Overview
SIST EN ISO 868:2003 is a widely recognized European and International Standard that specifies the method for determining the indentation hardness of plastics and ebonite using a durometer, commonly known as Shore hardness measurement. Developed and published by CEN in alignment with ISO 868:2003, this standard provides a reliable empirical testing procedure for assessing the hardness of polymeric materials through indentation, employing two durometer types:
- Type A: Designed for softer plastics and ebonite materials.
- Type D: Intended for harder plastics and ebonite materials.
This method measures the depth of penetration of an indenter under specified conditions, offering essential insights for quality control and material evaluation in plastics manufacturing and research sectors.
Key Topics
Method Principle
The Shore hardness test method applies an indenter with calibrated force to the surface of the test specimen and measures the extent of indentation. Indentation hardness is inversely proportional to the penetration depth. Factors influencing results include:
- Indenter shape and size (Type A and Type D have distinct indenters)
- Applied force magnitude
- Duration of load application
Test Apparatus
The equipment consists of a durometer with these components:
- Presser Foot: With a specific hole diameter centered suitably to ensure contact.
- Indenter: Hardened steel rod with precise dimensions differing for Type A and Type D.
- Indicating Device: Measures the protrusion or indentation depth and provides a numerical Shore hardness reading.
- Calibrated Spring: Applies a specified force related to the hardness value, ensuring accuracy.
Specimen Requirements
- Minimum thickness: 4 mm to avoid substrate effects.
- Surface must be flat, smooth, and large enough to accommodate the presser foot contact area and ensure readings taken at least 9 mm from edges.
- Composite specimens are allowed but may influence readings due to layer interfaces.
Conditioning and Testing Atmosphere
Specimens and durometer must be conditioned at the test temperature, typically for one hour or more, ensuring stable and repeatable measurements. For materials sensitive to humidity, conditioning follows ISO 291 or relevant specifications.
Calibration
Calibration of the durometer spring is critical and involves comparing applied forces to calculated values within narrow tolerances, guaranteeing consistent force application during testing.
Procedure
- Position the test specimen on a hard, flat surface.
- Apply the durometer perpendicular to the specimen with minimal delay and pressure to ensure firm contact.
- Record the hardness value typically after 15 seconds; instantaneous readings may also be taken.
- Take at least five measurements spaced adequately apart to determine an average hardness value.
Reporting
Test reports must include:
- Reference to SIST EN ISO 868:2003 standard
- Material identification details
- Test specimen description and thickness
- Conditioning temperature and humidity
- Durometer type used (A or D)
- Time elapsed between specimen preparation and testing
- Individual reading values with time intervals
Applications
The SIST EN ISO 868:2003 standard is essential in industries and laboratories that deal with plastics and ebonite products, providing:
- Quality Control: Monitoring hardness to ensure material consistency during production.
- Material Specification: Helping define mechanical properties relevant to usage conditions.
- Research and Development: Evaluating new materials or formulations based on hardness.
- Product Comparison: Benchmarking materials in terms of firmness and wear resistance.
- Compliance and Certification: Demonstrating conformity to recognized hardness measurement procedures.
This standard is especially relevant for manufacturers of plastic components, rubber-like materials, electrical insulation, automotive parts, and consumer goods where hardness can impact performance and durability.
Related Standards
SIST EN ISO 868:2003 is part of a family of plastic and rubber hardness tests and should be considered alongside other standards:
- ISO 48 – Rubber, vulcanized or thermoplastic – Determination of hardness (particularly for softer materials with hardness between 10 IRHD and 100 IRHD).
- ISO 291 – Plastics – Standard atmospheres for conditioning and testing, ensuring equilibrium moisture and temperature during hardness testing.
- Other durometer-related standards defining test conditions, calibration, and instrumentation.
Using SIST EN ISO 868:2003 in conjunction with these related standards ensures comprehensive material characterization and testing procedure harmonization globally.
Keywords: SIST EN ISO 868:2003, Shore hardness, durometer test, plastics hardness test, indentation hardness, type A durometer, type D durometer, plastics testing standards, ebonite hardness, polymer hardness measurement, ISO 868, material quality control.
