# Manufacturing Processes of Integral Blade Rotors for Turbomachinery, Processes and New Approaches
## 2 Monolithic Components: Manufacturing Processes
### Super Abrasive Machining (SAM)  
Abrasive processes need to be considered as a possible alternative for IBRs manufacturing. There are some non-conventional abrasive technologies (abrasive flow machining, magnetic abrasive finishing or magneto-rheological abrasive flow finishing) characterized by their good performance for complex geometrical cavities with limited accessibility for conventional processes, achieving great dimensional accuracies and finishing surface quality requirements [60]. However, at the same time, these processes present low material removal rates, implying less productivity in terms of machining time and costs [61]. In the last decade, a new abrasive process was developed, known as Super Abrasive Machining (SAM), on the path of finding innovative technologies to cover these productivity issues. [PERSON] [62] defined this process as \"grinding at machining rates\". Therefore, this technology provides, under similar cutting conditions of single point machining, a finishing precision closer to grinding technology, which makes this process more versatile than grinding or milling techniques. The main difference  
Figure 12: Error estimation: tool cut position and principle of error [59]. between the conventional grinding and SAM is that grinding is commonly used for low material removal rates oriented to achieving final size and finishing requirements; in contrast, SAM is more adaptive for a variety and complex geometries and higher material removal rates, offering as well, elevated accuracy and surface quality. A notable difference between both processes resides on the type of abrasive tools used; SAM abrasive tools (Figure 13) cover a wide range of small geometries--diameters \(\leq 25\)mm--and they consist on single layer electroplated superabrasive grinding wheels. Nonetheless, it also needs to be stressed that rotational speeds required to obtain the adequate peripheral cutting speeds are very high, in most of the cases over 50,000 rpms [19]. Additionally, it is noteworthy that using these kinds of tools, due to process temperature and extreme cutting conditions, cutting fluids are required, particularly cutting oil [63; 64]. Regarding accessibility, SAM process presents accessibility problems in closed geometries as it happens with milling processes because the tools sizes are similar to milling ones. The grinding technique considered as the closest rival to SAM is creep feed grinding (CFG), characterized by large cutting depths (ap = 0.1-30 mm) and high cutting speeds (vc = 20-30 m/s). Creep-feed grinding is generally a surface grinding technique employed for heavy stock removal of difficult-to-machine materials, particularly where very precise and accurate form is required on the finished surface of the workpiece [65]. Comparing both techniques, SAM achieves the equivalent amount of material removed at higher speeds, with lower workpiece loads, and more accurate dimensional tolerances ([PERSON], 2008). These advantages make SAM a suitable and efficient alternative to manufacture IBRs nickel-based superalloys [66]. The use of SAM is recommended for three main application groups: (1) there are some manufacturing processes divided into different stages of machining, grinding and heat treatments, so in these cases, SAM could reduce all stages into only one. (2) The use on components from other near net shape processes. (3) Formed slots and flat surfaces finishing operations. Figure 14 shows some of the initial target for SAM application: fir-trees that are the junction area between the disc and single blades. Traditionally, these components are manufactured by broaching; however, this process is considered not cost effective and a time consuming. Therefore, [19] performed a set of experiments with single layer electroplated CBN (Cubic boron nitride) and diamonds wheels to manufacture fir tree roots using SAM process. For the same application field, [PERSON] et al.