1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards SYSTEM OF LIMITS AND FITS Do Not Use on New Programs. Being Replaced by Global Design Standards EDS-A-1102 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 (Superceded) EDS-A-1102SYSTEM OF LIMITS AND FI
2、TS PAGE: 1/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Note: This standard may be applied only for current project drawings generated by CATIA. It is Superceded for all future projects and replaced by Global Design Standards. 1. SCOPE This standard
3、specifies the system of limits and fits of shapes of 500mm max. in basic size. 1. Tolerancing in this standard, which mainly applies to cylindrical shapes, applies also to other shapes. 2. Examples of fits in this standard apply to simple geometrical shapes, such as cylindrical shapes and parallel d
4、ual face shapes. 3. Dimensions in this standard means those of completed products. 2. TOLERANCING TERMS 2.1. Shape : A mechanical part which is the object of the system of limits and fits 2.2. Inner shape : Shape that forms the inner part of the object 2.3. Outer shape : Shape that forms the outer p
5、art of the object 2.4. Hole : It mainly means the cylindrical inner shape, but includes other inner shapes other than the cylindrical shape. 2.5. Shaft : It mainly means the cylindrical outer shape, but includes other outer shapes other than the cylindrical shape. 2.6. Dimensions : Magnitude to indi
6、cate the size of a shape, for instance diameter of holes and shafts, which is generally expressed in mm. 2.7. True dimensions : Actual dimensions of a shape 2.8. Limits of size : The maximum and minimum sizes permissible for a specific dimension. The true dimension lies between them. (Fig. 1) 2.9. M
7、aximum limit of size : The maximum size permissible for a specific shape (Fig. 1) 2.10. Minimum limit of size : The minimum size permissible for a specific shape (Fig. 1) 2.11. Basic size : Theoretical size from which the limits for that dimension are derived (Fig. 1 and Fig. 2) The basic size is ei
8、ther an integer or a decimal. Ex: 32, 15, 8.75, 0.5 EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 2/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 2.12. Deviation: The algebraic difference between the size (actual size, limits of size, etc.) and the corres
9、ponding basic size or, (Size) - (Basic size) 2.13. Tolerancing method: Method of expressing standardized dimensional tolerances and deviations 2.14. Upper deviation: The algebraic difference between the maximum limit of size and the corresponding basic size or, (Maximum limit of size) - (Basic size)
10、 (Fig. 1 and Fig. 2) 2.15. Lower deviation: The algebraic difference between the minimum limit of size and the corresponding basic size or, (Minimum limit of size) - (Basic size) (Fig. 1 and Fig. 2) 2.16. Tolerance: Difference between the limits of size (Fig. 1 and Fig. 2) 2.17. Fundamental deviatio
11、n: Deviation that forms the basis of determining the relation between limits and basic dimensions. It becomes the upper deviation or lower deviation depending on the type of holes and shafts. In general, the closer to the datum line of the upper deviation or lower deviation becomes the fundamental d
12、eviation, which is common throughout grades for each hole and shaft type. 2.18. Tolerance zone: The zone between two lines representing the maximum and minimum limits of size that is determined according to the position relative to the datum line and tolerance size when tolerance is indicated (Fig.
13、2) 2.19. Tolerance zone class: Combination of tolerance zone position and tolerance grade 2.20. Maximum material condition: The limit of size where the actual shape becomes the maximum. Or, the minimum limit of size for an inner shape, and the maximum limit of size for an outer shape, 2.21. Least ma
14、terial condition: The limit of size where the actual shape becomes the minimum. Or, the maximum limit of size for an inner shape, and the minimum limit of size for an outer shape, 2.22. Standard tolerance: A tolerancing method. Entire dimensional tolerance that belongs to the fit system 2.23. Tolera
15、nce grade: A tolerancing method. A group of dimensional tolerance that belongs to the same level of the entire basic size. The tolerance grade is expressed by affixing a figure that represents the grade to IT, for instance IT7. 2.24. Datum line: A straight line that serves as the basis of deviation.
16、 It represents the basic size when showing limits of size or fits. EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 3/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Fig 1 Fig 2 This figure is simplified to show the relation between the tolerance zone, deviati
17、on and datum line. In simplified drawings like this, the datum line is drawn horizontally and the positive (+) and negative (-) deviations are indicated above and below the line respectively. 3. FITS TERMS 3.1. Fits: Relation between two mating parts before assembling holes and shafts 3.2. Clearance
18、: Dimensional difference between the hole and shaft when the hole size is larger than the shaft size EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 4/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology (Fig. 3) 3.3. Minimum clearance: Dimensional difference betw
19、een the minimum limit of hole size and maximum limit of shaft size in clearance fit 3.4. Maximum clearance: Dimensional difference between the maximum limit of hole size and minimum limit of shaft size in clearance fits and transition fits Fig 3 Fig 4 3.5. Interference: Dimensional difference betwee
20、n the hole and shaft before assembly when the hole size is smaller than the shaft size (Fig. 6) 3.6. Minimum interference: Dimensional difference between the maximum limit of hole size and minimum limit of shaft before assembly in interference fits (Fig. 7) 3.7. Maximum interference: Dimensional dif
21、ference between the minimum limit of hole size and maximum limit of shaft before assembly in interference fits and transition fits (Fig. 5 and 7) 3.8. Clearance fits: A fit between mating parts having limits of size so prescribed that a clearance results in assembly. When illustrated, the whole tole
22、rance zone of the hole is above the tolerance zone of the shaft. (Fig. 8) 3.9. Transition fits: A fit between mating parts having limits of size so prescribed as to partially or wholly overlap, so that either a clearance or interference may result in assembly. When illustrated, the tolerance zones o
23、f the hole and shaft are overlapped wholly or partially. Interference fits: A fit between mating parts having limits of size so prescribed that an interference results in assembly. When illustrated, the whole tolerance zone of the hole is below the tolerance zone of the shaft. (Fig. 9)EDS-A-1102SYST
24、EM OF LIMITS AND FITS PAGE: 5/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Fig 5 Fig 6 Fig 7Fig 8 Fig 9 3.10. Variation of fits: Algebraic sum of tolerance of the hole and shaft to be assembled 3.11. Fit method: Method of fit depending on holes and s
25、hafts that belong to specific tolerancing methods 3.12. Hole basis fits system: Fit systems to give clearance or interference necessary for assembling the shaft of several tolerance zone classes and the hole of one tolerance zone class. In this system, the minimum limit of hole size is the basic siz
26、e. In other words, the lower deviation of the hole becomes “0“. (Fig. 10) EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 6/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 3.13. Shaft basis fits system: Fit systems to give clearance or interference necessary
27、for assembling the hole of several tolerance zone classes and the shaft of one tolerance zone class. In this system, the maximum limit of shaft size is the basic size. In other words, the upper deviation of the shaft becomes “0“. (Fig. 10) 3.14. Basic hole: A hole selected as the basis in the hole b
28、asis fits system. In this standard, a hole whose lower deviation is “0“. 3.15. Basic shaft: A shaft selected as the basis in the shaft basis fits system. In this standard, a shaft whose upper deviation is “0“. Fig 10 Fig 11. 4. TEMPERATURE CONDITION Dimensions in this standard is at a temperature of
29、 20. 5. SYMBOLS 5.1. Tolerance grades and IT (ISO Series of Tolerance) EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 7/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology It means classifying accuracy into several grades for the same range of dimension. (Note)
30、It is arranged as follows according to the tolerance grade. IT01 - IT04: mainly gages IT05 - IT10: mainly fitting portions (commonly used) IT11 - IT16: mainly tolerance of portions without fits 5.2. Location of tolerance zone The tolerance zone location of holes is expressed with capital letters fro
31、m A to ZC and the tolerance zone location of shafts is expressed with small letters from a to zc. To avoid confusion, the following letters are not used. I, L, O, Q, W, i, l, o, q, w For example, the hole in the tolerance zone location H is called H hole, and the shaft in the tolerance zone location
32、 h is called h shaft. 5.3. Tolerance zone class Tolerance zone class is expressed using figures that represent tolerance grade after the tolerance zone location symbol. H7 for holes and h7 for shafts 6. INDICATION 6.1. Allowable limits of dimension Allowable limits of dimension are indicated by a to
33、lerance zone class symbol (hereinafter called tolerance symbol) or a deviation preceded by the basic size. 32H7, 80js15, 100g6, 100 -0.012 -0.0346.2. Limits of size may sometimes be used to indicate allowable limits of dimension. In this case, the maximum limit of size is presented at the top and th
34、e minimum limit of size at the bottom. EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 8/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 6.3. Grades, symbols and indication of holes and shafts 6.3.1. The type and the grade of holes and shafts are expressed by
35、 alphabets and arabic numerals respectively. Holes and shafts are differentiated by entering proper capital letters for holes and small letters for shafts. H 7 e 6 Indication grade Indication grade Indicate hole (H) Indicate shaft (e) 6.3.2. Types of holes and shafts are classified according to devi
36、ation serving as a base, and the symbol is as shown in Fig. 12. 6.3.3. To indicate holes, enter a symbol, which represents the hole type, and a figure of the same size, which represents grade, to the right of the basic size. To indicate shafts, enter a symbol, which represents the shaft type, and a
37、figure of the same size in case of holes, which represents grade, to the right of the basic size. 25 H 7 25 e 6 IT standard tolerance grade Type of hole/shaft Basic size Fig 12. EDS-A-1102SYSTEM OF LIMITS AND FITS PAGE: 9/22 ISSUED DATE: 1996. 03. 19 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO A
38、uto & Technology 6.4. Fits Fits are expressed by successively entering the common basic size of holes/shafts, tolerance symbol of the hole and tolerance symbol of the shaft. 52H7/g6, 52H7-g6, or 52 H7/g6 7. RELATED TABLES FOR COMMONLY USED FITS Deviations of holes and shafts for commonly used fits s
39、hall conform to Attachments 1 and 2. Calculation of standard tolerance of fits not used commonly shall conform to the formula shown in Attachment 1 of KS B 0401. 8. RELATED STANDARDS EDS-A-1103 Linear and angular dimensions EDS-A-1104 Tolerancing linear and angular dimensions ISO R 286 ISO system of
40、 limits and fits KS B 0401 System of limits and fits GM DAEWOO Auto & Technology Appendix 1. Calculation formula of fundamental deviation Basic size(mm) Shaft Hole Basic size(mm) Over To Toler. zone position Symbol DeviationFormula (1) (2) Deviation Symbol Toler. zone position Over To - 120 - 265+1.
41、3D - 120 120 500 a - es 3.5D EI + A 120 500 - 160 - 140+0.85D - 160 160 500 b - es 1.8D EI + B 160 500 - 40 - 52 D0.2 - 40 40 500 c - es 95+0.8D EI + C 40 500 - 10 cd - es Geometric mean of C and D or c and d EI + CD - 10 - 3,150 d - es 16D0.44EI + D - 3.150 - 3,150 e - es 11D0.41EI + E - 3,150 - 10
42、 ef - es Geometric mean of E and F or f and g EI + EF - 10 - 3,150 f - es 5.5D0.41EI + F - 3,150 - 10 fg - es Geometric mean of E and F or f and g EI + FG - 10 - 3,150 g - es 2.5D0.34EI + G - 3,150 - 3,150 h es 0 EI + H - 3,150 j None (4) J - 3,150 js - + es ei 0.5 ITn EI ES JS - 3, 150 - 500(3) - 5
43、00(3) Apply only to IT4 - IT7 k + ei 0.63D ES - K Apply only to IT4 - IT7 - 3,150(3) k ei 0 ES K - 3,150(3) - 500 IT7-IT6 - 500 500 3,150 m + ei 0.024D+12.6 ES - M 500 3,150 - 500 5D0.34- 500 500 3,150 n + ei 0.04D+21 ES - N 500 3,150 - 500 IT7+05 - 500 500 3,150 p + ei 0.072D+37.8 ES - P 500 3,150
44、- 3,150 r + ei Geometric mean of P and S or p and s ES - R - 3,150 - 50 IT8+14 - 50 50 3,150 s + ei IT7+0.4D ES - S 50 3,150 - 3,150 t + ei IT7+0.63D ES - T - 3,150 - 3,150 u + ei IT7+D ES - U - 3,150 - 500 v + ei IT7+1.25D ES - V - 500 - 500 x + ei IT7+1.6D ES - X - 500 - 500 y + ei IT7+2D ES - Y -
45、 500 - 500 z + ei IT7+2.5D ES - Z - 500 - 500 za + ei IT8+3.15D ES - ZA - 500 - 500 zb + ei IT9+4D ES - ZB - 500 - 500 zc + ei IT10+5D ES - ZC - 500 Notes (1) “D“ is the geometric mean of two sizes (in mm) which differentiate each basic size. (2) The basic unit of deviation for the formulas in this
46、table is W . (3) Except for tolerance class of IT4 IT7 and basic size of 500mm and below, the deviation which forms the basis of the whole K holes and k shafts is “0“. (4) Only numerical values are indicated in Appendix 5 and 6. EDS-A-1102 PAGE :10/22 VERSION: 3 GM DAEWOO Auto & Technology Appendix
47、2. Rounding of fundamental deviation Over 5 45 60 100 200 300 500 560 600 800 1,000 2,000Numerical value W To 45 60 100 200 300 500 560 600 800 1,000 2,000 - Rounded off to the multiple of the following integers (W ) ag shaft and AG hole 1 2 5 5 10 10 10 20 20 20 50 - Basic size 500mm or below kzc s
48、haft and KZC hole 1 1 1 2 2 5 5 5 10 20 50 100 Basic size above 500mm below 3150mm du shaft and DU hole 1 1 2 5 10 10 20 20 20 20 50 100 EDS-A-1102 PAGE :11/22 VERSION: 3 GM DAEWOO Auto & Technology Appendix 3. Tolerance zones of basic hole system (basic size of 30 mm) EDS-A-1102 PAGE :12/22 VERSION
49、: 3 GM DAEWOO Auto & Technology Appendix 4. Tolerance zones of basic shaft system (basic size of 30 mm) EDS-A-1102 PAGE :13/22 VERSION: 3 GM DAEWOO Auto & Technology Appendix 5. Preferred hole basic fits Unit : W Basic size(mm) Hole tolerance zone class Over To B10 C9 C10 D8 D9 D10 E7 E8 E9 F6 F7 F8 G6 G7 H6 H7 H8 H9 H10 JS6 JS7 K6 K7 M6 M7 N6 N7 P6 P7 R7 S7 T7 U7 X7 - 3 +180 +140 +85 +60 +100+60+34+20+45 +20 +60 +20 +24 +14 +28 +14 +398+14+
