Advanced output of silicone molds in vacuum casting processes by polyamide 12 powder supplementation

ABSTRACT

Vacuum casting of polyurethane in silicone molds is a widely used method for prototype replication and holds great potential for application in small batch production. Products produced in this way offer extremely good shape accuracy even in the nanometer range and high surface quality, as well as flexible material properties that are convenient for serial production. In this work, we present a new method for increasing the feasible output of silicone casting molds in vacuum casting processes. By supplementation of polyamide 12 powder, which is a waste product of the selective laser sintering process, to the silicone rubber the maximum output of the casting molds could be increased by up to 38.5% while the amount of new silicone used has been substituted by up to 20%. Both generic silicone samples and representative silicone molds have shown that with increasing polyamide content, aging characteristics decrease as the output increases. The improvement was quantified by comparative weight, hardness and thermogravimetric measurements. As surface energy and roughness measurements as well as extensive casting experiments have shown, the silicone surface and thus the product surface remains unimpaired.

GRAPHICAL ABSTRACT

KEYWORDS:

• Vacuum casting
• silicone
• polyamide
• diffusion
• isocyanate

Declarations of Interest

none

Additional information

Funding

This work was supported by Federal Ministry for Economic Affairs and Energy, grant Number ZF4036101RU5.

Notes on contributors

Martin Wortmann

Martin Wortmann is a Ph.D. student and teaching assistant in the Faculty of Engineering and Mathematic at the Bielefeld University of Applied Sciences. His research focuses on vacuum casting, diffusion processes in polymers, textile technologies and 3D-printing.

Andrej Hoffmann

Andrej Hoffmann graduated from the Bielefeld University of Applied Sciences with a bachelor's degree in Mechanical Engineering with a focus on plastics engineering and is now doing his Masters in Mechanical Engineering at the University of Paderborn.

Natalie Frese

Natalie Frese is a Ph.D. student in the Faculty of Physics at the Bielefeld University. Her research focuses on the development and investigation of carbon based nanomaterials such as carbon nanomembranes, carbon nanofoams and biological cells.

Alexander Heide

Alexander Heide is a research assistant at the Bielefeld University of Applied Sciences where he graduated with a bachelor’s degree in Mechanical Engineering with a focus on plastics engineering. During his work in the plastics analytic laboratory he also graduated with a master’s degree in Mechanical Engineering at the University of Paderborn.

Johannes Brikmann

Johannes Brikmann works as laboratory engineer and teaching assistant at the Bielefeld University of Applied Sciences. His field of research includes vacuum casting, 3D-printing and polymer analytics.

Niklas Brandt

Niklas Brandt graduated from the Paderborn University with a master’s degree in Mechanical Engineering with a focus on plastics engineering and worked part-time in research and development for the CNC Speedform AG. He is now a Ph.D. student at the Bielefeld University of Applied Sciences in the field of Selective Laser Sintering (SLS) processes and polymer analytics.

Michell Menzel

Michell Menzel is a former research assistant in the plastics analytic laboratory at the Bielefeld University of Applied Sciences and now works as laboratory engineer at the Heinze Kunststofftechnik GmbH.

Armin Gölzhäuser

Armin Gölzhäuser is a professor of experimental physics at the Bielefeld University and founder of the Bielefeld Institute for Biophysics and Nanoscience (BINAS) and the CNM Technologies GmbH, a start-up company dealing with applications of carbon nanomembranes. His research is focused on the fabrication, characterization and application of low dimensional nanostructures and functional materials.

Elmar Moritzer

Elmar Moritzer is professor of plastics engineering at the Paderborn University and chairman of the Fakultätentag für Maschinenbau und Verfahrenstechnik e.V. (FTMV) which represents the interests of university engineering education in mechanical engineering and in process engineering on a political level in Germany and Austria. His research focuses on the development, analytics and simulation of manufacturing processes in the field of plastics and rubber processing.

Bruno Hüsgen

Bruno Hüsgen is professor of plastics engineering at the Bielefeld University of Applied Sciences and deputy director of the Bielefelder Institut für Angewandte Materialforschung (BifAM). His research is focused on the development, analytics and simulation of polymer materials for plastic manufacturing processes. A special emphasis is on vacuum casting, 3D-printing and polymeric coatings.