Comparative Analysis of Complex Surface Machining in Automotive Part Stamping Tools: A Case Study with Ball Nose and Cylindrical End Milling

Complex surface machining is crucial for the competitiveness of the automotive industry, but it presents challenges such as high precision, efficiency, and productivity. In this context, this study aims to compare two different tool geometries in the machining process of tooling used in stamping parts for the automotive sector. For this purpose, two types of cutting tools were selected, the ball nose end mill and the cylindrical end mill. Machining tests were carried out on nodular cast iron, the material used to produce the tooling, in order to analyze the surfaces machined by the end mills, which allowed a comparison between the cutting tools, combined with the usual parameters of the machining process. The temperature was measured during the machining process. The machined surfaces were characterized by means of confocal laser and scanning electron microscopy, Vickers microhardness, x-ray diffraction residual stress analysis, and roughness of the machined surfaces. Additionally, the deviation and geometrical fidelity of the parts were analyzed. A 2³ factorial experiment design was developed, using the factors raised, and the tools were incorporated as blocks. The ball nose end mill showed better performance in the machining of complex surfaces, with lower roughness, higher material removal rate, and better surface finish. The results of the residual stress analysis suggest that the ball nose end mill provided a surface with lower residual stress compared to the cylindrical end mill. These findings indicate that the surface produced by the ball nose end mill is more resistant to the occurrence of cracks. The results demonstrated that the potential of the ball nose end mill for machining complex surfaces in the automotive sector contributes to the increased competitiveness of Brazilian tooling companies.

Keywords: characterization; roughness; complex surface machining; geometrical fidelity