Melt flow index testers, or extrusion plastometers, characterize the flow properties of a plastic melted mass. A method that is particularly useful in quality control and goods inwards testing, melt flow tests begin by heating the previously weighed out material within the extrusion barrel, which converts the material into granules.
A piston, along with a piston transducer, is placed into the extrusion barrel, and the test begins when the test weight puts pressure to the piston, forcing movement of the granules out of the instrument. The melt mass-flow rate (MVR) can then by achieved by measuring the distance that the piston travels per unit of time.
Equipment