Adhesive bonding has become the preferred joining technology of the 21st century. It allows the effective joining of the same or different materials and plays a vital role in ground-breaking lightweight multi-material structures. Besides having excellent mechanical properties, bonded joints are also used to provide heat conduction, electrical insulation, sealing properties, and bridge dimensional variation. Effectively designed bonding processes can be smoothly integrated into series production. Unlike welding, bonded joints do not adversely affect the mechanical properties of the substrates. Furthermore, process design allows bonded joints of high quality to be guaranteed. For all these reasons, adhesive bonding has now become widely used in many sectors of industry.
Adhesive bonding at Fraunhofer IFAM
Fraunhofer IFAM is the leading international R&D organization in the area of adhesive bonding technology, worldwide. For 50 years highly qualified scientists in various disciplines have devoted their energy to advancing the state-of-the-art of this joining technique. This long experience and expertise and the advanced facilities are utilized by the more than 200 people currently working in this area to provide high-quality services and carry out R&D projects for a variety of customers. The work ranges from the giving of advice to the detailed design and implementation of verified production concepts.
Adhesive bonding in industrial production
The integration of adhesive bonding into industrial production requires adhesive application technology adapted for the particular task. Adhesive selection must take account of the requirements of the end product and the production. The design of bonded joints is based on analytical data or numerical models. Experimentally determined parameters of materials, joints, and components are used for this. Simultaneously the flow and curing properties are characterized in order to design the production process. For demanding bonded joints and difficult surfaces it is often necessary to pretreat the substrate surfaces. The substrates are cleaned and activated or modified to enable the adhesives to adhere to them with good long-term stability. The aging behavior must be measured in order to estimate the service life. Dosing and application technologies are part of an automated joining process. To reduce cycle times, rapid curing methods are often employed. Effective production processes have integrated quality assurance systems and require appropriately trained staff.
Adhesive bonding in practice
Bonding processes must be customized: In the transport industry, for example, there is a huge difference between the bonding of bodywork in the car manufacturing industry, the bonding of glass in rail vehicle manufacture, and the bonding of sandwich structures in the aircraft manufacturing industry. Micro-joints in the electronics industry require special adhesives and have special physical boundary conditions. Here the quantities of adhesive required can be a million times less than when bonding large scale structures. Medical technology is putting new requirements on the safety and biocompatibility of adhesives. For aviation and aerospace applications it must be borne in mind that the adhesives must be able to withstand extremely high and extremely low temperatures. In the packaging industry key factors are the production costs and production rate.
Services and advice on adhesive bonding matters
The range of services and advice we offer cover adhesive selection, characterization of the mechanical and processing properties of adhesives, the design and qualification of bonded structures, thermoanalytical/spectroscopic/rheological and physical characterization, the development and application of dosing and application processes, advice on quality assurance matters for bonding processes, customer-specific design of industrial processes, the testing and manufacture of adhesive tapes, failure/damage analysis, and the rectification of production faults.
This work is facilitated by our extensive know-how regarding the polymer chemistry and formulation of adhesives and our state-of-the-art equipment for surface pre-treatment and surface analysis. A comprehensive range of training courses in adhesive bonding technology, at both national and international levels, with recognized certification is also offered by Fraunhofer IFAM. Furthermore, we provide companies with the assistance needed to ensure their bonding processes are in accordance with DIN 2304 "Adhesive bonding technology – Quality requirements for bonding processes". Fraunhofer IFAM provides approved DIN 6701 auditors for adhesive bonding in rail vehicle manufacture.
Please contact us. We provide you with expert advice.
Research objectives for adhesive bonding
Development and characterization of heat conducting and electrically conducting bonded joints in battery modules and drive trains
- Hybrid joints
Use of adhesive bonding in combination with mechanical joining methods such as riveting, folding, and clinching
- Rapid processes
Accelerated adhesive curing via thermal excitation and the realization of rapid handling strength using new dual-cure adhesives
Acquisition of improved understanding of the aging of bonded joints and the application of rapid tests for safe dimensioning
- Adhesive bonding in civil engineering
Development of bonding processes for load-bearing structures for windows, facades, wooden construction, and heavy-duty steel construction
- Quality assurance
Development of new processes for the inline monitoring of bonding processes
- DIN 2304
Introduction of the new standard for adhesive bonding in manufacturing companies that came into force on 1 January 2016