1、BRITISH STANDARD BS7752-2: 1994 Free running type wire thread inserts Part 2: Specification for ISO metric fine pitch threads UDC 621.882.082.1BS7752-2:1994 This British Standard, having been prepared under the directionof the General Mechanical Engineering Standards Policy Committee, waspublished u
2、nder the authorityof the Standards Board and comesinto effect on 15 October1994 BSI08-1999 The following BSI references relate to the work on this standard: Committee referenceGME/9 Draft for comment92/84541 DC ISBN 0 580 23315 4 Committees responsible for this British Standard The preparation of th
3、is British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical CommitteeGME/9, upon which the following bodies were represented: BEAMA Ltd. British Constructional Steelwork Association Ltd. British Industrial Fasteners Federation British Steel
4、 Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association Society of Motor Manufacturers and Traders Ltd. Washer Manufacturers Association of Great Britain The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Defence Ma
5、nufacturers Association General Municipal Boilermaker and Allied Trades Union Screw Thread Tool Manufacturers Association Society of British Aerospace Companies Ltd. Amendments issued since publication Amd. No. Date CommentsBS7752-2:1994 BSI 08-1999 i Contents Page Committees responsible Inside fron
6、t cover Foreword ii 1 Scope 1 2 References 1 3 Dimensions 1 4 Material 1 5 Finish 1 6 Insert selection 1 7 Installation 1 8 Marking 6 Annex A (informative) Insert selection 7 Figure 1 Insert wire profile in finished coiled state 2 Figure 2 Dimensions of insert in free (unfitted) state 4 Figure 3 Ins
7、ert in fitted state 5 Table 1 Dimensions of insert wire profile in finished coiled state 2 Table 2 Dimensions of insert in free (unfitted) state 3 Table 3 Insert fitted length 5 Table A.1 Recommended nominal lengths of insert to be inserted into a material of a given shear strength that can be used
8、with a bolt of a certainproperty class 7 List of references Inside back coverBS7752-2:1994 ii BSI 08-1999 Foreword This Part of BS7752 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. It is a Part of a series for free running wire thread inserts
9、. BS7752-1 provides a specification for ISO metric coarse pitch threads. 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 with a British Standard does not of itself confer i
10、mmunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 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
11、amendment table on the inside front cover.BS7752-2:1994 BSI 08-1999 1 1 Scope This Part of BS7752 specifies requirements for free running wire thread inserts which, when fitted into an appropriately prepared hole, will: a) provide ISO metric fine pitch female threads of tolerance class5H or6H with s
12、izes from M8 1 to M24 2 inclusive; b) accept ISO metric male threads conforming to BS3643-1:1981 and BS3643-2:1981; c) operate successfully in the temperature range50 C to+300 C. NOTEISO metric MJ male threads conforming to BS6293-1 and BS6293-2 may be used with these inserts. 2 References 2.1 Norma
13、tive references This Part of BS7752 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited
14、applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS7752 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative refere
15、nces This Part of BS7752 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Dimensions 3.1 Insert wire profile The
16、dimensions of the insert wire profile when it is in the finished coiled state shall be in accordance with Table 1 and Figure 1. 3.2 Unfitted insert The dimensions of an unfitted insert shall be in accordance with Table 2 and Figure 2. The surface roughness of the insert wire in the finished coiled s
17、tate shall not exceed84m. NOTE 1Minimum contact pressure is to be used when measuring the insert outside diameter to avoid distortion of the insert. NOTE 2Ignore any reduced leading coil if it is present when measuring the insert outside diameter. NOTE 3Since the relationship between the insert unfi
18、tted length and the number of coils is interdependent with coiling tension, the number of coils N is given for identification purposes only. NOTE 4The notch depth is to be sufficient to allow the tang to be broken off cleanly with a sharp blow after installation and then permit the free passage of a
19、 male threaded component. 4 Material The insert wire shall be manufactured from austenitic stainless steel of the type characterized as18% chromium,8% nickel. NOTEThe precise composition is at the manufacturers discretion. 5 Finish The finished coiled insert shall be in the natural condition. 6 Inse
20、rt selection The length of insert selected shall be such that no stripping of the tapped hole in the parent metal into which the insert is fitted occurs before tensile failure of the male threaded part that is screwed into the fitted insert. NOTEAnnex A gives guidance on the selection of insert leng
21、th required for different grades of bolt and tapped parent material strengths. 7 Installation The inserts shall be capable of being installed into threaded holes prepared in accordance with BS4377:1991. NOTE 1The class of fit produced by the installed insert, e.g.5H or6H, is dependent upon the class
22、 of fit of the threaded hole into which it is installed as well as the dimensional accuracy of the insert. The users attention is therefore drawn to the importance of maintaining the tolerance requirements of BS4377:1991. The insert fitted length shall be as given in Table 3 and Figure 3. NOTE 2It i
23、s recommended that the insert is fitted at least a distance equal to half of its thread pitch below the surface (seeFigure 3).BS7752-2:1994 2 BSI 08-1999 Table 1 Dimensions of insert wire profile in finished coiled state NOTESee Table 1 for dimensions. Figure 1 Insert wire profile in finished coiled
24、 slate Dimensions in millimetres Thread size X W T E diameter pitch min. max. min. max. min. max. min. max. M8 1 0.744 0.757 0.986 1.082 0.716 0.874 0.625 0.650 M10 1.25 0.935 0.947 1.242 1.354 0.897 1.095 0.787 0.813 M12 1.25 0.935 0.947 1.242 1.354 0.897 1.095 0.787 0.813 M14 1.5 1.123 1.138 1.509
25、 1.623 1.077 1.313 0.947 0.975 M16 1.5 1.123 1.138 1.509 1.623 1.077 1.313 0.947 0.975 M18 1.5 1.123 1.138 1.509 1.623 1.077 1.313 0.947 0.975 M20 1.5 1.123 1.138 1.509 1.623 1.077 1.313 0.947 0.975 M22 1.5 1.123 1.138 1.509 1.623 1.077 1.313 0.947 0.975 M24 2 1.501 1.516 2.012 2.164 1.435 1.750 1.2
26、65 1.298BS7752-2:1994 BSI 08-1999 3 Table 2 Dimensions of insert in free (unfitted) state Dimensions in millimetres Thread size Outside diameter D Nominal length a No. of coils N Tang length L Space for tang M diameter d pitch min. max. min. max. min. max. M8 1 9.29 10.25 1d 5.7 6.4 4.75 2.67 1.5d 9
27、.3 10.2 2d 12.9 14.0 2.5d 16.5 17.7 3d 20.1 21.5 M10 1.25 11.57 12.65 1d 5.7 6.4 5.50 3.33 1.5d 9.3 10.2 2d 12.9 14.0 2.5d 16.6 17.8 3d 20.2 21.6 M12 1.25 13.68 15.00 1d 7.1 7.9 6.70 3.84 1.5d 11.5 12.5 2d 15.8 17.0 2.5d 20.2 21.6 3d 24.5 26.1 M14 1.5 15.94 17.70 1d 6.9 7.7 7.20 4.50 1.5d 11.1 12.1
28、2d 15.4 16.5 2.5d 19.6 20.9 3d 23.8 25.3 M16 1.5 18.04 19.90 1d 8.1 8.9 8.30 4.98 1.5d 13.0 14.0 2d 17.8 19.0 2.5d 22.6 24.1 3d 27.5 29.1 M18 1.5 20.14 22.00 1d 9.4 10.2 9.30 5.46 1.5d 14.8 15.9 2d 20.3 21.6 2.5d 25.8 27.4 3d 31.2 33.1 M20 1.5 22.27 24.20 1d 10.6 11.4 10.40 6.00 1.5d 16.7 17.8 2d 22
29、.7 24.1 2.5d 29.8 30.4 3d 34.9 36.7 a Nominal lengths of an insert are defined in terms of multiples of the thread diameter d.BS7752-2:1994 4 BSI 08-1999 Table 2 Dimensions of insert in free (unfitted) state Dimensions in millimetres Thread size Outside diameter D Nominal length a No. of coils N Tan
30、g length L Space for tang M diameter d pitch min. max. min. max. min. max. M22 1.5 24.39 26.80 1d 11.8 12.7 11.40 6.43 1.5d 18.5 19.7 2d 25.2 26.6 2.5d 31.8 33.5 3d 38.5 40.5 M24 2 26.67 29.10 1d 9.4 10.3 12.50 7.26 1.5d 14.8 16.0 2d 20.0 21.8 2.5d 25.8 27.5 3d 31.2 33.2 a Nominal lengths of an inse
31、rt are defined in terms of multiples of the thread diameter d. 1) See note4 to3.2. 2) See note3 to3.2. Figure 2 Dimensions of insert in free (unfitted) stateBS7752-2:1994 BSI 08-1999 5 Table 3 Insert fitted length Table 3 Insert fitted length Dimensions in millimetres Thread size Nominal length Fitt
32、ed length diameter d pitch min. max. M8 1 1d 7.00 7.50 1.5d 11.00 11.50 2d 15.00 15.50 2.5d 19.00 19.50 3d 23.00 23.50 M10 1.25 1d 8.75 9.375 1.5d 13.75 14.375 2d 18.75 19.375 2.5d 23.75 24.375 3d 28.75 29.375 M12 1.25 1d 10.75 11.375 1.5d 16.75 17.375 2d 22.50 23.375 2.5d 28.75 29.375 3d 34.75 35.3
33、75 M14 1.5 1d 12.50 13.25 1.5d 19.50 20.25 2d 26.50 27.25 2.5d 33.50 34.25 3d 40.50 41.25 M16 1.5 1d 14.50 15.25 1.5d 22.50 23.25 2d 30.50 31.25 2.5d 38.50 39.25 3d 46.50 47.25 Dimensions in millimetres Thread size Nominal length Fitted length diameter d pitch min. max. M18 1.5 1d 16.50 17.25 1.5d 2
34、5.50 26.25 2d 34.50 35.25 2.5d 43.50 44.25 3d 52.50 53.25 M20 1.5 1d 18.50 19.25 1.5d 28.50 29.25 2d 38.50 39.25 2.5d 48.50 49.25 3d 58.50 59.25 M22 1.5 1d 20.50 21.25 1.5d 31.50 32.35 2d 42.50 43.25 2.5d 53.50 54.25 3d 64.50 65.25 M24 2 1d 22.00 23.00 1.5d 34.00 35.00 2d 46.00 47.00 2.5d 58.00 59.0
35、0 3d 70.00 71.00 Figure 3 Insert in fitted stateBS7752-2:1994 6 BSI 08-1999 8 Marking When designating for the purpose of an enquiry or order, the following information shall be given: a) general product description, i.e.wire thread insert; b) the number and date of this British Standard, i.e.BS7752
36、-2:1994 1) ; c) the letter “M” indicating that the product is ISO metric; d) the female thread diameter of the fitted insert in millimetres; e) the nominal length of the insert, i.e.2.5d. EXAMPLE. The designation of M18 wire thread insert of nominal length1.5d is as follows: Wire thread insert BS775
37、2-2:1994 M18 1.5d 1) Marking BS7752-2:1994 on or in relation to a product represents a manufacturers declaration of conformity, i.e.a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is solely the claimants responsibility. S
38、uch a declaration is not to be confused with third party certification of conformity, which may also be desirable.BS7752-2:1994 BSI 08-1999 7 Annex A (informative) Insert selection The standard engineering practice of balancing the tensile strength of the bolt material against the shear strength of
39、the material into which it is screwed applies equally to wire thread inserts. Table A.1 gives a recommendation as to what nominal length of insert will need to be inserted into a material having a certain shear strength, so that when it is used with a bolt of a certain property class, tensile failur
40、e of the bolt should occur before the insert is pulled from the material in which it is inserted. Table A.1 assumes that full thread engagement of the male fastener in the insert occurs. The following equation was used as a basis for the recommendations given in Table A.1. where H is the fitted leng
41、th of the insert (in mm); R mis the nominal tensile strength of bolt used (in MPa); S is the stress area of bolt used (in mm 2 ); R cis the shear strength of material into which the insert is to be inserted (in MPa); D 2is the mean pitch diameter of the tapped hole in the material in which the inser
42、t is to be inserted (in mm); 0.5is an arbitrary coefficient based on shearing of the material in which the insert is fitted occurring at the pitch diameter of the tapped hole. NOTEIf this equation is used to calculate a value for H and it falls outside the limits given in Table 3, then the next long
43、est nominal length of insert should be used. Table A.1 is given for guidance only and it remains the responsibility of the user to ensure that the insert nominal length chosen is suitable for the particular application concerned. Table A.1 Recommended nominal lengths of insert to be inserted into a
44、material of a givenshear strength that can be used with a bolt of a certain property class Shear strength of material into which the insert is to be inserted Recommended nominal length of insert Property class of bolt to be used MPa 4.8, 4.6 5.6 6.6 8.8 10.9 12.9 14.9 70 to99 2d 2.5d 2.5d 100 to149
45、1.5d 1.5d 2d 3d 150 to199 1d 1.5d 1.5d 2d 2.5d 3d 200 to249 1d 1d 1d 1.5d 2d 2d 2.5d 250 to299 1d 1d 1d 1.5d 1.5d 2d 2d 300 to349 1d 1d 1d 1d 1.5d 1.5d 2d U 350 1d 1d 1d 1d 1d 1.5d 1.5d8 blankBS7752-2:1994 BSI 08-1999 List of references (see clause2) Normative references BSI publications BRITISH STA
46、NDARDS INSTITUTION, London BS3643, ISO metric screw threads. BS3643-1:1981, Principles and basic data. BS3643-2:1981, Specification for selected limits of size. BS4377:1991, Specification for tapping of holes to receive wine thread inserts (ISO metric threads). Informative references BSI publication
47、s BRITISH STANDARDS INSTITUTION, London BS6293, MJ threads for aerospace construction. BS6293-1:1982, Specification for dimensions of basic profile. BS6293-2:1982, Specification for dimensions for bolts and nuts. BS7752, Free running type wire thread inserts. BS7752-1:1994, Specification for ISO met
48、ric coarse pitch threads 2) . 2) Referred to in the foreword only.BS7752-2: 1994 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 internat
49、ional level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside fro
