TOX®-Clinching versus spot welding
Higher dynamic strength than in spot welding!
Advantageous dynamic strength without notch effect in the joint - this means: the life of the TOX®-Round Joint lasts much longer than that of a weld point. The TOX®-Joint in customer test results of endurance tests for samples with TOX®-Round Joints and spot welds. The joints were exposed to an initial load of 1 kN and a frequency of approximately 35 Hz. The fatigue life of the joint was measured until failure.
A further, often most important aspect, is the significantly higher dynamic strength of the cold-formed TOX®-Clinch Joint in comparison with spot welding, where the heat brought into the joint changes the material structure which is detrimental for the strength of the welding spot. That’s why dynamically loaded welding spots are inferior to the TOX®-Round Joint with regard to joint strength.
The simple process cuts your manufacturing costs. The system efficiency and the service life of the tools are closely interdependent.
Cost comparison for the single joint technique between spot welding and TOX®-Joining for a mild steel application. The TOX®-Joining Technlolgy can be used in multipoint applications, which can increase considerably the cost difference between TOX®-Joining and spot welding.
Electric conductivity in the TOX®-Clinch Joint
The behaviour of the electric resistance is specially important when used in electrical appliances and electric conductors nowadays used in passenger cars as prefabricated door tracks for feeding the door electrics. A most reduced transition resistance is of the advantage. Here applies: the lower the transition resistance, the higher the electric conductivity.
From hitherto realized applications and comprehensive lab and field tests we gathered the following findings with regard to electric properties of the TOX®-Joining:
- The sheet/foil surfaces pressed together and deformed under high pressure to build the TOX®-Joint are favourable for electric conductivity.
- Coated surfaces flow also into the joint and reduce the transition resistance. The major part of the current flows through the joint. The surrounding surface contributes only little (10 %) to the current conduction. Decisive is the joint!
- Oiled, galvanized and glued surfaces of steel sheets have only little influence on transition resistance. A comparison between welding spots and clinch joints depends on the combined materials.
- For joining smallest electronic components, the TOX®-MICROpoint is the ideal solution for diam. 1 mm and larger: cold joining of thinnest sheets with smallest flange widths, no thermal change of material, minimal distortion in the piecepart.
- Plastic foil between sheets, punctured during the joining process, flows with the material and achieves almost a tenfold increase of the transition resistance.
- The combination “steel/aluminium” shows about the same results as a “steel/steel” arrangement.
TU Dresden proves electrical conductivity for TOX®-Round Joint
Now it is official: The excellent electrical conductivity of TOX®-Round Joint and TOX®-SKB Joints for joining sheet metal from the same or different materials with the same or different thickness was proven in a comprehensive study of the Technical University of Dresden! The intensive study on the topic of “Electrical property profile of formed joints” was performed by the institute for surface and production engineering together with the institute for electrical energy supply and high voltage technology of the TU Dresden. Leading representatives of the automotive industry and its suppliers as well as several manufacturers of joining and fastening technology products participated in the preliminary sessions of the PbA (project advisory board) performed by the “Joining” workgroup. Here, amongst others, a requirements profile and an experimental design were developed, whereby the experimental design was then fully used during implementation in practice. A basic distinction was made between the mechanical joining (e.g. pressure joining/clinching), the component connection (e.g. placing bolts, rivet nuts) and the mechanical joining with component connection (e.g. punched nuts). The trial was defined for “long-term stable mechanical joining of components with partially available functional integration through fastening of attachment parts (functional elements)”. With a view to the state of the art, the mechanical strength (shear, tensile and turning strength) was taken as much into account for this as the so far almost non-existing demand on the electrical properties of such joints. The practical background here is that the search for energy- and material-saving fastening and joining solutions is now being extended to electrical components and assemblies. In particular to get away from the additional, material- and energy-intensive procedures like spot welding, soldering or laser soldering and to give room to new, more economical manufacturing processes.
For more information about clinching technologies, contact us today!