Hybird manufacturing of high value metallic components through combination of additive manufacturing and conventional processes

Mehmeti, Aldi (2022). Hybird manufacturing of high value metallic components through combination of additive manufacturing and conventional processes. University of Birmingham. Ph.D.

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Abstract

Hybrid Components Manufacturing (HCM) through the combination of additive technologies, specifically metal 3D printing with other conventional production processes, for the manufacturing of innovative high-value components is of substantial growing interest for industrial adoption in the safety-critical, automotive and medical applications. The HCM technology provides the relative merits of each technology combined by overcoming the shortcomings of standalone competing technologies, such as rapid product production, reduced material waste, tool or master free dependant products. Yet, the full capabilities of the technology, its adaptation and its potential in batch manufacturing have not been addressed. The focused theoretical concepts and limited reports found in literature to produce hybrid products, initiated the exhaustive research presented in this thesis aiming to identify the suitability of the technology by developing special fixture solutions to enable batch manufacturing of hybrid products. First, by combining the capabilities of Metal Injection Moulding (MIM) with the Laser-based Powder Bed Fusion (L-PBF) process to produce small series of AISI 316L hybrid components. The research investigated systematically the mechanical properties and the performance of the MIM/PBF interfaces in such hybrid components assessed their reproducibility, repetition, and performance, and ultimately compared it against conventionally prepared counterparts from the state of the art and the standards. Furthermore, the feasibility of the proposed route was investigated by preparing actual hybrid 3D components, the effects of the laser irradiation, pre-processing and post processing on the structures was evaluated, coupled with proposed methodologies such as Hot Isostatic Pressing (HIP) for the optimisation of the hybrid products that delivered an increase in strength of near 70% compared to as-built components. Following, the technology is applied for the manufacture and repair of hybrid components through Directed Laser Deposition (DLD) from common Nickel-based superalloys. The investigation confirmed that the deposition and bonding of Ni-based alloys can be obtained without significant substrate preheating, just with optimum parameters combination such as laser power value, low scanning speed and large beam diameter. The investigated hybrid manufacturing approach showed that the substrate thickness, the inter layer deposition delay, heat treatment and final machining are critical factors to manage residual stresses. Ultimately, the new hybrid solution achieved to produce machine finished hybrid blisks with deposited CM247LC blades onto Inconel 718 disks, by applying appropriate deposition strategies in a conventional CNC machine tool with an integrated L-DED head. The proposed solution is a new production method that allows the production and subsequent repair of such components.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):