1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2002 09 30 Revised Updated and renumbered 1997 01 20 Revised Delete para 5.2; Updated C. Sales 1986 10 31 SM/ER4151TC Released. JPC. Lines Printed copies are uncontrolled Page 1 of 3 Copyright 2002, Ford Glo
2、bal Technologies, Inc. BOLT - SERRATED WSD-M1A291-A1 WSD-M1A291-A21. SCOPE The materials defined by this specification are heat treated steels with controlled surface hardness. 2. APPLICATION This specification was released to define the requirements of serrated shank, round headed bolts used in app
3、lications such as wheel bolts etc. 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.2 MATERIAL The choice of steel composition is at the manufacture
4、rs discretion and shall be suitable to meet the specified hardenability and other properties. The general quality of manufacture of the steel and wire product for bolt making shall conform to the relevant national standard for the country of sourcing. In the absence of a national standard or for ref
5、eree purposes, the steel shall conform to ISO 4954 section 1. Specific requirements for composition, mechanical properties and treatment condition of the wire shall conform to ISO 4954 or to the relevant national or industry standard. 3.3 HARDENABILITY The selected material shall have a minimum hard
6、enability according to the nominal thread diameter of the bolt. NOMINAL THREAD JOMINY HARDNESS HARDENING TEST DIAMETER mm HRC minimum Hardness at mid radius HV30 minimum Up to and including 10 mm 44 at 5 mm 450 ENGINEERING MATERIAL SPECIFICATION WSD-M1A291-A1/A2 Page 2 of 3 Copyright 2002, Ford Glob
7、al Technologies, Inc. Over 10 up to and including 20 mm 44 at 7 mm 450 Over 20 up to and including 24 mm 44 at 9 mm 450 3.4 HEAT TREATMENT All bolts shall be heat treated to the required level as indicated. 3.4.1 CORE HARDNESS, HV30 A1 300 - 380 A2 280 - 360 For referee purposes the core hardness sh
8、all be determined at the mid-radial position on a cross section taken either 1d from the threaded end or from the serrated zone. 3.4.2 SURFACE HARDNESS, HV5 A1 380 - 500 A2 350 - 460 The surface hardness shall be determined on the flat of the head at a position not within the nominal diameter of the
9、 bolt. No more than 0.02 mm of surface shall be removed during preparation of a suitable surface for the hardness test. 3.4.3 CASE DEPTH, max 0.25 mm Case depth shall be determined for referee purposes by the microhardness HV 0.3 method. The case depth is that depth with a hardness of 30 Vickers poi
10、nts above the actual core hardness. The surface hardness for this test shall be determined at 2.5 - 3 impression diagonals from the surface. The bolts shall contain no decarburisation and this shall be assessed in the spline region. 3.5 MANUFACTURE 3.5.1 Bolts up to and including 12 mm nominal threa
11、d size shall be cold forged and the serrations and threads shall be rolled before heat treatment. Bolts of more than 12mm diameter may be machined from bar. 3.5.2 Laps formed at the crest of serrations shall not be deeper than 75 % of the overall serration height. Laps formed in the crest of threads
12、 shall not extend deeper than 33 % of the thread height. No laps shall exist in the thread flanks below the effective diameter. Provided overall serration diameter is correct and the torque retention test is satisfactory, malformed serrations can be accepted. 3.5.3 The bolts shall be free from burrs
13、, seams, scale, irregular surface, sharp edges or other features which would adversely affect performance or ease of assembly. ENGINEERING MATERIAL SPECIFICATION WSD-M1A291-A1/A2 Page 3 of 3 Copyright 2002, Ford Global Technologies, Inc. 3.6 SPLINE PERFORMANCE A1 WHEEL BOLT APPLICATIONS When fitted
14、to a test plate the bolts must resist an applied torque of 70 Nm. For plant quality audit use of production hubs is permissible. The test torque shall be applied using a blind test nut such that the end of the bolt is fully seated in the base of the nut. The torque measuring tool shall have an accur
15、acy of +/- 3 % of the applied torque. The assessment of retention will be made by measuring the angular displacement of a fine scribe line marked through the head of the bolt onto the test plate or hub surface. Nil displacement is allowed. Test plates shall be manufactured from steel to BS970 Pt1 19
16、83 080M50 or C55 1.0535 hardened and tempered to HV260-300. Dimensions of test plate suitable for 12mm bolt are as follows:- Test Plate Thickness 9.50 - 9.60 mm Test Hole Diameter 12.73 - 12.76 mm Test Hole Chamfer 45 +/- 1 degree Test Hole Chamfer Depth 1.2 +/- 0.1 mm A2 OTHER APPLICATIONS Refer to
17、 WA975 WORLD WIDE STANDARD PARTS MANUAL 3.7 PROTECTIVE FINISH The protective finish shall be of a non embrittling type and shall be as released or as specified on the Engineering drawing for the part. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of this specification. 4.1 Comprehensive information on the acceptance of bolt defects is given in Worldwide Engineering Standard WA 990.
