Understanding Melt Flow Index (MFI)

The Melt Flow Index (MFI), also known as Melt Flow Rate (MFR), measures the flowability of a polymer when heated to a specific temperature under a defined pressure. During the test, a polymer sample is melted and forced through a small die using a set weight or pressure. The amount of polymer that flows through the die within a specific time (typically 10 minutes) is measured in grams per 10 minutes (g/10min). The Melt Flow Index Testing Machine value indicates the material's viscosity: a higher MFI suggests lower viscosity and easier flow, while a lower MFI indicates a thicker, more resistant material.