Overview
ISO 703:2017 establishes a standardized test method to determine the transverse flexibility (troughability) of conveyor belts, expressed as the ratio F/L. The method measures the maximum vertical deflection of a transverse belt section under its own weight and is intended to help assess whether a belt's troughing characteristics are suitable for the intended application. The method is not suitable for light conveyor belts covered by ISO 21183‑1.
Key Topics
- Scope and purpose: Determines transverse flexibility (troughability) as a ratio F/L to inform belt selection and quality control.
- Symbols and measures: Key symbols are F (vertical deflection corrected for belt thickness), L (flat length = full belt width), and d (belt thickness).
- Test piece: A rectangular section with longitudinal length (in belt direction) of (150 ± 2) mm, overall width L and thickness d as the overall belt thickness.
- Conditioning: Test pieces must be conditioned in accordance with ISO 18573 using atmosphere A, B or C and tested immediately after conditioning.
- Apparatus essentials: Two rigid horizontal bars, two clamps with suspension lugs, four equal-length steel suspension wires and means to measure deflection to the nearest millimetre.
- Procedure highlights:
- Fit the test piece carrying face uppermost into swivelling clamps.
- Allow the piece to fall under its own weight into the troughed position while suspending forces remain vertical.
- After 5 minutes measure the vertical deflection F and add 0.5·d to obtain the corrected F value.
- Result expression: Report the ratio F/L.
Applications
This test method is practical for:
- Belt selection: Determining suitable belts for troughed conveyor designs to avoid lateral travel and instability.
- Quality control: Routine verification of transverse flexibility during production and incoming inspection.
- Design assessment: Supporting engineering decisions for idler and troughing arrangements where transverse stiffness affects belt tracking and loading behavior.
Practical keywords: conveyor belt, troughability, transverse flexibility, F/L ratio, test method, conditioning, quality control.
Related Standards
- ISO 21183-1 - Light conveyor belts (method not suitable for these belts).
- ISO 18573 - Conveyor belts: test atmospheres and conditioning periods.
- ISO 583 / ISO 7590 - Methods for measuring belt thickness and cover thickness referenced for thickness measurement.
Test Report Essentials
Per ISO 703 the test report shall include:
- Reference to ISO 703
- Identification of the conveyor belt tested
- Test length L and thickness d
- Conditioning atmosphere used (A, B or C)
- Value of F/L and date of test
This structured, repeatable method helps manufacturers, inspectors and design engineers evaluate troughing performance and maintain consistent belt quality.
