Theory and Method
Melt Flow Rate Measurement Principle
The melt flow index tester operates on the extrusion plastometer principle defined in ISO 1133 and ASTM D1238. A thermoplastic resin sample is loaded into a heated barrel and brought to a defined test temperature. A piston under a defined load forces the molten polymer through a standard die (Φ2.095 mm × 8.000 mm) at the base of the barrel. The MFR (mass method, Procedure A) is calculated from the mass of the extrudate cut at timed intervals. The MVR (volume method, Procedures A and B) is calculated from the linear displacement of the piston over a defined time interval, using the known barrel cross-sectional area. The QualiFi™ 5000 automates both methods — including weight loading, timing, cutting, and result calculation — minimizing operator involvement and the associated measurement variability.
Dual PID Temperature Control System
The oven uses a specially customized high-temperature-resistant heater and temperature sensor rated for continuous operation from 50 to 450 °C. An intelligent dual PID control algorithm governs the heating output, producing fast, overshoot-free temperature rises with a response speed significantly faster than single-loop PID designs. Multi-stage independent temperature control distributes heat dynamically across the barrel, maintaining a temperature gradient of less than ±0.1 °C with distance along the barrel wall and keeping temperature deviation within ±0.3 °C across the 0–75 mm zone above the die. Temperature recovery after material loading is under 2 minutes — meeting and exceeding the ISO 1133 requirement.
High-Precision Displacement Measurement
Piston displacement is measured by a high-precision displacement module with a display resolution of 0.002 mm and a maximum allowable indication error of ±0.02 mm. Combined with a timer resolution of 0.001 s, this displacement precision enables accurate MVR calculation even at the lower end of the measurement range. The temperature measurement system achieves a resolution of 0.01 °C with a maximum allowable temperature indication error of ≤0.2 °C and fluctuation of ≤±0.2 °C — well within the limits specified by both ISO 1133 and ASTM D1238 for melt flow index tester performance.
Automatic Weight Lifting and Test Automation
The QualiFi™ 5000 uses an electric automatic weight lifting mechanism that loads and unloads test weights without any manual handling by the operator. The software controls all phases of the test sequence — preheating (no-load or loaded mode), weight loading, timed interval measurement, automatic cutting, and result calculation — producing MFR and MVR results with minimal operator intervention. For volume method tests, the software automatically calculates the equivalent MFR value from the input sample mass (spline mass), enabling direct comparison with mass method test results in the same session.
Measurement and Control Software
The menu-guided control software supports mass method (Procedure A), volume method A, and volume method B tests. Eight customizable test plans can be configured and saved for direct pre-test selection, eliminating repetitive parameter entry for routine materials. The software automatically identifies the effective test intervals specified by ISO and ASTM standards and starts the measurement accordingly. Temperature-time and MVR-number curves are displayed in real time, allowing operators to assess temperature stability and result in discreteness visually before accepting a test. The USB flash drive supports 5,000 groups of test result storage, and the included DMS data management software enables data export and formatted report generation. Optional PC software adds two-way control between the touch screen and a connected computer, with the ability to upload results to remote databases and information management systems. Multi-language support covers English, French, German, Italian, Russian, and Chinese.
