No abstract

If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -Fused deposition modeling (FDM) is a layer by layer technology with the potential to create complex and individual parts from thermoplastic materials such as ABS. The use of Polylactic acid (PLA) and tricalcium phosphate (TCP) as resorbable composite is state of the art in tissue engineering and maxillofacial surgery. The purpose of this paper is to evaluate the processing conditions and the performance of parts (e.g. mechanical properties) manufactured with a FDM machine. Design/methodology/approach -In this paper, the general suitability of PLA for the processing with FDM is evaluated and material specific effects (e.g. crystallization and shrinkage) are shown. Therefore, the characterization of the semi-crystalline biodegradable material by thermal, mechanical and microscopic analysis is carried out. Findings -Facts, which affect the functional properties of the samples, are analyzed. Among them, the processing temperature and sample size significantly affect the morphology of the final components. Components from PLA/TCP with sufficient mechanical properties for their potential use as scaffolds are obtained. Originality/value -Thus, the paper shows that by thermal analysis it is possible to identify major influences on processing and part properties.

No abstract

Additive manufacturing technologies, such as selective laser melting of polymers enable manufacturing of complex parts without tools and forms. Due to high temperature during processing, a degradation of the used plastic powder occurs. The unmolded material in the building chamber, the so-called partcake, can be removed from the finished component after building and reused for another process. To realize reproducible part properties refreshing of partcake powder is necessary. This paper presents results on the investigations of degradation behavior of polyamide 12 powder during selective laser melting process. The influence of different ambient conditions, e.g. ambient air, nitrogen and vacuum, is investigated in a model experiment. Oven aged polymer powders were analyzed with regard to their process relevant material properties. Considered material properties are phase transition temperatures, melting viscosity or molecular weight. The results of the investigations show, that the influence of high process temperatures on used material can be reduced using other ambient conditions. Process relevant material properties are minor affected by storage under vacuum. In addition to that the influence of different ambient conditions as well as a material pretreatment on the degradation behavior of sls materials, e.g. exclusion of intermolecular located oxygen, is analyzed. To correlate these results of the model experiment with real manufacturing process laser sintering experiments are done. PA12 powder is used for several building processes with refreshing. Produced specimens and resulting partcake powder are analyzed and correlated to the results of model experiment. Correlating effects, regarding process relevant material properties as well as aging influenced mechanical properties of specimens can be detected.

Additive manufacturing (AM) processes can provide great input for solving recently encountered challenges of the global market such as mass customization, highly dynamic environments, and the decrease of time needed from a draft to final products. This study aims at contributing to the issue of material limitations typically present in AM by researching possibilities of directly using technically relevant and commercially available polymer granules in melt extrusion processes. In order to extend the knowledge on the processing of semicrystalline polymers in melt extrusion based processes, different temperature induced influences on mechanical and morphological properties are investigated for poly(propylene). Mechanical tests are conducted to evaluate the effects and interdependencies of substrate, extrusion, and cooling temperature. Finally, based on the identified mechanical and rheological behavior of the material, a process window for the used materials is suggested.