Evaluation of Quality for Flow Drill Screw (FDS) Joining Process Based on Loosening Torque

• Published in: Journal of Welding and Joining Vol. 42; no. 5; pp. 481 - 486
• Main Authors: Kim, Tae-Jeong, Ko, Se-Jin, Oh, Wook-Jin, Lee, Ji-Hong
• Format: Journal Article
• Language: English
• Published: 대한용접·접합학회 31.10.2024
• Subjects: Mechanical joining; Flow drill screw; Torque; FDS; Quality tnspection; Non-destructive test
• ISSN: 2466-2232; 2466-2100
• DOI: 10.5781/JWJ.2024.42.5.5

Although the SPR process is widely used for joining of multi-materials, the FDS process is used when one-way joining is required, such as space constraints or closed cross-sectional parts. The quality inspection for the FDS process is basically an appearance inspection or cross-sectional inspection. There is no non-destructive test method that can be used in the actual mass production line, and a method of utilizing loosening torque is being studied. In this study, the factors affecting the loosening torque are analyzed, and an experimental equation that can predict the loosening torque is derived. Since friction force between the screw and the upper plate and sticking on the screw thread resist against loosening torque, the prediction equation for each factor is considered and the least square method is used to obtain the coefficients of the experimental equation. The prediction equation of the loosening torque derived through experiments on 36 material combinations predicts the experimental values well. When a quality requirement value with a given margin is applied, it can be used as a non-destructive test method.