ISO 48-6:2018

Overview

ISO 48-6:2018 is an international standard published by ISO that specifies the method for determining the apparent hardness of rubber-covered rollers using the International Rubber Hardness Degrees (IRHD) scale. This standard focuses on vulcanized or thermoplastic rubber roller covers and uses an IRHD method that measures the depth of penetration of a spherical indentor under a defined force. The testing apparatus is designed to accommodate the curved surfaces typical of roller covers, making this method particularly suitable for accurately assessing the hardness of these components in industrial and manufacturing settings.

Key Topics

• Apparent Hardness Measurement
  The standard defines apparent hardness as the hardness value obtained on the finished roller, which can be influenced by factors such as roller diameter, rubber thickness, and the roller core material.

• Testing Apparatus and Setup
  The apparatus is similar to that described in ISO 48-2 but adapted for curved surfaces. It includes bases designed for rollers with varied radii:

  • Rollers with radius > 50 mm use a base with two parallel cylindrical supports.
  • Rollers with radius from 4 mm to 50 mm require special jigs or V-blocks.
  • Extremely small rollers (radius < 4 mm) use method CM with wax support for secure placement.

• Testing Procedure
  The procedure involves positioning the roller horizontally with the test area uppermost, applying the indentor, and measuring indentation after specified force and time intervals. Three measurements are recommended per test area, at least 6 mm apart, to calculate the median apparent hardness.

• Conditioning and Temperature Control
  Testing should be conducted after a minimum of 16 hours post-forming/finished grinding, ideally at standard laboratory temperature, following ISO 23529 guidelines for conditioning. Temperature equilibrium between the roller and environment is essential to ensure consistent results.

• Expression of Results
  Hardness results are expressed in IRHD to the nearest whole number and reported as the median of three measurements per test area. The test report must document relevant roller details, test conditions, and measured hardness values.

Applications

ISO 48-6:2018 applies primarily to industries and laboratories involved in:

• Quality control of rubber-covered rollers used in printing, paper manufacturing, textiles, plastics processing, and material handling equipment.
• Specification compliance ensuring roller hardness meets design requirements for product performance and durability.
• Process control during production of vulcanized and thermoplastic rubber rollers to validate uniformity and surface characteristics affecting end-use functionality.
• Research and development for developing new rubber compounds or roller constructions by providing standardized hardness data for comparison.

The standard facilitates consistent and reliable hardness testing of rollers with complex curved surfaces, enabling manufacturers and users to maintain stringent quality and performance standards.

Related Standards

ISO 48-6:2018 is part of the ISO 48 series, which groups standards related to hardness determination of vulcanized or thermoplastic rubber. Relevant associated standards include:

• ISO 48-2:2018 – Hardness determination for rubber between 10 IRHD and 100 IRHD, serving as the base method adapted for rollers in ISO 48-6.
• ISO 48-7 and ISO 48-8 – Alternative methods for apparent hardness testing on rubber-covered rollers, applicable depending on roller size and properties.
• ISO 23529 – General conditioning procedures for rubber test pieces, referenced for temperature and environment control during hardness testing.
• ISO 6123-1 – Specifications for rubber or plastics covered rollers, including hardness requirements to ensure functional roller performance.

By aligning hardness testing with these related standards, ISO 48-6 supports harmonized evaluation processes across multiple sectors utilizing rubber-covered rollers.

Keywords: ISO 48-6, apparent hardness, rubber-covered rollers, IRHD method, vulcanized rubber, thermoplastic rubber, hardness testing, rubber roller quality control, ISO hardness standards, roller surface hardness, rubber roller testing apparatus.