Analysis of the influence of a rivet yield stress distribution on the micro-SPR joint – initial approach

One of the limitations related with joining several micro parts is the temperature generated during joining methods based on material heating. Temperature concentration could be a reason of severe difficulties with micro-manufacturing applications. It seems that modern mechanical joining technologies could significantly facilitate micro-parts fastening, since there is lack of temperature development during the process. Recently mechanical joining methods undergo considerable development and become more and more competitive in the industry. Among them, the self-piercing – SPR – technology is one of the most advanced and flexible. Initially, the automotive industry was a first application of the SPR, and then have been started to be use in other industry areas. In the paper, possibility of micro-rivet production by micro-forming with heat treatment elimination has been researched by means of FEM analysis. Required rivet strength is achieved by designed cold forming process and followed by effect of material hardening. Various stress distributions in the rivets are taken into account during numerical simulation to prove their influence on joining quality. Commercial FEM software MSC.Marc is used for numerical simulations.