1、 WORLDWIDE ENGINEERING STANDARDS General Specification GMW16551 Metric Screw Threads Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 1 of 6 1 Introduction 1.1 Scope. This standard specifies the characteristics of external and internal metric screw threads. 1.2 Designation.
2、 Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASME B1.3 ISO 965-2 ASME B1.16M ISO 965-3 ISO 68-1 ISO 1502 ISO 261 ISO 6157-1 ISO 724 ISO 6157-2 ISO 965-1 ISO 6157-3 2.2 GM Standards/Specificati
3、ons. GMW3059 GMW25 3 Requirements 3.1 Dimensions. Not applicable. 3.2 Screw Thread Conformance. Unless otherwise specified on the drawing, acceptability of screw threads shall be determined according to the following: ASME B1 Thread Acceptance and Gaging: B1.3 Screw Thread Gaging Systems for Dimensi
4、onal Acceptability of Screw Threads B1.16M Gages and Gaging For Metric M Screw Threads ISO General Purpose Metric Screw Thread Tolerances: ISO 68-1 Part 1: Basic Profile ISO 261 General Plan ISO 724 Basic Dimensions ISO 965-1 Part 1: Principles and Basic Data ISO 965-2 Part 2: Limits of Sizes for Ge
5、neral Purpose External and Internal Screw Threads - Medium Quality ISO 965-3 Part 3: Deviations for Constructional Screw Threads ISO 1502 Gauges and Gauging ISO 6157-1 Part 1: Bolts, Screws and Studs for General Requirements ISO 6157-2 Part 2: Nuts ISO 6157-3 Part 1: Bolts, Screws and Studs for Spec
6、ial Requirements GMW25 Mechanical Properties and Material Requirements for Externally Threaded Fasteners 3.2.1 Uncoated Fasteners. Unless otherwise specified on the drawing, acceptability of screw threads for uncoated fasteners shall be determined with gauges based on ISO 1502 or ASME B1.16M, with C
7、lass 6g tolerance applying to external threads and Class 6H tolerance applying to internal threads. During manufacturing, the pitch or groove diameter shall be statistically monitored using variable gauges for both internal and external threads. 3.2.2 Coated/Plated Fasteners. Unless otherwise specif
8、ied on the drawing, acceptability of screw threads for coated or plated fasteners shall be determined with Ring Go-gauge based on ISO 1502 or ASME B1.16M, with Class 6h tolerance applying to external threads and Class 6H tolerance applying to internal threads. The supplier is responsible to develop
9、appropriate before coating or plating thread dimensions in order to achieve the after coating or plating thread Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE EN
10、GINEERING STANDARDS GMW16551 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 2 of 6 tolerance class. Threads may be produced undersize or oversize to accommodate coating or plating, provided the finished product meets all specific material properties. Per ISO 1502 and ASME
11、 B1.3, if any properly calibrated Go-gauge accepts the threads, the parts shall be acceptable. 3.2.3 Coated/Uncoated Internal Threaded Fasteners of 6E Classification. On GM internally threaded fasteners which are used in integral applications such as weld nuts or clinch nuts prior to coating, a 6E t
12、hread tolerance classification is utilized. In Appendix B, Table B1 Limiting Dimensions of Internal Screw Threads - 6E, the thread classification is specified for inspection purposes. 3.2.4 Coated/Uncoated External Threaded Fasteners of 6e Classification. On GM external threaded fasteners which are
13、used in integral applications such as weld studs or clinch stud prior to coating, a 6e thread tolerance classification is utilized. In Appendix C, Table C1 Limiting Dimensions of External Screw Threads - 6e, the thread classification is specified for inspection purposes. 3.2.5 Maximum Allowable Torq
14、ue to Overcome Thread Damage During Gauging (External Threads Only). Maximum torque allowed for a given Go-screw thread ring gauge is specified in Table 1. Allowable torques for thread sizes not listed may be calculated. (See Appendix A.) Damage to externally threaded surfaces is described, in part,
15、 in Appendix A and may be cause for part rejection. Table 1: Maximum Allowable Gauging Torque for Thread Size Regardless of Coating Thread Size Maximum Allowable Torque Nm M6 0.32 M8 0.77 M10 1.5 M12 2.59 M14 4.12 M16 6.14 M18 8.75 M20 12 3.3 Surface Treatment. Not applicable. 3.4 Thread. 3.4.1 Exte
16、rnally Threaded Fasteners. Fasteners sizes M20 and lengths 150 mm shall be roll threaded unless otherwise agreed upon. Threading practice for fasteners of all other sizes shall be at the option of the supplier. 3.4.2 Internally Threaded Fasteners. Internally threaded fasteners may be rolled or cut a
17、t the option of the supplier. 3.5 Tolerances. Not applicable. 3.6 Surface Discontinuities. Reference: GMW25 for External Thread, ISO 6157-2 for Internal Thread. 3.7 Proof Load Requirements. Not applicable. 3.8 Acceptability. Not applicable. 4 Rules and Regulations 4.1 Legal Regulations. All material
18、s must satisfy applicable laws, rules, regulations and recommendations valid in the country of usage. 4.2 Language. In the event of conflict between the English and domestic language, the English language shall take precedence. 4.3 Inspection and Rejection. Samples of components or materials release
19、d to a GM general specification shall be tested for conformity with the requirements of this general specification and approved by the responsible Engineering department prior to commencement of delivery of bulk supplies. A new approval must be received for any changes, e.g., properties, manufacturi
20、ng process, location of manufacture, etc. If not otherwise agreed, all testing and documentation normally required for initial release must be completed. It is the responsibility of the supplier to inform the customer in a timely manner, without solicitation, and to include documentation of all modi
21、fications of materials and/or processes and to apply for a new release. If not otherwise agreed, all release tests shall be repeated and documented by the supplier prior to commencement of delivery of non-conforming bulk supplies. In individual cases, a shorter test can be agreed to between the resp
22、onsible Engineering department and the supplier. 4.4 Initial Source Approval. No shipments shall be made by any supplier until representative initial production samples have been approved by the appropriate Materials Engineering department(s) as meeting the requirements of this specification. 4.5 Al
23、l materials supplied to this standard must comply with the requirements of GMW3059, Restricted and Reportable Substances for Parts. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS
24、-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16551 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 3 of 6 5 Notes 5.1 Glossary. Not applicable. 5.2 Acronyms, Abbreviations, and Symbols. Ref Reference 6 Coding System This standard shall be referenced in other documents, drawi
25、ngs, etc., as follows: GMW16551 7 Release and Revisions This standard was originated in February 2011. It was first approved by the Fastening Expert Team in June 2011. It was first published in June 2011. Issue Publication Date Description (Organization) 1 JUN 2011 Initial publication. 2 AUG 2013 Ad
26、ded reference to GMW25, revised paragraphs 3.4.1, 3.4.2, and 3.6. (Chassis Fastening Expert Team) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STAN
27、DARDS GMW16551 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 4 of 6 Appendix A: Damage of External and Internal Threaded Surfaces Cause Damages, such as dents, scrapes, nicks and gouges, are produced by external action during manufacturing and handling of externally and
28、internally threaded product, for example, during product loading or transfer. Appearance No precise geometrical shape, location or direction identifiable due to an external action. Limits Damages as previously described shall not cause part rejection unless it can be shown that they impair function
29、or usability. Dents, scrapes, nicks and gouges on the first three threads (Partial and/or Full) shall be such that they allow screwing on a Go-screw thread ring gauge with torque values 0.0015 (diameter)3 maximum in newton-meters. A specific agreement on packaging, for example, may be necessary in o
30、rder to avoid/prevent damage during shipping. In addition, process controls may be needed to reduce drop height, transfer belt length, or any other process in manufacturing, heat treat or coating/plating facilities to reduce potential of such damage as previously described. Copyright General Motors
31、Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16551 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 5 of 6 Appendix B Table B1: Limit
32、ing Dimensions of Internal Screw Threads - 6E Nominal Allowance Minor Minor Pitch Pitch Major Major Thread E Diameter Diameter Diameter Diameter Diameter Diameter Size El Minimum Maximum Minimum Maximum Minimum (Ref.) Maximum (Ref.) M4 x 0.7 +0.056 3.298 3.478 3.601 3.719 4.056 4.275 M5 x 0.8 +0.060
33、 4.194 4.394 4.540 4.665 5.060 5.300 M6 x 1 +0.060 4.977 5.213 5.410 5.560 6.060 6.354 M8 x 1 +0.060 6.977 7.213 7.410 7.560 8.060 8.354 M8 x 1.25 +0.063 6.710 6.975 7.251 7.411 8.063 8.403 M10 x 1 +0.060 8.977 9.213 9.410 9.560 10.060 10.354 M10 x 1.25 +0.063 8.710 8.975 9.251 9.411 10.063 10.403 M
34、10 x 1.5 +0.067 8.443 8.743 9.093 9.273 10.067 10.464 M12 x 1.25 +0.063 10.710 10.975 11.251 11.431 12.063 12.423 M12 x 1.5 +0.067 10.443 10.743 11.093 11.283 12.067 12.474 M12 x 1.75 +0.071 10.177 10.512 10.934 11.134 12.071 12.524 M14 x 1.5 +0.067 12.443 12.743 13.093 13.283 14.067 14.474 M14 x 2
35、+0.071 11.906 12.281 12.772 12.984 14.071 14.572 M16 x 1.5 +0.067 14.443 14.743 15.093 15.283 16.067 16.474 M16 x 2 +0.071 13.906 14.281 14.772 14.984 16.071 16.572 M18 x 1.5 +0.067 16.443 16.743 17.093 17.283 18.067 18.474 M18 x 2.5 +0.080 15.374 15.824 16.456 16.680 18.080 18.665 M20 x 2.5 +0.080
36、17.374 17.824 18.456 18.680 20.080 20.665 M22 x 2.5 +0.080 19.374 19.824 20.456 20.680 22.080 22.665 Ref = Reference Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWI
37、DE ENGINEERING STANDARDS GMW16551 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 6 of 6 Appendix C Table C1: Limiting Dimensions of External Screw Threads - 6e Allow-ance Minor Minor Pitch Pitch Major Major Thread e Diameter Diameter Diameter Diameter Diameter Diameter Si
38、ze es Ref. Minimum (Rounded Form) Maximum (Flat Form) Minimum Maximum Minimum Maximum M4 x 0.7 -0.056 3.024 3.242 3.455 3.545 3.804 3.944 M5 x 0.8 -0.060 3.893 4.134 4.385 4.480 4.790 4.940 M6 x 1 -0.060 4.622 4.917 5.238 5.350 5.760 5.940 M8 x 1 -0.060 6.622 6.917 7.238 7.350 7.760 7.940 M8 x 1.25
39、-0.063 6.300 6.647 7.070 7.188 7.725 7.937 M10 x 1 -0.060 8.622 8.917 9.238 9.350 9.760 9.940 M10 x 1.25 -0.063 8.300 8.647 9.070 9.188 9.725 9.937 M10 x 1.5 -0.067 7.970 8.376 8.894 9.026 9.697 9.933 M12 x 1.25 -0.063 10.286 10.647 11.056 11.188 11.725 11.937 M12 x 1.5 -0.067 9.962 10.376 10.886 11
40、.026 11.697 11.933 M12 x 1.75 -0.071 9.635 10.106 10.713 10.863 11.664 11.929 M14 x 1.5 -0.067 11.962 12.376 12.886 13.026 13.697 13.933 M14 x 2 -0.071 11.309 11.835 12.541 12.701 13.649 13.929 M16 x 1.5 -0.067 13.962 14.376 14.886 15.026 15.697 15.933 M16 x 2 -0.071 13.309 13.835 14.541 14.701 15.6
41、49 15.929 M18 x 1.5 -0.067 15.962 16.376 16.886 17.026 17.697 17.933 M18 x 2.5 -0.080 14.666 15.294 16.206 16.376 17.585 17.920 M20 x 2.5 -0.080 16.666 17.294 18.206 18.376 19.585 19.920 M22 x 2.5 -0.080 18.666 19.294 20.206 20.376 21.585 21.920 Ref = Reference Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
