1、 WORLDWIDE ENGINEERING STANDARDS Design Standard GMW16812 Global Dimensioning and Tolerancing Addendum Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 1 of 16 1 Introduction Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of
2、 conflict between the English and domestic language, the English language shall take precedence. 1.1 Scope. General Motors Company has adopted an amended version of the American Society of Mechanical Engineers (ASME) Y14.5-2009 Dimensioning and Tolerancing standard (amended by this addendum) for use
3、 on all product engineering documentation. This addendum was created to address the following areas: Select an option from ASME Y14.5 Clarify a concept from ASME Y14.5 Discourage/disallow the use of a concept from ASME Y14.5 Include a concept not covered by ASME Y14.5 1.2 General Motors Authorizatio
4、n. This standard is authorized by the Global Dimensional Engineering Council (GDEC) 1.3 Application of this Standard. GMW16812 applies to all new vehicle and Powertrain Engineering drawings for all GM badged vehicles worldwide including vehicles and powertrains supplied to GM by Joint Ventures and A
5、llied Partners. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASME Y14.5-2009 2.2 GM Standards/Specifications. None 3 Requirements (Body of the GM Global Dimensioning and Tolerancing Addendum) The paragraph num
6、bering in this addendum is as follows: Paragraphs are generally numbered to coincide with numbers in ASME Y14.5. Paragraph numbers preceded by “GM“ are GM specific additions to Y14.5. Unless otherwise noted, paragraphs not preceded by “GM” replace the paragraph in Y14.5 that is identified by the sam
7、e number. Paragraph references noted in the figures refer to the paragraphs contained in this document. Note: Figures referenced in the text but not shown in this addendum are found in ASME Y14.5-2009. Paragraph titles noted as “reference“ are for index referencing only and do not reflect changes to
8、 Y14.5. The words shall/must/required describe strict requirements. Procedural steps defined by these words must be followed. The words should/preferred/recommended describe preferences. Procedural steps defined by these words must be followed whenever there is no valid reason to do otherwise. Copyr
9、ight 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 STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 2 of 16 Th
10、e words acceptable/allowed/may/might grant permission. They do not require or recommend the practice they specify; neither do they forbid or discourage alternative practices. The figures in this Addendum exhibit the arrow method of view projection per GM Engineering Standards. The note shown in Figu
11、re 1 shall appear on drawings, documents or within databases which are in accordance with the General Motors Global Dimensioning and Tolerancing Addendum 2013. The note shall be in the title block (or in the general notes). The note invokes this addendum. Figure 1: Note to Invoke GM Global Dimension
12、ing and Tolerancing Addendum 2013 Note: Numbering throughout this Section 3 will be as noted above, and will not be in the conventional GMW template format. 1 Scope, Definitions, and General Dimensioning (Reference) 1.2 References. The following revisions of American National Standards form a part o
13、f this Standard to the extent specified herein. A more recent revision may be used provided there is no conflict with the text of this Standard. In the event of a conflict between the text of this Standard and the references cited herein, the text of this Standard shall take precedence. Note: All ot
14、her standards referenced in ASME Y14.5-2009 have not necessarily been adopted by General Motors, and are not automatically invoked. Current company standards shall take precedence unless otherwise noted. 1.3 Definitions (Reference). 1.3.17.1 Datum Feature Simulator (Theoretical). Datum feature simul
15、ator (theoretical). The theoretically perfect boundary used to establish a datum from a specified datum feature or datum targets. GM 1.3.68 Uniform Thickness/Gap. A condition where two surfaces are nominally equidistant. GM 1.3.69 Uniform Thickness/Gap Feature. A pair of continuous surfaces or porti
16、ons thereof that are nominally equidistant and associated with a Uniform Thickness/Gap tolerance. The surface normal vectors directed away from each surfaces material side must be in opposite directions. Note: A Uniform Thickness/Gap feature is not a feature of size. GM 1.3.70 Free State. The condit
17、ion where no forces other than gravity are applied. GM 1.3.71 Restrained: The condition where forces in addition to gravity are applied. 1.4 Fundamental Rules. (Reference). Note: Fundamental rules (a) through (p) still apply from ASME Y14.5-2009. (p): Where a coordinate system is shown on the drawin
18、g, it shall be right-handed unless otherwise specified. Each axis shall be labeled and the positive direction shall be shown. See Figure 2. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license
19、from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 3 of 16 Figure 2: Right Handed Coordinate System, Paragraph 1.4(p) GM (q): Direct tolerancing methods as described in Paragraph 2.2 (a) and (b) of ASME Y14.5 shall n
20、ot be used to locate features or features of size. Angle tolerance as described in Paragraph 2.2 (a) and (b) shall not be used to orient features of size. Note: Direct tolerancing methods may be used for Uniform thickness/gap, size and depth of counterbores, size and depth of countersinks, size and
21、depth of spotfaces, size of chamfers, size of corner radii, thread depth, and surface intersections. See Figure 3. GM (r): Unless otherwise specified all dimensions apply after heat treat, and/or subsequent surface treatment. Copyright General Motors Company Provided by IHS under license with Genera
22、l Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 4 of 16 Figure 3: Direct Tolerancing, Paragraphs 1.4 GM (q) and 2.6.1 1.8 Dimen
23、sioning Features (Reference). 1.8.14 Spotfaces. Where the diameter of the spotfaced surface is specified, either the depth or the remaining thickness of material may be specified. Where applicable, a fillet radius may be indicated for the spotface. In some cases, such as with a through hole, a notat
24、ion may be necessary to indicate the surface to be spotfaced. See Figure 1-41 of ASME Y 14.5. A spotface may be specified by note only and need not be shown pictorially. 2 General Tolerancing and Related Principles (Reference) 2.6 Tolerance Accumulation (Reference). 2.6.1 Dimensional Limits Related
25、to an Origin. In certain cases, it is necessary to indicate that a dimension between two features shall originate from one of these features and not the other. The high points of the surface indicated as the origin define a plane for measurement. The dimensions related to the origin are taken from t
26、he plane or axis and define a zone within which the other features must lie. This concept does not establish a datum reference frame as described in Section 4 of ASME Y14.5. Such a case is illustrated in Figure 2-5 of ASME Y14.5, where a part having two parallel surfaces of unequal length is to be m
27、ounted on the shorter surface. In this example, the dimension origin symbol described in Paragraph 3.3.17 of ASME Y14.5 signifies that the dimension originates from the plane established by the shorter surface and dimensional limits apply to the other surface. Without such indication, the longer sur
28、face could have been selected as the origin, thus permitting a greater angular variation between surfaces. Note: For spotfaces, depth of chamfers, size of corner radii, thread depth, and location of surface intersections, the dimension origin symbol should be used when direct tolerancing is specifie
29、d. See Figure 3. 2.17 Statistical Tolerancing. Statistical tolerancing as described in Paragraph 2.17 of ASME Y14.5 and associated sub-paragraphs of ASME Y14.5 shall not be used. The statistical tolerance symbol described in Paragraph 3.3.10 and Figure 3-11 of ASME Y14.5 shall not be used. Copyright
30、 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 STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 5 of 16 GM 2.1
31、8 Uniform Thickness/Gap Tolerance. A Uniform Thickness/Gap tolerance specifies that the minimum and maximum actual Thickness/Gap value, as defined in (a) and (b), must be within the specified Uniform Thickness/Gap tolerance limits. (a) For a uniform thickness feature (external), the maximum actual t
32、hickness value is the minimum separation between two points a fixed distance apart that the entire uniform thickness feature will pass through. The minimum actual thickness value is the minimum distance between the surfaces of a uniform thickness feature. See Figures 5, 6 and 7. (b) For a uniform ga
33、p feature (internal), the minimum actual gap value is the maximum separation between two points a fixed distance apart that the entire uniform gap feature will pass over. The maximum actual gap value is the maximum distance between the surfaces of a uniform gap feature. See Figure 4. Figure 4: Unifo
34、rm Gap Tolerancing Internal Feature, Paragraphs GM 2.18 (B) and GM 3.3.31 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 STANDARDS GMW16812 Copyright
35、 2013 General Motors Company All Rights Reserved September 2013 Page 6 of 16 Figure 5: Uniform Thickness Tolerancing External Feature, Paragraphs GM 2.18(A) and GM 3.3.31 Figure 6: Uniform Thickness Tolerancing Cylindrical Feature of Size, Paragraphs GM 2.18(A) and GM 3.3.31 Copyright General Motors
36、 Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights Reserved September 2013 Page 7 of 16 Figure 7: Uniform Thi
37、ckness Tolerancing Formed Sheet Stock Part, Paragraphs GM 2.18(A) and GM 3.3.31 3 Symbology (Reference) 3.3 Symbol Construction (Reference). GM 3.3.31 Uniform Thickness/Gap Symbols. The symbolic means of indicating that a uniform Thickness/Gap tolerance applies. For a thickness feature (external), t
38、he notation THK follows a direct tolerance specification. See Figures 5, 6 and 7. For a gap feature (internal), the notation GAP follows a direct tolerance specification. See Figure 4. 4 Datum Referencing (Reference) 4.8 Datum Features (Reference). 4.8.2 Datum Feature Identification. Datum features
39、are identified on the drawing by means of a datum feature symbol. See Figures 3-2, 3-3, and 3-4 of ASME Y14.5. The datum feature symbol identifies physical features and shall not be applied to center lines, center planes, or axes. When the datum (plane, line, point, axis, etc.) is derived directly f
40、rom the depiction of the feature on a drawing or model, the datum feature symbol is associated to the representation of the feature. If the datum is derived from datum targets, the datum may be identified by a note such as Datum Axis A or Datum Plane A or with datum reference frame identification as
41、 described in 4-21 of ASME Y14.5. 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 STANDARDS GMW16812 Copyright 2013 General Motors Company All Rights
42、Reserved September 2013 Page 8 of 16 4.11 Establishing Datums (Reference). 4.11.6.3 Clarifying Applicable Maximum Material Boundary (MMB). In cases where the boundary is not clear, or another boundary is desired, the value of the boundary shall be stated, enclosed in brackets, following the applicab
43、le datum feature reference and any modifier in the feature control frame. The term BSC or BASIC may be used to indicate that the datum feature simulator is located at the basic location of the datum feature. See Figure 4-31 illustration (b) of ASME Y14.5. Where an MMB equal to Maximum Material Condi
44、tion (MMC) is the design requirement for a given datum feature, a zero geometric tolerance at MMC is specified to the datum feature as shown on datum features B and C in Fig. 4-16 of ASME Y14.5. See Paragraph 7.3.4 and Fig. 6-14 of ASME Y14.5. Note 1: MMB, Least Material Boundary (LMB) and Regardles
45、s of Material Boundary (RMB) are not used in the same cell of a feature control frame with BSC, BASIC, or a value, i.e., options are RMB, LMB, MMB, BSC, BASIC, or a specified value exclusively. Note 2: A specified numerical value is used only with a regular Feature of Size (FOS) datum feature. Note
46、3: BSC and BASIC cannot be used with a FOS datum feature. Note 4: Irregular FOS datum other than MMB, LMB, RMB, BSC, or BASIC must use a datum target (cannot use a numerical value in a datum feature reference portion of the Feature Control Frame (FCF). 4.11.7 Specifying Datum Features at LMB. The me
47、thod in Paragraph 4.11.7 of ASME Y14.5-2009 shall not be used. 4.11.8 Multiple LMBs. The method in Paragraph 4.11.8 of ASME Y14.5-2009 shall not be used. 4.11.10 Translation Modifier. Where it is necessary to indicate that the basic location of the datum feature simulator is unlocked and the datum f
48、eature simulator is able to translate to fully engage the feature, the translation modifier is added to the feature control frame following the datum feature reference and any other applicable modifiers. See Figures 4-19 and 4-32, illustration (b), and paragraph 3.3.26 of ASME Y14.5. When the transl
49、ation modifier is applicable and the direction of movement is not clear, movement requirements shall be specified. 4.12 Multiple Datum Features (Reference). 4.12.4 Pattern of Features of Size at RMB. Where RMB is applied in a feature control frame to multiple datum features of size used to establish a single datum, the datum feature simulator of
