The description of the material behaviour in the entrance zone in the single-screw-apparatus is of great importance.
At the department of plastics processing Leoben a new friction equipment has been developed. This friction equipment represents a vertical single screw apparatus. In the screw channel, via a radial load cell the radial pressure and via temperature sensors the temperature of the cylinder surface can be measured.
Now there is the possibility to analyse the external and internal coefficient of friction under different test conditions (pressure, temperature, velocity).
This work contains the dependency of the external coefficient of friction on temperature, pressure, and velocity for one LDPE and two PP-compounds. Furthermore the coefficient of pressureanisotropy as well as the powder density were determined for different pressures. The mass flow-rate acknowledges the effect of the coefficient of friction on the conveyance of single-screw-systems.
Furthermore, with this apparatus exists the possibility to test different screw geometry’s (pitch, screw-diameter, channel depth etc..). Easily interchangeable cylinder bushes (axial saw toothed grooves, tapered grooves) enabled the variation on the metal surface. So both grooved cylinders and different steel surfaces can be tested with relation to the frictional behaviour.