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D5672 – Standard Test Method Technical Guide
🔬 Test Overview and Scope
This test method provides a screening quality control test for determining if flexible polyurethane foam cushions are within the specified grade range for firmness. It is applicable to foams with thicknesses of 75 mm [3 in.] or greater. The method is based on the traditional industry standard thickness of 100 mm [4 in.] for Indentation Force Deflection (IFD), where a 25 % deflection corresponds to 25 mm [1 in.]. This allows for a quick assessment of whether the foam meets the 25 % IFD grade.
| 🟦 Parameter | 📏 Requirement |
|---|---|
| Minimum foam thickness | 75 mm [3 in.] |
| Standard reference thickness for IFD | 100 mm [4 in.] |
| Deflection depth applied | 25 mm [1 in.] (25 % of 100 mm) |
⚙️ Test Procedure and Deflection Technique
The test involves deflecting the foam cushion by 25 mm [1 in.] to assess firmness. This quick technique screens polyurethane foams for grade determination without requiring a full IFD curve. Cushion thicknesses less than 75 mm [3 in.] shall not be tested using this method. Values in U.S. Customary and SI units are to be regarded separately as standard; they may not be exact equivalents and must be used independently.
⚠️ Cushion thicknesses less than 75 mm [3 in.] shall not be tested for IFD using this test method.
📊 Standards and Terminology
This standard references several ASTM documents, including D3574 Test Methods for Flexible Cellular Materials, D883 Terminology Relating to Plastics, E456 Terminology Relating to Quality and Statistics, and E691 for precision. Terminology conforms to D883 and E456. The international standard ISO 2439 addresses the same subject but differs in technical content.
| 📐 Standard | 🎯 Description |
|---|---|
| D3574 | Test methods for slab, bonded, and molded urethane foams |
| ISO 2439 | Hardness determination (indentation technique) for flexible cellular materials |
💡 This method provides a quick screening tool that aligns with the traditional IFD convention of 25 % deflection on a 100 mm [4 in.] cushion. It is intended for production quality control, not for material qualification.
❓ Frequently Asked Questions
🔍 What is the purpose of this test method?
It is a screening quality control test to determine if flexible polyurethane foam cushions are within the specified grade range for firmness.
💡 What is the minimum thickness required for testing?
Foam thickness must be 75 mm [3 in.] or greater; foams less than 75 mm cannot be tested using this method.
⚡ How is the deflection depth determined?
The deflection depth is 25 mm [1 in.], which corresponds to 25 % deflection of the standard 100 mm [4 in.] cushion thickness.
📌 Why are two unit systems used?
The values stated in U.S. Customary or SI units are to be regarded separately as standard. They may not be exact equivalents, so each system shall be used independently.