# Manufacturing Processes of Integral Blade Rotors for Turbomachinery, Processes and New Approaches
## 2 Monolithic Components: Manufacturing Processes
### Algorithms to Optimise Manufacturing Processes  
The generation of 5-axis simultaneous tool-paths for manufacturing free form surfaces has been a growing field of research in recent years and covers multiple areas derived from the large number of factors involved in manufacturing processes. In particular, many algorithms are developed with the aim of improving machining strategies and obtaining a more productive process. These algorithms are programmed around three main crucial aspects: tool-paths generation, optimal tool position and the avoidance of collisions [80]. Nevertheless, the three aspects are correlated between them, thus the global solution to optimal strategies programming is divided in turn into the following stages: (1) Tool definition or selection, (2) tool-path pattern and direction definition, (3) surface contact points specification, and finally, (4) local and global collisions free verification to obtain tool axis orientation. The provided solution must meet the requirements of being free of collisions, fulfilling defined tolerances and minimizing machining time. Moreover, developed algorithms need to be efficient in terms of computational costs, memory usage and be adaptive to a spread range of surfaces. Related to IBRs, there is a common issue presented during the machining of warped surfaces consisted on the appearance of machining marks because of the sudden movements between free collision positions. With the aim of facing this issue, [PERSON] et al. [81] proposed a solution smoothing the tool-paths performed by a ball end mills, modifying and adapting rotational positions inside the collisions free zone. In line with this solution and oriented to blisk geometries, [PERSON] et [PERSON] [82] used boundary surfaces to prevent extreme tool orientation changes between two points. The traditional tool-path generation methods are iso-parametric, iso-planar and iso-scallop. The iso-parametric consists of generating the tool-paths while maintaining constant the parameter of the parametric surface [83]. The iso-planar, instead, generates the tool-paths dividing the surfaces into parallels planes in the Cartesian space, constraining it by the finishing required scallop. However, the defined constrain could offer a conservative solution not very productive and with excessive surface quality [84]. Finally, the iso-scallop method is based on keeping the scallop height constant along the entire surface, optimizing the successive stages from an initial pattern [85]. [PERSON] and [PERSON] [86] performed an experimental comparison between the three different methods machining a sculptured surface, concretely a double curvature surface, concluding that for this type of surfaces, the optimal method is the iso-scallop in terms of finishing tolerances and balanced with machining time. Among the most recent developments in tool-paths definition methods is the C-space (Configuration space methods) presented by [PERSON] et al. [87] and [PERSON] et al. [88]. This method analyses possible configuration for a solid/rigid component with determined levels of freedom and represented as points in a C- space. These points depend on the levels of freedom and the obstacles position. Thus, it offers the chance to know which combinations are free of collisions. Figure 15 shows the C-space method applied and the analysis of the feasible regions to be machined [89]. Another technique for tool orientation definition avoiding local collisions is known as Rolling Ball Method (RBM) [90]. This method calculates different tool-paths by adjusting the contact point in curve sections, avoiding local collisions. By following the same objective and related to roughing strategies for non-ruled complex geometries, [PERSON] et al. [91] developed a solution calculating a ruled surface around the original non-ruled surface, simplifying calculus and tool-paths. [PERSON] et al. [92] proposed a methodology dividing impeller roughing into \(3+2\) axes operations, calculating collision-free regions for tool-paths. [PERSON] et al.