pps proceeding - Abstract Preview
pps proceeding
Symposium: S19 - Additive technology
Poster Presentation
 
 

Novel fused filament fabrication procedure and printhead to process thermoplastic elastomers

Gattinger Johannes (1)*, Fischer Stefan (1)

(1) Technical University of Munich, Institute of Medical and Polymer Engineering - Bavaria - Germany

Present FFF-Printers are restricted in the range of printable thermoplastic elastomers (TPE). Commercially available printers are incapable to process TPE with low hardness due to the established extrusion principle. Common soft TPE filaments have a hardness in a range of 80 – 90 Shore A. TPE-Filament with a hardness below that is so far not reliable processible. Current FFF-Printers work with the principle of pushing a thermoplastic filament in the print head where the filament is melted and the polymer melt is deposited in lines for each layer onto the build plate using a fine nozzle. Soft TPE filament cannot be pushed this way from the extruder in the print head because it buckles or bends in the inliner or knots in excess space. This problem is countered by a novel FFF process, filament and print head. In this process, a fiber reinforced TPE filament is used whereby the fiber roving is removed in the print head and just the pure TPE is deposited to build the part. The reinforcement leads to a much stiffer filament, which prevents from buckling or knotting while feeding the print head. Furthermore during the extraction of the roving a pulling force can be applied on the roving and therefore the filament can be pulled in the print head, which prevents the filament from buckling and leads to a pressure on the remaining TPE in the print head to press out the melt through the nozzle. A standard extruder can be used to support the feeding of the print head in addition to the pull in force on the fiber roving. A prototype of such a print head and a fiber reinforced TPE filament (Twaron® 1000, 1680 dtex, Teijin Aramid, Arnhem, NL and THERMOLAST® K TF5THT, 47 Shore A, KRAIBURG TPE GmbH & Co. KG, Waldkraiburg, Germany) was developed and manufactured. First results were promising and showed that such a FFF process is realizable though at this stage some more development on the printer and filament has to be done.