ISO 868

ISO 868 provides guidelines on how to measure the hardness of plastic materials using a durometer, which measures resistance to indentation. This test determines the Shore hardness, a quick and non-destructive way to assess the surface hardness and rigidity of plastic materials using standardized indenters.

Purpose of ISO 868 Testing:

• It establishes a consistent methodology for assessing the surface hardness of plastic materials through indentation resistance.
• The test involves pressing a calibrated durometer with a specific indenter geometry (typically Shore A for softer materials or Shore D for harder plastics) against the material surface and reading the depth of penetration on a standardized scale from 0 to 100.
• Shore hardness indicates how easily a material's surface can be indented, with higher values indicating harder, more rigid materials and lower values indicating softer, more flexible materials.
• The test is quick, non-destructive, and portable, making it ideal for quality control and material verification in production environments.
• Having a standardized test method ensures results are reproducible and comparable across different laboratories and manufacturers.

Application to 3D Printing Filament:

• Many 3D printing filaments are made of plastics (like PLA, ABS, PETG, TPU, and others) with varying hardness levels. Understanding surface hardness is crucial for applications where wear resistance, scratch resistance, or tactile properties are important.
• Manufacturers can use ISO 868 testing to verify that their filament meets specified hardness requirements, ensuring consistent surface properties across production batches, particularly important for flexible filaments (TPU/TPE) and engineering materials.
• Designers and engineers might test 3D printed parts (or the filament itself) according to ISO 868 standards to validate performance in applications where hardness affects functionality, such as gaskets, seals, grips, or wear-resistant surfaces.
• The standardized nature of ISO 868 testing helps in comparing different filament brands or formulations, ensuring that the material's surface hardness is predictable, which is especially important when selecting between soft flexible materials and rigid engineering plastics.

Benefits for 3D Printing and End Users:

• Quality Control: It allows filament producers to verify consistent hardness across production batches, ensuring that flexible filaments maintain their softness and rigid materials maintain their stiffness.
• Material Selection: Users can review ISO 868 results (if available) to choose a filament with appropriate hardness for their application, whether they need a soft flexible TPU (Shore 85A-95A) or a hard rigid engineering plastic (Shore 70D+).
• Predictable Performance: Understanding the Shore hardness ensures that 3D printed parts will have the expected surface properties, which is critical for gaskets, seals, grips, wheels, protective bumpers, and applications requiring specific tactile or wear characteristics.

References

Read more about ISO 868 on the ISO's website.