Automatic Melt Flow Index Tester

What is the Automatic Melt Flow Index Tester?

An automatic melt flow index tester performs piston displacement measurement, timed cutting and weight handling under program control, so results no longer depend on operator timing. It is the right choice for laboratories running regular QC series on several polymer grades each shift.

Overview

Automatic testers combine a motorised weight-lifting mechanism, a position encoder on the piston and a programmable cutter with a temperature controller and data logging. The operator selects a stored method, the instrument preheats for the programmed time, then either cuts and drops segments onto a balance-linked tray or records displacement to calculate melt volume-flow rate, converting it to mass flow using stored melt density. Because the weight is raised and lowered mechanically, the risk of operator injury and of changing loads mid-test is reduced. Software normally holds methods for each standard condition, exports results to a laboratory system and records the raw displacement curve, which supports traceability for accredited QC laboratories and for resin suppliers issuing certificates of analysis.

How does it work?

A melt flow tester consists of a heated vertical barrel with a defined bore, a hardened steel die at the bottom, a piston and a set of certified weights. Polymer granules are loaded, compacted and held at the test temperature, then extruded through the die under a specified load. In method A, timed portions of extrudate are cut and weighed, and the result is expressed in grams per ten minutes. In method B, an encoder records piston displacement against time and the melt volume-flow rate is calculated in cubic centimetres per ten minutes, which can be converted to mass flow using the melt density. Temperature, load, die geometry and thermal equilibration time are all fixed by the method, because melt viscosity depends steeply on temperature and shear rate.

What are the key features?

• Automatic weight lifting and lowering
• Piston displacement encoder with 0.01 mm resolution
• Programmable cut intervals from 10 s to 999 s
• Stored methods for common ISO and ASTM conditions
• Result export in CSV and to laboratory information systems
• Balance interface for automatic mass-flow calculation

What are the technical specifications?

A typical automatic melt flow index tester configuration offers temperature range of 50–400 °C, temperature accuracy of ±0.2 °C, piston displacement resolution of 0.01 mm, MVR measuring range of 0.1–1500 cm³/10 min, automatic cut interval of 10–999 s, programmable and load weights of 1.2 / 2.16 / 3.8 / 5 / 10 / 21.6 kg. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Automatic Melt Flow Index Tester is used in multi-grade resin QC series in one shift, supplier certificates of analysis verification, compounding and masterbatch process control and recycled polymer batch qualification. Across the wider Melt Flow Testers class, laboratories also deploy it for polyolefin resin production and grade certification, incoming inspection of polyethylene and polypropylene and recycled plastics quality screening.

Which standards and certifications apply?

Relevant standards and methods include ISO 1133-1, ISO 1133-2, ASTM D1238, GB/T 3682.1, GB/T 3682.2 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Install the tester on a level, vibration-free bench away from draughts, and allow the barrel to reach thermal equilibrium before the first test, which usually takes 15 to 30 minutes. Clean the barrel and die after every test or every material change, using purging compound for degraded polymer; never scrape the barrel bore with hardened tools. Verify temperature with an external thermometer in the bore at defined intervals, check die dimensions against the method tolerance, and keep weights traceable. Dry hygroscopic polymers before testing, discard any extrudate containing bubbles or voids, and repeat the test when a single cut deviates strongly from the others.

How do I select the right Automatic Melt Flow Index Tester?

Choose an automatic tester when throughput, traceability or operator safety matters more than initial cost. Confirm that the method library includes the conditions you use, and that MVR results can be recalculated to MFR with your own melt densities. Ask whether the cutter accepts both manual and automatic operation, because some laboratories need a manual fallback, and check how the software handles a repeated test on the same material.

How does it compare with other Melt Flow Testers variants?

Start from the standard your customer or specification cites, because ISO 1133 and ASTM D1238 fix different loads and procedures. Method A is sufficient for routine resin grading, while method B is preferable when the laboratory needs a fast result or the material is difficult to cut cleanly. Choose a high-temperature barrel when the scope includes engineering polymers such as polyamide, polysulfone or polyether ether ketone, and a corrosion-resistant barrel for PVC and fluoropolymers. Automatic units pay back where more than about ten tests per day are run, and multi-station units suit polyolefin plants that compare several production lines in one shift. Specify the load set, temperature range, data export format and cleaning accessories.