EN 4474-2016 pdf download.Aerospace series – Aluminium pigmented coatings Coating methods.
This EN 4474 defines the coating methods and characteristics of aluminium pigmented coatings to EN 4473 which may be applied to fasteners in titanium, titanium alloys, heat resisting nickel base or cobalt base alloys and corrosion resisting steels.
2 Purpose of process
To reduce galvanic corrosion, friction and risk of seizing.
3 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 2516, Aerospace series — Passivation of corrosion resisting steels and decontamination of nickel base alloys
EN 3032, Aerospace series — Test method for dry film lubricants — Thickness measurement
EN 4473, Aerospace series — Aluminium pigmented coatings — Technical specification
EN 9100, Quality Management Systems — Requirements for Aviation, Space and Defence Organizations
EN ISO 1463, Metallic and oxide coatings — Measurement of coating thickness — Microscopical method
EN ISO 2409, Paints and varnishes — Cross-cut test
EN ISO 2431, Paints and varnishes — Determination offlow time by use offlow cups
EN ISO 2884-1. Paints and varnishes — Determination of viscosity using rotary viscometers — Part 1:
Cone-and-plate viscometer operated at a high rate of shear
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
ISO 8080, Aerospace — Anodic treatment of titanium and titanium alloys — Sulphuric acid process
4 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
4.4
scratch
gouged out or scoring of metallic coating
4.5
run
localized excess amount of coating to the extent of creating a drip or running of coating
4.6
indentation
indent or uneven surface thickness (orange peel)
4.7
flaking
particles of coating falling oft due to poor adhesion or excess coating
4.8
crack
separation of coating due to improper mix or poor adhesion of material
4.9
sampling plan
plan according to which one or more samples are taken in order to obtain information and to reach a decision, if possibly
4.10
Acceptable Quality Limit (AQL)
maximum percent defective (or the maximum number of defects per hundred units) that, for purposes of sampling inspection, can be considered satisfactory as a process average
Note I to entry: Variant: quality level which in a sampling plan corresponds to a specifIed but relatively high probability of acceptance.
5 Apparatus
5.1 For application by dipping
Container with a lid, stirring device and temperature control.
The apparatus shall be capable of applying the specified thickness, for example by controlling the speed of immersion and removal and by draining or centrifuging the parts.
5.2 For application by spraying
A dry, oil free air fed gun shall be used, with settings adapted to the characteristics of the aluminium pigmented coating used and to the shape of the parts to be coated.
Preferably a mechanical stirring device in the reservoir.
NOTE 1 A device allowing for rotation of the parts to be coated and the automatic displacement of the gun will give a more uniform application.
NOTE 2 Use of an aerosol spray is not suitable as it does not always ensure acceptable reproducibility.
5.3 For curing
An oven capable of curing temperatures prescribed by the coating manufacturer and controlled by periodical calibration,
6 Information for the processor
The following information is to be given:
designation of the aluminium pigmented coating to EN 4473;
— percentage of solvent plus reference of the solvent product;
— number of the material standard and metallurgical condition of the latter;
— areas to be processed;
— thickness of the pigmented coating, if necessary, (see Table 1);
— duration and temperature of curing.
7 Surface roughness of parts prior to application
It shall be specified on the drawing or in the definition documents.
NOTE The surface roughness is an important factor affecting adhesion and behaviour of the coating in service.
8 Surface preparation
8.1 Parts in titanium and titanium alloys.EN 4474-2016 pdf download.