1、This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. JUNE 2015 Page 1 of 11 NAVISTAR, INC. Material, Parts, and Process Specifications
2、(MPAPS) NUMBER: MPAPS S-EM-56.101-GS/PL Former Designation: ESP-EM-56.101-GS TITLE: Prevailing Torque Hex Nuts All Metal Metric Series (Noun Code 5780) CURRENT REV No.: 1506 DATE: June 2015 WRITTEN/EDITED BY: Materials Engineering APPROVED BY: Materials Engineering SUPERSEDES: ESP-EM-56.101-GS - Aug
3、ust 2012 PRINTED COPIES OF THIS DOCUMENT MUST BE VERIFIED FOR CURRENT REVISION This specification may involve hazardous materials, equipment, and procedures. This specification does not purport to address all of the safety issues associated with its use. The user is responsible to consult appropriat
4、e safety and health practices and to determine the applicability of regulatory limits prior to use. Change Notice: Changed to New MPAPS format; Combined GS, GI, PP. 1.0 GENERAL: Implementation of this standard must be in accordance with the policies and procedures outlined in MPAPS S-A-0.101. There
5、may also be supplemental group instructions in regard to use of metric standards that should be taken into account. This standard may differ in some respects with certain segments of ISO and national standards. In recognition of these possible differences, the sizes and tolerance ranges used were es
6、tablished in an effort to enable the use of commercially available items, dimensionally interchangeable worldwide. This specification contains elements of the following standards: American National Standards Institute: 18.16.3M International Organization for Standardization: ISO 2320, 7042, 7719 Pre
7、vailing torque type is a nut which is frictionally resistant to rotation due to a self-contained prevailing torque feature, and not because of a compressive load developed against the bearing surface of the nut. Prevailing torque is the torque necessary to rotate the nut on its mating externally thr
8、eaded component, with the torque being measured while the nut is in motion, and with no axial load in the mating component. Inch series prevailing torque hex nuts - all metal, may be found in MPAPS S-E-56.101-GS/PL. Letter symbols designating dimensional characteristics are in accord with those used
9、 in ANSI and ISO standards. 2.0 APPLICATION GUIDE: To ensure full benefit of the prevailing torque feature, two fully formed threads must be visible beyond the top surface of the nut. NUMBER: MPAPS S-EM-56.101-GS/PL TITLE: Prevailing Torque Hex Nuts All Metal REVISION: 1506 This document is restrict
10、ed and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. JUNE 2015 Page 2 of 11 3.0 CONTENTS: 4.0 DESIGN CONSIDERATION: The use of thru hardened washers is recommen
11、ded in high strength bolted connections and in Class 8.8 applications involving oversized or slotted holes. Optimum uses for prevailing torque nuts are with short length bolts, joints where the pre-load may be less than the service load, soft materials, and joints subjected to severe vibration. Coar
12、se thread series only will be considered as part of this standard, because of the following advantages: Less tendency to cross thread. Less likely to be seriously affected by manufacturing errors such as decarburization and oversized minor diameter of internal threads. In the event of a failure of m
13、atched class bolt/nut combination, the tendency will be toward bolt fracture rather than undetectable strip. Page General 1 Application Guide 1 Design Consideration 2 Metric-Inch Related Sizes 3 Threads 3 Thread Tolerances 3 Performance Requirements 3 Property Class 3 Mechanical Properties 3 Color C
14、oding 4 Method of Designation 4 Policy for Selecting Parts for New Design 4 Width Across Flats 4 Thickness 4 Wrenching Height 4 Bearing Surface 4 True Position of Tapped Hole 4 Countersink 5 Threads 5 Material 5 Finishes 5 Restricted Chemical Substances 5 Workmanship 5 Performance Requirements 5 Tes
15、t Methods 6 Dimension of Hex Nuts 10 Part List 11 Technical Information 11 NUMBER: MPAPS S-EM-56.101-GS/PL TITLE: Prevailing Torque Hex Nuts All Metal REVISION: 1506 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Stand
16、ards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. JUNE 2015 Page 3 of 11 5.0 METRIC INCH RELATED SIZES: During the inch to metric design transition period, the following chart of related sizes can be used for reference. This information is not to be considered as a
17、recommendation for substitutions but only as a means of determining approximate dimensional equivalents. Metric Series Approximate Metric Series Approximate mm Inch Series mm Inch Series 6 1/4 16 5/8 8 5/16 20 3/4 10 3/8, 7/16 24 7/8, 1 12 1/2 30 1-1/8, 1-1/4 14 9/16 36 1-1/2 6.0 THREADS: The ISO ba
18、sic profile is essentially the same geometric configuration as the unified screw thread basic form. The threads will be coarse series, tolerance class 6H. 7.0 THREAD TOLERANCES: The medium ISO class of fit 6H/6g is approximately the same as the 2A/2B allowance in the U.S. unified thread series for c
19、omparable size. For example: Thread Allowance M10 x 1.5 - 6H/6g 0.032 mm (.00126 in) 3/8-16 UNC 2A/2B .0013 in (0.033 mm) 8.0 PERFORMANCE REQUIREMENTS: Proof, clamp loads, and prevailing torques are listed in section 25.0. Nuts will not be used for special applications such as those requiring weldab
20、ility, corrosion resistance, or ability to withstand temperatures above 230C or below minus 50C for plated nuts and above 300C to below minus 50C for unplated nuts. 9.0 PROPERTY CLASS: The property class designation for steel nuts is equal to one hundredth of the approximate proof load stress in meg
21、apascals (1 MPa = N/mm2). 10.0 MECHANICAL PROPERTIES: The property class designation system for prevailing torque steel nuts will be a number which is one-hundredth to the approximate proof load stress in megapascals (MPa). The proof load stress corresponds to the minimum tensile strength of the hig
22、hest class of bolt or screw with which the nut can be used. Property Class Designation for Prevailing Torque Nuts Property class designation 10 Proof load stress, MPa 1040 It is recommended that the class of nut be used with each class of bolt as indicated in the following: Recommended Bolt and Nut
23、Combination Class of Bolt All Class of Nut 10 Caution! If it is necessary to combine a class 10 nut with a bolt of a lower class than 10.9, the prevailing torque characteristics will be significantly altered. NUMBER: MPAPS S-EM-56.101-GS/PL TITLE: Prevailing Torque Hex Nuts All Metal REVISION: 1506
24、This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. JUNE 2015 Page 4 of 11 11.0 COLOR CODING: Not recommended, except in cases where a
25、dequate insurance is needed to prevent mixing of “metric parts“ with look-alike “inch parts.“ The color blue is standard identifier used in some industries. This must be handled internally at individual plants where needed and is meant to be supplemental to the normal finish and easily deleted when
26、the need for supplemental identification no longer exists. The supplemental blue color should not be used on finishes such as chromium bright which are specified for cosmetic purposes or phosphate coating which may cause a loss of color identity. 12.0 METHOD OF DESIGNATION: Prevailing torque nuts wi
27、ll be designated on purchase orders by size, word description, material class, finish and part number as follows: M10, Prevailing Torque Nut, All Metal, Class 10, PHC, Part Number The absence of a specification for pitch indicates that coarse thread is required; e.g., a coarse thread of the dimensio
28、ns M10 x 1.5 is designated as “M10.“ 13.0 POLICY FOR SELECTING PARTS FOR NEW DESIGN: Approved parts are so designated to reduce variety of parts and assure maximum availability and cost savings: For new design, parts shall be selected from “Approved“ part list only. Nominal Sizes: M6, M8, M10, M12,
29、M16, M20, M24, M30, and M36 Material: Class 10 Finish: Phosphate Coating (PHC) 14.0 WIDTH ACROSS FLATS: The width across flats will be distance, measured perpendicular to the axis of the nut, between two opposite wrenching flats. The maximum width across flats may be exceeded by 0.05 mm to allow for
30、 nut deformation caused by introduction of the prevailing-torque feature. The width across flats may be less than the specified minimum in the deformed portion of the nut containing the prevailing-torque feature. 15.0 THICKNESS: The nut thickness will be the overall distance, measured parallel to th
31、e axis of the nut, from the top of the nut to the bearing surface of hex nuts. Raised identification markings, if present, will be excluded. 16.0 WRENCHING HEIGHT: The wrenching height is the distance, measured at a corner of the hex, from the bearing surface of hex nuts, to the last plane of full f
32、ormed hex, i.e., the plane perpendicular to the nut axis which is closest to the top of the nut and at which the width across corners is within its specified limits. Wrenching height for hex nuts is dimension M, in Table 1, and is subject to measurement. 17.0 BEARING SURFACE: Hex nuts will have a ch
33、amfered bearing surface. The diameter of the bearing surface will not exceed the width across flats nor be less than the bearing face diameter specified on the page. The bearing surface will be flat and perpendicular to the axis of the thread within the total runout limit specified on the last page.
34、 18.0 TRUE POSITION OF TAPPED HOLE: The axis of tapped hole will be located at true position with respect to the axis of nut body within a tolerance zone having a diameter equivalent to 3 percent of the maximum width across flats, regardless of feature size. NUMBER: MPAPS S-EM-56.101-GS/PL TITLE: Pr
35、evailing Torque Hex Nuts All Metal REVISION: 1506 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. JUNE 2015 Page 5 of 11 19.0 COUN
36、TERSINK: The tapped hole will be countersunk on the bearing face, and may be countersunk on the top face. The countersink included reference angle will be 90 deg to 120 deg. The maximum countersink diameter will be 1.15 times the nominal thread diameter (major diameter) for nuts M4 and smaller, the
37、nominal thread diameter plus 0.75 mm for M5 through M8 nuts, and 1.08 times the nominal thread diameter for M10 and larger nuts. The minimum countersink diameter will be the nominal thread diameter. 20.0 THREADS: Threads, prior to introduction of the prevailing-torque feature, will be metric coarse
38、threads with class 6H tolerances in accordance with ANSI B1.13M. Nuts M10 and smaller will assemble a minimum of one-half turn, and nuts M12 and larger will assemble a minimum of one full turn by hand on a basic GO thread plug gage. The plug gage will be without a chip groove, and will have a point
39、with dimensions conforming to those for the point on metric hex head bolts given in MPAPS S-BM-1.101-GS/PL. 21.0 MATERIAL: Steel, Class 10 per MPAPS F-31, Part II. 22.0 FINISHES: In accordance with the Navistar Engineering Material Specification and class listed below: Plain (PLN) Free from dirt and
40、 rust and coated with a light oil film. Phosphate Coated (PHC) MPAPS G-1, Class B-2. Zinc Aluminum Clear (ZACLR) MPAPS G-4518, Type II. All nuts will be provided with a supplementary lubricant following plating which will be clean and dry to the touch. Lubricant will not deteriorate due to temperatu
41、re and humidity variations so as to affect nut performance for a period of one year when nuts are stored, shipped, or handled in a normal manner. 23.0 RESTRICTED CHEMICAL SUBSTANCES: Effective January 1, 2007, all product supplied to the requirements of this specification must comply with the requir
42、ements of the MPAPS B-50 specification. 24.0 WORKMANSHIP: Nuts will not contain an excess of surface imperfections which might affect their serviceability, such as burrs, seams, laps, loose scale, and other irregularities. 25.0 PERFORMANCE REQUIREMENTS: The prevailing torque developed by nuts during
43、 their first installation or any subsequent installation or removal, will not exceed the maximum first installation torque as specified in Table 1 when tested as specified in this standard. In addition, the prevailing torque developed by nuts during their first and fifth removals will not be less th
44、an those specified in Table 1. NUMBER: MPAPS S-EM-56.101-GS/PL TITLE: Prevailing Torque Hex Nuts All Metal REVISION: 1506 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all p
45、atent liability. 2015 by Navistar, Inc. JUNE 2015 Page 6 of 11 Table 1 - Proof Loads, Clamp Loads and Prevailing Torques for Nuts Nominal Size Proof Load, kN Clamp Load, kN Prevailing Torque, Nm Class 9 Class 10 Class 10 First Installation Max First Removal Min Fifth Removal Min M6 18.1 20.9 12.5 4
46、0.55 0.4 M8 34.4 38.1 22.8 8 1.15 0.8 M10 54.5 60.3 36.1 14 2 1.4 M12 80.1 88.5 52.5 21 3.1 2.1 M14 109 121 71.6 31 4.4 3 M16 149 165 97.5 42 6 4.2 M20 - 260 152 72 10.5 7 M22 - 321 189 90 13 9 M24 - 374 220 106 15 10.5 M30 - 595 350 140 19 14 M36 - 866 509 180 24 17 5 Note: The clamp loads for clas
47、s 10 nuts are equal to 75 percent of the proof load of property class 10.9 bolts. Proof loads are given in MPAPS F-31, Part I. 26.0 TEST METHODS: 26.1 Proof Load Test: The test sample nut will be assembled on a test bolt or on a hardened mandrel with a minimum of three threads projecting through the
48、 nut. For referee test purposes, the hardened mandrel will be used. The maximum torque occurring during the assembly of the nut on the test bolt or mandrel will be recorded. A tensile load equal to the specified proof load for the nut, as given in Table 1, will be applied through the test bolt or ma
49、ndrel against the nut bearing surface in an axial direction. The nut will resist this load without thread stripping or rupture. The torque necessary to remove the nut from the test bolt or mandrel will not exceed the maximum torque occurring during assembly. Test Bolt: The bolt used for proof load testing nuts will have threads conforming to ISO 965, Part I, Class 6g tolerances. The test bolt will have a proof load capability
