Influência do comprimento em balanço da fresa inteiriça de metal duro na qualidade dos furos usinados

Abstract

Despite significant technological advancements, it remains impossible to manufacture a part with dimensions that match the exact specifications of a design. Consequently, discrepancies are observed between the ideal and actual part dimensions. To avoid compromising the performance of machine components or systems, these dimensional discrepancies have been standardized within tolerance ranges according to specific dimensions. Hole drilling is extensively employed in the industry, yet it presents challenges, such as the need for multiple tools to machine larger-diameter holes, leading to increased production time, as well as resulting in average dimensional accuracy (IT10 to IT12) and requiring rework for holes with tighter tolerances. In mold and die milling, the use of helical interpolation for hole-making has emerged as an alternative to overcome inherent challenges associated with hole opening and enlarging. This study aimed to investigate the influence of tool overhang variation on hole-making through helical interpolation, employing the following experimental procedure. The cutting speed was fixed, while two different tool overhangs were adopted: the first with an overhang ratio (tool free length to tool shank diameter) of three, and the second with a ratio of five. Hot-work tool steel workpieces were machined on a CNC machine using solid carbide end mills without cutting fluid. Finally, tool wear, hole diameter, and hole roundness were measured. The results allowed us to conclude that different conditions imposed on the process did not impact flank wear over time, except for the first two holes. Flank wear curves, diameter variation, and roundness deviation displayed a tendency to converge over time, which can be attributed to the anti-vibration characteristics of the tool, as specified in the manufacturer’s catalog. Finally, it was concluded that the hole-making strategy utilized could be adopted as an alternative for machining holes with diameters larger than the tool itself.