Temperature response of LOCTITE 648 anaerobic adhesive and hoop channels to enhance its effectiveness under high interference

The strength of a shaft-hub hybrid joint is affected by several factors, such as working temperature, interference level and coupling procedure. The first part of this study deals with temperature effect on the static response of shaft-hub hybrid joints. LOCTITE 648 anaerobic adhesive was applied for coupling 42CrMo4 tempered steel shafts to 16CrNi4Pb hardening steel hubs. The performance up to 100°C was experimentally investigated, involving press-fitted as well as shrink-fitted joints with interference up to 0.2%. Adhesive stripping upon coupling, adhesive degradation at high temperature and also frictional contribution decrease were highlighted. Afterwards, in the second part, the question of the adhesive being teared off under high interference was tackled. A hoop-channeled geometry was proposed, to increase the amount of adhesive remaining trapped at the joint interface. Hoop channels in the shafts proved to act as adhesive reservoir, thus facilitating adhesive dragging over the entire engagement length. Their effects on the joint strength were experimentally determined for both press-fitting and shrink-fitting coupling methods. The results, processed by the statistical tools of Analysis of Variance, orthogonality and pairwise tests, indicate the modified geometry is significantly beneficial for high interference press-fitted joints. Conversely, it may even be detrimental for shrink-fitted ones.