Laser surface texturing for novel interference fit joint fixation

In this project, a new type of manufactured interference fit joint was examined. Interference fit joints hold components together in many industries, including the automotive, ICT, and aerospace industries. The interference fit joint consists of a pin and a hub region. As the rod is inserted into the hub, deformation of the material results in a joint bond strength. Laser surface texturing of metal pins for was used for manufacture of interference fit joints. The material examined was mild steel EN3B, a carbon steel with a difficult to machine and has high melting point. The laser parameters investigated in this study were the laser power, the laser scan percentage overlap and the focal position. These have significant effects on the resulting surface texture geometry. The peak-to-valley and peak-to-peak displacements can be controlled using the laser. The process obtained different surface geometries such as groove or moiré stochastic structures. The process parameters and their levels were used to alter the specific volume of material raised above the pin surface. Higher volumes characteristics resulted in larger interference fit joint bond strengths. The laser parameters obtained surface textures as well as on the various dimensions of melt pool volume, grain sizes and diameter increase of the pin of the joint. The phase transformations also resulted in various microstructure properties on the samples. The interference fit pin was 60 mm in length and 9.8 mm in diameter. Surface textures were produced on the engagement length of 10 mm along the length of the pin. The results of the investigation obtained a range of textured diameter increases from 10mm to 10.8mm and surface roughness from 38.8μm to 92.7μm. The insertion force values were between 0.91kN and 29.4kN and pull-out force values were between 0.15kN and 7.81kN. The process parameters which were the most significant for the diameter increase where the laser power and the percentage overlap of the laser spot. The surface roughness had a significant correlation with the focal position and the laser power on the specimen. The interference-fit joints achieved joints that safer compared with conventional interference fit joint. This was due to the fact that the bond strengths of joints had lower 95% error bars of the specimens. These joints also exhibited re-grip on excess loads compared with the traditional interference fit joint used in the automotive manufacturing industry