Online product quality monitoring through in-process measurement

Abstract Online monitoring of product quality is key to automated machine operation and process optimization. This paper demonstrates an in-process sensing technique for online product quality assessment, using injection moulding as an example. The system measures four parameters within the injection mould cavity, which are directly correlated with the part quality: melt pressure, temperature, velocity, and viscosity. Relationship between the sensor data and quality characteristics, e.g., thickness and width of the part, are established by incorporating governing physics for pressure–volume–temperature with other mechanistic models. Good agreement between sensor measurements and experimental results is confirmed from tests performed on a production-grade machine.