Analysis of the effect of friction coefficients in enclosed narrow gap machining of Ti6Al4V

Abstract Circular sawing of Ti6Al4V presents significant challenges due to high tool wear and unstable chip formation, both of which are strongly influenced by frictional conditions at the tool-workpiece interface. As the friction coefficient is known to impact the contact length, temperature at the tool-chip interface and chip morphology, friction coefficients are of great interest. First, a two-dimensional cutting simulation was performed to estimate contact pressures and sliding speeds occurring during the cutting process. The friction coefficients were then identified for the secondary shear zone at machining-relevant sliding speeds and contact pressure using a pin-on-disk tribometer. A velocity dependent friction model is identified for uncoated carbide and Ti6Al4V serving as input for a three-dimensional sawing simulation, in which friction at the upper tool wall is varied systematically. The simulations revealed that changes in the local friction coefficient significantly affected chip morphology until the process reliability is also affected by oscillating chip formation. These results highlight the critical role of frictional properties in determining process stability during circular sawing of titanium alloys and they provide a foundation for improving tool design and cutting conditions in high-performance machining applications.