Análise da influência da geometria do quebra-cavaco na usinagem de aço 4140 temperado com ferramentas revestidas

Abstract

The turning of hardened steels imposes severe thermomechanical conditions on cutting tools, making insert selection a critical factor for operational success. This study experimentally investigates the performance of two distinct machining strategies for hardened SAE 4140 steel (48.50 HRC): one based on maximum cutting edge robustness, using an insert with a chipbreaker for heavy roughing (RP-MC6035); and another focused on minimizing cutting forces, with a chipbreaker for general machining (MA-UE6020). Continuous turning tests were conducted, evaluating tool damage via optical microscopy and part quality through surface roughness (Ra and Rt). The results showed that, contrary to expectations, the maximum robustness insert suffered catastrophic edge fracture, resulting in an inferior surface finish. Conversely, the general-purpose insert exhibited progressive and controlled wear, producing higher-quality surfaces. Statistical analysis confirmed a strong correlation between the damaged tool area and increased roughness. It is concluded that, for severe continuous cutting conditions, the strategy of minimizing cutting forces through a more efficient cutting geometry was more decisive for tool preservation than applying a robust edge with high toughness.