ISO 1133-1 is an international standard test method for determining melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastic materials under defined temperature and load conditions.
It is widely used for incoming inspection, production QC, and material certification checks where melt flow is used as a practical indicator of processability and lot-to-lot consistency. If you need help matching your material’s required temperature/load condition to the right procedure and instrument configuration, talk with our team.
ISO 1133-1:2022 — Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics — Part 1: Standard method
ISO 1133-1:2022 (Edition 2, published June 2022) defines standard procedures for measuring melt flow of thermoplastics using an extrusion plastometer (commonly called a melt flow indexer / melt flow tester).
The standard is commonly invoked by individual material specifications, which typically state the exact temperature and applied load condition to be used when reporting MFR or MVR for a resin grade.
Quick Definition
ISO 1133-1 in one line: A standard method to measure how much molten thermoplastic flows through a standardized die under a specified temperature and load, reported as MFR and/or MVR.
What it produces: Melt mass-flow rate (typically reported as g/10 min) and melt volume-flow rate (typically reported as cm³/10 min), reported with the specific test condition used (temperature and load).
What This Standard Covers
ISO 1133-1 specifies two procedures for melt flow determination under defined temperature and load conditions.
Procedure A: A mass-based approach where extrudate is collected over timed intervals and weighed to determine MFR.
Procedure B: A displacement-based approach where the piston movement is used to determine MVR.
The standard also notes that the test conditions are normally specified in the relevant material standard, and it identifies that a separate part (ISO 1133-2) is used when materials are significantly affected by time-temperature history and/or moisture during measurement.
Why This Standard Matters in Testing
MFR/MVR testing is a fast, repeatable QC tool used to monitor material consistency, screen for degradation or contamination, and confirm that resin lots meet a stated melt flow requirement before processing.
It is also important for supplier-buyer alignment because many datasheets and purchasing specs reference melt flow at a specific condition. Matching the cited condition and procedure is essential for meaningful comparisons.
Common Materials, Product Types, or Applications Covered
ISO 1133-1 is used for thermoplastic materials that can be evaluated by melt flow under the specified test conditions.
Common material forms: Pellets/granules, powders, and similar feedstock forms intended for melting in a heated barrel.
Typical use contexts: Resin receiving inspection, compounding checks (including filled vs. unfilled comparisons where MVR can be particularly useful), and routine production monitoring where melt flow is a release criterion.
Common Test or Verification Workflow
Most labs run ISO 1133-1 as a condition-driven verification test tied to a material specification.
Typical workflow: Select the required temperature and load from the applicable material specification or customer requirement, prepare the instrument at temperature, charge the barrel, apply the specified load, and run either Procedure A (mass collection) or Procedure B (displacement measurement) to obtain MFR and/or MVR.
Reporting focus: The reported result is only meaningful when paired with the exact test condition (temperature and load) and the procedure used. Converting between MFR and MVR can require melt density at the test temperature.
Equipment Commonly Used for This Standard
ISO 1133-1 is typically performed on a melt flow index tester (extrusion plastometer) configured to control temperature, apply a defined load, and measure either extrudate mass (Procedure A) or piston displacement (Procedure B).
Common equipment elements: Heated barrel and die, piston and weight set (or equivalent loading system), temperature control and verification tools, a cutting/collection setup for extrudate, a balance for Procedure A, and displacement measurement hardware/software for Procedure B.
Quoting tip: The deciding factors are usually the required temperature range and stability, the load set needed for your cited condition, whether you need A, B, or both procedures, and how you want to capture and report data (manual vs. automated). If you are equipping a QC lab or upgrading for automation, you can request pricing for a melt flow tester package matched to your required conditions and throughput.
How to Read This Designation or Revision
ISO 1133-1 indicates Part 1 of the ISO 1133 series for melt flow rate testing of thermoplastics.
ISO 1133-1:2022 identifies the 2022 published edition (Edition 2). Earlier editions may still appear in legacy specifications, so labs typically confirm the exact cited year/edition when aligning procedures and reporting.
Related Standards, Methods, or Frameworks when useful
ISO 1133-2: Used when rheological behavior is significantly affected during testing (for example, where time-temperature history and/or moisture sensitivity drives the need for a different method approach).
Material standards that cite ISO 1133-1: Many polymer material specifications reference ISO 1133-1 and define the required temperature and load condition for compliance reporting.
Get help selecting an ISO 1133-1 melt flow tester setup
If you share the exact ISO 1133-1 condition(s) you need to run (temperature, load, and whether you report MFR, MVR, or both), we can recommend practical configurations for QC or R&D workflows. To compare options and lead times, request a detailed quote.