In this work, two types of die designs were presented. The designed dies were produced, mounted on food extruder and used for several experiments in our laboratory. The dies differ in shape, length and diameter. Some of the die design considerations and extrusion process optimization parameters employed include: the throughput of the extruder, desired shape, size and uniformity of the extrudate, the relationship between the flow and pressure drop in the die and the relationship between shear rate and viscosity of the food dough. Specific die design considerations also include: die nozzle dimensions such as diameter and length, and number of die hole, ratio of die length to diameter (L/D ratio) and flow, deformation and temperature relationship. This will be the first time that a systematic design work on dies for food extruder is being carried out and reported. The designed dies in this work will be able to handle food dough mostly cereal flours, the die nozzles are circular, nozzles diameters range from 2.5 – 5 mm and nozzle lengths range from 14 – 90 mm. The dies are designed for twin screw extruder screw diameter of 50 –60 mm, extruder output of 30 – 50 kg/h and 100 – 300 rpm screw speeds. The dies were able to withstand temperature of 250 0C and up to 12 MPa of pressure as frequently experienced in food extrusion processes.

Full text: IJEIR_1185_Final.pdf