Development of a predictive analytical cutting force and torque model for flat bottom drilling of metals using mechanistic approach

By far a large scale of industrial components is being manufactured from metallic materials. Most of these components possess holes in order to fulfill design and application requirements, such as assembly of screws, pins or passing channels for fluids. Depending on the utilized manufacturing method and positioning of these components during machining processes, these holes are being drilled even in vertical or inclined orientations with respect to the jig and fixturing systems. In vertical drilling of the flat surfaces conventional or indexable inserted drill are the commonly used tools. However, these types of tools do not demonstrate sufficient performance on the surfaces drilled holes due to the occurred run-out, vibrations when being used in inclined features. Therefore, flat bottom drills have been developed in order to be used for curved or inclined surfaces. Thus, optimization of the tool and components design requires a deeper knowledge on the cutting forces and torques when using flat bottom drills. In this study, a predictive analytical cutting force model is developed for flat bottom drills for both vertical and inclined plunging using mechanistic approach in Matlab. The model is established on the distributed elementally cutting along the tool radius considering both rake and relief faces based upon the orthogonal and oblique cut principles. Accordingly, the performance of the developed model for different cutting tools with various geometries and machining parameters have been evaluated and verified with experimental results of flat bottom drilling of brass alloy.