Composite production rates will need to increase markedly to meet future demand, especially in the case of mainstream automotive. Coupled with that is need to keep quality levels high and costs down. Scrap represents a large portion of this cost and should be minimised.
Due to the complexities of composite manufacture there are numerous sources of variation. These variations mean that a composite part cannot be considered to be “flawless”. Instead acceptable levels of variation are established. These requirements govern whether or not a part is scrapped based on a set of measurements. These measurements are carried out assuming that there are no flaws arising from the design of the part.
This paper details the attempt to manufacture a flat panel followed by some more complex features in order to determine if the acceptance criteria can be rigidly adhered to. Using a process map developed from previous work the phases of manufacture are detailed and their potential sources of variability.
The results are that even a flat panel cannot be made due to highly stringent ply position requirements stated in the acceptance criteria. Increasing the complexity of the geometry resulted in fibre orientation measurements which could not guarantee that the whole part was within tolerance for fibre angle.
It was discovered that there is no in-process definition of thickness, bridging or wrinkling. This means that these features will only be captured in a final dimensional inspection after curing. At this stage the part has attained its maximum embedded cost.