Overview
EN ISO 20567-3:2012 - Paints and varnishes: Determination of stone-chip resistance of coatings - Part 3: Single-impact test with a free-flying impact body (ISO 20567-3:2012) specifies a laboratory method to evaluate the resistance of coatings (particularly automotive finishes) to single stone impacts. The standard defines the test principle, apparatus, test panels, procedure, calibration and evaluation so that results are comparable between laboratories.
Key topics and technical requirements
- Test principle: A single, free‑flying impact body is projected at the coated test panel; damage is quantified by the area of coating removed and, for multi-layer systems, by the layer-by-layer damage.
- Apparatus: Single‑impact tester with an accelerating tube, light‑beam speed measurement, adjustable panel holder and temperature control (−20 °C to +30 °C). Calibration method is described in Annex A.
- Impact body: Hardened steel ball, nominal diameter 2 mm, mass 0.033 g (in accordance with ISO 3290‑1). Each ball is used once.
- Impact parameters: Speed (250 ± 10) km/h [(69.4 ± 2.8) m/s]; impact angle (2.0 ± 0.5)° to the normal.
- Test panels: Steel panels 200 × 100 mm, thickness 0.7–1.0 mm; preparation per ISO 1514; coating thickness measured per ISO 2808.
- Conditioning and temperatures: Panels conditioned at least 16 h at (23 ± 2) °C and (50 ± 5) % RH. Preferred test temperatures: 23 °C, 0 °C and −20 °C.
- Repetitions: At least five test runs on each of two panels (minimum ten impacts per coating).
- Evaluation and reporting: Remove delaminated fragments (e.g., nitrogen jet) and measure damaged area; report layer‑specific damage, test conditions, calibration details and precision information. The standard includes clauses on precision (repeatability and reproducibility).
Applications and users
- Automotive OEMs and suppliers: Assess stone‑chip resistance of clearcoats, basecoats and multi‑layer paint systems during product development and specification.
- Coating manufacturers: Compare formulations, validate improvements and support performance claims.
- Independent test laboratories and quality control: Routine acceptance testing, batch verification and forensic failure analysis.
- R&D and durability engineering: Study temperature effects and impact mechanics on coating adhesion and fracture.
Related standards
Keywords: EN ISO 20567-3:2012, stone‑chip resistance, single‑impact test, free‑flying impact body, paints and varnishes, automotive coatings, test panels, impact speed, coating evaluation.
