Overview
ISO 48-7:2018 specifies a standardized method for determining the apparent hardness of rubber-covered rollers (vulcanized or thermoplastic) using a Shore-type durometer. Intended for situations where only medium precision is required, the method adapts the Shore penetration technique (as in ISO 48-4) to measurements made directly on the curved surface of conditioned roller covers rather than on flat test pieces.
Key topics and technical requirements
- Scope: Apparent Shore hardness of rubber-covered rollers; method appropriate for rollers where medium precision suffices.
- Instruments: Shore A and D durometers (as specified in ISO 48-4). Use type D for high-hardness rollers (if Shore A readings > 90); use type A if Shore D readings < 20.
- Specimen conditioning: Follow general specimen preparation and conditioning guidance (ISO 23529). Tests should not be done earlier than 16 hours after forming/rectification (for arbitration cases > 72 hours).
- Test position and procedure:
- Mount roller with axis horizontal and test area facing upward.
- Hold durometer with penetrator perpendicular to the curved surface; apply the footpress swiftly without shock.
- Read value at 3 seconds for vulcanized rubber and 15 seconds for thermoplastic rubber (other durations allowed if reported).
- Recommended use of supporting fixtures or centering masses to improve repeatability (recommended masses: 1 kg for Shore A, 5 kg for Shore D).
- Take three measurements in a test zone at points at least 6 mm apart.
- Expression of results: Report the median of the three readings for each zone, rounded to the nearest whole number.
- Reporting: Include detailed cylinder description, reference to ISO 48-7:2018, conditioning duration/temperature, test temperature/humidity, test duration, procedural deviations, number of zones, individual results, median hardness, and test date.
Important note: roller diameter, cover thickness and core material can influence the measured apparent hardness, especially for thin covers.
Applications and users
ISO 48-7:2018 is practical for:
- Quality control and production inspection of rubber-covered rollers in printing, paper, converting, and material-handling industries.
- Materials engineers and testing laboratories assessing in-service roller hardness.
- Manufacturers specifying roller covers and end-users checking conformity during assembly or maintenance.
Keywords: ISO 48-7:2018, Shore durometer, apparent hardness, rubber-covered rollers, Shore A, Shore D, hardness testing, vulcanized rubber, thermoplastic rubber.
Related standards
- ISO 48-4 - Shore durometer method (penetration hardness)
- ISO 23529 - Specimen preparation and conditioning for rubber tests
- ISO 6123-1 - Roller hardness specifications (useful for interpreting variation along a roller)