# Manufacturing Processes of Integral Blade Rotors for Turbomachinery, Processes and New Approaches
## 2 Monolithic Components: Manufacturing Processes
### Super Abrasive Machining (SAM)
[68] performed electrochemical SAM experiments on finishing fir trees analyzing roughness and overcut, observing low forces (37 N) with an average depth of cut of 0.92 mm. Furthermore, SAM was presented in [69] as a solution to increase machining efficiency during the production of blades and turbine discs. It was tested with the blades from IBRs or impellers. In fact, Rolls-Royce [70] claims that under the correct performance, the process is capable of stock removal at a rate of 80 cubic millimeters per second per millimeter of wheel width. That is, eight times the achievable rate using plated CBN (Cubic boron nitride) wheel technology for super abrasive machining of nickel alloys on a conventional grinding machine. Following this researching line, [PERSON] et al. presented a comparison between SAM and conventional milling applied to blisk geometry  
Figure 13: A variety of SAM tools geometries [19]. made of Inconel(r)718, performing roughing and finishing operations comparing cutting forces, surface roughness and dimensional deviation [67]. Additionally, slotting using SAM was performed and compared to conventional milling in terms of surface roughness, analyzing the cross-section and the appearance of white layer, residual stresses and microhardness, observing better results for SAM process under similar cutting conditions [71]. In a similar manner to the tendency of flank milling, flank SAM is also considered as a more productive and effective process. Hence, [PERSON] presented in [72] a solution for obtaining Pratt and Whitney non-developable blisk geometry through flank SAM. As it was mentioned before, non-developable surfaces are not suitable for flank techniques, so this author proposed a surface modification, preserving aerodynamics and structural properties, and supplementing the manufacturing process with new tool-paths and shaped cutting tools. The results present a successful process in which the combination of flank SAM technology with the shaped cutting tools opens the possibility of new surface designs more efficient aerodynamically. For that purpose, the developed method follows these steps: (1) redesigning blade surface for improving the performance; (2) adapting the designed surface to make feasible flank SAM technique, iterating mechanical, aerodynamic and structural simulations; and finally, (3) blade manufacturing using two CBN electroplated abrasive tools, one for suction surface and another one for pressure surface. Table 1 shows a summary of the most significant patents related to super abrasive tools and main applications, frequently developed by the main turbine manufacturer as Pratt and W\(\rightarrow\)hitney, General electric and United Technologies Corporation (UTC), among others. \begin{table}
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**Patent Number \& Title** & **Description** & **Figures** \\ \hline \hline \end{tabular}
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Table 1: Patents related to super abrasive machining. Figure 14: Bladed disc fir-trees manufacturing using SAM [67]. \begin{table}
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**Patent Number \& Title** & **Description** & **Figures** \\ \hline US 7101263 Hank superabrasive & This patent develops a new superabrasive conical tool for using flank SAM on complex geometries as turbine blades. & \\ US 7007382 Slot machining. UTC [75]. & This patent presents a methodology for initial slots in fir-trees in three different stages. (1) Slot base, (2) right lateral side and (3) left lateral side. & \\ US7303461B1 Method of machining airfoils by disc tools. Pratt and Whitney [76]. & This patent develops a grinding peripheral strategy to remove material on airfoils discs using multi-axis simultaneous motions. & \\ US 7789732 Superabrasive tool. UTC [77]. & A special abrasive machining tool for point machining in different steps. The body is composed of a tool tip abrasive coating. & \\ US 7896728 Machining methods using superabrasive tool. UTC [78].