*2.4. Machining Strategies*

Machining strategies were programmed with Siemens® NX manufacturing module. First of all, the roughing operation was programmed with the aim of reducing machining time, chip thickness and

cutting forces [18] as much as possible and obtaining a near to net shape geometry. As can be seen in Table 2, the roughing operation (Figure 2) consisted of two different steps. First, a cavity mill strategy was performed, and then, a variable contour strategy was used in order to obtain a near to net shape geometry for finishing strategies. In R-I a frontal mill was used and in R-II a conical mill.


**Figure 2.** R-I (**a**) and R-II (**b**) roughing strategies.

For finishing operations (Table 3), different strategies and conditions were tested for the gear teeth. Different radial depths and cut patterns (zig and zig-zag) were evaluated, for both 5 continuous axes (F-II) machining operations and 3 + 2 axes (F-I) machining. In the latter machining operation (3 + 2), the tool axis is fixed and perpendicular to the head of each tooth, as can be seen in Figure 3. Machining conditions were S = 11,900 rpm and F = 400 mm/min.



**Figure 3.** Finishing strategies. F-I (**a**) 3 + 2 finishing strategy. F-II (**b**) 5 continuous axes finishing strategy.
