GMT-PROCESSING CONTROL BY ONLINE MONITORING MACHINE PARAMETERS

Compression moulding of Glass Mat Reinforced Thermoplastics (GMT) is n owadays generally performed on advanced, servohydraulic presses with a ctive ram-parallelism control. The internal control data of the press system reflect the responses to various flow phenomena in the mould. T his paper gives an overview of how these data can be used for on-line controlling of parts production. The standard variation of the work do ne by each ram parallel-control cylinder is introduced as a suitable p arameter to describe charge placement variability. Tests with real par ts were performed to determine the practical value of a combination of three control parameters: the work done on the material, the standard deviation of the work done by the four ram parallel-control cylinders and the ram position during the cooling phase. The results show that this combination enables us to identify unequivocally the causes of pr ocess variations.