# Manufacturing Processes of Integral Blade Rotors for Turbomachinery, Processes and New Approaches
## 1 Introduction
The classification of manufacturing processes is conditioned by component characteristics, sector of applications, material requirements and geometrical definition. Among IBR definition, the geometry is divided into two main groups based on the relation between the length or blade areas and the diameter of the disc. Figure 2 presents IBRs manufacturing processes in accordance with this relation, which shows the use of monolithic manufacturing processes for small-medium diameters and union processes for big diameters [7]. The first group, where the component size is elevated, involves geometries as the fan at first stages of low-pressure compressors. These components are commonly made by forging and manufactured  
Figure 1: HF-120 turbofan engine (GE-Honda). Blisk and impeller examples [3]. by union processes; applying a welding process between single blades and the main disc. Among welding processes, Linear Friction Welding (LFW) and Inductive High Frequency Pressure Welding (IHFP) are found [8]. The LFW process consists in fixing strongly the disc while single blades are oscillating along a linear movement; the generated friction leads to the necessary heat to obtain a welding clad between both components. Finally, a milling process is performed to remove the remained extra material [9]. At the present time, this technique obtains welding results with high integrity, low distortions and fine grain microstructure in the thermal affected zone [10]. The IHFP process uses a high-frequency alternating current that generates an elevate electromagnetic field heating the materials up to the required temperature [2]. Inside this group, the Abrasive Water-Jet Cutting (AWJC) is presented as an alternative for blisk roughing strategies with blades length over 150 mm and cutting widths of 100 mm [11]. The second group encompasses IBRs geometries with small blades size compared with the component diameter, such as high-pressure compressor stages. Currently, these components are manufactured using High Speed Cutting (HSC) of a monolithic piece due to the process flexibility, and the wide knowledge of this conventional process. Alternative manufacturing processes include: Casting, Pulse/Precise Electro Chemical Machining (PECM), Electro Discharge Machining (EDM), Additive Manufacturing (AM), Grinding and Super Abrasive Machining (SAM). With the aim of reducing material waste and manufacturing times, near-net-shape processes are becoming an alternative as a primary process: Additive Manufacturing (AM), Casting and Sintering. Nonetheless, the high complexity of these components is still a handicap compared with the forging preforms that achieve good mechanical properties and higher resistances due to optimal metallic material fiber orientation [12,13]. One of the most popular post-treatments to optimize these primary processes is known as Hot Isostatic Pressing (HIP). The HIP consists in applying elevate temperature (482 \({}^{\circ}\)C for aluminum to 1320 \({}^{\circ}\)C for nickel-based superalloys) and pressure (range: 50.7-310 MPa, being 100 MPa the most common pressure) simultaneously on the part, removing porosity and improving mechanical properties [14]. Considering those new alternatives and their combination in order to obtain the optimal IBR manufacturing process, [PERSON] et al. [4] performed a technological and economic analysis determining seven different process chains combining milling, PECM, ECM and AM, establishing a complete machining process as the reference process. Following the same objective of finding the optimal IBR manufacturing process chain (Figure 3) shows a comparative chart between 20 reliable process chains, based on a previous technological analysis, defined for a Ti-based impeller manufacturing [15]. Figure 2: Integral blade rotors (IBRs) manufacturing methods subjected to material resistance and geometry [7].