Semi Automatic Melt Flow Indexer (MFI)

Theory and Method

Melt Flow Rate Measurement Principle

The QualiFi™ 6000SA 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 the defined test temperature. A piston under a defined load forces the molten polymer through a standard die (Φ2.095 mm) at the base of the barrel. MFR (mass method, Procedure A) is calculated from the mass of extrudate cut at timed intervals; MVR (volume method, Procedures A and B) is calculated from piston displacement over a defined time interval. The QualiFi™ 6000SA automates weight lifting, timing, cutting, and result calculation — and additionally automates compaction, residual extrusion, and barrel cleaning through its pneumatic systems reducing the total number of manual steps per test cycle compared to the QualiFi™ 5000.

Pneumatic Compaction System

Material compaction (the process of pressing the loaded polymer charge down into the barrel before the test begins) is performed pneumatically on the QualiFi™ 6000SA with adjustable compaction time and compaction load from 10 to 50 kg. On conventional melt flow index testers, compaction is applied manually with a feeding rod, introducing operator-to-operator variability in applied force and compaction duration. The pneumatic approach delivers a defined, repeatable compaction force on every test cycle regardless of operator technique, directly improving the run-to-run repeatability of MFR/MVR results particularly for high-viscosity materials and powders that are sensitive to void content and density variation in the pre-test charge.

Pneumatic Residual Extrusion and Barrel Cleaning

After each test, residual polymer remaining in the barrel must be removed before the next sample is loaded. The QualiFi™ 6000SA performs this in two pneumatic steps. First, residual material extrusion uses an adjustable pneumatic load (10–50 kg) to push remaining polymer out of the barrel and die rapidly replacing the manual push-rod operation required on standard melt flow index testers. Second, pneumatic barrel cleaning uses compressed air to clear remaining residue from the barrel interior. Together these two operations reduce post-test cleaning time substantially and minimize the physical effort and contact with high-temperature components that the manual cleaning process requires, contributing to the safety-enhanced positioning of the 6000SA.

Weight Fall-Prevention Guard

The weight stack on a floor-standing melt flow indexer operates at a height that makes uncontrolled weight descent a realistic operator safety concern particularly during test setup, weight changes, or if a mechanical failure occurs during loading. The QualiFi™ 6000SA adds a dedicated weight fall-prevention guard that physically constrains the weight stack and prevents uncontrolled descent events. This is a hardware-level safety feature not present on the QualiFi™ 5000, and its inclusion reflects the taller, floor-standing form factor of the QualiFi™ 6000SA where the weight stack operates at greater height above the work surface.

Dual PID Temperature Control and High-Precision Displacement

Temperature control, displacement measurement, and software operation are identical to the QualiFi™ 5000 platform. A specially customized high-temperature heater and sensor rated for continuous operation from 50 to 450 °C are governed by an intelligent dual PID algorithm — delivering fast, overshoot-free temperature rise, multi-stage balanced heat distribution with distance gradient less than ±0.1 °C, and post-loading temperature recovery within 2 minutes. Piston displacement is measured at 0.002 mm resolution with a maximum indication error of ±0.02 mm, and the timer resolution is 0.001 s — enabling accurate MVR calculation across the full 0.01–3000 cm³/10min measurement range.