The volumetric melt flow rate meter evaluates material flowability by measuring the volume of molten material flowing through a standard mold per unit time. The measurement method includes key steps such as instrument preparation, sample processing, parameter setting, test execution, and result calculation, as follows:
1、 Instrument preparation and calibration
Check the equipment: Ensure that the melt flow rate meter is in good working condition, including the heating system, piston displacement sensor, timer and other core components functioning properly.
Calibration instrument: Calibrate according to the instrument manual to ensure accurate measurement of parameters such as temperature and pressure. For example, using standard weights to verify the accuracy of the load device.
Cleaning the material cylinder and mouth mold: Wipe the inner wall of the material cylinder with clean white gauze to ensure that there is no residue; Use a mouth mold cleaning rod to clean the mouth mold hole and avoid impurities affecting the test results.
2、 Sample preparation and loading
Weighing the sample: Weigh a certain mass of sample (such as polyethylene, polypropylene, etc.) according to the testing requirements to ensure that the sample quality meets the instrument requirements.
Loading samples: Load the samples into the material cylinder through a funnel, compact them with a loading rod, and remove any air bubbles. The entire process should be completed within 1 minute to prevent the sample from melting or degrading prematurely.
Install the piston rod: Insert the piston rod into the port on the barrel, ensuring that the piston rod is in close contact with the inner wall of the barrel without leakage.
3、 Parameter setting and constant temperature
Set test parameters: Set the test temperature (such as 190 ℃, 230 ℃, etc.), sampling time interval (such as 10 seconds, 30 seconds, etc.), sampling frequency (such as 3 times, 5 times, etc.), and loading load (such as 2.16kg, 5kg, etc.) on the instrument operation interface.
Start the heating system: plug in the power plug, turn on the power switch, and the instrument starts to heat up. After the temperature stabilizes to the set value, maintain a constant temperature for at least 15 minutes to ensure that the sample is fully melted and the temperature is uniform.
4、 Test execution and data recording
Start the testing program: After maintaining a constant temperature for 15 minutes, put on gloves and remove the piston rod, and compact the sample again (if necessary). Then place the piston rod back into the barrel, press the "TIME" countdown for 5 minutes, and apply the standard test load to the piston.
Recording piston displacement: During volumetric testing, real-time monitoring of changes in melt volume is required through a piston displacement sensor. When the piston rod descends into contact with the displacement device, the instrument automatically starts recording the distance of piston movement.
Sample cutting (optional): To verify the results of the volumetric method, automatic or manual cutting methods can be set to cut the sample. However, when using the volumetric method for testing, the automatic cutting time is usually set to a longer value (such as 999 seconds/time), so that the cutting device does not cut the material and only records the volume change.
5、 Result calculation and report generation
Calculate the melt volume flow rate (MVR): Based on the piston movement distance (l) recorded by the instrument and the predetermined measurement time (t), use the formula MVR=427 × l/t to calculate the melt volume flow rate. Among them, 427 is the approximate value of the product of the average cross-sectional area of the piston and barrel (0.711cm ²) and the reference time (600 seconds); L is the predetermined measurement distance for piston movement or the average value of each measurement distance (unit: cm); T is the predetermined measurement time or the average value of each measurement time (unit: seconds).
Repeat testing and taking the average: To improve testing accuracy, it is recommended to measure each sample three times in a row, calculate the MVR value separately, and take the average as the final result.
Generate test report: Select the print result function, and the instrument will automatically generate a test report containing information such as test parameters, MVR values, and average values.