Due to the increasing use of hard to machine nickel-based alloys in aircraft engines, electrochemical machining (ECM) is an important manufacturing alternative, especially in blade and blisk (blade integrated disk) production. However, caused by constantly changing properties of the electrolyte during machining, it is difficult to predict suitable tool electrode (cathode) geometry for a given workpiece contour a priori. Especially temperature and gas evolution affect the conductivity of the electrolyte significantly and thus lead to local deviations in dissolving rate. So this paper presents optical in situ measurements of electrochemical machining the nickel-based alloy Inconel 718 in terms of highspeed and thermography camera recordings. With the help of these measurements on the one hand a deeper process understanding is generated and on the other hand the findings will serve as input and validation for an interdisciplinary process simulation model based on conservation equations. Finally this model will be used to calculate a complex geometry and will be compared to experimental results.
Additive manufacturing technologies are becoming more and more important for the implementation of efficient process chains. Due to the possibility of a near net shape, manufacturing time for finish-machining can significantly be reduced. Especially for conventionally hard to machine materials like gamma titanium aluminides (g-TiAl), this manufacturing process is very attractive. Nevertheless, for most applications, a rework of these generative components is necessary. Independently of the mechanical material properties, electrochemical machining is one promising technology of machining these materials. Major advantages of electrochemical machining are its process-specific characteristics of high material removal rates in combination with almost no tool wear. But electrochemical machining results are highly dependent on the microstructure of the material regarding the surface roughness. Therefore, this article deals with research on electrochemical machining of electron beam melted g-TiAl TNB-V5 compared to a casted form of this alloy. The difference between the specific removal rates as a function of current density is investigated using electrolytes based on sodium nitrate and sodium chloride. Moreover, the dissolving behavior of the electron beam melted and casted structure is analyzed by potentiostatic polarization curves. The surface roughness is heavily dependent on a homogeneous dissolution behavior of the microstructure. Thus, the mean roughness as a function of current density is investigated as well as rim zone analyses of the different structures.
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