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TPGOA Technical Insights

Melt Flow Index

The melt flow index (MFI), also known as the melt flow rate (MFR), determines the melt flow properties (measured in g/10 min) of a material at a specific shear stress (related to applied load) and temperature. An extrusion plastometer, more commonly referred to as a melt indexer, is used to determine the MFI of virgin, compounded, and post-processed thermoplastics.

The MFI test is used widely among the various segments of the plastics industry. Resin suppliers, for example, look for MFI variations as a QC check to detect and troubleshoot variations in their polymerization and/or compounding processes. As part of their materials’ inspection procedures, some processors use the test to determine the amounts of recycled material that can be used in their product while still maintaining end-product specifications. The difficulty is that any two labs can easily come up with different results, making it difficult to determine whether a material meets a desired MFI spec.

Verify Your Equipment

To ensure good test results, it is important that the testing machine (and auxiliary equipment such as scales and micrometers) be verified using equipment traceable to national metrological standards. The verification procedure will check the dimensions of the machine, as well as the temperature-control and distance-measuring devices installed on the machine, for conformance to the relevant test standard. The frequency of verification is determined by an organization’s quality program.

TPG makes every effort to insure that the information contained herein is accurate - however, we accept no liability for the content of this piece, or for the consequences of any actions taken on the basis of the information provided.
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