The shear strength of brake pad adhesive layers is a critical factor that affects the brake performance and safety. This study examined the effects of retention time (0–24 h), adhesive thickness (1–3 layers), and solvent ratio (10–20%) on shear strength using response surface methodology (RSM) with a central composite design (CCD). Analysis of variance revealed that among the main variables, only retention time had a statistically significant effect on shear strength. Nevertheless, the combination of solvent ratio with retention time, as well as solvent ratio with adhesive thickness, played an important role in the shear performance. A second-order quadratic model was developed to represent these effects and provide accurate predictions of shear strength. The proposed model shows strong predictive ability, with a determination coefficient (R²) of 0.82, indicating that the selected factors and their interactions account for 82% of the variation in shear strength. The process parameters optimization showed that the highest cold shear strength of 3.55 MPa can be achieved with a solvent content of approximately 15%, a single adhesive layer (about 60 µm), and zero retention time. These findings emphasize the importance of both individual effects and interactions, and show that careful control of process parameters can significantly enhance the shear strength of the adhesive line in brake pad production.
Partovinia et al. (2025) studied this question.