1、BRITISH STANDARD AEROSPACE SERIES BS EN 2536:1995 Hard anodizing of aluminium alloys The European Standard EN 2536:1995 has the status of a British Standard UDC 669.715.691.5:621-793:629.7BSEN2536:1995 This British Standard, having been prepared under the directionof the Aerospace Standards Policy C
2、ommittee, waspublished under the authorityof the Standards Boardand comes into effect on 15October1995 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference ACE/44 Draft for comment 90/75749 DC ISBN 0 580 23145 3 Cooperating organizations The European Comm
3、ittee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suome
4、n Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazio
5、ne Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Association s
6、uisse de normalisation UnitedKingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBSEN2536:1995 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN 2536 3 National annex NA (informative) Commit
7、tees responsible Inside back cover National annex NB (informative) Cross-references Inside back coverBSEN2536:1995 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Aerospace Standards Policy Committee and is the English language version of EN2536, A
8、erospace series Hard anodizing of aluminium alloys, published by the European Committee for Standardization (CEN). EN2536 was produced as a result of international discussions in which the UnitedKingdom took an active part. A British Standard does not purport to include all the necessary provisions
9、of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2
10、to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2536 August 1995 ICS 49.040.40 Descri
11、ptors: Aircraft industry, metal finishing, aluminium, aluminium alloys, anodizing English version Aerospace series Hard anodizing of aluminium alloys Srie arospatiale Anodisation dure des alliages daluminium Luft- und Raumfahrt Hartanodisieren von Aluminiumlegierungen This European Standard was appr
12、oved by CEN on1995-07-13. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stan
13、dards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to
14、 the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN E
15、uropean Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 Copyright reserved to CEN members Ref. No. EN 2536:1995EEN2536:1995 BSI 11-1999 2 Foreword This European Standard has been prepared by the
16、 European Association of Aerospace Manufacturers (AECMA). After inquiries and votes carried out in accordance with the rules of this Association, this Standard has successively received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its
17、 presentation to CEN. This European Standard shall be given the status of a National Standard, either by publication of an identical text or by endorsement, at the latest by February1996, and conflicting national standards shall be withdrawn at the latest by February1996. According to the CEN/CENELE
18、C Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. Contents Page Foreword 2 1 Sco
19、pe 3 2 Purpose of process 3 3 Influence and limitations of process use 3 4 Normative references 3 5 Definitions 4 6 Classification 4 7 Information for the processor 4 8 Condition of parts prior to processing 4 9 Process schedule 4 10 Machining after anodizing 6 11 Removal of the anodic coating 6 12
20、Required characteristics 6 13 Testing 7 14 Quality assurance 7 15 Health, safety and environmental aspects 8 16 Designation 8 Table 1 6EN2536:1995 BSI 11-1999 3 1 Scope This standard specifies the hard anodizing of aluminium alloys used in aerospace construction. It shall be applicable whenever refe
21、renced. 2 Purpose of process To improve: the resistance to abrasive and erosive wear; the electrical insulation; the thermal insulation. To use the dimensional increase produced by the process for repair of parts out of tolerance on machining or worn in service (special case). 3 Influence and limita
22、tions of process use The anodizing produces an increase: of the dimensions by about50% of the coating thickness; of the surface roughness (factor of1,3 to3,0, if expressed inRa). Anodizing results in a reduction of the fatigue strength which may reach60%. Shot peening before anodizing reduces the ex
23、tent of this reduction. The best results as regards the properties of the anodized layer are obtained on machined surfaces; no grinding before anodizing. Round off sharp corners. Not recommended for use on parts or items where there is a risk of retention of corrosive substances. Avoid anodizing bot
24、h faces on areas with a thicknessk2mm. The thickness of the anodized layer is in general: 304m to1204m for alloys of category1; 304m to604m for alloys of category2. Restrict thickness to254m on the splines and threads. 4 Normative references This European Standard incorporates by dated or undated re
25、ference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorp
26、orated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. ISO 1463, Metallic and oxide coatings Measurement of coating thickness Microscopical method. ISO 2106, Anodizing of aluminium and its alloys Determination of mass per unit area (s
27、urface density) of anodic oxide coatings Gravimetric method. ISO 2360, Non-conductive coatings on non-magnetic basis metals Measurement of coating thickness Eddy current method. ISO 2376, Anodization (anodic oxidation) of aluminium and its alloys Insulation check by measurement of breakdown potentia
28、l. ISO 2859-1, Sampling procedures for inspection by attributes Part1: sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection. ISO 4516, Metallic and related coatings Vickers and Knoop microhardness tests. ISO 9227, Corrosion tests in artificial atmospheres Salt spray tes
29、ts. EN 2000, Aerospace series Quality assurance EN aerospace products Approval of the quality system of manufacturers. EN 2101, Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys. EN 2284, Aerospace series Sulphuric acid anodizing of aluminium and wrought aluminium all
30、oys. EN2536:1995 4 BSI 11-1999 EN 2334, Aerospace series Acid chromate pickling of aluminium alloys 1) . FEDSTD141C:Method6192-1, Abrasion resistance (TABER abraser) 2) . 5 Definitions 5.1 batch unless otherwise specified, it comprises parts of the same nature (form, size, material), treated at the
31、same time in the same bath 5.2 pre-production parts parts representing future production 6 Classification 6.1 Types of anodizing 6.1.1 Type A: unsealed hard anodizing. It provides the maximum wear resistance but does not improve essentially the corrosion resistance. 6.1.2 Type B: sealed hard anodizi
32、ng. It gives a good compromise between wear resistance and corrosion resistance. 6.2 Categories of alloys 6.2.1 Category 1 Alloys containing less than1% of copper. 6.2.2 Category 2 Alloys containing between1% and5% of copper. 7 Information for the processor In addition to the designation, the follow
33、ing information shall be given: the number of the substrate standard and the metallurgical condition of the substrate; areas to be processed; position of electrical contact points or alternatively areas where they are forbidden. The boundary between the masked and processed areas shall be, if possib
34、le, in an area of a geometry change. 8 Condition of parts prior to processing The final heat treatment shall be carried out. 9 Process schedule Unless otherwise specified, the sequence of operations is as follows: masking and mounting of the parts; cleaning; pickling; anodizing; sealing, if necessar
35、y. Information concerning the individual operations is given below: 9.1 Masking and mounting of the parts Masking may be carried out using: 1) In preparation at the date of publication of this standard. 2) This standard is published by: Department of Defense (DOD), the Pentagon, Washington DC20301,U
36、SA.EN2536:1995 BSI 11-1999 5 special varnishes or waxes easily removable by solvents; plugs in suitable material; chromic acid anodizing (EN2101) or sulphuric acid anodizing (EN2284), sealed and completed with wax or varnish. Generally, the anodizing is carried out over the whole surface of the part
37、 and the area intended for hard anodizing is machined to remove the masking anodic coating. The supporting jigs shall be in aluminium alloy or titanium. They shall make effective electrical contact with the parts. 9.2 Cleaning Solvent degreasing with allowed products, followed by alkaline cleaning i
38、s in general sufficient (seeEN2101, AnnexA). 9.3 Pickling Pickling operations are forbidden on parts masked by sealed anodizing without wax or varnish. The pickling shall remove the natural oxides or other contamination not eliminated by the cleaning without altering the specified characteristics. A
39、s a general rule, the pickling is done in a sulphuric-chromic bath according to EN2334. In exceptional cases, for certain alloys in category2, alkaline pickling may be used (seeEN2101, AnnexA). 9.4 Anodizing 9.4.1 Electrolyte Aqueous sulphuric acid solution with or without additional elements. The c
40、oncentration shall not vary by more than 10% from the values specified by the processor. The chloride content shall be less than200mg/l, expressed asNaCl. The aluminium content shall be less than25g/l for the limits of concentration chosen. The water shall have a conductivity ofk1mS/m (measured at t
41、he source of the supply). 9.4.2 Anodizing parameters The anodizing parameters (temperature, voltage, time) shall be suitable for the alloy and the composition of the bath. The treatment temperature may vary from20 C to+15 C, depending on the process. The control systems shall make it possible to ens
42、ure in a strongly and uniformly agitated bath, a tolerance of 2 C. The current used can be: direct; direct with superimposed alternating; alternating; pulsed. 9.5 Sealing When this operation is specified, it shall be carried out in water, without or with inhibitors under the following conditions: 9.
43、5.1 Without inhibitor On making up the bath the conductivity of the water shall be less than1mS/m with a pH between5,5 and7,5 (measured at the source of the supply). Sealing shall be carried out at a minimum temperature of97 C for at least10min. The bath shall be renewed when the conductivity is gre
44、ater than10mS/m. 9.5.2 With inhibitors An inhibitor (e.g. potassium dichromate) shall be added to water with a conductivity1mS/m. The sealing shall be carried out at a minimum temperature of97 C for at least10min. The pH shall be maintained between5,5 and6,9. The concentration of inhibitor shall be
45、established and maintained within limits ensuring the quality defined by this standard.EN2536:1995 6 BSI 11-1999 10 Machining after anodizing If, for certain applications, grinding or honing is necessary, the thickness shall be chosen to take account of it. This shall be indicated in the design docu
46、ments. 11 Removal of the anodic coating The treatment used shall allow to obtain a surface roughness equal to that obtained after normal surface preparation. If necessary, mechanical reworking may be carried out after the purchasers agreement. 12 Required characteristics 12.1 Appearance Acceptable d
47、efects: crazing (checking of micro cracks on the surface); showing up to the grain flow; fissures and cavities on the microscopic scale within the anodic coating. Not acceptable defects: irregularity of colouring on the same part; blistering; flaking; burning; pitting. 12.2 Thickness It shall comply
48、 with the requirements of the design documents. 12.3 Microhardness SeeTable 1, unless otherwise specified. Table 1 For other thickness the microhardness value shall be agreed between the purchaser and processor. 12.4 Abrasion resistance, unsealed condition Unless otherwise specified, the max. mass l
49、osses measured on test pieces hard anodized to(50 5)4m (arithmetic mean of three measurements) under a load of1000g and10000cycles shall be: category 1 : 20mg corresponding to a removal of3,54m; category 2 : 40mg corresponding to a removal of7,04m. 12.5 Electrical insulation Unless otherwise specified, the min. value of the insulation breakdown voltage measured on test pieces hard anodized to(50 5)4m (arithmetic mean of ten measurements) shall be:
