ISO 604 Compressive Properties of Plastics
ISO 604 is an international standardized test method used to determine the compressive properties of rigid and semi-rigid thermoplastic or thermoset materials. Using compression platens to apply a force, the properties obtained are compressive strength, strain at compressive strength, compressive yield stress, and if required, modulus. ISO 604 is used alongside its tensile test standard equivalent, ISO 527, which together provide the fundamental material properties of polymers that are found in every industry and even every household around the globe.
Depending on the maximum expected forces, ISO 604 can be performed on either a single column or dual column universal testing machine such as those available in Instron's 6800 or 3400 Series. Compression platens with integral spherical seats are ideal for ensuring platen to platen parallelism, which is a requirement within ISO 604.
ISO 604 Test Setup | |
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3400 Series Universal Testing System |
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Bluehill Universal Software |
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2530 Series Load Cell |
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2501 Series Compression Platens |

Depending on your application, the following fixtures are commonly used for ISO 604 testing:
- upper compression platen with integral spherical seat (diameters vary from 2" to 8”)
- lower rigid platen of matching size
- 2601-04X series LVDT (linear displacement transducer)
- LVDT mount for platens (2601-071)
ISO 604 Accessories | |
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Self-Aligning Spherical Seat |
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Anti-Buckling Support Jig |
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2601-04x Series LVDT |

- The ISO 604 method is included in the Plastics test method suite in Bluehill Universal.
- If the specimen is too thin, an anti-buckling support jig should be used to prevent the specimen from buckling.
- If reporting the modulus calculation, make sure the extensometer and load cell are both verified in the range where the calculation is being made. Labs commonly make the error of reporting calculations outside of the verified range of their devices.