1、AEROSPACE STANDARDMA1568Issued 1987-07Reaffirmed 2006-05Nut, Self Locking - UNS S66286, 425C nuts having shorter threaded portion shall allow GO thread plug gage to enter a minimum of three quarters of a turn.3.2.4 Construction: The nut shall be of the prevailing torque-type, self contained, all met
2、al unit, including the self locking feature. The locking feature shall not operate by means of separate movement and shall not depend upon pressure on the bearing surface for locking action. Tool marks resulting from producing the self locking feature shall blend smoothly without abrupt change.3.3 H
3、eat Treatment:The nuts shall be solution and precipitation heat treated in accordance with the heat treating procedure specified in the material specification, except nuts formed from sheet stock may be precipitation heat treated after forming.3.4 Product Marking:Each part shall be identification ma
4、rked as specified on the part drawing. Depressed characters shall have a rounded root form, depressed 0.15 mm max.3.5 Plating:Unless otherwise specified on the part drawing, parts shall be silver plated in accordance with AMS 2411. On nuts with nominal thread sizes 6 mm and larger, the plating on th
5、e thread shall be not less than 5 m when measured on the pitch diameter. Microscopic measurement of a sectioned nut shall be used as the referee method. Nuts with nominal thread sizes below 6 mm shall show complete coverage on the thread surfaces. Plating on the other surfaces shall be 8 15 m thick,
6、 unless otherwise specified on the part drawing. No plating shall be applied to the retaining plate for floating plate nuts and channel for gang channel nuts, unless otherwise specified on the part drawing.3.6 Mechanical Properties:3.6.1 Hardness: Unless otherwise specified on the part drawing, the
7、hardness after heat treatment as in 3.3 shall be uniform and within the range of 29 39 HRC or equivalent, except nuts formed from sheet stock shall be within the range of 29 44 HRC, when tested in accordance with MIL-STD-1312-6. Sizes up to and including 10 mm nominal thread size shall be sectioned
8、and mounted. Mounting optional for other sizes.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE MA1568 - 5 -3.7 Metallurgical Properties:3.7.1 Microstructure: Wrenching nuts, shank nuts, and nut e
9、lements of plate and gang channel nuts shall have microstructure of completely recrystallized material.3.7.2 Grain Size: Shall be predominantly 5 or finer with occasional grains as large as 2 in the base of the nut as determined by comparison of a polished and etched specimen with ASTM E 112 plate 2
10、. In case of disagreement on grain size by the comparison method, the intercept (Heyn) procedure shall be used.3.8 Quality:Parts shall be uniform in quality and condition, clean, sound, smooth, and free from burrs and foreign materials and from imperfections detrimental to their performance.3.8.1 Fl
11、uorescent Penetrant Inspection: Parts shall be subject to fluorescent penetrant inspection in accordance with AMS 2645. Acceptance criteria of surface discontinuities shall be in accordance with Appendix J.3.9 Product Performance Test:Refer to Tables VII and VIII for details of sample sizes for Acce
12、ptance Test Plan and Qualification Approval Test Plan.3.9.1 Axial Tensile Strength: Nuts shall withstand the minimum tensile load as specified in Table I without rupture, stripping or appearance of cracks when tested as follows:3.9.1.1 As Received Condition at Room Temperature: Nuts in as received c
13、ondition tested in accordance with DOD-STD-1312-108, using alloy steel test bolts hardened and tempered to 40 HRC min or equivalent, shall withstand the axial tensile load specified in Table I, applied at the rate specified at room temperature.3.9.1.2 After Bake, at Room Temperature: Prior to testin
14、g, the nut shall be assembled on a bolt as specified in 3.10 with at least two thread pitches protruding and baked for 6 hrs 0.25 at 650C 8 for nuts made from bar or forging and tension height wrenching nuts formed from sheet, and at 425C 8 for anchor nuts and shear height wrenching nuts formed from
15、 sheet, and then cooled to room temperature. A new test bolt shall be used for each axial tensile test. Nuts shall be tested, after baking, at room temperature in accordance with DOD-STD-1312-108 and shall withstand the axial tensile load in Table I, applied at the rate specified.Copyright SAE Inter
16、national Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE MA1568 - 6 -TABLE I. Axial Tensile Load3.9.1.3 Shank Nuts: Nuts with shanks designed to be flared at assembly (See Fig. 1) shall be tested as in 3.9.1 except that the
17、 bearing plate hole shall be 0.1 0.2 mm greater than the max shank diameter. It is not necessary to flare the shank for this test. The bearing plate hole shall be chamfered sufficiently to clear the shank nut bearing surface-to-shank max fillet.3.9.2 Wrench Torque: Wrenching nuts with spline drive w
18、renching feature shall be tested as specified in Appendix B and shall withstand the wrench torques specified in Table II applied through 15 engagement cycles without any permanent deformation which can interfere with the use of socket wrenches conforming to MA1586. Wrenching nuts with hexagon or dou
19、ble hexagon wrenching features shall be tested in the same manner and shall withstand Table II wrench torques in the same manner as spline drive nuts except double hexagon socket-type wrench shall be used.TABLE II. Wrench TorqueCopyright SAE International Provided by IHS under license with SAENot fo
20、r ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE MA1568 - 7 -3.9.3 Push Out Load: Anchor nuts of the types in 3.9.3.1 (normal series and miniature series rivet hole spacing) shall be tested as specified in Appendix C and shall withstand the push out loads for the appl
21、icable series specified in Table III without separating from the plate for the normal and miniature series or from the channel for the normal series. Nuts shall be serviceable after this test.3.9.3.1 The push out test in 3.9.3 is applicable to gang channel nuts, plate nuts (floating and non-floating
22、 except side by side, corner and side mounted types). See Appendix A for definition of types.TABLE III. Push Out Load3.9.4 Torque Out: Anchor nuts of the types in 3.9.3.1 (normal series and miniature series rivet hole spacing) shall be tested as specified in Appendix D and shall withstand the torque
23、 out loads for the applicable series specified in Table IV without cracking, rupture, or being deformed to a degree which will prevent normal use. This test shall be performed with no axial load on the bearing surface of the nut.TABLE IV. Torque Out Load3.9.5 Permanent Set: Nuts shall be tested as s
24、pecified in Appendix E and shall not exceed the max permissible locking torque or be less than the min breakaway torque values specified in Table V. The bolt or mandrel shall project thru the nut a min of three full thread pitches.Copyright SAE International Provided by IHS under license with SAENot
25、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE MA1568 - 8 -3.9.6 Reusability Test at Room Temp. After Bake: Nuts 5 mm nominal thread size and larger shall be tested for five consecutive cycles as specified in Appendix F, loading initially to 517 MPa in accordance
26、 with 3.9.6.3. The assembly shall be heated in a furnace to 650C 8 for nuts made from bar or forging and tension height wrenching nuts formed from sheet, and to 425C 8 for anchor nuts and shear height wrenching nuts formed from sheet, and held at heat for 6 hrs 0.25, removed from the furnace and coo
27、led to room temp.3.9.6.1 Wrenching and Reference Recording: Wrenchable nuts shall be turned relative to the fixture. The wrenchability of the tested nuts shall permit assembly of standard wrench. For non-wrenchable nuts, the bolt head shall be turned. For reference information, the assembly and brea
28、kloose torques shall be recorded for each heat cycle.3.9.6.2 Locking Feature Torque Requirements: Nuts tested as in 3.9.6 shall conform to the min breakaway torque in Table V, Column 1, for each cycle. The self locking torque shall be measured on installation and removal, and shall not exceed the to
29、rque in Table V, Column 4, nor shall be less than the breakaway torque in Table V, Column 1.3.9.6.3 Loading by Elongation: Loading shall be determined by measurement of elongation of the bolt at room temperature using bolts having a shank diameter equal to the thread pitch diameter. The correct load
30、ing shall be determined by using a modulus of elasticity of 203.4 GPa. Stress area for the bolt shall be based on Formula (2) area given in MA1520. The elongation shall be equal to 0.002542L (where L = length of bushing) elongation of bolts using standard bushing as specified in Appendix F.3.9.7 Reu
31、sability Test at Room Temperature, As Received Condition: Nuts shall be tested for 15 cycles as specified in Appendix G, loading to assembly torque specified in Table V, Column 5. Wrenchable nuts shall be turned relative to the fixture. For non-wrenchable nuts, the bolt head shall be turned. Locking
32、 feature torque shall conform to the min breakaway torque and max self locking torque in Table V, Column 1 and 3, respectively, for each cycle. The self locking torque shall be measured on installation and removal, and shall not exceed the torque in Table V, Column 3, nor shall be less than the brea
33、kaway torque in Table V, Column 1. After testing, the nut shall assemble freely with the fingers up to the self locking feature. Bolt threads shall remain serviceable and permit assembly of a new nut freely with the fingers up the self locking feature.3.9.8 Three Cycles Test at Room Temperature: Nut
34、s shall be tested as specified in Appendix H, loading to assembly torque specified in Table V, Column 5. Wrenchable nuts shall be turned relative to the fixture. For non-wrenchable nuts, the bolt head shall be turned. Nuts shall conform to the min breakaway torque in Table V, Column 2 for the first
35、cycle, and Column 1 for the subsequent two cycles. The self locking torque shall be measured on installation and removal, and shall not exceed the torque in Table V, Column 3, nor shall be less than the breakaway torque in Table V, Column 1.Copyright SAE International Provided by IHS under license w
36、ith SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE MA1568 - 9 -TABLE V. Locking Feature Torques and Assembly Torque3.9.9 Accelerated Vibration Test: Nuts shall be tested in accordance with DOD-STD-1312-107 and shall be loaded to assembly torques specified i
37、n Table VI. The loaded nut assembly shall withstand 30,000 cycles continuous vibration at 30 Hz and amplitude (total travel) 11.25 mm without relative rotation exceeding 360, without cracking of nut, and without being capable of turning by hand.TABLE VI. Assembly Torque for Accelerated Vibration Tes
38、t3.9.9.1 At Room Temperature, As Received Condition: Nut shall be loaded as specified in 3.9.9 on spacer then removed and reinstalled four additional times on the same bolt to the assembly torques in Table VI. The final assembly shall be with the block ready for the vibration test. The loaded nut as
39、sembly shall then be vibrated at room temperature in accordance with 3.9.9 requirements, and nuts shall conform to the requirements of 3.9.9 after the vibration test.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without licens
40、e from IHS-,-,-SAE MA1568 - 10 -3.9.9.2 At Room Temperature After Baking: Nuts shall be loaded as specified in 3.9.9 on spacer as specified in Appendix F, and the loaded nut assembly shall be heated in a furnace to 650C 8 for nuts made of bar or forging and tension height wrenching nuts formed from
41、sheet, and to 425C 8 for anchor nuts and shear height wrenching nuts formed from sheet, and held at heat for 6 hrs 0.25, and cooled to room temperature. Nut shall then be removed from the assembly and reinstalled four additional times on the same bolt to the assembly torques in Table VI. The final a
42、ssembly shall be on the test fixture in the block ready for the vibration test. The loaded nut assembly shall then be vibrated at room temperature in accordance with 3.9.9 requirements, and nuts shall conform to the requirements of 3.9.9 after the vibration test.3.9.10 Flareability: Unless otherwise
43、 specified on the part drawing, the shank of shank (clinch) nuts shall be capable of being flared with a 60 included angle conical tool to a diameter equal to 120% of max shank diameter without cracking.3.10 Test Bolts:Except as specified in 3.9.1.1, test bolts shall be unplated and conform to MA337
44、4 with threads to MA1370 class 4h6h.3.11 Test Lubrication:Stud-mandrel or bolt threads and nut bearing surface, and for non-wrenchable nut tests the bolt bearing surface, shall be lubricated with engine oil MIL-L-7808 or equivalent before each installation of the nut.4. QUALITY ASSURANCE PROVISIONS:
45、4.1 Responsibility for Inspection:The vendor of parts shall supply all parts for vendor tests and shall be responsible for performing all required tests. Subsequent to qualification, there shall be no changes in the manufacturing method and operations sequence without requalification of the parts. R
46、esults of such tests shall be reported to the purchaser as required by 4.4. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the parts conform to the requirements of this specification.4.2 Classification of Tests:The inspection and testin
47、g of parts shall be classified as follows:(a) Acceptance Tests(b) Qualification Tests4.2.1 Acceptance Tests: Tests classified as acceptance or routine control tests are listed in Table VII.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking p
48、ermitted without license from IHS-,-,-SAE MA1568 - 11 -4.2.2 Qualification Tests: Tests to determine conformance to all technical requirements of this specification and part drawing are listed in Table VIII.4.3 Sampling:4.3.1 Acceptance Tests: Acceptance tests shall be performed on each inspection l
49、ot. See 8.2.3.4.3.1.1 Non-Destructive Tests - Visual and Dimensional: A random sample shall be selected from each inspection lot, the size of the sample to be as specified in Table X. The classification of defects for nuts will be as specified in Table IX. Defects not classified in Table IX shall be classified as Minor B defects. All dim
