Overview
SIST EN ISO 845:2009 – Cellular plastics and rubbers – Determination of apparent density (ISO 845:2006) – defines a standardized procedure for determining the apparent overall density and the apparent core density of cellular plastics and rubbers. This European Standard facilitates consistent testing and reporting across industries by specifying how density measurements are to be conducted for cellular materials, whether or not they possess skins formed during moulding or extrusion.
Understanding the density of cellular plastics and rubbers is critical for evaluating product quality, performance, and compliance in manufacturing and quality assurance workflows.
Key Topics
- Apparent Overall Density: Refers to the mass per unit volume of a sample including all skins formed during the moulding process. Applicable where a skin is present.
- Apparent Core Density: Characterizes the density after removal of moulded skins, allowing assessment of the core material properties.
- Sample Preparation: Test specimens must be large enough for accurate measurements, with a minimum volume of 100 cm³. Specimens should be conditioned for stability and tested after a waiting period post-manufacture.
- Measurement Method: The standard outlines procedures for measuring specimen dimensions (in accordance with ISO 1923) and mass with high accuracy to calculate density.
- Test Conditions: Conditioning in standard atmospheres (as defined in ISO 291) is required to ensure comparable results.
- Statistical Reporting: Results must include mean density and standard deviation, providing a robust data set for quality assessment.
- Skin Presence: For materials without skins (as formed during manufacturing), the determination of "overall density" is not applicable-only "core density" is measured.
Applications
The method specified in SIST EN ISO 845:2009 is widely used for:
- Quality Control: Manufacturers of foam, insulation panels, or elastomeric rubbers rely on accurate density measurement to verify consistency, structural integrity, and compliance with product requirements.
- Research and Development: Materials scientists employ this standard to compare new cellular material formulations and optimize their properties.
- Regulatory Compliance: Industries such as automotive, aerospace, and construction implement this standard to meet mandatory specifications and ensure safety and performance.
- Product Identification: Apparent density can indicate correct material specification, detect defects, or identify process anomalies in finished goods.
- Comparative Analysis: Enables benchmarking between different batches, suppliers, or manufacturing techniques by providing a uniform approach to density determination.
Related Standards
For organizations implementing SIST EN ISO 845:2009, the following related standards may also be relevant:
- ISO 291 – Plastics – Standard atmospheres for conditioning and testing: Specifies environmental control for pre-test specimen conditioning.
- ISO 1923 – Cellular plastics and rubbers – Determination of linear dimensions: Establishes dimensional measurement procedures required by ISO 845.
- EN ISO 845:1995 (superseded by the 2009 edition): Earlier version, replaced for technical alignment.
Adhering to these reference standards helps ensure the validity and comparability of test results when determining the apparent density of cellular materials.
By standardizing the process for apparent density determination of cellular plastics and rubbers, SIST EN ISO 845:2009 supports manufacturers, quality control laboratories, and regulatory agencies in achieving reliable product characterization and maintaining high standards across various industries.
