out of today's impasse and that the political decision-making levels and regulatory administrations will demonstrate at least the same creativity in the innovation-required exnovation, i.e. the abolition and withdrawal of bureaucracy and regulatory dirigisme, that they have applied to its innovation-preventing development. If this does not happen, Germany and Europe will also lose their global, creative leadership in adhesive bonding technology and will also lag behind in this area of development. We cannot really want that. Political decision-makers must immediately refocus on the utilisation of what is internationally technically possible and necessary. And when I say »necessary«, I also mean the responsible handling of chemicals (www.weiterbildung.ifam.fraunhofer.de/en/blog/risk-based-vs-hazard-based-assessment.html). Adhesive bonding technology must be given the technological significance it deserves as a key technology of the 21^st century at national and European political decision-making levels and thus receive the appreciation it deserves.

Thank you for the interview!