ASTM D1621
Compression Platens for Rigid Cellular Plastics (Foam)
ASTM D1621 Compression Platens – Universal Grip Data Sheet (PDF)
ASTM D1621 measures the compressive properties of rigid cellular plastics such as polyurethane, polystyrene and polyisocyanurate foams. A foam block is compressed between flat platens at a controlled rate. Universal Grip supplies large, precision-ground platens with a spherically seated upper platen so the load spreads evenly over the whole specimen face.
What ASTM D1621 Measures
The test reports compressive strength at yield, or at 10% deformation if the foam shows no yield, along with compressive modulus. Insulation board, structural core and packaging foam makers use it for product specifications and quality control. The results depend strongly on density and rise direction, so specimens are cut and oriented consistently.
How the ASTM D1621 Test Works
Cut square or round specimens with a minimum height of 25.4 mm (1 in); the height must not exceed the width or diameter.
Measure the specimen and center it on the lower platen.
Compress at 2.5 mm/min (0.1 in/min) for each 25.4 mm of specimen thickness.
Continue to about 13% of the original height.
Report strength at yield or at 10% deformation, and compressive modulus.
Specimens and Setup
Cross-sections range from 25.8 cm² (4 in²) to 232 cm² (36 in²), so choose platens that cover the full face.
Cut faces flat and parallel; uneven faces crush first and lower the modulus.
Record the foam rise direction and test in a consistent orientation.
Use a deflectometer or crosshead compensation for accurate strain.
Confirm specimen size and rate against your copy of the current standard.
Universal Grip ASTM D1621 Fixture
Large, flat platens cover the full specimen face
Spherically seated upper platen for self-alignment
Precision-ground, parallel bearing surfaces
Platen sizes to suit common foam specimens
10 kN standard capacity; higher capacities on request
Steel or aluminum with corrosion-resistant finish; clevis or threaded adapters
Applications
Rigid insulation foam QC
Polyurethane and polystyrene foams
Structural core foams
Packaging foam evaluation
Related Standards and Products
Send us your specimen dimensions, required capacity and machine connection through our contact page and we will quote an ASTM D1621 compression platen set. Request a quote
ASTM D1621 FAQ
What if the foam has no yield point?
D1621 then reports compressive strength at 10% deformation. Many rigid foams show a clear yield, but some keep stiffening, so the 10% point gives a consistent comparison.
What test speed does D1621 use?
The crosshead moves at 2.5 mm/min (0.1 in/min) for every 25.4 mm (1 in) of specimen thickness, so thicker specimens are tested faster.
Why a spherically seated platen?
Foam faces are rarely perfectly parallel. The spherical seat lets the upper platen settle flat on the specimen so the load is even across the face.
Is D1621 for flexible foam?
No. D1621 is for rigid cellular plastics. Flexible foams such as seating foam are tested to ASTM D3574.