1、D - 07 -31 MIL-N-3337C 53 m 999990b 0096720 T W I MIL-N-3337C 14 JUNE 1985 Superseding MIL-N-3337B 2 Aug 1966 MILITARY SPECIFICATION NUT, SHEET SPRING This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification controls
2、requirements df nuts manufactured from sheet metal with an aperture capable of receiving, gripping and securely holding threaded fasteners and related items, I 1.2 Classification. Sheet spring nuts ghali be furnished in one of the following types, and shall be of the screw dizes listed in Table i at
3、id Table II, as specified (see 3.1.2 and 6.2): Type I - For use with coarse-thread series machine screws. Type II - For use with (sheet metal) thread-forming screws. 2. APPLICABLE DOCUMENTS O * 2;l Government documents. * 2.1.1 Specifications and standards, Unless otherwise specified (see 6,2), the
4、following specifications and standards of the issue listed in that issue of the Department of Defense Index of Specifications and Standards (DoDISS) specified in the Solicitation, form a part of this specification to the extent specified herein. SPECIFICATIONS FEDERAL FF-S-92 Screw, Machine, Slotted
5、, Cross-Recessed or Hexagon Head QQ-P-416 Plating, Cadmium (Electrodeposited) TT-C-490 Cleaning Method and Pre-Treatment of Ferrous Surfaces I FF-S- 107 Screw, Tapping and Drive for Organic Coatings .I- PPP-H-1581 Hardware (Fasteners and Related Items) Packaging of MILITARY DOD-D-1000 Drawing, Engin
6、eering atid Associated List J. I MIL-M-6874 Metal Spraying, Process For Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: 78241 by using the self addressed Standardization Document Improvement Pro
7、posal (DD Form 1426) appearing at the end of this document or by letter, .1L the Engineering Division, San Antonio Air Logistics Center, Kelly AFB, Texas FSC 5310 THIS DOCUMENT CONTAINS 10 PAGES / Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-N
8、-3337C 53 777990b 0096723 3 MIL-N-3337C STANDARDS FEDERAL FED-STD-66 Steel, Chemical Composition and Hardenability FED-STD-151 Metal, Test Methods MILITARY MIL-STD-105 Sampling Procedures and Tables for Inspection by Attribut es MIL-STD-130 Identification Marking of U.S. Military Property MIL-STD-12
9、9 Marking for Shipment and Storage MIL-STD- 794 Parts and Equipment, Procedures for Packaging and MS90723 Nut, Sheet Spring “J“ Type MS90724 Nut, Sheet Spring “U“ Type -k MIL-STD-147 Palletized Unit Loads J. Packing of, * connection with specific acquisition functions should be obtained from the con
10、tracting activity or as directed by the contracting officer). JC 2.2 Other publications, The following document(s) form a part of this specification to the extent specified herein. which are indicated as DoD adopted shall be the issue listed in the current DoDISS and the supplement thereto, if appli
11、cable. -k AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) (Copies of specifications and standards required by manufacturers in The issues of the documents ASTM D 3951 Standard Practice for Commercial Packaging. American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvani
12、a 19103). (Application for copies of ASTM publications should be addressed to the A- 2.3 Order of precedence. In the event of a conflict between the text of this specification and the references cited herein, the text of this specifica- tion shall take precedence, 3. REQUIREMENTS 3.1 Design. The she
13、et spring nut shall consist of one piece, designed for engagement and locking with standard coarse-thread machine or thread-forming screws, The machine screw threads shall conform to the American National coarse-thread Class 2B fit. The thread-forming screw threads shall conform to self-tapping thre
14、ads of FF-S-107. The sheet spring nut shall conform to the type, dimensions, material, finish and size of Military Standards MS90723 or MS90724, or as specified in the contract or order. be in conformance with pertinent Government, industry, or vendor drawings, as specified by the procuring activity
15、. screws; Type I for coarse-thread machine screws as specified in Table I, and Type II for thread forming screws as specified in Table II (see 6.2). 3.1.3 Contact edges, All edges shall be burred or so formed that they 3.1.1 The form of element incorporating the sheet spring nut feature shall (see 6
16、.1). 3.1.2 Size. The nuts shall be made in various sizes for use with standard will not damage the surface contacted in assembly. ? 3.2 Performance. I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1 rl O U _-.=.-e- $, MN CI *rl mvi MIL-N-333 7C 000
17、00 00000 u)u)u)uJu) d Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-flIL-N-3337C 53 9799906 0076923 5 MIL-N-3337C ri ci z 8 H H 3 FI k O w 3 cd d 4 ,.-., Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-
18、,-,-I- MIL-N-3337C 53 m 7979706 0076724 7 - MIL-N- 3 3 3 7C 3.2.1 Minimum torque, A screw assembled to the spring nut with the minimum torque specified in Table I and Table II shall not loosen when subjected to the vibration requirements of column 6, 7, and 8 of Tables I and II. 3.2.2 Failure torque
19、. The nuts shall not fail at a torque load of less than the values given in column 3 of Tables I and II. 3.2.3 Tension. The nuts shall withstand a pull normal to the plane of the sheets of not less than the tensile load given in column 4 of Tables I and II, without permanent set. The nuts shall not
20、fail when a pull normal to the plane of the sheets less than the tensile load given in column 5 of Tables I and II is applied. 3.2.4 Vibration. Sheet spring nuts shall withstand being vibrated with a simple harmonic motion, without any evidence of failure, for at least 20 hours at the frequency, dou
21、ble amplitude, and loads given in Tables I and II, when assembled with the minimum torques specified in Tables I and II. 3.2.5 Endurance. Sheet spring nuts shall withstand without any evidence of failure, 15 cycles of tightening and loosening operations as specified in 4.3.6. At the end of this test
22、, the nut screw thread, locking element, spring devices, or other parts of the assembly shall not be distorted or damaged in any manner that might affect subsequent use. 3.3 Finish. Noncorrosion-resistant metals shall be cadmium plated in accordance with QQ-P-416, Type II, Class 3. For applications
23、not involving electrical bonding, noncorrcsion-resistant metals may be alternately treated with a heavy phosphate coating conforming to TT-C-490, Grade A, followed by a prime coat of zinc-chromate primer conforming to TT-P-1757. O 3.4 Interchangeability. All parts having the same manufacturers part
24、number shall be directly and completely interchangeable with each other with respect to installation and performance. Changes in manufacturers part numbers shall be governed by the drawing number requirements of DOD-D-1000. 3.5 Identification of product. All nuts, where practicable, shall be marked
25、as to the thread size, type of screw used, and manufacturers identification thereof in accordance with the requirements of MIL-STD-130. 3.6 Workmanship. All details of workmanship shall be in accordance with highgrade manufacturing practice. The nuts shall be free from tool marks, burrs, flaws, and
26、all other defects. 4. QUALITY ASSURANCE PROVISIONS k 4.1 Responsibility for inspection. Unless otherwise specified in the con- Except as otherwise specified tract or purchase order, the contractor is responsible for the performance of all inspection requirements as specified herein. in the contract
27、or purchase order, the contractor may use his own or any other facilities suitable for the perf ormance of the inspection requirements speci- fied herein, unless disapproved by the Government. The Government reserves the right to perform any of the inspections set forth in the specification where su
28、ch inspections are deemed necessary to assure supplies and services conform to prescribed requirements. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_.s_s_ MIL-N-3337C 53 9999906 0096925 9 MIL-N-3337C 4.2 Sampling. Sampling for inspection shall be
29、 in accordance with MIL- Sampling for STD-105, Inspection Level II and AQL of 6.5 percent defective, the Torque Tension, Vibration, Corrosion, and Endurance tests specified in accordance with Inspection Level L4 of the appendix to MIL-STD-105 and AQL of 2.5 percent defective, 4.2.1 All screws and fi
30、xtures necessary for the tests specified herein shall be furnished by the contractor at no cost to the Government. shall be in accordance with 3.1. Screws 4.3 Inspection and tests. 4.3.1 Inspection. The sheet spring nuts shall be examined for conformance with this specification with respect to mater
31、ial, workmanship, configuration, contact edges, marking, and finish. 4.3.2 Torque, All sample nuts subjected to these tests shall be mounted on a test fixture as shown on Figure 1. The screw shall be tightened in the nut to the values shown in column 2 of Tables I and II. Steel screws shall be used
32、in testing steel sheet spring nuts and shall have dry threads. resistant steel screws shall be used in testing corrosion-resistant steel sheet spring nuts and shall have dry threads. Corrosion- 4.3.3 Tension. The tension test shall be conducted on a test fixture as shown on Figure 2. torque shown in
33、 columns 2 of Table I and II, as applicable, and the test jig assembled in a suitable test machine and subjected to the Tensile test load and failure load shown in columns 4 and 5. The screw shall be tightened in the nut to the installation 4.3.4 Vibration. Sheet spring nuts shall be mounted as show
34、n on Figure 3, and subjected to the vibration requirements of Tables I and II for the specified period of time. specified in Tables I and II. The screws shall be assembled with the minimum torques 4.3.5 Corrosion. The sheet spring nuts shall withstand salt spray tests in accordance with FED-STD-151
35、or 192 hours without indications of corrosion which cannot be wiped off with a damp cloth. a corroded area is defined as exposure or corrosion of the basic metal. For purposes of this requirement, 4.3.6 Endurance. The nut shall be tested on the test fixture shown on Figure 1. The screw shall be tigh
36、tened in the nut to the values shown in column 2 of Tables I and II. The screw shall then be loosened. These operations constitute one complete cycle, 4.4 Uniformity. Sheet spring nuts supplied under contract shall be identical in every respect to the sample tested and found satisfactory, and to the
37、 detail drawings thereof , except for changes previously approved by the Government, Any unapproved changes from the accepted test sample or from the drawings shall constitute cause for rejection. * 4.5 Inspection of packaging. The sampling and inspection of the preserva- tion, packing, and containe
38、r marking shall be in accordance with the require- ments of Paragraph 5.1, 5.2, and 5.3 of this specification, 6 - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-N-3337C 53 W 7977706 0076726 O MIL-N-3337C 5. PACKAGING * 5.1 Preservation, Preserv
39、ation shall be Level A, C or Commercial as specified (6.2.1). Jn 5.1.1 Level A. The sheet spring nuts shall be preserved in accordance with PPP-H-1581, * 5.1.2 Level C. The Level C preservation for the sheet spring nuts shall conform to the MIL-STD-794 requirements for this level. Jn 5.1.3 Commercia
40、l. The commercial preservation of the sheet spring nuts shall be in accordance with the requirements of ASTM D 3951. * 5.2 Packing. Packing shall be Level A, B, C or commercial, as specified (see 6.2.1). Jn 5.2.1 Level A and B. The sheet spring nuts shall be packed for shipment in accordance with PP
41、P-H-1581, except fiberboard boxes shall not be used for Level A packing. * 5.2.2 Level C. The level C packing for the sheet spring nuts shall conform to the MIL-STD-794 requirements this level. Jn 5.2.3 Commercial. The preserved sheet spring nuts shall be packed in accordance with the requirements o
42、f ASTM D 3951. * 5.2.5 Palletization. When specified (See 6.2.1) unitized loads, commen- surate with the level of packing specified in the contract or order, shall be palletized in accordance with MIL-STD-147. Unitized loads shall be uniform in size and quantities to the greatest extent possible. If
43、 the container is of a size and quantities to the greatest extent possible, If the container is of a size which does not conform to any of the pallet patterns specified in MIL-STD-147, the pallet pattern used shall first be approved by the contracting officer . * 5.3 Marking. Jn 5.3.1 Levels A, B, a
44、nd C. In addition to any special or other identifica- tion marking required by the contract (See 6.2.1) each unit pack, intermediate and exterior container and unitized load shall be marked in accordance with MIL-STD-129 and shall include the date of manufacture or date vulcanized for the type of ho
45、se specified in the contract or order, * 5.3.2 Commercial. Comercial markings shall be in accordance with the requirements of ASJ D 3951. Jn 5.4 General. * 5.4.1 Exterior containers. Exterior containers (see 5.2.1, 5.2.3, and 5.2.4) shall be of minimum tare and cube consistent with the protection re
46、quired and shall contain equal quantities of identical stock numbered items to the greatest extent practicable, Jn 5.4.2 Packaging inspection. The inspection of these packaging requirements shall be in accordance with 4.5. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted withou
47、t license from IHS-,-,-MIL-N-3337C 6. NOTES 6.1 Intended Use. The sheet spring nuts controlled by this specification are for other than aircraft primary or secondary structural applications and for use in fastening together of nonstructural items. * 6.2 Ordering data. * 6.2.1 Acquisition requirement
48、s. Acquisition documents should specify the f o 1 lows : a. b. d. e. f. marking g* C. Title, number and date of this specification. Type and size required. Material. (See 3.1) Design. (See 3.1) Finish required (See 3.3) Selection of applicable levels of preservation, packaging, packing, When palleti
49、zed loads are required (see 5.4) (See 3.1.2) and commercial/industrial (See 5.1, 5.2 and 5.3) 6.3 For Bureau of Ships and Air Force use, the limitations of Standard MS33538 should be considered, * 6.4 Changes from previous issue. The margins of this specification are marked with asterisks to indicate where changes (additions, modifications, corrections, deletions) from the previous issue were made, This was done as a convenience
