Vacuum moulding is used to make single and/or large composite parts with a one-sided tool and a vacuum bag to form the component. This process is similar to vacuum bagging for thermoset composites. Silicone reusable membranes can be used for some matrix materials.
Key Processing Points:
Position COMFIL® on an open-faced mould.
Place a vacuum bag over the COMFIL® and seal the material to the mould.
Remove the air from the bag, sandwiching the COMFIL® between the bag and the mould.
Heat mould to achieve material temperature of app. 25-50 degree C over the melting temperature of the matrix material.
Cool the part to below 50-100 degree C.
Similar to vacuum bagging for epoxy prepregs.
VACUUM CONSOLIDATION OF HYBRID YARN FABRICS WITH LPET MATRIX
Vacuum consolidation of thermoplastic composites is suitable for production of small to very large components in smaller series. In principal, the process consists of four steps: 1) Lay-up the hybrid yarn fabric into the mould, 2) vacuum bag and evacuate the material, 3) heat the material and the mould to the process temperature under vacuum, and 4) cool it all back to room temperature. The process temperature can either be obtained by built-in heating elements in the mould or by heating the entire mould in an oven, and therefore, there are practically no limits on the size of the components which can be produced.
The vacuum consolidation process has been developed and optimised for the hybrid yarn material, and the process window for glass fibre/modified PET (LPET) hybrid yarn fabric has been examined by varying the process temperature, the time at temperature, and the vacuum level. It is possible to obtain an acceptable laminate quality by using a process temperatures as low as 210 °C. However, the lower the temperature the longer time at temperature is required. The time at temperature can be as low as 12 minutes, if high temperature and full vacuum are used. Furthermore, a vacuum level of only 65% of full vacuum is sufficient if high temperature and long time at temperature are utilised. It is concluded that the vacuum consolidation technique is a very robust process with a large process window, and therefore, very suitable and attractive for industrial use; even in a crude workshop environment.