Compression Testing of Foam per ASTM D3574

ASTM D3574 is a widely accepted test standard for testing soft polyurethane foam. Samples come in a variety of forms including slab, bonded, and molded flexible cellular urethane foams. There is a wide range of applications for D3574 including car seats, furniture, mattresses, bedding, pillows, foam products and materials, and bolsters.

There are several test procedures in this standard to help determine the compression, deflection, tear and tensile characteristics of flexible cellular materials (urethane foams and polyurethane foams). IFD (Indentation force deflection) and ILD (indentation load deflection) are two of the more common compression tests in this standard. Our engineers are very familiar with foam testing to ASTM D3574 and can help guide you through the process with the correct compression test machine. We recommend you purchase and read the full ASTM standard to achieve the best results.

Test B1 - Deflection based Indentation Force Deflection (IFD/ILD)

IFD test data

This test is one of the more common methods used from ASTM D3574. The indentation force deflection, or IFD test measures the force necessary to produce 25% and 65% deflections in foam products. The specimen for Test B1 consists of the entire product or a suitable portion of it and should be no less than 380mm W X 380mm L X 100mm thick. One sample is required. You can use our G223 Spherical Seat Compression Platen for Test B1.

Test Procedure

  1. Measure the specimen thickness.
  2. Place the specimen on the lower compression platen of your compression tester.
  3. Preflex the specimen by twice lowering and raising the upper platen to 75-80% of the thickness at a rate of 250 mm per minute.
  4. Allow the specimen to rest for 6 minutes with the platen not contacting the specimen.
  5. Bring the platen down into contact with the specimen at 50 mm per minute and determine the thickness at a force of 4.5 N.
  6. Indent the specimen at 50 mm per minute by 25% of thickness. Determine the force after 60 seconds.
  7. Increase the deflection to 65%. Determine the force after 60 seconds.
  8. Record the IFD/ILD values.

You can learn more about testing to ASTM D3574 Test B1 here.

Test B2 - Force Based Indentation Force/Load Deflection (IFD/ILD)

Indentation Residual Gauge Length test for urethane foams used to determine how thick the padding is after being loaded by an average weight person. If possible a completed manufactured product should be used as your testing specimen. One sample is required. You can use our G223 Spherical Seat Compression Platen for Test B2 as well.

Test Procedure

  1. First, measure the specimen thickness.
  2. Place the specimen on the lower platen in the compression tester.
  3. Preflex the specimen by twice lowering and raising the upper platen to 330 N at a rate of 200 mm per minute.
  4. Allow the specimen to rest for 6 minutes with the platen not contacting the specimen.
  5. Bring the platen down into contact with the specimen at 50 mm per minute to a force of 4.5 N.
  6. Indent the specimen at 50 mm per minute with 110 N. Determine the thickness after 60 seconds.
  7. Increase the force to 220 N at 50 mm per minute. Determine the thickness after 60 seconds.
  8. Record the IRGL values

Test C - Compression Force Deflection (CFD)

Compression force deflection measures the force necessary to produce a 50 % compression over the entire top area of the foam specimen. The standard specimen for this test is 50mm X 50mm X 25 mm thick or larger. 3 samples are required. Use our G223 Spherical Seat Compression Platen for this test.

Test Procedure

  1. Measure the specimen thickness.
  2. Place the specimen on the lower support platen in the compression tester.
  3. Preflex the specimen by twice lowering and raising the upper platen to 75-80% of the original thickness at a rate of 250 mm per minute.
  4. Allow the specimen to rest for 6 minutes with the platen not contacting the specimen.
  5. Bring the upper compression platen down into contact with the specimen to a load of 140 Pa.
  6. Compress the specimen 50% of this thickness at 50 mm per minute.
  7. Determine the final force and displacement.
 
ASTM D3574 Test E Tensile Test of Foam

Test E - Tensile Strength and Elongation

This tensile test determines the effects of a tensile force applied to foam. Measurements are made for tensile stress, tensile strength, and ultimate elongation. Dog bone specimens are cut from a 12.5 mm thick flat sheet of foam. 3 samples are required for this test. G240KP Pneumatic Vice Grips can be used for high volume testing or for very accurate and consistent clamping force. G240K mechanical vice grips can also be used. You will want to record tensile stress, tensile strength, and ultimate elongation for Test E.

Test Procedure

  1. First symmetrically place the dog bone tabs of the specimen into the top and bottom vice grips of your tensile test machine.
  2. Run tensile test machine at 500 mm per minute.
  3. Record continuously the force and displacement during the test until rupture.

Test F - Tear Resistance Strength

Tear test to determine the tear propagation resistance of foam. This test is similar to ISO 8067. For Test F, specimens are generally about 152 mm long blocks with the width and depth the same as the material pad thickness. A 40 mm cut is placed down the middle of one end and 3 samples are required. G240KP pneumatic vice grips can be used for high volume testing or for very accurate and consistent clamping force. G240K mechanical vice grips can also be used.

Test Procedure

  1. First clamp the specimen in the jaws of the grips symmetrically so that each tab is held in one jaw.
  2. Begin the tensile test at 500 mm/min until rupture.
  3. Record the maximum force and cross sectional dimensions of the specimen.

Test I3 - Dynamic Fatigue Test by Constant Force Pounding

There are multiple fatigue tests defined in ASTM D3574. Test I3 determines the loss of force support at 40 % IFD, loss in thickness, and the structural breakdown as assessed by visual inspection. Method I3 is similar to ISO 3385. This test will measure the IFD properties of the foam specimen before and after fatigue cycling.

One specimen is necessary for this test. The specimen should be 380mm X 380mm X 50mm. The foam should then be conditioned for at least 12 hours and fatigued at 23 degrees C and 50% relative humidity. For fatigue testing we would recommend the 800 Series Fatigue Test Machines with G223 Spherical Seat Compression Platens.

Test Procedure

  1. First measure the 40% IFD of the specimen in accordance with Test B1. Measure the original thickness with 4.5 N contact force after preflexing.
  2. Set the counter of the system to zero, fatigue the specimen with 750 N of force with an indenter with a diameter of 250 mm for the following procedures:
    Procedure A – 8,000 cycles at 70 cycles per minute
    Procedure B – 80,000 cycles at 70 cycles per minute
    Procedure C – 12,000 cycles at 10 cycles per minute
  3. Final measurement: Within 60 minutes after the fatigue test is complete, repeat measurement of 40% IFD using the original thickness to determine the final force reading.

Test M - Recovery Time of Viscoelastic or Memory Foam

Recovery time tests determine the recovery time of slow recovery (memory) foams. For Test M recovery time is measured in seconds. This test uses the standard specimen described in Test B1, IFD testing. One specimen should be tested. For Test I3 and M, you will need a fatigue tester, so we recommend our 800 Series Fatigue Test Machine with a G223 Spherical Seat Compression Platen.

Test Procedure

  1. Place the specimen on the perforated support platen and bring the indenter foot into contact with the specimen with a 4.5 N preload to determine the initial thickness.
  2. Immediately indent the specimen 75% at a speed of 1,000 mm/min. Hold for 60 seconds.
  3. Return the indenter to a 5% deflection at 1,000 mm/min. Start the stopwatch immediately upon upward movement of the indenter.
  4. Record the time in seconds it takes the foam specimen to recover to 4.5 N.

Appendix X6 - Hysteresis Loss

Hysteresis test data

Hysteresis tests measure the difference in area under the curves during loading and unloading, representing energy loss.

Advice From Our Engineers

You are seeking to quantify the firmness of your foam. There are many simple ways you can do that, but it is likely you will need to use this quantified information to dialog with your foam suppliers and/or customers. This is a very common situation in the foam industry. In order to regulate the quantified information, ASTM has defined a very specific test and test system being ASTM D3574. If you can certify your test results to that standard then your test reports will be directly comparable to tests run on other companies’ test machines and there can be no confusion about the testing. In order to be able to certify your results you need a test machine that was designed and built to the details of the standard, and you need to run the test exactly as the standard directs. Our test machines do that for you.

Recommended Test Machine

Our test engineers would recommend the 110 or 120 Universal Test Machines for forces up to 500 lbs. These versatile test machines can be configured to test in both tensile and compression. The 110 and 120 are lower force options best for foam testing, the 120 having more test space for larger specimens. The 370 Universal Test Machine would be used for higher forces or very large specimens.

For tests I3 and M, our engineers recommend the 800 Series Fatigue Test Machine in order to complete the fatigue tests. All of our test machines configured for ASTM D354 are supplied with perforated base plates for supporting the foam samples. These specialized base plates allow air to escape from the foam during compression.

Most customer choose to configure their 110, 120 or 370 Universal Test Machines with the Flexible Soft Foam Basic Software Package. This package is perfect for users testing mostly to ASTM D3574 B1. This software is a perfect supporter for this standard and supplied graphs for load vs displacement and displacement vs time. Customers requiring the additional tests of ASTM D3574 can utilize our Flexible Soft Foam Premium Software package. Call one of our engineers to learn more about which package is best for you.

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