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Rolle-zu-Rolle-Fertigung von Mikrostrukturen durch Ultraschallheißprägen

By Bastian Memering

Abstract

With ultrasonic hot embossing microstructures can be embossed from a metal tool into semi-finished plastic products such as films, sheets or filaments. Because usually no vacuum or long heating and cooling processes are necessary, short cycle times of a few seconds can be realized. Significantly more time must be spent on the manually alignment and fixing of the semi-finished products, as well as the demoulding of the embossed structures by hand. These manual steps have now been replaced by an automated roll-to-roll production process. Both films and filaments with ultrasonic hot embossed microstructures can be produced from roll-to-roll. Up to six films are handled automatically from feed rollers, led to the fixing unit, are ultrasonic hot embossed, demolded and rewound onto another roll. Various microfluidic structures such as channels, heat exchangers or mixers were embossed. Since the embossing result is dependent on the temperature, the temperature curve and its influence on the ultrasonic hot embossing process especially at the short cycle times of the automated production were determined. The temperature of the embossing tool was monitored during the entire process. Because of the faster temperature rise very short cycle times could not be reached for larger structures without affecting the embossing result. Minimum cycle times of 3 - 6 seconds for the tested structures were reached. Plastic filaments can also be micro structured with the automated system. The raw filament, 400 micron in thickness, is unwound from a supply roll, embossed and then wound again onto another roll. The embossed microstructures function as predetermined breaking points. Displaying different load levels the filaments can be used as overload sensors in synthetic fiber ropes. Because in this case the process of ultrasonic hot embossing takes less than one second, the cycle time is mainly affected by the distance between the predetermined breaking points. With a distance of 300 mm between the predetermined breaking points, the manufacturing time for one kilometer sensor is about four hours. In addition to the development of the sensors with predetermined breaking points, the produced sensors were integrated and tested in different synthetic fiber ropes

Topics: info:eu-repo/classification/ddc/620, Ultraschall, Mikrostruktur, Kunststofffolie, Chemiefaser, Ingenieurwissenschaften, roll-to-roll, ultrasonic hot embossing, automation
Year: 2014
OAI identifier: oai:publications.rwth-aachen.de:444793
Provided by: RWTH Publications
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