Direct Metal Laser Sintering (DMLS) is a rapid prototyping technique that allows for direct and rapid manufacturing of complex components. DMLS is however an intricate process and the quality of the final product is influenced by multiple manufacturing parameters (or DMLS settings) and powder characteristics. The effect which each of these manufacturing parameters and powder characteristics has on the final parts is not well understood and the success of process manufacturing mainly relies on empirical knowledge. Consequently high dimensional deformation and relatively poor mechanical properties are still experienced in many DMLS products, in particular in copper-based laser sintered parts. A need therefore exists to systematically examine the effect of process parameters on the quality of final parts in order to determine the most appropriate manufacturing parameters for specific applications of copper-based laser sintered parts. This document summarises the effect of different process parameters on the quality of Direct Metal 20 laser sintered parts produced with a EOSINT M250 Xtended laser sintering machine from powder consisting of Ni5Cu, Cu15Sn – Cu5Sn and Cu8P – Cu2P material grains. The quality of the sintered parts is defined in terms of the microstructures, porosities and dimensional deformations obtained. The effects of three different geometric sintering strategies currently in standard use namely Solid Skin, Skin Stripes and Skin Chess were examined, and the more appropriate process parameters and scanning technique for the available set-up is presented. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Direct Metal Laser Sintering (DMLS) is a rapid prototyping technique that allows for direct and rapid manufacturing of complex components. DMLS is however an intricate process and the quality of the final product is influenced by multiple manufacturing parameters (or DMLS settings) and powder characteristics. The effect which each of these manufacturing parameters and powder characteristics has on the final parts is not well understood and the success of process manufacturing mainly relies on empirical knowledge. Consequently high dimensional deformation and relatively poor mechanical properties are still experienced in many DMLS products, in particular in copper-based laser sintered parts. A need therefore exists to systematically examine the effect of process parameters on the quality of final parts in order to determine the most appropriate manufacturing parameters for specific applications of copper-based laser sintered parts. This document summarises the effect of different process parameters on the quality of Direct Metal 20 laser sintered parts produced with a EOSINT M250 Xtended laser sintering machine from powder consisting of Ni5Cu, Cu15Sn – Cu5Sn and Cu8P – Cu2P material grains. The quality of the sintered parts is defined in terms of the microstructures, porosities and dimensional deformations obtained. The effects of three different geometric sintering strategies currently in standard use namely Solid Skin, Skin Stripes and Skin Chess were examined, and the more appropriate process parameters and scanning technique for the available set-up is presented. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

<p>U disertaciji su predstavljena istraživanja uticajnih parametara u procesu izrade alata za utiskivanje tehnikom aditivne proizvodnje, tačnije tehnikom deponovanja istopljenog materijala (FDM). Izrađena je kontrolna grupa alata za utiskivanje konvencionalnom tehnikom hemijskog nagrizanja i SLA tehnikom 3D štampe. Cilj istraživanja je definisanje optimalnih procesnih parametara izrade alata za<br />utiskivanje FDM tehnikom štampe. Ustanovljena je metodologija za karakterizaciju proizvodnih parametara koja se može primeniti na ostale tehnike aditivne proizvodnje. Analizom dobijenih rezultata i zaključaka istraživanja ustanovljena su ograničenja i mogućnosti zamene konvencionalnih alata za utiskivanje alatima izrađenim tehnikama 3D štampe.</p> / <p>The study of the influencing parameters in the production process of embossing dies using Fused Deposition Modelling (FDM) additive manufacturing technique, was investigated in this dissertation. Embossing dies, produced using conventional chemical etching and vat photopolymerization technique, were developed as a control group. This research aims to define the optimal process parameters of Fused Deposition Modelling (FDM) in embossing dies manufacturing. A new methodology for the characterisation of production parameters, which can be applied to other additive production techniques, has been established. By analysing the results and the conclusions of this research, the possibility of replacing<br />conventional embossing dies produced using 3D printing techniques has been established as well as its limitations.</p>

Mimicking nature gives rise to many important facets of biomaterials. This study is inspired by nature and reports on the fabrication of an intercalated polymer-NiTi nanocomposite that mimics the structural order of urethral tissue performing micturition. PTFE is chosen due to its hydrophobicity, low surface energy, and thermal and chemical stability. NiTi has been selected as a prime candidate for this research due to its excellent mechanical stability, corrosion resistance, energy absorbance, shape memory and biocompatibility. Nanoscale engineering of intercalated nanocomposites is done by PVD sputtering PTFE and NiTi. FTIR spectroscopy confirms that PTFE reforms as polymer chains after sputtering. Suitable PVD sputtering parameters were selected by investigating their influence on deposition rates, microstructure and properties of PTFE and NiTi thin films. PTFE forms stable nanocomposite coatings with NiTi and displays favourable surface interactions, known as ‘intercalation’. Intercalated PTFE-NiTi films were fabricated as layered and co-sputtered thin films. Co-sputtered nanocomposites contained nearly one-third vacant sites within its internal microstructure because of intercalation while intercalation introduced minute pits in fibrous NiTi columns of layered nanocomposites. These pits allow PTFE to extend their chains and crosslinks, resulting in microstructural and functional changes in the thin films. Intercalated PTFE-NiTi nanocomposites offer a close match to the natural tissue in terms of responding to the fluid contact (wetting angle modifications), and allow the soft and hard matter to incorporate in one framework without any chemical reactions (intercalation). An intercalated microstructure in co-sputtered and layered nanocomposites was verified by EDS-SEM and EDS-TEM techniques. The functional responses were witnessed by changes in water contact angle (WCA) and coefficient of friction (CoF) values measured on the film surface. The WCA (99°) and CoF (0.1 – 0.2) of the intercalated nanocomposite (sample PNT12) were different to the NiTi (top layer). WCA and CoF indicate the internal microstructural interactions because of intercalation. Although the pseudoelastic behaviour of NiTi can provide additional fluid response but the difficulty is an absence of crystallinity in as-deposited NiTi, and the heat treatment that melts PTFE. However, DSC and XRD techniques were employed to find the optimum NiTi composition and transition temperatures for phase transformation related to pseudoelasticity. This study provides the basis to incorporate the shape memory (pseudoelasticity or thermal shape memory effect (shape memory effect)) features of NiTi into the intercalated nanocomposite in future. The intercalated PTFE-NiTi nanocomposite reveals a fascinating research precinct, having the response generating characteristics similar to that of natural tissue.