Customised properties of parts manufactured using the selective laser sintering process are achievable by variation of build parameters. The energy density, controlled by laser power, distance between scan lines and speed of the laser beam across the powder bed, all have a very strong influence on the density and the mechanical behaviour of the parts. The present paper investigates the influence of the energy density on physical and mechanical properties of parts produced using polyamide. Additionally, the effect of part orientation during the build is examined. Knowledge of the influence of these parameters allows one to establish trendlines which link build settings to resulting part properties, and hence to fabricate customised parts with predetermined properties.

In this paper, the use of the Selective Laser Sintering (SLS) process for the generation of bone tissue engineering scaffolds from PCL and PCL/TCP is explored. Different scaffold designs are generated and are assessed from the point of view of manufacturability, porosity and mechanical performance. Large scaffold specimens are generated, with a preferred design, and are assessed through an in vivo study in a critical size bone defect in the sheep tibia with subsequent microscopic, histological and mechanical evaluation. Further explorations are performed to generate scaffolds with increasing TCP contents.Scaffold fabrication from PCL and PCL/TCP mixtures with up to 50 mass-% TCP is shown to be possible. With increasing macroporosity the stiffness of the scaffolds is seen to drop, however, the stiffness can be increased by minor geometrical changes, such as the addition of a cage around the scaffold. In the animal study the selected scaffold for implantation did not perform as well as the TCP control in terms of new bone formation and the resulting mechanical performance of the defect area. A possible cause for this is presented.

Selective laser sintering (SLS) enables the fabrication of complex geometries with the intricate and controllable internal architecture required in the field of tissue engineering. In this study hydroxyapatite and poly--caprolactone, considered suitable for hard tissue engineering purposes, were used in a weight ratio of 30:70. The quality of the fabricated parts is influenced by various process parameters. Among them Four parameters, namely laser fill power, outline laser power, scan spacing and part orientation, were identified as important. These parameters were investigated according to a central composite design and a model of the effects of these parameters on the accuracy and mechanical properties of the fabricated parts was developed. The dimensions of the fabricated parts were strongly dependent on the manufacturing direction and scan spacing. Repeatability analysis shows that the fabricated features can be well reproduced. However, there were deviations from the nominal dimensions, with the features being larger than those designed. The compressive modulus and yield strength of the fabricated microstructures with a designed relative density of 0.33 varied between 0.6 and 2.3 and 0.1 and 0.6 MPa, respectively. The mechanical behavior was strongly dependent on the manufacturing direction.

A current challenge in bone tissue engineering is to create scaffolds with suitable mechanical properties, high porosity, full interconnectivity and suitable pore size. In this paper, polyamide and polycaprolactone scaffolds were fabricated using a solid free form technique known as selective laser sintering. These scaffolds had fully interconnected pores, minimized strut thickness, and a porosity of approximately 55%. Tensile and compression tests as well as finite element analysis were carried out on these scaffolds. It was found that the values predicted for the effective modulus by the FE model were much higher than the actual values obtained from experimental results. One possible explanation for this discrepancy, viz. the surface roughness of the scaffold and the presence of micropores in the scaffold struts, was investigated with a view to making recommendations on improving FE model configurations for accurate effective property predictions.3

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