The drying behaviour of cemented carbide paste extrudates was investigated in an industrial drying oven at temperatures in the range 40 to 100C. In addition to the expected evaporation of the volatile alcohol component of the paste binder, extra mass loss was recorded at the higher temperatures. This was attributed to the removal of wax present in the paste particulates. The rate of drying was investigated by removing parts periodically, weighing them and returning them to the oven. Discs, cylindrical rods and tubes with different aspect ratios were tested in order to identify a general drying model. End effects were confirmed to be important for short parts, such as rods with aspect ratio < 10. Whilst a shrinking core model could be fitted to the disc drying data very well, it failed to describe the results for rods. A pseudo-Fickian model was found to describe all three geometries reasonably well. The effective diffusion coefficients obtained by fitting the model to the data were similar in magnitude but exhibited systematic variation with rod diameter, which were attributed to differences in strain-induced microstructure during extrusion.
