1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2017 SAE InternationalAll rights reserved. No part of this publi
3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out
4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on thisTechnical Report, please visithttp:/standards.sae.org/J1701_201702SURFACE VEHICLEINFORMATION REPORTJ1701 FEB2017Issued 1996-07Reaffirmed 2013-04Revised 2017-02Su
5、perseding J1701 APR2013Torque-Tension Tightening for Inch Series FastenersRATIONALEThis revision is limited in scope. Section 5.4 (Check Procedure) has been removed from this Information Report. It was determined to be outside the scope as an advisory guide.FOREWORDFundamentally, threaded fasteners
6、are required to create a clamping force or load on the assembled joint to prevent loosening. To accomplish this, a tensile loading is applied onto a bolt or screw by itself or by a nut tightened on the bolt or screw.The axial stress in them produces a clamping force equal to the product of the proof
7、-load stress, reduced by a design factor, and the core area of the bolt or screw.Although clamping or tension load can be measured by load cells and strain gauges, these methods are impractical on theproduction line. The most practical methods of achieving control of joint clamp load involve torque
8、control, tightening anglecontrol, or combinations of torque and angle. In some cases, a torque versus angle yield method is utilized, particularly when tightening 5/8 in and larger fastener sizes, but measurement and assembly equipment is sensitive. Therefore, it becomes very important to understand
9、 the relationship between torque and tension.1. SCOPEThis SAE Information Report is provided as an advisory guide. Individual application discretion is recommended. The content has been presented as accurately as possible, but responsibility for its application lies with the user. The document cover
10、s the variables in the torque-tension relationship: friction, materials, temperature, humidity, fastener and mating part finishes, surfaces, and the kind of wrenching employed.Also, described in this document is the torque management required to achieve correct fastener joint tightening.The thread f
11、it of fasteners must be in accordance with Class 2A for external and Class 2B for internal inch threads.SAE INTERNATIONAL J1701 FEB2017 Page 2 of 52. REFERENCES2.1 Related PublicationsThe following publications are provided for information purposes only and are not a required part of this SAE Techni
12、cal Report.2.1.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org.SAE J174 Torque-Tension Test Procedure for Steel Threaded Fasteners - Inch SeriesSAE J995 Mech
13、anical and Material Requirements for Steel NutsSAE J1648 Protective Coatings for Fasteners3. EXPLANATION OF TIGHTENING TERMS3.1 Torque is the product of force x lever arm length. It is the moment resistance of the fastener and its components to tightening, expressed in in-oz, in-lb, and ft-lb.3.2 Tu
14、rn Screw or Bolt and Turn Nut Terms describe which mating part is tightened. For turn screw, the head of the screw or bolt is turned against a panel into either a panel with a tapped thread or separate nut component.3.3 For turn nut, the nut is threaded onto a screw or bolt and is tightened against
15、the panel surface.3.4 Clamping Load occurs when the screw or bolt is stretched when the fastener is tightened. It is equal and opposite to the tensile force developed in the screw or bolt and is expressed as pounds (lb).3.5 Inertia is the tendency of a body to continue in motion after being subjecte
16、d to a force in a specific direction until acted upon by an outside force. In tightening, friction between mating parts and bearing against panel or part surfaces is the major contributing outside force and has to be overcome. Inertia of the rotating power tool is another factor which must be consid
17、ered.4. VARIABLES IN THE RELATIONSHIP OF CLAMPING LOAD TO APPLIED TORQUE4.1 FrictionThe friction resistance torque is the most important of all of the variables. It has two components, the friction resistance of the applied nut fastener with respect to mating part threads, and the bearing surface ag
18、ainst joint members. Increasing the clamping tension force on the screw or bolt increases the resistance to turning.4.2 Fastener MaterialsCharacteristic properties of hardness and surface condition can contribute to friction variability thus affecting tightening torque to obtain the same clamping lo
19、ad.4.2.1 Nonheat-treatable low-carbon stainless steels and other soft alloys cause increased friction resistance resulting in higher tightening torque for a given clamp load.4.2.2 Hardened steel or hard alloy fasteners have a harder slippery surface reducing friction and thereby requiring lower tigh
20、tening torque.4.2.3 Special materials, rubber, plastics, etc., either as fabricated fasteners or attached to them, also affect torque if they contact the rubbing surfaces during the tightening.SAE INTERNATIONAL J1701 FEB2017 Page 3 of 54.3 Surface Conditions, such as coatings or effects of the envir
21、onment applied to fasteners and bearing surfaces will affect tightening torque requirements for a given clamp load.4.3.1 The roughness, coarseness, or abrasiveness of coatings will increase required torque.4.3.2 Decreased friction due to the nature of the coating including oil, wax, teflon, or other
22、 lubricants will reduce required torque.4.3.3 Interferences due to dirt, rust, burrs and galling, or seizing caused by soft coatings (zinc is an example) on fasteners, mating parts, and panels increases required torque.4.3.4 Hardness of the fastener, its mating part, or the joint material will reduc
23、e required torque.4.3.5 Temperature contraction, especially if the assembly tightening was made while warm, will reduce clamping load. If the fastener is at a higher temperature than the assembly, then the clamping load increases upon cooling.Adjustments to assembly torque must accommodate these con
24、ditions.4.3.6 Humidity will cause reduced friction reducing required torque.4.3.7 Joint relaxation can occur if joint material can deform under load and/or time. In such cases, special torque sequencing may be required.4.4 WrenchingThe method of tightening has a profound influence on required torque
25、.4.4.1 The slow deliberate turning by hand wrenching allows the assembly to settle somewhat during tightening thus negating some of the effects of joint relaxation.4.4.2 High air pressure or electric power tool fastener tightening involving rotation contribute to lower torque. The use of inertia les
26、sens the effect of static friction, but can increase torsional loading of bolts or screws.5. TORQUE MANAGEMENTTo determine how much hand or power tool torque should be applied to a fastener assembly or how much turn-of-the-nut tightening is required, consideration must be directed to the development
27、 of these methods.5.1 Theoretical Calculations to Obtain Torque Guide5.1.1 Empirical Equation(Eq. 1)where:T = torque (in-lb, ft-lb)D = screw or bolt nominal size (inch)W = screw or bolt tension (lb-oz)K = torque factor5.1.2 The tension of the screw or bolt is calculated by multiplying the usable scr
28、ew or bolt tensile strength by the tensile-stress core area of the screw or bolt. The nominal clamp load stress is assumed as 75% of proof load.T KDW=SAE INTERNATIONAL J1701 FEB2017 Page 4 of 55.1.3 The torque factor is the critical parameter in Equation 1 influenced primarily by the frictional cond
29、itions along the thread flank and at the bearing surfaces.The other influence on “K” is the relative resiliency of the fastener and joint material.a. Therefore:(Eq. 2)where:K1 represents the torque factor wasted by friction on the bearing surface of the nut or bolt, approximately 50% of the total to
30、rque factorK2 factor represents the wasted friction on the contact flanks of the threads, about 40% of the total “K”K3 factor represents the useful torque producing the bolt tension, about 10% of the total “K”b. K is 0.15/0.20 when bolts, nuts, and washers of the fastener joint are clean and coated
31、with a thin film of protective oil.When dirt, rust, and other defects of field storage and environmental exposure are present, K can be 0.25/0.40. Refer to Table 1 for torque K factors for other conditions.Table 1 - Torque factors for surfaceconditions of mating fastenersMating Parts KDry, clean wit
32、h thin film of oil 0.15/0.20Additional lubricating coatings of oil,wax, or dissimilar plating or hard washer 0.10/0.15Thread and head bearing surfacescovered with high-performance lubri- can be ascants or with anti-seize compounds low as 0.05Combinations of certain materials such asAustenite stainle
33、ss steel screws/bolts can be asand parts not lubricated or coated high as 0.355.2 Clamp load and torque calculations based on the aforementioned formula for dry and lubricated conditions are tabulated in Table 2.5.3 Turn-of-the-Nut MethodThe previous sections dwelled on tightening torque to produce
34、clamping tension. The turn-of-the-nut method can produce satisfactory clamping when the joint is completely closed prior to the turn movement.Since the basis for tightening threaded fasteners is screw or bolt tension, stretching the bolt by turning the nut a number of degrees clockwise after finger
35、or snug tight will accomplish this. The bolt stretch is the degrees turned portion of the 360pitch dimension. The number of degrees turned depends upon the strength of the bolt and the joint thickness.This document has not elaborated on the method because it is not effective unless the joint is clos
36、ed under the screw/bolt head or nut. Nevertheless, turn-of-the-nut is the most practical for 5/8 inch and larger sizes.K K1 K2 K3+ +=SAE INTERNATIONAL J1701 FEB2017 Page 5 of 5Table 2 - Torque-tension relationships for SAE grades 2, 5, and 8NominalSizeandThreads/InchStressArea (1)in2Grade 2ClampLoad
37、lbGrade 2TorqueDry K = 0.2in-lbGrade 2TorqueLub K = 0.15in-lbGrade 5ClampLoadlbGrade 5TorqueDry K = 0.2in-lbGrade 5TorqueLub K = 0.15in-lbGrade 8ClampLoadlbGrade 8TorqueDry K = 0.2in-lbGrade 8TorqueLub K = 0.15in-lb0.250-28 0.03637 1500 75.0 56.0 2319 116.0 87.0 3273 164 1230.250-20 0.03182 1313 66.
38、0 49.0 2029 101.0 76.0 2864 143 1070.3125-24 0.05806 2395 150.0 112.0 3700 230.0 173.0 5225 327 2450.3125-18 0.05243 2163 135.0 101.0 3342 209.0 157.0 4719 295 2210.375-24 0.08783 3623 272.0 204.0 5600 420.0 315.0 7905 593 4450.375-16 0.07749 3196 240.0 180.0 4940 370.0 278.0 6974 523 3920.4375-20 0
39、.11870 4896 428.0 321.0 7567 662.0 496.0 10683 935 7000.4375-14 0.10630 4385 384.0 288.0 6777 593.0 445.0 9567 837 6280.500-20 0.15995 6598 660.0 495.0 10197 1020.0 764.0 14396 1440 10800.500-13 0.14190 5853 585.0 439.0 9046 904.0 678.0 12771 1277 958NominalSizeandThreads/InchStressArea (1)in2Grade
40、2ClampLoadlbGrade 2TorqueDry K = 0.2ft-lbGrade 2TorqueLub K = 0.15ft-lbGrade 5ClampLoadlbGrade 5TorqueDry K = 0.2ft-lbGrade 5TorqueLub K = 0.15ft-lbGrade 8ClampLoadlbGrade 8TorqueDry K = 0.2ft-lbGrade 8TorqueLub K = 0.15ft-lb0.5625-18 0.20298 8373 78 59 12940 121 91 18268 171 1280.5625-12 0.18195 75
41、05 70 53 11600 109 82 16376 154 1150.625-18 0.25595 10558 110 82 16317 170 127 23036 240 1800.625-11 0.22600 9322 97 73 14407 150 113 20340 212 1590.750-16 0.37296 15385 192 144 23776 297 223 33566 420 3150.750-10 0.33446 13796 172 129 21532 269 201 30101 376 2821.000-12 0.66304 42269 704 528 59674
42、995 7461.000-8 0.60574 38616 644 483 54517 909 681Tensile Strength 74000 psi 120000 psi 150000 psiProof Load Stress 55000 psi 85000 psi 120000 psiCAUTION:The previously listed torque and resulting tension are provided as an advisory guide. Individual application discretion is recommended. The conten
43、t has been presented as accurately as possible, but responsibility for its application lies with the user.NOTE 1: The stress area of threaded series not included in Table 2 may be computed from the equation:(Eq. 3)where:As= Stress area in in2D = Diameter in inchesn = Threads per inch6. NOTES6.1 Revi
44、sion IndicatorA change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only.PREPARED BY THE SAE FASTENERS COMMITTEEAS 0.7854 D 0.9743 n 2e=
