I have some years ago investigated the material/mold/machine interaction and behaviour when working with highly viscous materials to find a practical solution to optimizing the injection speed in that situation.
Later on I met the practical approach on how to determine the power-law curve for a material to help you pick the best injection speed for a certain material. These two topices are of course almost identical and about applied rheology.
The idea is to measure injection time and pressure at different injection speeds. These data are coverted to values for shear rate and apparent vsicosity. Then by graphical evaluation one picks the injetcion time where the process/material is least sensitive to changes. (I have written an article with more detail in Plast Panorama, but as it is in Danish only a limited audience in SPE could have read it).
I have also tried to add a n'th-power regression line to predict what inejction time is the best, but even though the regression line fit very good I still miss some kind of conclusion covering all cases and not only the specific.

Has anyone else met this methodolgy (I know G&A Moulding use it for training and for optimizations of the process) and do you have any experience especially when it does not "behave properly"?
Carsten Lund