1、 WORLDWIDE FASTENER STANDARD WF900 Date: 2013-05-23 Printed copies are uncontrolled Copyright 2013, Ford Global Technologies, LLC Page 1 of 3 DIMENSIONAL, MATERIAL REQUIREMENTS AND MECHANICAL PROPERTIES OF FLAT, TOOTHED, CONICAL, BOWED AND WAVY WASHERS 1. SCOPE This standard specifies the dimensiona
2、l, material, heat treatment, hardness and performance requirements for flat and conical washers for general use and for use in bolt, screw, or nut and washer assemblies. Toothed, bowed, and wavy washers as well as hardness classes A, D, E, and F shall not be used for new design and were moved to WF9
3、00 Appendix A for reference purposes. 1.1 REFERENCES ASTM E140 Hardness conversion tables for metals ISO 7093 Plain Washers - Large Series - Part 1 and 2 ISO 7089 Plain Washers - Normal Series ISO 4759 Tolerances for fasteners Part 3 ISO 6507 Metallic materials - Hardness test - Vickers test. 2. DIM
4、ENSIONS AND TOLERANCES 2.1 General Dimensions and tolerances shall be in accordance to ISO 4759-Part 3 2.2 FLAT WASHERS The nominal inside diameter, outside diameter and thickness shall be as specified per ISO 4789 and ISO 7093 Part 1 and 2 as appropriate. 2.3 TOOTHED, CONICAL, BOWED AND WAVY WASHER
5、S Dimensions and tolerances shall be as specified in (WF900 Appendix A). 2.4 ASSEMBLED The inside diameter of washers for use in bolt, screw, or nut and washer assemblies shall be such as to permit rotation whilst disassembly is prevented. WORLDWIDE FASTENER STANDARD WF900 Date: 2013-05-23 Printed c
6、opies are uncontrolled Copyright 2013, Ford Global Technologies, LLC Page 2 of 3 3. MATERIAL, HEAT TREATMENT AND HARDNESS Material, heat treatment and hardness requirements are specified below in Table 1. Alternative hardness testing methods may be used with values extracted form ASTM E 140 but Vick
7、ers Hardness test to ISO 6507 HV5 shall be the referee method. Table 1 Material Heat Treatment and Hardness Washer Material, Heat Treat & Hardness Class Material Heat Treatment Hardness Flat Conical B Steel Harden or Case Harden and Temper 300 - 390HV Toothed Bowed Wavy C Steel Harden and Temper 410
8、 - 520HV Austemper 450 - 570HV Flat G Steel - 100 - 260HV NOTE: The above requirements also apply to the washer component of bolt, screw, or nut and washer assemblies. 1) Washers used with case hardened and tempered screw and washer assemblies shall be copper flashed prior to heat treatment to avoid
9、 carbon pick up. 4. PERFORMANCE 4.1 RECOVERY FROM COMPRESSION (TOOTHED, CONICAL, BOWED AND WAVY) Toothed, Conical, Bowed and Wavy - After compression between parallel surfaces for a minimum of 2 minutes with the load specified in (Table 11, WF900 Appendix A), the minimum height of the free washer sh
10、all be as shown for h2. When the same load is re-applied for the same period no further permanent set shall be acceptable. Mating countersunk holes and cones shall be used for countersunk toothed washers. 4.2 TWIST TEST ON TOOTHED WASHERS The rim of the washer shall be cut or severed. Separation of
11、the ends to 90 shall not result in fracture. WORLDWIDE FASTENER STANDARD WF900 Date: 2013-05-23 Printed copies are uncontrolled Copyright 2013, Ford Global Technologies, LLC Page 3 of 3 RECORD OF REVISIONS Date Revisions 2008-03-01 The term used to express the “Material, Heat Treat & Hardness“ was c
12、hanged from Type to Class, to avoid confusion with the term “Washer Type.“ Heat Treatment Class F was added to allow low carbon steels to be used for hardened or case hardened assemblies. Low carbon steels are commonly used and do not respond to the heat treatment, resulting in a relatively low hard
13、ness. 2013-05-23 Removed figures/tables 1-4 and made a direct reference to applicable ISO standard. Moved figures/tables 5-11 into WF900 Appendix A Moved hardness classes A, D, E, and F from Table 12 to WF900 Appendix A Changed Table 12 to Table 1 Added applicable ISO specification to references Added G to Table 1 Added reference to WF900 Appendix A to the scope
