A Step Towards Rapid Manufacturing

14 February 2002

PhD thesis defence Dipl.-Ing. Steffi Finke (TNO Industrie Eindhoven), Faculty of Engineering, ‘Solid Freeform Fabrication of Metal Components by Extrusion and Deposition of Semi-Solid Metals'

There is an increasing interest in products made by solid freeform fabrication (SFF) based on 3D computer-aided design (CAD) models. SFF refers to the joining of materials layer by layer to form complex shapes and is probably better known as Rapid Prototyping, Rapid Tooling or Rapid Manufacturing. However, conventional SFF techniques do not allow the production of metallic prototypes without post processing, such as debinding, sintering, infiltration or machining. On the other hand, the extrusion and deposition of semi-solid metals (EDSSM) is thought to be an SFF technique capable of producing fully dense metallic prototypes or pre-series parts. The objective of this work was to demonstrate the feasibility for producing such parts with EDSSM, and to develop the process.
The conclusions obtained from this thesis show that EDSSM is a feasible process for low melting temperature metals. EDSSM has the potential to be developed into a SFF process for fully dense engineering alloys. A process window was developed based on the results of the experiments and the wire feed velocity was found to be a key variable for process control.
The results of the experiments showed that homogeneous flow of the material can be obtained, but that segregation between solid and liquid phase occurs under certain process conditions. A rheological two-phase model was used to describe the segregation phenomena. It also revealed information on possibilities of process parameter adjustments necessary to eliminate segregation during EDSSM. Finally the feasibility of using engineering alloys, such as Al-based alloys was evaluated and a materials selection tool was proposed.

supervisor: prof. dr. W. Wei
second supervisor: prof. dr. ir. H.J.J. Kals
information: drs. B. Meijering, telefoon (053) 489 43 85