A Melt Flow Index machine is used to measure the flow characteristics of molten plastics, which is crucial for understanding their processing behavior. The device measures the mass of polymer extruded through a standard die under a specific load and temperature. The MFI value indicates the ease with which a polymer flows when heated, providing essential information about the polymer's viscosity and molecular weight. This test helps manufacturers evaluate the quality and consistency of the polymer, assisting in selecting the appropriate material for various industrial applications like molding and extrusion.