Manufacturing Technical Paper

Other general limitations to the conventional

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Unformatted text preview: powder layer. A liquid is ejected from a printer head onto the thin layer of powder according to the sliced 2D profile on a computer model. The binder droplet wets the surrounding powder particles. The binder drops continue wetting the adjacent powder particles and spread within the powder bed. Reaction between the binder and the powder particles results in local hardening and thus builds up a small piece of the final solid. The fabrication piston moves down by an amount equal to the layer of powder attached. The figure below shows a schematic of the fabrication process. Figure 3: 3 Dimensional Printing Schematic [12] A study was carried out by Hermann Seitz et al to investigate the capabilities of a ceramic- based process chain for the fabrication of porous scaffolds for bone tissue engineering using hydroxyapatite [27]. Figure 4: SEM Scan of cross- section of a sintered material (channel test part) [27] The SEM scan above shows the pore structure of the bulk material. Compared to the conventional method of fabricating scaffolds, this method showed significant improvement in pore size consistency. The pores are in a range between 10 and 30 microns. This demonstrates the particles had a good connection through sintering. In the experiment, the diameter of the structure was 7.8 mm. The dimensions of the channels created ranged between 447 ± 37 microns in the z- direction, 569 ± 33 microns in the x- direction and 530 ± 25 microns in the y- direction. For good osteointegration, a mean pore diameter of 565 microns of inner channels in a scaffold is required [27]. There has been a significant improve...
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This note was uploaded on 01/14/2014 for the course MECH 810 taught by Professor Various during the Fall '13 term at Queens University.

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