1、FORD WORLDWIDE FASTENER STANDARDDate: 1996-10-01Engineering Standards & 1 of 2 Printed copies are uncontrolled .Systems Engineering (ESSE)WE 953General Specifications, Assembly Information, Mechanical and Performance Requirements for Single ThreadSpring Nuts1. SCOPE. This standard covers performance
2、 and other requirements for single thread form spring nutsdesigned for assembly on panels 0.6 to 3.8 thick.NOTE: The design of the thread impression, retaining feature and other features may vary betweenmanufacturers, provided all requirements of this standard are met.1.1 REFERENCES.ISO 683/18 - Hea
3、t-treated steels, alloy steels and free cutting steels - Part 18: Wroughtunalloyed steels in the normalized, or normalized and cold-drawn, or hot-rolled and cold-drawn condition.ISO 6932 - Cold reduced carbon steel strip with a maximum carbon content of 0.25%.2. MATERIAL AND HEAT TREATM ENT.2.1 MATE
4、RIAL. The material shall be spring steel, the specific grade of material shall be at thediscretion of the manufacturer to meet the performance requirements and provide adequateductility.2.2 HEAT TREATMENT. Harden and Temper to HV420 - 520 or Austemper to HV500 - 570.3. PERFORMANCE.3.1 ASSEMBLY AND R
5、ETENTION. Spring nuts shall preassemble onto steel test plates of thicknessequal to the two extremes of the panel range specified for the nut to be tested. The maximuminstallation force during the assembly of the spring nut shall be 55 N. The minimum force to thenremove the spring nut shall be 2 N.3
6、.2 TORQUE AND CLAMP FORCE TEST. A spring nut shall be assembled on a test panel (SeeFigure 1 and Table 2) of thickness equal to the maximum thickness of the panel range specified forthe nut to be tested with a device suitable for measuring clamp force incorporated. A test screw(See Clause 4) shall t
7、hen be driven into the assembled spring nut until the installation torquespecified in Table 1 is achieved. The clamp force shall not be less than the minimum clamp forcespecified in Table 1.Upon disassembly, the thread impression shall return to a condition that will accept re-entry of thescrew.3.3
8、DESTRUCTIVE TORQUE TEST. Using the same method as described in Clause 3.2, but withouta device for measuring clamp force, a spring nut shall be assembled on a test panel (See Figure 1and Table 2) of thickness equal to the maximum thickness of the panel range specified for the nutto be tested and a t
9、orque applied to a test screw (See Clause 4) driven into the spring nut. Torqueto cause failure shall not be less than the value specified in Table 1.3.4 TENSILE TEST. Using the same assembly procedure as described in Clause 3.2 but replacing theclamp force measuring device with a tensile load measu
10、ring device, a test screw (See Clause 4)shall be driven into the spring nut but not tightened to induce any pre-load. A tensile load shallnow be applied to the screw until the spring nut fails. The tensile load to cause failure shall not beless than the value specified in Table 1.4. TEST SCREW. The
11、test screw shall be Type AB as specified in WD900 and shall not be less than 25mmlong. The surface coating shall be S309 in accordance with WX100.Table 1. Performance requirementsScrew Size Installation TorqueNmClamp Force kN MinimumDestructive TorqueNmMinimum TensileStrength kNST3.5 1.35 1.06 1.92
12、2ST4.2 2.25 1.67 2.82 2.22ST4.8 3.47 2.3 5.2 3.53ST6.3 6.78 3.34 9.04 4FORD WORLDWIDE FASTENER STANDARDDate: 1996-10-01Engineering Standards & 2 of 2 Printed copies are uncontrolled .Systems Engineering (ESSE)WE 953General Specifications, Assembly Information, Mechanical and Performance Requirements for Single ThreadSpring NutsTable 2. Test panelScrew Size Distance from Edge AHole Diameter GPanel RangeST3.5 0.75 x B 4.8 SeeST4.2 Where B is the spring 5.6 ClauseST6.3 nut throat depth 7.9 3MATERIAL: Cold rolled steel to ISO 6932 or ISO 683/18.Figure 1. Test panel
