Ferritic stainless steels contain 16%–30% chromium and about 0.05%–0.25% carbon in their compositions. As the carbon and chromium content is high, precipitation of carbide particles provides high strength but also causes brittleness. Ferritic stainless steels are of moderate formability with an excellent corrosion resistance and relatively inexpensive. In this study, the predetermined JC model parameters of the AISI 430 ferritic steels have been verified by comparing the experimental drilling process and drilling simulations. Firstly, the drilling experiments of 430 steel with the uncoated tungsten carbide drill have been performed at three different feed rates and cutting speeds. Then, the pre-determined JC parameters have been adapted into a simulation software running with the finite element method and after the drilling simulations have been operated under the same drilling conditions. By comparing the experimental and numerical data based on the thrust force (Fz), a deviation of 4.83% has been calculated and the validity of the material's JC parameters has been demonstrated.

Verification of Johnson-Cook parameters of ferritic stainless steel by drilling process: experimental and finite element simulations

Simulation and experimental investigation of drilling of Ti-6Al-4V alloy

The application of solid carbide tri-flute drills is important for machining high- precision holes. The main advantages of a tri-flute drill are high productivity, very good self-centering and relatively small deviation from the base axis of the hole. The profile of the helical chip groove in the radial section and the shape of the thinning of the drill are the most important factors controlling the cutting precision and overall performance. In this work, various types of groove shape have been investigated and a new method for designing and rationalizing the cutting part shape of a tri-flute drill has been developed. The key result of this paper is a new method of the design of the cutting edge with minimized change in the radius of curvature, which allows to more evenly distribute the force load in the cutting zone and, hence, to decrease the probability of the drill failure. A comprehensive study of the geometric parameters of the drill cutting edges allowed determining the necessary curvature with a minimum number of node points and accounting for the initial position of the transitional section and chisel edge angle. New relationships between the curvature of cutting edge and the shape of the chip groove derived in this work provide a theoretical foundation for the further development of practical recommendations for designing the high-performance tri-flute drills.

Federico Faini

Papers

FEM Simulation of Tool Wear in Drilling