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D2207-00 – Standard Test Method Technical Guide
📐 Test Apparatus and Specimen Requirements
The D2207 test method defines a specific apparatus setup to ensure consistent and reproducible measurements of bursting strength. The primary equipment includes a ball burst fixture attached to a vertical testing machine conforming to Test Method D2209. The spherical ended plunger (the “ball”) shall have a diameter of exactly 0.250 in. (6.4 mm).
A dead-mass type thickness gauge, as specified in Test Method D1813, is required to measure the specimen thickness prior to the test. Test specimens can be cut from the leather sample using a die, knife, or shears.
| 🟦 Apparatus | 📏 Specification | 🎯 Reference Standard |
|---|---|---|
| Bursting Plunger (Ball) | 0.250 in. (6.4 mm) diameter | Section 6.3 |
| Testing Machine Cross-Head Speed | 4 ± 1 in./min (1.6 ± 0.4 mm/s) | Section 6.1, Note 1 |
| Thickness Gauge | Dead-mass type | ASTM D1813 |
✅ Key Tip: The testing machine must be capable of maintaining a cross-head speed of 4 ± 1 in./min (1.6 ± 0.4 mm/s). This specific rate is critical for achieving reproducible results across different laboratories as noted in the standard.
⚙️ Test Procedure and Speed Selection
Prior to testing, all leather specimens must be conditioned in accordance with Practice D1610. The specimen is then securely mounted in the ball burst fixture. The testing machine is operated at the specified jaw separation speed of 4 ± 1 in./min (1.6 ± 0.4 mm/s).
As the spherical plunger is forced through the leather, the maximum load registered on the machine is recorded as the bursting load. The standard provides detailed illustrations (Fig. 1 and Fig. 2) for the burst tester and required modification parts.
| 📐 Parameter | ⚡ Required Value | 📌 Notes |
|---|---|---|
| Cross-head Speed | 4 ± 1 in./min | Equivalent to 1.6 ± 0.4 mm/s |
| Plunger Diameter | 1/4 in. (0.250 in.) | Spherical ended ball |
| Standard Units | Inch-pound | SI values in parentheses provided for information only |
⚠️ Important Note on Applicability: This test method is designed for light- and medium-weight leathers, such as shoe uppers and garments. Section 1.1 of the standard explicitly states that it does not apply to wet blue leather.
📊 Key Measured Properties and Calculations
The primary result from the D2207 test is the Bursting Strength. This value is calculated by dividing the maximum force recorded during the test (the bursting load) by the thickness of the specimen.
Formula: Bursting Strength (lb/in.) = Bursting Load (lbf) / Thickness (in.)
The standard notes a good correlation between bursting strength and tensile strength (Test Method D2209), making this method suitable for development, control, and service evaluation of the leather. The bursting load and extension are generally proportional to the diameter of the plunger.
❓ Frequently Asked Questions
🔍 What is the diameter of the ball used in the ASTM D2207 burst test?
The standard specifically requires a spherical ended plunger (ball) with a diameter of 0.250 in. (6.4 mm).
💡 How is the Bursting Strength calculated?
Bursting strength is calculated by dividing the bursting load (the maximum force registered by the machine) by the thickness of the leather specimen. The result is expressed in pounds per inch (lb/in.) of thickness.
⚡ What is the required cross-head speed for the testing machine?
The testing machine must be operated at a jaw separation speed of 4 ± 1 in./min, which is equivalent to 1.6 ± 0.4 mm/s.
📌 Can this test method be used for wet blue leather?
No, Section 1.1 of the standard explicitly states that this test method does not apply to wet blue. It is intended for light- and medium-weight leathers like shoe uppers and garments.