Tribo-Device to Quantify of Friction in Rake Face Using Line Contact Mechanism Under Different Machining Conditions. (c2021)

Abstract

In typical body contact, the friction force is proportional to the load between the two surfaces. However, in cutting conditions, it is more complicated due to the presence of sliding and shearing actions on the interface. The purpose of this research is to introduce and evaluate a new Tribo-Device aims to isolate the aggressive contact on the rake face in order to better understand the high-pressure contact effect on it. The device that is based on line-contact mechanism mimics the normal force applied on the rake face to associate a pressure field results in friction forces, which represents accurately the contact zone. The design validation process depends on a comparison of forces between the experiments, conventional cutting simulation and another finite element model that simulates the functionality of the introduced device. The friction factor used in the simulations is calculated using the experimental analysis. The stress maps generated at the contact of the two FEM models are also compared. The results show that the new device has high potentials in simulating high contact pressure on the rake face. The research will give an enhanced understanding of the tribological properties at the tool-chip interface under high contact pressure. The introduced device is also used to evaluate the effect of sliding speed, normal load, cryogenic coolant and solid lubricants on the tribological properties occurred at the interface. The results show that sliding speed and normal load have a notable influence on friction factor, wear mechanisms and tool life. In addition, it was shown that solid lubricants are mainly useful in reducing friction forces generated at the interface, therefore, improve tool life by protecting it from the aggressive mechanical load. On the other hance, cryogenic gases can be considered as a coolant and lubricant. However, its best performance is at high temperature zones. The results of this research can be used to make corrective actions on cutting simulation, test cutting tool coatings under aggressive wear condition and evaluate new types of metal cutting lubricants.