ISO 48-7:2018

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)