Reduction of Production Costs of Thermoplastic CFRP-Parts

Abstract

In recent years, much research has been devoted in understanding and production of carbon fiber reinforced plastic (CFRP) parts. Still, the overall costs of CFRP-parts are high and offer potential for reduction. To be able to compete with metallic parts it is necessary to analyze the complete CFRP-part production process with focus on optimization and reduction of costs. In this work two optimization aspects along the production chain of thermoformed CFRP-parts are being addressed: -Turning a 3-step process into a 2-step process -Reduction of manual interaction At the first issue the effect on the part quality by dropping the consolidation step of the ply-package to an organo sheet is examined. The common production process of thermoplastic CFRP-parts includes the processing of organo sheets. These organo sheets can be produced by vacuum- or press consolidation, which are representing very time, energy and therefore cost intensive steps. For this investigation the unconsolidated ply-package is directly inserted into a clamping frame and subsequently transferred to an infrared (IR) preheating station. In this station the ply-package is thermally activated and after achieving process temperature it is formed to the final geometry by the hot press. Here the influence of variation of different process parameter to the quality of thermoformed parts is evaluated. The investigated process parameter are including the number and position of the welding points at single plies, the dwell time and temperature at the IR-station as well as pressure, duration and temperature during the press step. Afterwards the quality of the parts that has been produced with and without the consolidation step is analyzed and compared against the background of efficiency. With the second issue the enhancement of the level of automation is addressed. On that score the transport of the ply-packages / organo sheets inside a clamping frame along the thermoforming process is investigated. For this purpose a special clamping frame was developed, that is able to strain the organo sheet automatically and keeps it under continuous tension and allows the necessary flexibility during the whole process. With the application of this clamping frame we are able to get rid of the manual spring mounting into the organo sheet, the actual state of the art, which results in shorter cycle times and reduced effort. This paper shows that the production of thermoformed parts can be optimized at several points. By choosing the right process parameters we aim to drop the consolidation step. Furthermore the cycle time can be reduced by use of an automatic clamping frame. These achievements can contribute to a lower total price of thermoplastic CFRP-parts and therefore enhance their position at the competition with metallic parts.