Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5171-15 – Standard Test Method Technical Guide
ASTM Designation D5171-15 (Reapproved 2020) defines the standard test method for evaluating the impact resistance of plastic sew-through buttons. This procedure is critical for quality assurance in the textile and apparel industry, ensuring buttons can withstand the mechanical stresses of assembly and end use.
📐 Specimen Geometry and Classification
This test method applies strictly to plastic sew-through flange buttons. Key dimensional parameters influencing performance include the face diameter (expressed in ligne size), overall thickness, and the number and spacing of sew-through holes. Prior to testing, all specimens must be conditioned in accordance with Practice D618. Definitions for standard terms such as “button” and “face” are provided in Terminology D2050.
⚙️ Test Procedure and Impact Parameters
Individual conditioned buttons are centered on a solid anvil beneath a vertical drop tube. A preselected mass is released from a preselected height specific to the button’s ligne size. Following the impact, the button is retrieved and carefully examined under 5X magnification for any evidence of breakage, cracking, or chipping. The method specifies values in both metric and imperial units, which must be used independently.
| 🟦 Size Class | 📏 Ligne Range | 📐 Drop Height (mm / in) | ⚡ Mass (g / lb) | 🎯 Pass Criterion |
|---|---|---|---|---|
| Small | Up to 24 | 600 mm (23.6 in) | 200 g (0.44 lb) | No cracks / chips |
| Medium | 28 – 36 | 900 mm (35.4 in) | 300 g (0.66 lb) | No cracks / chips |
| Large | 40 – 48 | 1200 mm (47.2 in) | 300 g (0.66 lb) | No cracks / chips |
| X-Large | 54 & above | 1500 mm (59.1 in) | 400 g (0.88 lb) | No cracks / chips |
Note: The specific drop height and impact mass depend on the button ligne classification as defined by the standard.
⚠️ Thermal Effect Warning (Note 1)
Buttons may successfully pass this ambient temperature impact test but subsequently fail during garment pressing. The introduction of heat during pressing can significantly reduce the plastic resin’s ability to resist impact-related failure and is not evaluated by this method.
📊 Significance, Use, and Bias Assessment
Test Method D5171 is suitable for the acceptance testing of commercial shipments of plastic buttons. The ability of a button to resist impact is influenced by its resin formulation, shape, ligne size, thickness, and hole configuration. When reporting results, specifically for inter-laboratory comparisons, the probability of statistical bias must be addressed using competent statistical assistance.
💡 Inter-Laboratory Statistical Protocol
If a statistical bias is identified between laboratories, Section 5.1.1 mandates comparative testing using homogeneous samples and an unpaired statistical test at a predetermined probability level to resolve the discrepancy.
❓ Frequently Asked Questions
🔍 What constitutes a test failure in this method?
Any visible breakage, cracking, or chipping observed under the required 5X magnifying glass immediately following the impact constitutes a failure.
💡 Why are hole spacing and thickness critical factors?
The standard specifically identifies these geometric variables, alongside resin formulation and shape, as primary influencers of impact resistance. Improper hole spacing or inconsistent thickness can act as stress concentrators during the impact event.
⚡ Can a button pass this test but still fail in production?
Yes, the standard explicitly notes that a button may pass the ambient impact test but fail during garment pressing due to the softening effect of heat, which is not a factor in this ambient test method.
📌 Why is 5X magnification specified for inspection?
Micro-cracks and small chips can be invisible to the naked eye but may propagate during use. Standardized 5X magnification ensures consistent and reliable detection of such structural damage across all testing facilities.