1、BRITISH STANDARDBS EN 2786:2008Aerospace series Electrolytic silver plating of fastenersICS 49.030.01g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g5
2、8BS EN 2786:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2008 BSI 2008ISBN 978 0 580 60314 3National forewordThis British Standard is the UK implementation of EN 2786:2008.The UK participation in its preparation was entrusted
3、to Technical Committee ACE/12, Aerospace fasteners and fastening systems.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct ap
4、plication.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 2786March 2008ICS 49.030.01English VersionAerospace series - Electrolytic silver plating of fastener
5、sSrie arospatiale - Argentage lectrolytique des lmentsde fixationLuft- und Raumfahrt - Elektrolytisches Versilbern vonVerbindungselementenThis European Standard was approved by CEN on 12 December 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the condi
6、tions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three o
7、fficial versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria
8、, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE
9、FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 2786:2008: E2 Contents Page Foreword3 1 Scope
10、4 2 Normative references 4 3 Purpose of process .4 4 Technical requirement 4 5 Required characteristics.5 6 Classification of tests6 7 Quality assurance6 BS EN 2786:20083 Foreword This document (EN 2786:2008) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardi
11、zation (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Services of the member countries of ASD, prior to its presentation to CEN. This European Standard shall be
12、given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2008, and conflicting national standards shall be withdrawn at the latest by September 2008. Attention is drawn to the possibility that some of the elements of this docum
13、ent may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: A
14、ustria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN
15、2786:20084 1 Scope This standard specifies the electrolytic silver plating of fasteners used in aerospace applications. It shall apply whenever referenced. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the
16、 edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 2828, Aerospace series Adhesion test for metallic coatings by burnishing. EN 2830, Aerospace series Adhesion test for metallic coatings by shearing action. EN 2831, Ae
17、rospace series Hydrogen embrittlement of steels Test by slow bending. EN 2832, Aerospace series Hydrogen embrittlement of steels Notched specimen test. EN 9100, Aerospace series Quality management systems Requirements (based on ISO 9001:2000) and Quality systems Model for quality assurance in design
18、, development, production, installation and servicing (based on ISO 9001:1994). 3 Purpose of process To prevent galling or seizure. 4 Technical requirement 4.1 Preparation Parts shall have chemically and/or electrolytically clean surfaces prepared with minimum abrasion, erosion or pitting, prior to
19、immersion in the plating solution. Treatments which may produce hydrogen embrittlement shall be avoided. After cleaning and prior to immersion in the plating solution, parts may be etched in a suitable solution such as ferric chloride and/or hydrochloric acid, to promote adhesion. Electrical contact
20、 between the parts and the power source shall be established in such a manner as to ensure that neither chemical/immersion deposition nor electrical arcing or overheating will occur. 4.2 Procedure The parts shall be silver plated over a suitable nickel and/or silver strike by an approved method to t
21、he thickness quoted in the product standard or in the definition document. The plated parts shall be removed from the plating solution then thoroughly rinsed and dried. BS EN 2786:20085 5 Required characteristics 5.1 Appearance The silver plate shall be sound, smooth, continuous, uniform in color an
22、d free from blisters and other imperfections (see 5.4.2). Abrasion of plating on corners and edges of threaded fasteners is acceptable, but plate shall be continuous on the threads. Marking of the cone section of self-locking nuts, produced in off-setting the locking beams or other deformation, is a
23、cceptable. 5.2 Composition Silver as plated shall be not less than 99,9 % pure, the process of plating shall be controlled to produce this purity. 5.3 Post treatments De-embrittlement is mandatory on martensitic steel where the tensile strength can exceed 1 100 MPa. De-embrittlement, where applicabl
24、e, shall be carried out as soon as possible, but no later than 16 h after plating, the time and temperature are optional. Where de-embrittlement is specified, the parts or test pieces shall be tested to EN 2831 or EN 2832 or parts shall be subjected for 200 h at ambient temperature to an axial load
25、equal to 75 % of the tensile strength of the part and must show satisfactory results. No fracture is permissible before 200 h. 5.4 Adhesion 5.4.1 General To be checked on parts or test pieces. These parts or test pieces shall be heated in air to the following applicable temperature held at temperatu
26、re within 8 C for no less than two hours and cooled in still air. a) Parts with a maximum test temperature of up to and including 425 C: The temperature of any de-embrittlement shall be considered sufficient. If no de-embrittlement is carried out, the temperature shall be the maximum test temperatur
27、e of the parts. b) Parts with a maximum test temperature of more than 425 C: The temperature shall be the maximum test temperature of the parts. 5.4.2 Adhesion requirements After heating, parts or test pieces shall be visually examined at 10 times magnification. Parts shall be free of detrimental bl
28、isters and of indications of poor bond such as flaking and lifting of the plating. Some small blisters are acceptable provided the parts meet the adherence requirements. Blisters 0,38 mm and larger in diameter, are not acceptable. After visual examination, the parts or test pieces shall be subjected
29、 to one of the following adhesion tests, EN 2828, EN 2830 or any other adhesion test that is agreed. BS EN 2786:20086 6 Classification of tests 6.1 Acceptance tests The following tests shall be carried out on each lot: a) Appearance (see 5.1); b) Thickness (as defined on the product standard or defi
30、nition document) to be measured by an agreed method; c) Adhesion (see 5.4, 5.4.2). NOTE A lot shall be all parts of the same size and shape, made of the same alloy, plated to the same thickness in the same set of solutions within one 24 h period. 6.2 Periodic tests The following tests shall be perfo
31、rmed at a frequency selected by the process controller: a) Composition (see 5.2); b) Post treatments (see 5.3). 7 Quality assurance EN 9100. BS EN 2786:2008blankBS EN 2786:2008BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible for p
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