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D1447-07 – Standard Test Method Technical Guide
📐 Test Method Scope and Applicability
ASTM D1447-07 (Reapproved 2021) establishes a photoelectric test method for measuring the length and length uniformity of cotton fibers. The method applies to fibers from raw or partially processed cotton, including card mat and some cotton waste, but excludes blends with other fibers, reclaimed fibers from yarns or fabrics, and 100% synthetic fibers. Values are reported in SI units, and users must address safety, health, and environmental practices per local regulations.
The standard is specifically designed for use with Digital Fibrograph models, ensuring consistent results for acceptance testing when laboratory levels are controlled using identical reference cotton standards. For comparative testing, statistical analysis is recommended to detect bias between laboratories.
⚙️ Test Procedure and Key Parameters
Fibers are arranged on combs to form a beard, with fibers caught at random points along their lengths. The beard is then scanned photoelectrically from base to tip. The amount of light transmitted through the beard provides a measure of the number of fibers extending at each distance from the combs. The Fibrograph displays both the cumulative fiber amount and length readings from the fibrogram on separate dials.
💡 Tip: Condition test specimens according to Practice D1776 in a standard atmosphere before measurement to ensure accurate and reproducible results. Proper sampling per D1441 is also critical.
Detailed instructions for manual and servo models were included in earlier editions of this standard; refer to current documentation for digital equipment setup.
📊 Key Measured Properties and Standards
The standard defines essential parameters for fiber length analysis. The table below summarizes relevant terminology from Terminology D7139.
| 🟦 Term | 📏 Description |
|---|---|
| Fibrogram | Graphical representation of fiber length distribution |
| Mean Length | Average length of all fibers in the sample |
| Uniformity Index | Ratio of mean length to upper-half-mean length |
| Upper-Half-Mean Length | Average length of the longer half of fibers |
Referenced ASTM standards support the method, as listed below.
| 🟦 Standard | 📏 Title |
|---|---|
| D123 | Terminology Relating to Textiles |
| D1440 | Length and Length Distribution of Cotton Fibers (Array Method) |
| D1441 | Sampling Cotton Fibers for Testing |
| D1776 | Conditioning and Testing Textiles |
| D3025 | Standardizing Cotton Fiber Test Results using Calibration Cotton Standards |
| D7139 | Terminology for Cotton Fibers |
⚠️ Note: For complete terminology, consult Terminology D7139 for cotton fibers and D123 for general textile terms. This standard does not cover synthetic fibers or blends.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D1447-07?
It specifies a photoelectric method for measuring the length and length uniformity of cotton fibers from raw or partially processed cotton, excluding blends and synthetics, using the Digital Fibrograph.
💡 How is the test performed?
Fibers are combed into a beard and scanned photoelectrically. Light transmission indicates the number of fibers at various distances from the combs, yielding length data.
⚡ What equipment is required?
The test uses a Digital Fibrograph for photoelectric measurement. Proper conditioning per D1776 and sampling per D1441 are necessary.
📌 What key measurements are obtained?
Primary measurements include mean length, upper-half-mean length, and uniformity index, which describe fiber length distribution and uniformity.