Developing a time-, cost- and energy efficient process chain for hollow bicycle parts
To achieve highest performance, components for bicycles are usually manufactured using thermoset prepreg systems. The high achievable fiber volume content and high impregnation quality enable a maximum of mechanical performance. In the state of the art process, an autoclave is used for the curing step, despite the high amount of energy needed for heating, cooling and air compression as well as the long cycle times. The research project “ProLight” conducted by Institut für Verbundwerkstoffe GmbH and all ahead composites GmbH was dedicated to develop a time-, cost- and energy efficient process chain for hollow bicycle parts. Thus, products can be manufactured within short cycle times and enable professionals and ambitioned hobby cyclists to use the highest performance available.
A bicycle fork has been optimized using Finite Element Analysis (FEA) to determine the best layup for high performance at low weight. Based on this part design, a tool with integrated vacuum application for a hose blowing pressing process using a simple hot press has been developed. Simultaneously, a large variety of prepreg systems has been analyzed to determine curing behavior and to choose the best material for the intended process. The achieved part qualities are in no way inferior to those achieved by an autoclave process, whereas the cycle time could be reduced from several hours to only a few minutes.
When considering the energy efficiency, heat transfer using conduction in a hot press is very advantageous compared to convection heating in an autoclave and enables to save more than half of the energy used. Furthermore, heat recovery strategies have been developed in this project to further reduce the energy used for alternating heating and cooling phases.
Currently, the involved companies are considering further possibilities to reduce cycle times. When analyzing the curing cycle of the used prepreg systems, the time to increase the degree of cure from 90% to 99.5% usually takes more than half of the entire cycle time. A holistic study of the effects of fast prepreg pressing on laminate quality and part performance shall enable the exploitation of this potential for savings. All in all, this will enable all ahead composites GmbH to keep on profitably producing high performance bicycle components “Made in Germany”.
The project "Development of an online binder application and placement method for the automated manufacturing of load-optimized preforms" was funded by the Federal Ministry for Economic Affairs and Energy (BMWi) within the ZIM program, (funding reference: KF2088339RE4).
Dipl.-Ing. Oliver Rimmel,
Institut für Verbundwerkstoffe GmbH (IVW), Kaiserslautern
phone +49 (0) 631 / 316 07-33,
Dipl.-Ing. (FH) Christian Gemperlein,
CEO all ahead composites GmbH, Veitshöchheim,
phone +49 (0) 931 / 991 27-007,