Análise do desempenho de brocas helicoidais com ponteiras intercambiáveis na furação do aço ASTM A572 GR5050

Abstract

Drilling represents a fundamental operation in the metal-mechanical industry, characterized by the high complexity of machining parameters and its relevance in obtaining components with high dimensional accuracy. This study evaluated the performance of helical drills with interchangeable tips manufactured from carbide substrate with PVD TiAlN coating, considering different tool geometries while maintaining a constant nominal drilling diameter. The interchangeable tips evaluated were models A, B, C, and D. The experiments were conducted on ASTM A572 Grade 50 steel plates with a thickness of 20 mm, using a DOOSAN VERTICAL DNM750LII CNC machining center. For each tip model, 450 holes were machined, resulting in a representative experimental dataset. The performance analysis included the evaluation of tip wear through scanning electron microscopy, as well as measurements of hole diameter, circularity, and surface roughness parameters (Ra and Rz). Statistical analysis was performed using analysis of variance (ANOVA) to verify the existence of significant differences among the evaluated tool models. The model C tip exhibited the best overall performance, providing greater process stability, lower surface roughness values, and lower hole circularity deviations, which were associated with its selfcentering geometry. The model B tip showed improved dimensional accuracy of the machined holes, consistent with the expected behavior of double-margin tips due to the presence of a guiding margin, whereas the model A tip presented greater variation in hole diameter, related to its conventional geometry. The model D tip exhibited more severe wear and greater process instability due to corner fracture. Statistical analysis confirmed significant differences among the evaluated models, demonstrating the direct influence of tip geometry on the final machining quality.