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D5458-95 – Standard Test Method Technical Guide
📐 Scope, Terminology, and Significance
The ASTM D5458‑95 (Reapproved 2020) standard provides a test method for quantifying the peel cling of stretch wrap film. Cling is defined as the property of a material’s ability to adhere to itself. This characteristic is essential for stretch wrap materials, which elongate under tension and conform to packaged items through elastic recovery.
This test method directly measures cling between two layers of film, evaluated in both a stretched and an unstretched condition. As stated in the standard, “cling is of critical importance in maintaining a tight wrap after a load is stretch wrapped.” The scope applies to films used in unitizing pallet loads, and the results are expressed in inch‑pound units.
⚙️ Apparatus and Material Specifications
Conducting the test requires a universal testing machine with a constant rate of grip separation and several specialized components. The table below summarizes the key specifications for the required apparatus.
| 🛠 Component | 📏 Specification (per D5458) |
|---|---|
| Load Cell Capacity | 500‑g |
| Precision Sample Cutter | 1 ± 0.001 in. (25.4 ± 0.03 mm) |
| Sample Template (Inside Dimensions) | 5 × 20 in. (125 × 500 mm) |
| Rubber‑Faced Jaw Grip | 1 × 1.5 in. (25 × 38 mm) |
| Pneumatic Air Supply (if used) | 60 to 70 psi (with appropriate filter) |
| Separation Paper | 8.5 × 12 in. (approx. 125 × 280 mm) bond |
⚠️ Units Standardization: The standard explicitly states that values in inch‑pound units are regarded as the standard. SI values in parentheses are mathematical conversions provided for information only and are not considered standard.
📊 Understanding the Peel Cling Test Method
The procedure is a straightforward peel cling test. A 1 in. (25 mm) wide film strip is first adhered to a flat film specimen attached to a specialized inclined surface (the cling attachment). The universal testing machine then measures the force required to remove or peel the film strip from the flat film.
To ensure accurate and reproducible results, the test relies on standardized preparation techniques. Samples are cut using a picture‑frame template with inside dimensions of 5 by 20 in. (125 by 500 mm) and a precision cutter yielding a 1 in. ± 0.001 in. strip. A lightweight jaw equipped with rubber‑faced grips secures the strip, and a 500‑g load cell records the force during separation.
| 📄 Referenced Standard | 📚 Purpose in Context of D5458 |
|---|---|
| D996 | Provides general terminology for packaging and distribution environments. |
| D4332 | Establishes standard conditioning practices for test specimens. |
| E122 | Practice for calculating sample size to estimate average characteristics. |
💡 Conditioning for Accuracy: Adherence to Practice D4332 is critical for conditioning the film samples prior to testing. Consistent temperature and humidity levels help minimize variations in cling properties and ensure repeatable force measurements across different laboratories or production lots.
❓ Frequently Asked Questions
🔍 What is the specific width of the film strip used in the D5458 peel cling test?
The standard calls for a film strip that is exactly 1 in. (25 mm) wide. It is cut using a precision sample cutter that ensures a width of 1 ± 0.001 in. (25.4 ± 0.03 mm).
💡 What load cell capacity is required for this test method?
The test apparatus must be equipped with a load cell having a 500‑g load capacity to accurately measure the low forces involved in peeling the film strip from the flat surface.
⚡ What is the primary significance of “cling” in stretch wrap applications?
As noted in the standard, cling is of