Joining technology is a core area of mechanical engineering and manufacturing technology. It covers all processes that connect at least two components permanently or detachably. Without joining technology, there would be no motors, electrical devices or vehicle bodies, because only joining turns individual parts into functional assemblies.
In the electrical and automotive industry, joining technology is particularly relevant, as electrical insulation, mechanical strength and high reliability are required simultaneously. Whether welding, adhesive bonding, riveting or screwing: the choice of the right joining process determines the service life, cost and quality of the end product.
Fundamentals of joining technology
According to DIN 8580, joining technology is one of the six main groups of manufacturing processes. It is divided into three main categories:
- Material-bonded connections: components are joined by atomic or molecular bonds. Typical processes: welding, soldering, adhesive bonding.
- Form-fit connections: parts interlock geometrically. Typical processes: riveting, pin connections, folding, snap connections.
- Force-fit connections: the connection is maintained by friction or clamping. Typical processes: screwing, press fits, keyed joints.
Many practical applications combine these principles, for example screw connections with additional adhesive or welded seams combined with bolts.
Important joining processes at a glance
- Welding: material-bonded connection by melting or pressure. Widely used in steel and body construction.
- Soldering: connection via a filler solder, without liquefying the base material. Important for printed circuit boards and electrical contacts.
- Adhesive bonding: polymer-based joining technology of growing importance, as adhesives can combine mechanical strength, damping and electrical insulation.
- Screws and nuts: detachable force-fit connections with high flexibility.
- Riveting: form-fit connection, non-detachable, particularly used in lightweight construction and aircraft construction.
- Press and shrink fits: force-fit processes by mechanical joining of shafts, gears or bearings.
- Ultrasonic and laser welding: modern processes for plastics and metal foils, increasingly used in battery and e-mobility production.
Requirements and quality aspects
A joining process is not selected solely based on strength. Further criteria are:
- Mechanical properties: tensile strength, shear strength, fatigue strength.
- Thermal resistance: behaviour under temperature cycles or continuous load.
- Electrical properties: insulation or conductivity, depending on the application.
- Corrosion resistance: protection against oxidation or electrolyte influences.
- Economic efficiency: investment and process costs, cycle times.
- Assembly friendliness: automatability, testability and dismountability.
In electrical engineering, dielectric strength and insulation resistance also play a role, especially when insulation parts or insulating films are integrated into the joining process.
Standards and norms
Numerous standards apply to joining technology, including:
- DIN 8580: classification of manufacturing processes.
- DIN EN ISO 4063: numbering and designation of welding processes.
- ISO 1465 / ISO 4587: test methods for adhesive bonds.
- DIN ISO 2768: general tolerances, also relevant for joined assemblies.
- IEC 60085: insulation material classes for materials that perform insulating functions during joining.
Use in electrical and automotive industries
- Electric motors: screwing of housings, adhesive bonding of magnets, welding of laminated cores.
- Battery and e-mobility production: laser welding of copper and aluminium foils, ultrasonic joining for cell connectors.
- Printed circuit board assembly: soldering and adhesive bonding of components.
- Automotive body construction: spot welding, adhesive bonding and riveting of sheet metal.
- High-voltage systems: screwing and adhesive bonding of insulation parts made from aramid paper, mica composite or FR4 panels.
Benefits and challenges
Benefits
- Wide variety of processes for every requirement.
- Combination of strength, tightness, insulation and design freedom.
- Advanced adhesive and welding processes enable lightweight construction and new material combinations.
Challenges
- Ensuring reproducible quality.
- Selection of the correct process depending on the load case.
- Testability and quality assurance, particularly for adhesive bonds.
- Thermal influences during welding and soldering that can change material properties.
GOBA Takeaway
Joining technology is the link between design and function. It determines whether a component operates reliably in service or fails prematurely. In the electrical industry, an additional factor is added to strength and economic efficiency: electrical safety. Modern developments, from laser joining to high-performance adhesives, open up new possibilities but also require precise standards conformity and process control. For purchasers, designers and quality managers, only the combination of material knowledge, process engineering and standards assurance ensures economical and safe joining processes.
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