Yang, S., Mohebi, M. M. and Evans, J. R. G.
A novel solid freeforming method using simultaneous part and mould construction
Rapid Prototyping Journal, 14, (1), . (doi:10.1108/13552540810841544).
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Purpose: the purpose of this paper is to present a new powder-based solid freeforming method based on conventional furnace sintering after co-deposition of mould and part powder materials.
Design/methodology/approach: based on acoustic powder deposition, both mould and part powder materials are delivered simultaneously into the forming area according to the cross section of the 3D computer file. The part is formed in the form of loose powder surrounded by the mould powder again in a loose state. The whole assembly can then be sintered by a conventional method and the mould powder, which has a higher sintering temperature than that of part powder, remains in the loose state after sintering and can be removed.
Findings: complex-shaped components containing re-entrant cavities and the capability of being made with 3D functional gradients can be rendered directly as a powder preform suitable for subsequent compaction or direct sintering in a conventional furnace. The flowability and compatibility of the powders need to be selected carefully and the track distance between part/mould powders is important for forming a vertical wall.
Research limitations/implications: the main factors affecting building from powder tracks are identified, including the effect of track distance at an interface on integrity, discontinuous feeding on bends and the effects of fill strategies. The flow rates of the part and mould powder as well as their geometrical maps are controlled computationally. Materials and instrumental aspects are discussed.
Originality/value: this paper describes a method to produce complex-shaped object without residual stress and expensive lasers and the process could be modified to include 3D functional gradients
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