Press-fit process analysis and parameter optimization for nuts with washers

This study focuses on hexagonal flange face nuts assemblies with washers that are integrated through a pressing process. We established a mechanical model for nut-washer pressing based on the characteristics of this process. Utilizing the finite element model in Deform-3D, we conducted numerical simulations to enhance the quality of the pressing, ensuring that the washer and nut remain securely attached while allowing for free rotation post-pressing. Furthermore, we employed the response surface method to select the punch angle, punching speed, and punching stroke as test factors. A three-factor and three-level response surface test matrix was developed to investigate the impact of these factors on punching pressure, aiming to identify the optimal parameter combination with punching pressure as the optimization objective. The results indicate that an optimal punch angle of 45°, a punching speed of 8 mm/s, and a punching stroke of 1.4 mm yield high-quality press fit and optimal punching pressure. The process tests validate the reliability of the parameter combination scheme for the press-fit process, effectively guiding future implementations.