1、BRITISH STANDARD BS3520:1962 Specification for Dental wrought precious metal alloy wireBS3520:1962 This BritishStandard, having been approved by the Dental Industry Standards Committee and endorsed by the Chairman ofthe Chemical Divisional Council, was published under theauthority of the General Cou
2、ncil on 13June1962 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference DNC/1 and DNC/1/3 Draft for comment AB(DNC)6247 ISBN 0 580 03632 4 Co-operating organizations The Dental Industry Standards Committee, under whose supervision this BritishStandard was
3、prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty* Association of Dental Hospitals of Great Britain and Northern Ireland* British Dental Association* British Dental Manufacturers Association* Dental Education Adviso
4、ry Council* Department of Health for Scotland* D.S.I.R.National Engineering Laboratory* Ministry of Health* Royal College of Surgeons of England Royal Society of Medicine The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with t
5、he following, were directly represented on the committee entrusted with the preparation of this standard: Air Ministry British Surgical Trades Association (Inc.) Institute of British Surgical Technicians (Dental Section) Institute of Dental Surgery Iron and Steel Institute London Dental Study Club W
6、ar Office Amendments issued since publication Amd. No. Date CommentsBS3520:1962 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Composition 1 3 Condition 1 4 Tensile properties 1 5 Freedom from defects 2 6 Designation of wire size 2 7 Information to
7、be provided by the manufacturer or vendor 2 8 Marking 2 Table 1 Composition of types A and B dental wrought precious metal wire 1 Table 2 Tensile properties of dental wrought precious metal alloy wire 2BS3520:1962 ii BSI 12-1999 Foreword This standard makes reference to the following BritishStandard
8、: BS18, Tensile testing of metals. The preparation of this BritishStandard was authorized by the Dental Industry Standards Committee and forms one of a series applying to dental materials, including cobalt chromium casting alloys, gold casting alloys and gold solders. Two types of wrought precious m
9、etal alloy wire have established use in dental practice, the alloy containing not less than15percent of gold (type B) tending to be more subject to discoloration and tarnishing, depending on the clinical conditions, than the alloy containing not less than33percent of gold (type A). There also tends
10、to be less latitude in heat treatment for the type B alloy than the type A alloy. The committee responsible for the preparation of this BritishStandard considered, however, that the properties of the two types of alloy were well known to the dental profession and that there existed a need for the tw
11、o types of materials to be specified in this BritishStandard. Because of the advantages of dental wrought precious metal alloy wire being supplied in the annealed condition, this has been specified unless for special purposes the purchaser requires the material to be in a hardened condition. It is a
12、lso required that the manufacturer should make available instructions for proper heat treatment. The specification of tensile properties has been restricted to specimens of round cross-section since it has not proved practicable to deal with the tensile requirements of wire of different cross-sectio
13、n. Although it was considered impracticable to specify a range of wire sizes in the first edition of this BritishStandard, it is hoped that as a result of the recommendations made in the Note to Clause6, it will be possible for the present multiplicity of sizes to be simplified in future. Considerat
14、ion will be given to the specification of wire sizes for a subsequent revision of this standard. NOTE 1Where metric equivalents are stated, the figures in British units are to be regarded as the standard. The metric conversions are approximate. More accurate conversions should be based on the tables
15、 in BS350, “Conversion factors and tables”. NOTE 2In place of the customary, but incorrect, use of the pound and kilogramme as units of force, the units called pound-force (abbreviation lbf) and kilogramme-force (abbreviation kgf) have been used in this standard. These are the forces which, when act
16、ing on a body of mass one pound or onekilogramme respectively, give it an acceleration equal to that of standard gravity. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance wi
17、th 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, pages1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. T
18、his will be indicated in the amendment table on the inside front cover.BS3520:1962 BSI 12-1999 1 1 Scope This BritishStandard specifies requirements for dental wrought precious metal alloy wire as follows: Type A, containing not less than33percent by weight of gold; Type B, containing not less than1
19、5percent by weight of gold. 2 Composition The composition of the wire shall be in accordance with Table 1. Table 1 Composition of types A and B dental wrought precious metal wire 3 Condition The material shall be supplied in the annealed condition unless otherwise specified by the purchaser. 4 Tensi
20、le properties a) Preparation of test specimens. Test specimens of the alloy shall be of round cross-section of1.0 0.2mm diameter. The specimens shall be in accordance with BS18 1) . They shall have a gauge length of2in(50.8mm) and, for the determination of permanent set and tensile strength, shall b
21、e hardened by heat-treatment in accordance with the manufacturers instructions. b) Tensile requirements. The tensile properties of two test specimens as determined by the methods described in BS18 1)and in the following shall be in accordance with Table 2. Should a test specimen fail to meet the req
22、uirements, a further two specimens shall be tested. The material shall be considered satisfactory only if both re-test specimens satisfy the requirements. i) Permanent set. For the determination of permanent set, an initial load calculated to produce20000lbf/in 2 (1400kgf/cm 2 ) stress shall be appl
23、ied to the hardened specimen following which a gauge reading shall be taken. The specimen shall then be loaded at a rate of200 50lbf/min(90.7 22.7kgf/min) to a stress of90000lbf/in 2 (6328kgf/cm 2 ) and the load maintained for one minute. The load shall then be slowly reduced to the initial value ca
24、lculated to produce a stress of20000lbf/in 2 (1400kgf/cm 2 ) and a second gauge reading taken. The difference between the two gauge readings shall not exceed0.0010inch per inch of gauge length. An averaging strain gauge shall be used and the values shall be recorded to0.0001in(0.0025mm). ii) Tensile
25、 strength. After the determination of permanent set, the specimens shall be reloaded at a rate of200 50lbf/min(90.7 22.7kgf/min) until rupture occurs. iii) Elongation. Elongation shall be determined on the specimens of the alloy that have been annealed by heat-treatment in accordance with the manufa
26、cturers instructions. Should a test piece break outside the gauge length resulting in an elongation below the value specified, the test piece may be discarded and another test made from a fresh test piece. Material Type A Type B Gold and metals of platinum group Gold Base metal Silver Weight percent
27、 65minimum 33minimum (not specified) (not specified) Weight percent 40minimum 15minimum 20maximum Balance NOTEMetals of the platinum group comprise the following: ruthenium rhodium palladium osmium iridium platinum 1) BS18, “Tensile testing of metals”.BS3520:1962 2 BSI 12-1999 Table 2 Tensile proper
28、ties of dental wrought precious metal alloy wire 5 Freedom from defects The wire shall be free from imperfections which have a deleterious effect on the appearance or serviceability in dental use. 6 Designation of wire size The nominal wire size shall be designated by the cross-sectional dimensions
29、expressed in millimetres. The dimensions of the wire shall be subject to a tolerance of3percent on the nominal size. NOTEAs a first step towards simplification of the multiplicity of sizes which have been introduced in the past, it is recommended that the range of nominal sizes of dental wrought pre
30、cious metal alloy wire should be taken from an arithmetic series of dimensions starting from0.5mm and having a common difference of0.1mm, e.g.0.5mm,0.6mm,0.7mm, etc. Subsequent consideration is to be given to the introduction of a preferred range of sizes when further experience has been gained of t
31、he use of the sizes included in the recommended series of dimensions. 7 Information to be provided by the manufacturer or vendor The manufacturer or vendor shall publish instructions for heat treatment of the material. 8 Marking Each package of wire shall be clearly marked with the following: a) The
32、 name or trade mark of the manufacturer or vendor; b) Weight of the contents; c) Cross-sectional dimensions in accordance with Clause6; d) The solidus temperature; e) The number of this BritishStandard, i.e.BS3520. NOTEThe mark BS3520 on the product is a claim by the manufacturer that it complies wi
33、th the requirements of the standard. The BritishStandards Institution is the owner of the registered certification trade mark shown below. This mark can be used only by manufacturers licensed under the certification mark scheme operated by the BSI. The presence of this mark on a product is an assura
34、nce that the goods have been produced to comply with the requirements of the BritishStandard under a system of supervision, control and testing operated during manufacture and including periodical inspections at the manufacturers works in accordance with the certification mark scheme of the BSI. Fur
35、ther particulars of the terms of licence may be obtained from the Director, BritishStandards Institution,2Park Street, London,W.1. Test Condition Requirement Permanent set Tensile strength Elongation(2in gauge length) hardened hardened annealed 0.0010inch per inch maximum as determined in accordance
36、 with Clause4 bi) 135000lbf/in 2 (9491kgf/cm 2 )minimum 15percent minimumblankBS3520:1962 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the
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