Overview
ISO 4592:1992 - "Plastics - Film and sheeting - Determination of length and width" defines reference methods for measuring the “free” length and the average “free” width of rolls and samples of plastic film and sheeting. The standard is intended as a benchmark method (for rolls up to 100 m) to which other measuring methods or automated systems can be calibrated. It also specifies a reference procedure for measuring sample widths down to 5 mm (with limited accuracy near that minimum).
Keywords: ISO 4592:1992, plastics film length measurement, plastics sheeting width determination, reference method.
Key topics and technical requirements
- Scope: Reference method for roll length up to 100 m and for average roll/sample width (sample width ≥ 5 mm).
- Length method:
- Condition roll by unfolding into an accordion with folds ≤ 5 m and no more than 20 directly superimposed folds; leave at least 1 hour before measuring (30 min for non-roll samples).
- Use a planar measuring surface (preferably ≥ 10 m long) marked at 1 m intervals with one 1 m subdivided to 0.1 m.
- Use a sharp knife or razor and a metal graduated rule/profile (wider than the roll) to square cut and align edges.
- Procedure: unwrap progressively, mark edges against the surface scale, measure successive lengths to the nearest 0.1 m, and sum for total roll length.
- Width methods (two modes):
- Mode A (width > 100 mm): flat surface and a metal rule graduated to 1 mm; determine edge position to 1 mm and report average width.
- Mode B (width 5–100 mm): flat surface with 100 mm transverse engraved scale and a x10 micrometric loupe for 0.1 mm resolution.
- For sample lengths ≤ 5 m, measure width at least 3 times along the sample; for > 5 m, at least 10 times. Report average.
- Accuracy note: if width is only slightly greater than 5 mm, method accuracy is ~2%.
- Interlaboratory precision: fidelity not declared due to lack of interlaboratory data; the standard remains the calibration reference.
Applications and users
- Quality control in film and sheet manufacturing (packaging, industrial films).
- Laboratory testing and certification labs performing dimensional verification.
- Manufacturers and suppliers validating in-line or automated measuring systems against a reference method.
- Buyers and inspection teams requiring a documented, repeatable procedure to report roll length and average width.
Keywords: measurement of roll length, free width of film, plastics dimensional testing.
Related standards
- Developed by ISO/TC 61 (Plastics). For complementary dimensional, mechanical or conditioning methods consult other ISO plastics testing standards published by ISO/TC 61.
