Summary of Tests
ASTM D3574 is a testing standard that includes several different tests used to measure the physical properties of foam materials. It includes both tension (Test E and F) and compression (Test B1, C, M, X6) tests.
More information on each test can be found below.
ASTM D3574 B1 – Indentation Force Deflection (IFD) Testing
Summary of Test
ASTM D3574 B1 is a testing specification that measures the indentation force deflection of urethane foam and foam-like substances. The test procedure below follows the publication’s listed compression ratios, but many users pick the rates that are important to their testing.
A universal tensile testing machine is needed to complete the test procedures. Force capacities at the two deflection points are recorded as well as the support factor and original thickness. Before conducting ASTM D3574 B1, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Preflex the foam specimen by compressing its thickness 75 percent to 80 percent of its original size. Preflex to 75-80% of the original height once more.
- Let the specimen stand for approximately six minutes after the preflex.
- Apply a preload to the specimen as specified in the testing standard. The software will measure the thickness of the specimen.
- Compress the foam downward to 25 percent of its thickness at the rate specified in the standard. Wait approximately one minute. Record the force capacity applied in Newtons.
- Compress the specimen further to 65 percent of its original thickness at the same rate. Wait approximately one minute. Record the force capacity applied in Newtons.
ASTM D3574 C – Foam Force Deflection Testing
Summary of Test
ASTM D3574 is a commonly used standard for tests involving flexible cellular foam materials. Section C specifies a method for measuring the compression force necessary to produce a 50% deflection over the entire top surface of the foam test specimen. This analysis will help to better characterize and compare various foams and determine their ideal applications. This test is very similar to ISO 3386, but with slight technical differences that prohibit a direct comparison.
A universal tensile testing machine with a flat compression foot is needed to complete the test procedures. Before conducting ASTM D3574 C, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Prepare at least three test specimens as described in the standard. Larger specimens can be used, as long as the compression foot can encompass the entire top surface area of the specimen.
- Preflex the foam specimen twice by compressing to 75 to 80 percent of its original thickness. The testing speed is specified in the standard.
- Let the specimen rest for approximately six minutes after the preflex.
- Apply the preload specified in the standard and measure the thickness of the foam specimen.
- Compress the foam to 50% of its original thickness at the rate specified in the standard. Wait approximately one minute. Record the force capacity applied in Newtons.
ASTM D3574 E – Foam Tension Testing
Summary of Test
ASTM D3574 Test E determines the tensile strength and elongation of slab, bonded, and molded flexible cellular urethane foams. The D3574 Test E test procedure is similar to other polymer tests, but gripping the sample and measuring elongation require a bit more care. The minimum sample thickness is 12.5mm. Thicker samples are more commonly tested, therefore, manual or pneumatic vise grips with at least a 20mm wide opening are best.
Measuring elongation is tricky because the sample is “dogbone” shaped. Using grip separation to measure elongation is less than ideal due to the non-uniform specimen width between grips. Despite this, it is still common to measure elongation using grip separation because clip-on contacting extensometers distort the sample and cause premature breakage. Non-contact optical extensometers work well for this application, but they can be cost prohibitive.
Prior to conducting ASTM D3574 E, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Use a sharp die to prepare a dogbone sample. Sample dimensions are shown in Figure 1 of the ASTM D3574 Test E specification. Die A of Test Method D412 is also acceptable.
- Clamp the sample ends in the grips and record the distance between the grips.
- Pull the sample at a constant rate of grip separation as specified in Test E.
- Record force and grip separation until specimen break.
ASTM D3574 F – Foam Tear Testing
Summary of Test
ASTM D3574 F covers the tear resistance of foam by the block method. Complete instructions for the foam tear strength test can be found in ASTM D3574 F which applies to slab, bonded, and molded flexible cellular urethane foams (polyolefin foams are tested similarly). Tear strength is determined by measuring the peak force during the tear test. This provides a measure of the material’s resistance to tearing. The specification does not call for it, but it is common to measure the average load over an extension range. Average force over extension range calculations are built into all ADMET testing systems. For example, if you tear your sample four inches, you may want to average the load from 1″ to 3″ to eliminate start and end of test force conditions.
The D3574 F foam tear strength test is similar to testing other polymers, but due to sample thickness, gripping the foam is sometimes a challenge. The specimen is usually 1″ wide by 1″ thick with 1/2 of the 1.5” long split clamped by each grip. Foams do not typically have high tear strengths, so low force (1kN) capacity manual or pneumatic vise grips with at least a 20mm wide opening work best.
Prior to conducting ASTM D3574 F, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Prepare a block shaped sample with the dimensions specified in the standard. Place a 1.5” long cut in one end of the sample.
- Clamp the cut end of the sample in the upper and lower grips.
- Pull the sample at the grip separation rate specified in ASTM D3574 Test F until rupture or until at least a 50mm length is torn.
- Record the maximum force.
ASTM D3574 M – Foam Recovery Time Testing
Summary of Test
ASTM D3574 is a commonly used standard for tests involving flexible cellular foam materials. Test M specifies a method for measuring the recovery time of slow recovery (viscoelastic) foams, like memory foam. It is an important test in the mattress industry.
A universal tensile testing machine and compression platen configuration like found in traditional IFD tests is needed to complete the test procedure. Before conducting ASTM D3574 Test M, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Prepare and condition the test specimen according to the geometries and guidance described in the test standard for IFD testing.
- Place the specimen onto the perforated base compression platen. Lower the circular top platen onto the top of the specimen to apply a small preload and identify specimen thickness.
- Indent the specimen to 75% of its original thickness at the speed referenced in the test standard.
- After a specified dwell time, quickly retract the machine to the specified deflection (close to original height), and record the amount of time required to reach 4.5 ± 0.5 N force applied to the top platen.
ASTM D3574 N – Foam Hysteresis Energy Loss Testing
Summary of Test
ASTM D3574 is a commonly used standard for tests involving flexible cellular foam materials. ASTM D3574 N specifies a method for measuring the hysteresis energy loss of foams. Hysteresis loss is defined as the difference between the loading energy and the unloading energy expressed as a percentage of the loading energy. This analysis will help to better characterize and compare various foams and determine their ideal applications. The test may be performed as either an Indentation Force Deflection (IFD) test, or as a Compression Force Deflection (CFD) test.
Prior to conducting ASTM D3574 N, it is important to read the entire specification in the relevant ASTM publication.
Testing Procedure
- Prepare and preflex samples in accordance with ASTM D3574 Test B1 (IFD) for samples with area larger than the indenting platen. For samples with area smaller than the compression platen, prepare and preflex samples in accordance with ASTM D3574 Test C (CFD).
- Wait 6 ± 1 minutes after preflex to allow foam sample to rest.
- Indent the sample at the rate specified in the standard.
- Immediately remove the indentation force at the same rate as the initial indentation.
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