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D5625-97 – Standard Test Method Technical Guide
📐 Specimen Geometry and Types
This test method determines the average length, width, and squareness of sheets of paper. It is especially useful for printing and writing papers cut to specific sizes, with applicability ranging from dimensions as small as 1.6 in. (41 mm) to as large as 60.2 in. (1530 mm). The procedure ensures accurate and reproducible measurements critical for seamless processing in printing or copying machines.
| 🟦 Property | 📏 Range (in.) | 📐 Range (mm) |
|---|---|---|
| Minimum Dimension | 1.6 | 41 |
| Maximum Dimension | 60.2 | 1530 |
⚙️ Test Procedure and Apparatus
The apparatus features a square or rectangular glass plate larger than the specimen, inscribed with dimension scales photo-engraved in 0.01-in. (0.25-mm) increments. It is housed in a hardwood or rigid frame and back-illuminated by a soft uniform light source. A register bar attached to the frame from the 0.00/0.00 corner aids in accurate sheet positioning for measurement.
| 🎯 Component | ⚡ Specification |
|---|---|
| Scale Increments | 0.01 in. (0.25 mm) |
| Plate Material | Glass |
| Illumination | Back-illuminated soft uniform light source |
| Register Bar | Attached to frame for precise sheet alignment |
🔍 Tip: The equipment can also measure the uniformity of hole punching and various process variables related to sheet cutting.
📊 Key Measured Properties
The test method focuses on measuring the two principal dimensions—length and width—of paper sheets. Accurate sheet dimensions are required for compatibility with printing and copying machines. Additionally, sheet squareness measurements can be performed to assess geometric conformity. The values stated in SI units are regarded as the standard, with inch values provided for reference.
Standard specifications for material, such as cut-sized papers, can be verified using this method. Reference practices like D 585 and D 685 are essential for sampling and conditioning.
💡 Best Practice: Always condition specimens according to Practice D 685 before testing to ensure consistent and reliable results.
❓ Frequently Asked Questions
🔍 What is the dimensional range for measurement?
The test method covers sheet dimensions from 1.6 in. (41 mm) to 60.2 in. (1530 mm).
💡 How is squareness defined in this standard?
Squareness measurements evaluate the geometric conformity of the sheet, ensuring the corners are at right angles.
⚡ What are the key apparatus specifications?
The device uses a glass plate with scales in 0.01-in. (0.25-mm) increments, a back-illuminated light source, and a register bar for sheet positioning.
📌 What referenced standards apply?
Important references include Practices D 585, D 685, Terminology D 1968, and Practice E 122 for sample size estimation.