Analytical modeling of exit Burr in drilling of Ti6Al4V alloy

Abstract

Burrs affect precision components and cause assembly related problems, and in general, decrease manufacturing productivity. Drilling burr formation involves multiple stages that are influenced by variation in thrust forces, temperature, stress conditions, and deformation modes in the unsupported length of the workmaterial below the drill. Several of these have not been adequately investigated so far. Therefore, the objective of this work is to model the complex phenomena that occur just before the exit of the drill tip from the bottom surface of the hole, and up to the complete exit of the drill point from the work surface. Accordingly, two models have been developed: (i) to estimate onset of bending in conjunction with theory of plasticity, which leads to the formation of a small drill cap under the pressure of steady-state drilling thrust forces, and (ii) to evaluate exit burr size that involves stretching and bending of a thin layer below the drill tip, using the principle of energy conservation. It is observed that a fracture is initiated at the chisel edge corner resulting in the formation of a small drill cap. The exit burr size predicted by the model is within one standard deviation from the average burr height as determined from the experimental data.

Drilling Burr Minimization by Changing Drill Geometry

“…Studies have shown that the change allowed for a significant reduction in the size of burrs ( Figure 11 ). The results obtained are in line with the models presented by Rana et al [ 12 ] and Mittal et al [ 13 ].…”

“…As noted by Rimpault et al [ 11 ], there is a correlation between the values of these forces and the size of burrs formed. Analytical model of burr formation in Ti-6Al-4V alloy and its experimental verification was already presented in great detail by Rana et al [ 12 ]. Another model (specific for high-speed microdrilling) was developed by Mittal et al [ 13 ].…”

Numerical Analysis of the Forming Mechanism of Exit Burrs in Metal Milling under Ice Boundary Constraint

“…Studying the formation process of burrs is a necessary premise to control and minimize burrs, and it has certain guiding significance for exploring active burr suppression methods. The analytical method is currently the main method for people to analyze the burr formation mechanism and explore the relationship between cutting variables and burr geometry [5]. Zhang et al [6] investigated the burr formation mechanism in micro end milling by considering the minimum chip thickness, as well as the size effect of cutting edge radius.…”