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1. ASSESSMENT OF SURFACE FINISH AND DIMENSIONAL ACCURACY OF TOOLS MANUFACTURED BY METAL CASTING IN RAPID PROTOTYPING SAND MOULDS

Author

Nyembwe, K., De Beer, D. J., Van der Walt, J. G., and Bhero, S.

Subjects
Tools, Metal casting, Rapid prototyping, Sand moulds, Industrial engineering. Management engineering, T55.4-60.8
Abstract

In this paper, an initial assessment of the quality parameters of the surface finish and dimensional accuracy of tools made by metal casting in rapid prototyping (RP) sand moulds is undertaken. A case study from a local tool room, dealing with the manufacturing of an aluminium die for the lost wax process, is employed. Modern techniques, including surface roughness analysis and three dimensional scanning, are used to determine and understand how each manufacturing step influences the final quality of the cast tool. The best surface finish obtained for the cast die had arithmetic average roughness (Ra) and mean average roughness (Rz) respectively equal to 3.23m and 11.38m. In terms of dimensional accuracy, 82% of cast-die points coincided with the Computer Aided Design (CAD) data, which is within the typical tolerances of sand cast products. The investigation shows that mould coating contributes slightly to the improvement of the cast tool surface finish. The study also found that the additive manufacturing of the sand mould was the chief factor responsible for the loss of dimensional accuracy. These findings indicate that machining will always be required to improve the surface finish and the dimensional accuracy of cast tools in RP sand moulds.

Published
2012
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7. A REVIEW OF ADDITIVE MANUFACTURING OF α- β TI ALLOY COMPONENTS THROUGH SELECTIVE LASER MELTING AND LASER METAL DEPOSITION

Author

chandramohan palanisamy, Bhero, S., Manikandasubramanian, K., and Ravishankar, B.

Subjects
Additive manufacturing, lcsh:TA1-2040, lcsh:Technology (General), Laser, Titanium alloys, lcsh:T1-995, lcsh:Engineering (General). Civil engineering (General), LMD, SLM
Abstract

Additive Manufacturing (AM) is a rapid prototyping technique extensively used to build complex structures and intricate shapes without the necessity of post process machining. This process exists for two decades and still needs to attain its growth in order to meet the commercial requirements. In this article, Laser Metal Deposition (LMD) and Selective Laser Melting (SLM) of α-β titanium alloys and CP-Ti are reviewed. The reported investigations are categorized into 2 major classifications, namely:(i) Micro and macro structure and resulting mechanical properties of α-β Ti and CP-Ti, (ii) Effect of process parameters. Scholarly publications on SLM and LMD of α-β Ti alloys and CP-Ti are surveyed. The limitations of this emerging but promising method of manufacture are discussed.

Published
2018

8. Tool manufacturing by metal casting in sand moulds produced by additive manufacturing processes

Author

Nyembwe, Kasongo Didier, Van der Walt, J.G., Bhero, S., Central University of Technology, Free State. Faculty of Engineering and Information Technology, School of Mechanical Engineering and Applied Mathematics, De Beer, D.J., Nyembwe, Kasongo Didier, Van der Walt, J.G., Bhero, S., Central University of Technology, Free State. Faculty of Engineering and Information Technology, School of Mechanical Engineering and Applied Mathematics, and De Beer, D.J.

Abstract

Thesis (D. Tech. ( Mechanical Engineering )) - Central University of technology, Free State, 2012, In this study an alternative indirect Rapid Tooling process is proposed. It essentially consists of producing sand moulds by Additive Manufacturing (AM) processes followed by casting of tools in the moulds. Various features of this tool making method have been investigated. A process chain for the proposed tool manufacturing method was conceptually developed. This process chain referred to as Rapid Casting for Tooling (RCT) is made up of five steps including Computer Aided Design (CAD) modeling, casting simulation, AM of moulds, metal casting and finishing operations. A validation stage is also provided to determine the suitability of the tool geometry and material for RCT. The theoretical assessment of the RCT process chain indicated that it has potential benefits such as short manufacturing time, low manufacturing cost and good quality of tools in terms of surface finish and dimensional accuracy. Focusing on the step of AM of the sand moulds, the selection of available AM processes between the Laser Sintering (LS) using an EOSINT S 700 machine and Three Dimensional Printing using a Z-Corporation Spectrum 550 printer was addressed by means of the Analytic Hierarchy Process (AHP). The criteria considered at this stage were manufacturing time, manufacturing cost, surface finish and dimensional accuracy. LS was found to be the most suitable for RCT compared to Three Dimensional Printing. The overall preferences for these two alternatives were respectively calculated at 73% and 27%. LS was then used as the default AM process of sand moulds in the present research work. A practical implementation of RCT to the manufacturing of foundry tooling used a case study provided by a local foundry. It consisted of the production of a sand casting pattern in cast iron for a high pressure moulding machine. The investigation confirmed the feasibility of RCT for producing foundry tools. In addition it demonstrated the crucial role of casting simulation in the prevention of casting de

Published
2014

9. Tool manufacturing by metal casting in sand moulds produced by additive manufacturing processes

Author

De Beer, D.J., Van der Walt, J.G., Bhero, S., Central University of Technology, Free State. Faculty of Engineering and Information Technology, School of Mechanical Engineering and Applied Mathematics, De Beer, D.J., Van der Walt, J.G., Bhero, S., and Central University of Technology, Free State. Faculty of Engineering and Information Technology, School of Mechanical Engineering and Applied Mathematics

Abstract

In this study an alternative indirect Rapid Tooling process is proposed. It essentially consists of producing sand moulds by Additive Manufacturing (AM) processes followed by casting of tools in the moulds. Various features of this tool making method have been investigated. A process chain for the proposed tool manufacturing method was conceptually developed. This process chain referred to as Rapid Casting for Tooling (RCT) is made up of five steps including Computer Aided Design (CAD) modeling, casting simulation, AM of moulds, metal casting and finishing operations. A validation stage is also provided to determine the suitability of the tool geometry and material for RCT. The theoretical assessment of the RCT process chain indicated that it has potential benefits such as short manufacturing time, low manufacturing cost and good quality of tools in terms of surface finish and dimensional accuracy. Focusing on the step of AM of the sand moulds, the selection of available AM processes between the Laser Sintering (LS) using an EOSINT S 700 machine and Three Dimensional Printing using a Z-Corporation Spectrum 550 printer was addressed by means of the Analytic Hierarchy Process (AHP). The criteria considered at this stage were manufacturing time, manufacturing cost, surface finish and dimensional accuracy. LS was found to be the most suitable for RCT compared to Three Dimensional Printing. The overall preferences for these two alternatives were respectively calculated at 73% and 27%. LS was then used as the default AM process of sand moulds in the present research work. A practical implementation of RCT to the manufacturing of foundry tooling used a case study provided by a local foundry. It consisted of the production of a sand casting pattern in cast iron for a high pressure moulding machine. The investigation confirmed the feasibility of RCT for producing foundry tools. In addition it demonstrated the crucial role of casting simulation in the prevention of casting de

Published
2012

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