Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2024
Thesis Language: Turkish
Student: Melisa ALTINTAŞ
Principal Supervisor (For Co-Supervisor Theses): Gökhan Küçüktürk
Co-Supervisor: Evren Tan
Abstract:
In additive manufacturing (AM) methods, unlike in the conventional methods, the massive production of multi-part assembly is possible. Especially, during production of some complex parts using AM methods such as electron beam melting (EBM), removing supports that are used for dissipation of generated heat, is not possible after production. If generated heat could not be dissipated through parts, parts gaps may be merged with overhang, surface defects could be occurred. In this study, the nonfunctionality of support structure through EBM method and the production of consolidated rotating structures at radial build direction with minimal gap are researched. The effect of the distance between inner and outer parts, using lattice structure on the surface deterioration, overhang behavior and surface roughness were investigated in regions within the different volume of the part. Fifty parts have been produced. The amount of clearance and overhang and surface roughness were measured. As a result of the studies, it was observed that inner part behaves like a contactless support over outer part for consolidated rotational parts that have between 400 μm and 1.000 μm clearance. Producible minimal clearance is related to quantity of material subjected to overhang, thickness of contactless support and its height. The smallest clearance tested that was able to fulfill the rotational function, based on the performed productions, was found to be 400 μm. On the other hand, when clearance decreases, surface roughness could decrease down to 15 Ra. On the other hand, Beside the producible minimal clearance part, powder drain is crucial. Although there is no merge, if powder that occurs on the gap could not drained, rotation could not be functionalized. It has been observed that lattice structures have positive effects both in terms of heat transfer and in powder drainage. It has also been monitored that surface sag has dramatically fallen in the parts with lattice structures. It has been observed that body centered cubic lattice structured parts is the most effective among the tested.
Key Words : Additive manufacturing, electron beam melting, rotating consolidated parts, contact-free support structures, surface defects, overhang