ISO 20567-4:2023

INTERNATIONAL ISO
STANDARD 20567-4
First edition
2023-03
Paints and varnishes — Determination
of stone-chip resistance of coatings —
Part 4:
Mobile multi-impact testing on a small
testing area
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus and test equipment . 2
5.1 Stone-chip resistance tester . 2
5.2 Consumables . . . 5
5.2.1 Chilled-iron grit . 5
6 Apparatus functional test . 6
7 Procedure .6
8 Ev a luat ion . 7
9 Test report . 8
Annex A (normative) Pictorial reference standards for evaluating stone-chip resistance.9
Annex B (informative) Examples of suitable methods for removing loose coating .10
Bibliography .11
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes.
A list of all parts in the ISO 20567 series can be found on the ISO website.
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iv
Introduction
The stone-chip resistance of the body finish is an important quality characteristic. A standard
procedure for testing this characteristic is the method according to ISO 20567-1, which is performed
with a stationary tester on a large test area. The method described here can be used in mobile form.
v
INTERNATIONAL STANDARD ISO 20567-4:2023(E)
Paints and varnishes — Determination of stone-chip
resistance of coatings —
Part 4:
Mobile multi-impact testing on a small testing area
1 Scope
This document specifies a mobile method for evaluating the resistance of automotive finishes to chilled-
iron grit projected onto the surface under test to simulate the effect of stone chipping.
Results from the test specified in this document are not comparable with results specified in
ISO 20567-1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes
of openings
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 4618, Paints and varnishes — Vocabulary
ISO 11124-2, Preparation of steel substrates before application of paints and related products —
Specifications for metallic blast-cleaning abrasives — Part 2: Chilled-iron grit
ISO 11125-2, Preparation of steel substrates before application of paints and related products — Test
methods for metallic blast-cleaning abrasives — Part 2: Determination of particle size distribution
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The stone-chip resistance of the coating is tested with many small, sharp-edged impact bodies, which
impact in portions and are largely independent of one another. The material used in the test is chilled-
iron grit, which is projected onto the coating at an angle of 90° using compressed air. The extent of the
damage depends on the working pressure, the grit, the projection duration and the design of the tester.
Loose fragments of coating material are removed. The degree of damage is evaluated by comparison
with pictorial reference standards.
5 Apparatus and test equipment
Ordinary laboratory apparatus, together with the following shall be used.
5.1 Stone-chip resistance tester
5.1.1 Tester including pressure regulator, hoses, connections and connection adapters (see Figures 1
and 2).
The dosing device shall be designed such that chilled-iron grit for the test (see 7.2) can be delivered in
(10 ± 1) s.
The compressed air supply for the tester (compressed air line system or compressor) shall have an oil
separator and water separator and shall meet the following requirements:
— output pressure min. 400 kPa;
— inner diameter of the connection hose min. 9,52 mm (3/8 inch);
— the connection hose between the compressed air supply and the tester shall be dimensioned (inside
diameter, length) such that the correct working pressure can be set (see 6.1).
Key
1 sample
2 projection window
3 a
...