Adhesive Bonding

The joining technology for lightweight construction and sustainable production

Adhesive bonding is the pioneering joining process of the 21st century. It enables the reliable bonding of identical as well as dissimilar materials with an adhesive and is thus essential for the advancing multi-material lightweight construction. Unlike welding or riveting, adhesive bonds do not weaken the mechanical properties of the parts to be joined. In addition to mechanics, bonded joints integrate specific requirements: They can conduct heat, electrically insulate, seal or bridge tolerances. Professionally designed adhesive bonding processes integrate into series production without interference. Adhesive bonds can be assured of high quality through process design. For these reasons, adhesive bonding has become established across all industries in recent decades.

Adhesive bonding at Fraunhofer IFAM

Fraunhofer IFAM is the internationally leading independent research institute in the field of "adhesive bonding". For 50 years, highly qualified, multidisciplinary teams have been working on the development of this multifaceted joining technology. The many years of experience, the high level of diversification of the more than 200 employees in the divisions, and the comprehensive equipment allow rapid and high-quality processing of services as well as research and development orders. The supplier-independent solutions range from one-day consultations to the detailed design and implementation of tested production concepts and can cover the entire bonding process chain.

 

Adhesive bonding in manufacturing

The integration of adhesive bonding into industrial manufacturing requires an approach tailored to the specific application. Adhesive selection must take into account the requirements for the end product and for the manufacturing process. The design of bonded joints is based on analytical or numerical calculation. This is based on experimental characteristic values of materials, joints and components. At the same time, the flow and curing properties are characterized in order to design the manufacturing process. For demanding bonded joints or for difficult surfaces, pretreatment of the component surfaces is often necessary. The materials are cleaned and activated or modified so that adhesives can adhere to them for a long time. The aging behavior must be analyzed and thus the service life estimated. The dispensing and application technology are part of the automated joining process. Rapid curing processes are often used to reduce cycle times. Reliable production integrates quality assurance procedures and requires qualified personnel.

 

Adhesive bonding applied

Bonding processes have to be designed individually: In the transportation industry's body-in-white bonding of automotive construction, windscreen bonding of rail vehicle construction and sandwich bonding of aviation differ greatly from each other. Micro-bonding in electronics requires special adhesives and boundary conditions, as the adhesive quantities are millions of times lower than those for bonding in civil engineering. Medical technology places new demands on the safety and biocompatibility of adhesives. In the aerospace sector, it must be noted that adhesives can be used at extremely high and extremely low temperatures. In the packaging industry, on the other hand, manufacturing costs and speeds play a decisive role.

 

Consulting around adhesive bonding

The range of services covers the entire bonding process chain and adhesive selection, characterization of the mechanical as well as the processing properties of adhesives, design and validation of bonded structures, thermoanalytical, spectroscopic, rheological, physical characterization, development and application of dispensing and application processes, consulting on quality assurance of bonding processes, customer-specific design of industrial processes, testing and production of adhesive tapes, analysis of damage cases and elimination of production faults.

The range of services is complemented by many years of experience in the polymer-chemical formulation of adhesives and by the diverse possibilities of surface pretreatment and surface analysis. The long-established, comprehensive and globally offered portfolio of further training in adhesive bonding technology, with versatile courses and globally recognized qualifications, completes the range of services. The verification of the standard-compliant implementation of industrial bonding technology based on DIN 2304 "Adhesive Bonding Technology - Quality Requirements for Adhesive Bonding Processes" and DIN 6701 " Adhesive Bonding of Rail Vehicles and Vehicle Parts" is also part of the range of services. Fraunhofer IFAM also provides approved auditors for both standards.

 

Current research goals in the field of adhesive bonding

 

Electromobility Development and characterization of thermally or electrically conductive bonded joints in battery modules or powertrains
Hybrid joining Reduction of defects during bonding in combination with mechanical joining processes such as riveting, hemming or clinching
Fast processes Accelerated adhesive curing through thermal excitation or fast handling strengths through new dual-cure adhesives
Aging Understanding the aging behavior of adhesives and applying quick tests for safe dimensioning
Adhesive bonding in civil engineering Development of adhesive bonding for load-bearing civil structures in window construction, facade construction, timber construction and heavy steel construction
Quality assurance Development of new methods for inline control of sub-steps of the bonding process
Development of standards for quality assurance Transfer of DIN 6701 into a European standard (EN 17460) and DIN 2304 into an ISO standard (ISO 21368)

 

 

Download the Institute Profile (PDF)

 

Adhesive chemistry and development

 

Characterization of adhesives

 

Bonded structures

 

Industrial bonding processes

 

Quality assurance and further training in adhesive bonding technology

 

Mechanical joining techniques and adhesive bonding: Hybrid joining

Hybrid joints combine different joining technologies and are increasingly used in various industries. The decisive strength of a hybrid joint is that advantages of the elementary joining technologies are used and disadvantages are compensated. Adhesive bonding can be advantageously combined with various mechanical joining processes, depending on the application and industry.

 

A new generation of gapfillers

Heat dissipation from batteries is essential to protect them from overheating. Therefore, only effective heat dissipation can ensure strong drive performance and a long service life of electric vehicles. This is enabled with gap fillers. Dr. Holger Fricke and Victor Schmadalla will present the results of the "OWES" project at the "Battery Systems" conference.

 

Methodical adhesive selection

The selection of the right adhesive is a fundamental element of any manufacturing process, because if an unsuitable adhesive is used, this can lead to problems such as corrosion, reduced bond strength over the lifetime, adhesive creep with an increasing risk of failure of the bonded joint, and many other difficulties. For this reason, the experts at Fraunhofer IFAM have specialized, among other things, in providing manufacturer-independent support for customer-specific adhesive selection.