SAE J400-2022 PDF

Full title and description

SAE J400 (J400_202208) — Test for Chip Resistance of Surface Coatings. This SAE Recommended Practice (revised August 26, 2022) specifies a laboratory gravelometer procedure to evaluate the resistance of organic surface coatings and coating systems to chipping caused by gravel or other projectiles; the method is intended primarily for flat test panels but may be applied to finished parts when interpreted with the document’s limitations and intent.

Abstract

Provides a controlled test method that reproduces the effect of gravel or road debris striking exposed paint or coated surfaces of vehicles. The standard describes equipment, test-panel preparation, test conditions (including temperature options), gravel/media specification, test execution, a gravelometer rating system, precision, and reporting requirements. It is intended for use by coating laboratories, OEM specification writers, and quality/control testing facilities.

General information

• Status: Revised (current 2022 revision).
• Publication date: August 26, 2022.
• Publisher: SAE International (formerly Society of Automotive Engineers).
• ICS / categories: 25.220 — Surface treatment and coating (notably organic coatings 25.220.60).
• Edition / version: J400_202208 (revision of J400_201210).
• Number of pages: 12 pages (recommended-practice document).

Scope

Defines a laboratory procedure using a gravel-projecting device (gravelometer) to assess chip/stone-impact resistance of organic surface coatings and coating systems. The scope covers test apparatus, media preparation, mounting and conditioning of panels (including low-temperature testing options), impact parameters, post-test evaluation (including adhesive tape checks and rating), statistical precision and reporting format. The method is principally for flat test panels but notes possible extension to finished parts with appropriate interpretation.

Key topics and requirements

• Gravelometer test apparatus design and operational parameters (air pressure, feed rate, nozzle geometry, mounting fixtures).
• Specification and preparation of impact media (standardized gravel/rock fraction and conditioning).
• Panel preparation, surface system definition, and conditioning (ambient and low-temperature options).
• Test execution: number of shots, exposure time, and reproducible test set-up to simulate field damage.
• Post-impact evaluation: gravelometer rating system, loose-coating removal checks (adhesive tape method), and photographic or tabular reporting of results.
• Precision, repeatability guidance, and recommended test reporting elements to support comparison and specification compliance.

Typical use and users

Used by automotive OEM paint and coatings engineers, paint formulators, independent test laboratories, supplier quality teams, and compliance/validation groups to evaluate stone-chip resistance during development, quality control, and specification verification. Also used by third-party test houses that perform OEM or aftermarket component testing. Typical applications include automotive exterior panels, coated plastic parts, and comparative evaluation of clearcoats, basecoats, and protective films.

Related standards

Closely related and often cross-referenced test methods and specifications include ASTM D3170 (standard test method for chipping resistance/stone-chip testing), DIN / ISO gravel/stone-impact standards (for example DIN EN ISO 20567 series), and various OEM gravel/stone-chip specifications (Ford, GM, VW, BMW and others). These documents describe comparable gravelometer approaches and OEM-specific parameter sets.

Keywords

gravelometer; stone-chip; chip resistance; surface coatings; paint testing; SAE J400; gravel impact; chip rating; coating durability; automotive coatings; test procedure.

FAQ

Q: What is this standard?

A: SAE J400 (J400_202208) is a recommended-practice test method that defines a gravelometer procedure to evaluate the chip (stone/ gravel) resistance of surface coatings, primarily for automotive applications.

Q: What does it cover?

A: It covers apparatus requirements, impact media, panel preparation, test conditions (including optional low-temperature testing), test execution, a gravelometer rating system, precision and reporting requirements. The method is intended to reproduce field-like stone-impact damage in a laboratory setting.

Q: Who typically uses it?

A: Automotive OEM engineers, paint/coating formulators, supplier quality teams, independent and contract test laboratories, and standards/specification writers use it for development, QC and compliance testing.

Q: Is it current or superseded?

A: The current revision is the August 26, 2022 revision (J400_202208), which revises the prior 2012 edition (J400_201210). As of the 2022 revision the document is published as a revised SAE recommended practice.

Q: Is it part of a series?

A: J400 is part of SAE’s materials/test-methods collection addressing coatings and durability testing; it is commonly referenced together with related SAE, ASTM and ISO/DIN methods that address coatings performance and environmental/impact testing. Specific OEM gravel/stone-chip specifications often reference or adapt the J400 approach.

Q: What are the key keywords?

A: gravelometer, stone-chip resistance, chip testing, coating durability, gravel impact, SAE J400, chip rating.