search query: @keyword Stereolitografia / total: 11
reference: 2 / 11
| Author: | Lahtinen, Sampo |
| Title: | 3D-Printed molds for micro-injection molding |
| 3D-tulostetut muotit mikro-ruiskuvalamista varten | |
| Publication type: | Master's thesis |
| Publication year: | 2015 |
| Pages: | ix + 112 s. + liitt. 41 Language: eng |
| Department/School: | Materiaalitekniikan laitos |
| Main subject: | Soveltava materiaalitiede (MT3001) |
| Supervisor: | Seppälä, Jukka |
| Instructor: | Korhonen, Harri |
| Electronic version URL: | http://urn.fi/URN:NBN:fi:aalto-201503062005 |
| Location: | P1 Ark Aalto 2695 | Archive |
| Keywords: | stereolithography 3D-printing trachea prosthesis micro-injection molding injection mold stereolitografia 3D-tulostaminen henkitorvi proteesi mikro-ruiskuvalu ruiskuvalumuotti |
| Abstract (eng): | Stereolithography (SLA) 3D-printed micro-injection molds could decrease the price and lead times when compared to traditional steel molds. In addition, an increase in design freedom could be achieved. This thesis aims to study the feasibility of SLA 3D printed injection molds in general as well as in manufacturing of patient specific trachea prostheses. Perfactory SXGA+ Mini Multi Lens SLA was utilized. Resin used was Envisiontec's HTM140V2 high temperature molding resin. Molds created were tensile test specimen, three different tubes, and one 1:1 scale trachea mold. Tensile specimens were molded from USP Class VI (United States Pharmacopeia) and ISO 10993-5 approved biocompatible thermoplastic polyurethanes of different hardness (Shore 5A-75A) and polypropylene (PP). Tensile specimen molded with SLA molds were compared to ones molded with steel mold. General quality of parts was observed by eye and with light microscope. More accurate surface quality studies were done with scanning electron microscope (SEM). Thermal properties were compared using differential scanning calorimetry (DSC) and mechanical properties with tensile tests. As a result, no significant differences in mechanical or thermal properties were observed. Parts produced with SLA molsd were not more birttle and no increased crystallinity was observed when compared to parts molded with steel molds. It was concluded that due to small size of the micro-injected parts, that itself enables fast cooling, the lower heat conductivity of SLA molds compared to steel molds does not cause alterations on the properties of molded parts. SLA molds lasted for 15 injection cycles on average, 50 cycles being the maximum. Failure occurred in brittle manner. Most significant contributor to the breaking was warping of the molds during printing and post-curing. Another significant contributor to the breaking was relatively high mold closing pressure of 130 bar. Trachea tube prototypes were molded using TPU5A and TPU15A. Designs with different wall thicknesses of 2 mm and 1 mm were tested. In addition a mold with denser "cartilage" rings spacing and a mold with realistic trachea dimensions were produced. The quality of produced tubes was good. The shape of the tube was clearly transferred from mold to the part. Tube prototype molds lasted for 4 cycles. Breaking occurred in brittle manner, likely initiated by high mold closing pressure. Realistic trachea mold lasted only for one cycle. Nonetheless the poor cycle performance of the realistic trachea mold, it yielded a good quality trachea prosthesis with realistic dimensions from Shore 5A TPU. |
| ED: | 2015-03-08 |
INSSI record number: 50689
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