Modeling of burr thickness in milling of ductile materials

Abstract

Accuracy and surface finish play an important role in modern industry. The presence of undesired projections of materials, known as burrs, negatively affect the part quality and assembly process. To remove burrs, a secondary operation known as deburring is required for the post-processing and edge finishing of machined parts. The thickness of the burr is of interest as it describes the time and method necessary for deburring of the machined part. Burr thickness (B t) measurements are costly and non-value-added operations that in most cases require the use of a scanning electron microscope for accurate burr characterization. Therefore, to avoid such expenses, the implementation of alternative methods for predicting the burr thickness is strongly recommended. In this research work, an analytical model for predicting the burr thickness in end milling of ductile materials is presented. The model is built on the geometry of burr formation and the principle of continuity of work at the transition from chip formation to burr formation that also takes into account the cutting force influence on burr formation. A very good correlation was found between the modeled and experimental B t values. The model has shown a great sensitivity to material properties such as yield strength and specific cutting force coefficient (K c). In addition, the sensitivity of the proposed model to the feed per tooth (f t) and depth of cut (a p) was considerably high. The proposed model allows the prediction of the thickness of the exit up milling side burr, without the need for experimental measurement and/or approximation of shear angle (Φ), friction angle (λ), and the tool chip contact length (L), unlike existing analytical burr size prediction models. Besides analytical modeling, statistical analysis is performed on experimental results in order to distinguish dominant process parameters on B t. It is observed that the depth of cut and feed per tooth are the main parameters which significantly affect the B t, while the speed has only a negligible effect on it.