Improving the Life Performance of Axial Joints: Experimental Investigation of the Relationship Between Plastic Bearing Tightness and Torque

Abstract

In this study, the effect of the production configuration of the plastic bushing used in the tie rod, a critical component of the automotive steering system, and the subsequent conditioning processes on the torque was investigated through a wide-sample experimental study. Components having two different design versions were screened in 16 different configurations covering the interaction matrix of clearance and interference fit, thermal conditioning, resting time and grease type; breakaway torque and working torque measurements were recorded over a total of 514 measurements. The results show that the production parameters have a significant effect on the torque characteristics; in particular, in the post-furnace (2-day) configuration of the Design 1 specimen with the clearance-fit tolerance limit, the breakaway torque dropped from an average of 11.78 N·m to 4.33 N·m (approximately −63%). In the Design 2 specimen, the interference-fit combination exhibited high torque values independently of the thermal condition. The outputs of the study establish a permanent infrastructure for defining configuration-acceptance criteria, determining the configurations to be preferred in the production line, and for correlation steps.