Melt Flow Index Tester

Melt Flow Index (MFI) is a measure of how many grams of a polymer flow through the die in ten minutes. The test is performed at a given temperature depending on the plastic. The force used to push the plastic through the system is supplied by a weight which sits on top of a ram. Gravity then takes over and forces the plastic through a die. The test sample is then collected and weighed. The results are then extracted to determine how many grams of plastic came out over a 10 minute period. Therefore the units we use for the test results are “grams/10 minutes”. The test method is described in more detail under ASTM D1238 and ISO 1133.