Manual Melt Flow Index Tester

What is the Manual Melt Flow Index Tester?

A manual melt flow index tester uses operator-placed weights and hand-timed cuts to determine how much polymer extrudes from a heated barrel in ten minutes. It is the standard entry-level instrument for routine polyethylene and polypropylene grading where sample throughput is modest.

Overview

The manual tester keeps the proven mechanical layout of the melt index method: a thermostatically controlled barrel, a hardened die of defined bore and length, a weighted piston and a base with a levelling system. The operator selects the load from the standard, loads and compacts the granules, waits for the preheat time, then cuts extrudate at fixed intervals with a knife and weighs the portions. Temperature is held by a PID controller at the method value, usually 190 °C for polyethylene and 230 °C for polypropylene. Because cutting is manual, reproducibility depends on operator technique, so the unit suits laboratories running a few tests per day and where the difference between operators can be controlled by training and written work instructions.

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?

• PID-controlled barrel with digital temperature display
• Certified load weights from 1.2 kg to 21.6 kg
• Hardened steel die, Ø 2.095 mm, per the standard
• Stainless-steel barrel bore of 9.55 mm
• Manual cutting station with guide and tray
• Levelling feet and spirit level for correct alignment

What are the technical specifications?

A typical manual melt flow index tester configuration offers temperature range of 50–400 °C, temperature accuracy of ±0.2 °C, temperature stability of ±0.1 °C, load weights of 1.2 / 2.16 / 3.8 / 5 / 10 / 21.6 kg, die dimensions of Ø 2.095 ± 0.005 mm × 8.000 ± 0.025 mm and barrel bore of 9.55 mm. 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 Manual Melt Flow Index Tester is used in routine polyethylene and polypropylene grading, incoming inspection at plastics converters, teaching and method training laboratories and low-volume recycled resin screening. 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 Manual Melt Flow Index Tester?

Select the manual tester when fewer than about ten measurements per day are required, when budget is the deciding factor, and when operators can be trained to cut consistently. Specify the load set from the material standards you follow, and confirm the barrel temperature range covers your highest test temperature. Ask for a spare die and a certified thermometer, because both are needed for routine verification.

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.