
Melt flow index tester is the most popular and accurate way to determine the viscosity of plastic material. During the test procedure, 10 grams of plastic granules pass through a standardized hot capillary and are pressured by a standard weight in a period of 10 minutes. The value of Melt Flow Rate hence obtained as per the ASTM D 1238 standard is the value that helps to know the plastic viscosity. The testing instrument calculates the material at defined temperature and shear stress.
Practically, a high melt flow index indicates a lower viscosity. This also means that a material with an MFI rate of 20 will flow easily as compared to that of plastic that has an MFI of 5. The Melt flow index rate for different types of plastic granules is different and these values are used to make a rough comparison between the characteristics of different materials.
Many manufacturers use this data to quality of the raw materials and to help make required changes in the process of manufacturing. For example, if a material from Lot A you are processing has an MFI of 10, and the new Lot B has an MFI of 15. The manufacturers can think about the changes that should be done and make the appropriate adjustment to balance the production from both the lots.
Melt Flow Rate of a thermoplastic is a simple calculation of the rate of flow of the melted polymer. It can be evaluated with the help of a testing machine known as Melt Flow Index tester. The result we get through a MFI test is called the melt volume rate (MVR) or the melt flow rate (MFR).
In general terms, Melt Flow Rate is the amount of mass or volume of a polymer that flows through a small vessel at a predefined pressure and temperature.
Working process of Melt Flow Indexer
The melt flow indexer is a simple test procedure wherein a minimal amount of plastic granules sample is heated inside a barrel at a specified temperature. The melted plastic then flowed out of a capillary die when pressed with the help of a piston and dead weight. Once the melted plastic sample comes out of the die, it is removed and weighed to get the MFI, MVR and MFR calculations.
Applications of Melt Flow Index Tester
Ascertaining Melt Flow Index of plastic is very beneficial because of the following reasons:
- Typical index value can be evaluated for verifying in-house material.
- It is used to conduct quality checks of raw materials.
- Compare the quality of the previous raw material with the new lot.
- Evaluate the quality of all plastic material used during the production process.
- Estimate the flow properties using simple extrusion processes.
- Helps to predict how a polymer will react with different processes and techniques of manufacturing.
The MFI test can be performed using different weights and in different temperatures depending on the need of the application but it should comply with the standards. It is not only used for R&D purposes but also for process control and quality control in laboratories.
To know more information about its features, price, and technical specifications, give us a call or email us at [email protected].
Thanks to Pacorr Testing instruments, we have all the required quality testing instruments that have helped us to ensure the best quality delivered to our clients.

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