Where different joining processes show their strengths

The diversity of modern metal joining processes enables tailored solutions for the most varied requirements. Every industry poses its own challenges to joining technology. The choice ranges from high-precision micro-joints to robust large structures.

In microelectronics, soldering is the dominant technology. Printed circuit boards, sensors and semiconductor components are precisely joined together. The low process temperatures protect sensitive electronic components. Without this technique, modern smartphones and computers would be unthinkable.

The automotive industry relies on a combination of various processes:

In plant engineering, welding processes dominate for load-bearing structures. Pipelines, pressure vessels and steel girders require high-strength joints. Arc welding processes such as gas-shielded welding guarantee the necessary stability here. Plasma welding is frequently used for piping systems in process engineering.

Power plant technology uses both welding and brazing-soldering procedures. Boiler tubes are welded, while heat exchangers are often brazed. Furnace brazing in a protective gas atmosphere enables the serial production of complex assemblies. This combination ensures high reliability under extreme operating conditions.

Further important fields of application include:

Complex decision-making in practice

Choosing the optimal joining process presents engineers with multifaceted tasks. Numerous technical and economic considerations feed into this decision. A blanket solution does not exist.

The material combination forms the starting point of every consideration. Some materials can be welded excellently, others can only be soldered. Aluminium and copper, for example, require different approaches. The chemical composition influences the melting behaviour and the wetting properties.

Component geometries further restrict the choice of process. Narrow gaps favour soldering processes through capillary action. Thick cross-sections often require the energy input of welding processes. Accessibility and component size likewise play an important role.

The required mechanical properties set further boundary conditions. High-strength joints argue for welding processes. With lower strength requirements, soldering offers advantages through gentle process control. Dynamic loads or vibrations require particular attention.

Thermal loads during later operation significantly influence the choice of process. Components with high operating temperatures need temperature-resistant joints. The thermal expansion of different materials must be taken into account. Brazed-soldered joints can score points here through their ductility.

Economic considerations must not be ignored. Investment costs for equipment, energy consumption and process times vary greatly. The quantity influences the amortisation of automated systems. Qualified personnel and their availability are also to be taken into account.

The existing manufacturing infrastructure sets practical limits. Not every company has all welding technologies. Existing equipment and know-how influence feasibility. Sometimes an adjustment of the design leads to better results than the acquisition of new equipment.

Quality assurance and the testability of the joints round off the decision picture. Some processes allow simpler non-destructive testing. Documentation requirements in regulated industries can be decisive. The reproducibility of the processes ensures consistent quality.

Non-destructive testing methods at a glance

Non-destructive testing methods offer a decisive advantage: the examined components remain intact and can continue to be used. These methods allow the inspection of series parts without material loss. They form the backbone of industrial quality assurance.

The most important non-destructive methods include the following techniques:

Each method has specific strengths and limits. Ultrasonic testing, for example, works quickly and cost-effectively but does not achieve the level of detail of radiographic testing. Specialists therefore frequently combine several methods for a comprehensive evaluation.

The selection of the appropriate testing method depends on the material, the component geometry and the expected types of defect. Modern testing techniques increasingly use digital evaluation systems. These enable more precise documentation and traceability of the results.

Mechanical testing methods for quality assurance

Mechanical testing methods evaluate the performance of joints under realistic loads. These destructive tests cannot, of course, be carried out on series parts. They do, however, provide indispensable insights for process validation and qualification.

The most important mechanical testing methods in the analysis of brazing-soldering procedures include:

Tensile tests are among the most fundamental tests. They show how much load a joint can take before it fails. The fracture surface provides additional indications of the joint quality.

Fatigue tests are increasingly gaining in importance. Many components are subject to repeated load cycles during operation. These can lead to fatigue fractures, even if the individual load is below the static strength.

The combination of various testing methods enables a holistic quality assessment. Non-destructive methods inspect series production. Metallographic and mechanical tests validate the process and ensure the long-term reliability of the joints.