Influence of cutting fluid on reliability of threaded fastener joints

This study reports on the effect of cutting fluids on friction behavior of the threaded fasteners. Underhead and thread friction are measured during tightening process of the hex-head threaded fasteners coated with different zinc-based coatings: electroplated zinc, zinc flake, and electroplated zinc nickel, commonly used in the automotive industry. The tests and data analysis are conducted considering ISO 16047 as a baseline. Test conditions are set close to the actual production conditions found in the motor vehicle industry. Water-based and ester-based cutting fluids are selected to unveil their impact on the reliability of the threaded fastener joints. It is shown that a change in the underhead interface conditions from dry to lubricated drastically reduces friction for the electroplated zinc and zinc nickel coatings.