Technical Guide for Hairiness Tester Procurement: The Fundamental Divide Between Optical vs. Capacit

In yarn hairiness detection, the core principle differences between optical and capacitive methods dictate their application boundaries. Optical systems quantify surface hairiness via light scattering/projection imaging:

• Laser Scattering Method: Emits parallel laser beams onto yarn, captures scattered light signals via photodiode arrays, and calculates hairiness density (H-value) with ±0.1 hairs/cm precision. Ideal for smooth filaments (e.g., synthetics).

• Projection Counting Method: Uses high-resolution CCD cameras for vertical yarn imaging, identifying hairs ≥3mm via algorithms (miss rate <2%). Tailored for short-staple yarns (cotton/linen/wool).

Capacitive methods rely on dielectric constant measurement: They detect mass variations (unevenness) but physically cannot sense surface hairiness—micron-level fibers negligibly affect dielectric properties. Using capacitive devices for hairiness testing yields invalid data.

Core Parameter Matrix:

Procurement Checklist: 

1.  Optical Module Certification: Verify compliance with ISO 16532-2 (laser) or ASTM D5647 (projection).

2.  Calibration Traceability: Demand NIST/CNAS certificates (laser wavelength tolerance ≤±5nm; CCD resolution ≥5μm).

3.  Software Algorithm: Ensure hair-yarn separation tech (prevents misinterpreting yarn body shadows as hair).

4.  Environmental Robustness: Confirm temperature-controlled sealed chambers (±1°C fluctuation causes ±8% H-value error).

Critical Technical Warning:
Capacitive devices claiming "hairiness detection" fraudulently reinterpret unevenness signals as hair data—violating GB/T 3292.1 fundamentals. Adhere to the iron rule: "Optics or Nothing" to avoid technical fallacy.

Tags: Yarn and feathers, capacitance method, optical method