Machining of Thin-walled Parts Produced by Additive Manufacturing Technologies

Abstract

The study aims at investigation of structure, properties and machinability rate of raw and thermal treated titanium-based powder material used to produce the thin-walled components by one of the most widespread additive manufacturing technologies, electron beam melting (EBM). The microstructure and material properties of raw EBM parts in horizontal cross-section and in vertical ones are different, i. e. the raw EBM samples structure and properties are anisotropic. To reduce anisotropy by modifying microstructure of EBM parts, a thermal treatment (hot isostatic pressing, HIP) was applied. In addition, when using additive manufacturing, the part surface roughness is quite coarse while the dimensions may be out of tolerance. Thus, making the end product after additive manufacturing often requires a finishing cutting operation. Examining the quality of end product in terms of geometric tolerance and thin walls thickness stability is also included in this study. In particular, when milling thin-walled parts produced by EBM technology, the form accuracy and the surface roughness are the functions of variable wall stiffness which is estimated in a local cutting zone. This fact must be taken into account when selecting the cutting conditions. For this purpose, a specially designed measuring information system has been used to control the vibrations during machining process.