This part specifies the method of marking dimensional tolerances and fit tolerances in mechanical drawings. This part applies to the marking method of dimensional tolerances (linear dimensional tolerances and angular dimensional tolerances) and fits in mechanical drawings. GB/T 4458.5-2003 Method of marking dimensional tolerances and fits in mechanical drawings GB/T4458.5-2003 Standard download decompression password: www.bzxz.net

GB/T4458 "Mechanical Drawing" general drawing and annotation methods are divided into five parts: Part 1: Mechanical Drawing
Part 2: Mechanical Drawing
Part 3: Mechanical Drawing
Drawing Methods
Part and Component Numbers and Arrangement Methods in Assembly Drawings Axonometric Drawings
Dimension Annotation
Part 4: Mechanical Drawing
Part 5: Mechanical Drawing
Dimension Tolerance and Fit Annotation
GB/T4458.5—2003
This part is Part 5 of GB/T4458. This part replaces GB/T4458.5—1984 "Dimension Tolerance and Fit Annotation in Mechanical Drawings". Compared with GB/T4458.5-1984, the main changes of this part are as follows: 1. Added Chapter 3 "Basic Requirements", which specifies the code of tolerance zone and tolerance grade, font writing, dimension annotation, etc.;
Added 5.4 in Chapter 5 when a part needs to be matched with purchased parts (all non-standard parts); The writing format has been modified according to the requirements of GB/T1.1-2000. This standard is proposed and managed by the National Technical Committee for Standardization of Technical Product Documents. Drafting units of this standard: Mechanical Science Research Institute, Dalian Maritime University, Hefei University of Technology, Anhui Woyang Kangda Automobile Brake Co., Ltd., Xi'an Institute of Science and Technology.
The main drafters of this standard: Qiang Yi, Zou Yutang, Li Xuejing, Li Yong, Zhou Jinghuai, Cao Wengang. The previous versions of the standards replaced by this standard are: GB130-74; GB/T4458.5--1984. 1 Scope
Mechanical Drawing
Dimension Tolerance and Fit Notation
This part specifies the notation method of dimension tolerance and fit tolerance in mechanical drawings. GB/T4458.5--2003
This part applies to the notation method of dimension tolerance (linear dimension tolerance and angular dimension tolerance) and fit in mechanical drawings. 2 Normative References
The clauses in the following documents become the clauses of this part through reference to this part of GB/T4458. For all dated referenced documents, all subsequent amendments (excluding errata) or revisions are not applicable to this part. However, parties to an agreement based on this part are encouraged to study whether the latest versions of these documents can be used. For all undated referenced documents, the latest versions are applicable to this part.
GB/T1800 Limits and fits (eqvISO286.1) GB/T1182 General rules, definitions, symbols and drawing representations of geometric and positional tolerances (eqvISO1101) GB/T14691-1993 Technical drawing fonts (eqvISO3098/1, ISO3098/2) GB/T4458.4--2003 Dimensioning of mechanical drawings 3 Basic requirements
3.1 The code of tolerance zone and the code of tolerance grade shall comply with the provisions of GB/T1800. 3.2 The writing of fonts shall comply with the provisions of GB/T14691. 3.3 The dimensioning shall comply with the provisions of GB/T4458.4-2003 4 Tolerance annotation on part drawings www.bzxz.net
4.1 The tolerance of linear dimensions shall be marked in one of the following three forms. 4.1.1 When using tolerance zone codes to mark the tolerance of linear dimensions, the tolerance zone code should be noted on the right side of the basic dimension (Figure 1, Figure 2). 4.1.2 When using limit deviations to mark the tolerance of linear dimensions, the upper deviation should be noted on the upper right side of the basic dimension; the lower deviation should be noted on the same bottom line as the basic dimension. The font size of the upper and lower deviation numbers should be smaller than the font size of the basic dimension numbers (Figure 3, Figure 4). 4.1.3 When the tolerance zone code and the corresponding limit deviation are marked at the same time, the latter should be enclosed in parentheses (Figure 5, Figure 6). #65k6
Figure 1 Tolerance annotation method for writing tolerance zone codes (~) $65H7
Figure 2 Tolerance annotation method for writing tolerance zone codes (II) 1
GB/T4458.5—2003
065 0:.82
Figure 3 Tolerance annotation method for writing limit deviations () 65k6 (c8.82)
Figure 5 Method of noting tolerance zone code and
limit deviation at the same time (I)
Figure 4 Method of noting tolerance zone code and
limit deviation (II)Shen 65H7(*0.03)
Figure 6 Method of noting tolerance zone code and
limit deviation at the same time (II)
4.1.4 When marking the limit deviation, the decimal points of the upper and lower deviations must be aligned, and the "0" on the right side of the decimal point is generally not marked; if the number of digits after the decimal point of the upper and lower deviation values ​​is to be the same, "0" can be used to fill it (Figure 7). 4.1.5 When the upper or lower deviation is "zero", it is marked with the number "0" and aligned with the unit digit before the decimal point of the lower or upper deviation (Figure 8).
4.1.6 When the tolerance zone is symmetrically arranged relative to the basic dimension, that is, the absolute values ​​of the upper and lower deviations are the same, the deviation number can be written only once, and the symbol "士" should be noted between the deviation number and the basic dimension, and the height of the two numbers should be the same (Figure 9). 50 -0.815
$15-0.011
4.2 Additional symbol annotation method for linear dimension tolerance Figure 7
Limit deviation annotation method (I)
Limit deviation annotation method (II)
Figure 9 Limit deviation annotation method (III)
60-0.08
4.2.1 When the dimension only needs to limit the limit in a single direction, the symbol \max\ or "min" should be added to the right of the limit dimension (Figure 10, Figure 11).
4.2.2 If the surfaces of the same basic size have different tolerances, they shall be separated by thin solid lines and their tolerances shall be marked in the form specified in 4.1 (Figure 12).
GB/T4458.5--2003
4.2.3 If the relationship between the dimensional tolerance and the shape tolerance of an element needs to meet the inclusion requirements, the symbol "?" shall be added to the right of the dimensional tolerance in accordance with the provisions of GB/T1182 (Figures 13 and 14). R5max
Figure 10 Method of notation of one-way limit dimensions (I) 9p0.o
Figure 11 Method of notation of one-way limit dimensions (II)
Method of notation of different tolerance requirements for surfaces of the same basic sizeFigure 12
Figure 13 Method of notation of linear dimension tolerances that need to meet inclusion requirements (I) 5 Method of notation of fit on assembly drawings
Figure 14 Linear Dimension tolerance must meet the inclusion requirements. Notes (II) 5.1 When marking the matching code of linear dimensions in assembly drawings, it must be marked in the form of a fraction on the right side of the basic dimension, with the tolerance zone code of the hole in the numerator and the tolerance zone code of the shaft in the denominator (Figure 15). If necessary, it is also allowed to mark in the form of Figure 16 or Figure 17. 30%
Linear dimension matching code
Notes (I)
Linear dimension matching code
Notes (II)
30H7/f6
Linear dimension matching code
Notes (III)
GB/T4458.5—2003|| tt||5.2 When marking the limit deviation of matching parts in the assembly drawing, it is generally marked in the form of Figure 18: the basic size and limit deviation of the hole are noted above the dimension line; the basic size and limit deviation of the shaft are noted below the dimension line. It is also allowed to mark in the form of Figure 19. If it is necessary to clearly indicate the code of the assembly part, it can be marked in the form of Figure 20. 50*9.25
3 Method of marking the limit deviation of matching parts (I)
Figure 19 Method of marking the limit deviation of matching parts (II)
50%25Piece 2
50-8:Piece 1
Figure 20 Note The limit of matching parts
Method of noting deviations (III)
5.3 When marking the fitting requirements of parts (shafts or holes) that match standard parts, you can only mark the tolerance zone code of the part (Figure 21). Figure 21 Method of noting the fitting requirements of standard parts and purchased parts 5.4 When a part needs to be matched with purchased parts (all non-standard parts), it should be marked in the form specified in 5.1. 6 Method of marking angular tolerance
The marking of angular tolerance is shown in Figure 22, and its basic rules are the same as the marking method of linear dimension tolerance. 4
30°45
60°10±30
Method of noting angular tolerance
GB/T 4458.5—2003
20°max
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