Machining of complex-shaped parts with guidance curves

Nowadays, High Speed Machining (HSM) is usually used for production of hardened material parts with complex shapes such as dies and moulds. In such parts, toolpaths generated for bottom machining feature with the conventional parallel plane strategy induced many feed rate reductions especially when boundaries of the feature have a lot of curvatures and are not parallel. Several machining experiments on hardened material lead to the conclusion that a tool path implying stable cutting conditions might guarantee a better part surface integrity. To ensure this stability, the shape machined must be decomposed when conventional strategies are not suitable. In this paper, an experimental approachbased on High Speed Performance simulationis conducted on a master bottom machining feature in order to highlight the influence of the curvatures towards a suitable decomposition of machining area. The decomposition is achieved through the construction of intermediate curves between the closed boundaries of the feature. These intermediate curves are used as guidance curve for the toolpaths generation with an alternative machining strategy called “guidance curve strategy”. For the construction of intermediate curves, key parametersreflecting the influence of their proximity with each closed boundary and the influence of the curvatures of this latterare introduced. Based on the results, a method for defining guidance curves in 4 steps is proposed.