1、GM DAEWOO Auto Therefore, indicating the entire surface by the datum feature generates errors in measured values or causes bad reproducibility. (Fig. 7.6) It is thus desirable to use datum targets (point, line or area serving as a basis) to avoid such problems. The method is as shown in Fig. 7.7. Fi
2、g 7.7 Symbol of datum target Supplementary explanation 1. It is desirable to indicate the datum targets in the main view. In complex drawings, entering it in the drawing as shown in Fig. 7.8 is also desirable. 2. The position of targets is indicated either by enclosing the basic dimension by a recta
3、ngular frame or by using toleranced dimension. Notes) In case of enclosing the basic dimension by a rectangular frame, dimensional tolerance is not EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 14/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technolo
4、gy Fig 7.8 Example of datum target indication EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 15/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 8. INDICATION OF GEOMETRIC TOLERANCE Indication method Description Basic example of feature indicat
5、ion Fig 8.1 Indication of individual feature Set the arrowhead of leader to the indicated feature (or its extension line) vertically. The position of arrowhead of shall separate from that of the dimension line.Tolerance zone of Fig. 8.1 Basic example of axis indication Fig 8.2 Indication of related
6、feature Set the arrowhead of leader to the indicated axis or the arrowhead of dimension line vertically. When datum is used, place the letter symbol for datum (the figure is for 20 axis) in the right column of feature control frame Remark) In Fig. 8.2b, datum may either of axes Tolerance zone of Fig
7、. 8.2 P1/P2/A Applied example 1. Multiple features Fig 8.3. When number of features is indicatedWhen multiple features are indicated by a tolerance, do as in this figure or as in the following column. Tolerance zone of Fig. 8.3 EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 16/25 ISSUED DA
8、TE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Indication method Description Applied example 2 Commonness of feature tolerance a) When tolerance zone is not common Indicate feature directly using branch line or enter letter symbol in feature control line Applied e
9、xample 2 Commonness of feature tolerance b) When tolerance zone is not common Fig 8.4 When branch leader line or symbol is used When making multiple feature tolerance zone in two parallel planes 0.1 apart in the above method, enter “common tolerance zone“ in feature control frame.Tolerance zone of F
10、ig. 8.4b P1/P2Applied example 3 Commonness of axis tolerance Fig 8.5 Indication of common axis When it is necessary to put the axis of multiple features in a tolerance zone, set the leader line to the axis vertically Using a common leader line for three or more axes of different feature shall be avo
11、ided if possible. Tolerance zone of Fig. 8.5 (P1/P2) EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 17/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Indication method Description Example of multiful tolerance Fig 8.6 Indication of one featur
12、e with two tolerances When multiple tolerances are indicated for a feature, use corresponding number of feature control frames. In case of tolerance zone of 0.01 (concentric circle), up to 2 cylinders of width 0.06 are allowed. Fig 8.7 Indication of part of feature When indicating tolerance for spec
13、ific section L, place “/“ and length after tolerance Tolerance zone of Fig. 8.6 P1/P2/A Fig 8.8 Indication of specific section In order to clearly indicate the location, draw thick chain lines in parallel to feature and designate the location. Tolerance zone of Fig. 8.7 P1/P2/X Example of partial to
14、lerance Fig 8.9 When tolerance for entire surface and that of a portion are different Make two tolerance columns and enter the partial tolerance in the lower column.Tolerance zone of Fig. 8.9 A/P1/P2/P3/P4EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 18/25 ISSUED DATE: 1996. 04. 10 REVISE
15、D DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Indication method Description Indication of form in tolerance zone Fig 8.10. Indication of form When indicating changed form in the tolerance zone, put a note just after tolerance column or on the leader line Remark) General tolerance 8 0.1
16、5 Tolerance zone of Fig. 8.10 Indication of specific direction a) When angle is not designated b) When angle is designated Fig 11 Indication of curved portion When the feature is curved one, face the arrowhead of leader to the normal direction of the curve When feature dimension meets dimensional to
17、lerance by two point measurement, tolerance zone may move in parallel. Tolerance zone of Fig. 8.11a When tolerance zone of specific angle is required, indicate angle . P1 and P2 may move in parallel as in case of a) Tolerance zone of Fig. 8.11b EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE
18、: 19/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology Indication method Description Fig 8.12. Stud bolt When tolerance zone is indicated outside the feature, insert after tolerance and before dimension that shows the location respectively. And show the a
19、rea in thin phantom line. a) Location tolerance (Part interference exist) b) Tolerance zone of tolerance Fig. 8.12 (No parts interference) Tolerance zone according to presence of projected tolerance Example of projected tolerance Fig 8.13. Key groove It shows projected tolerance applied to symmetric
20、al drawing. Projected tolerance can be used to positional tolerance and orientation tolerance. Tolerance zone of Fig. 8.13 EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 20/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 9. MAXIMUM MATERIAL PR
21、INCIPLE 9.1. Definitions 9.1.1. Maximum material size (MMS) It is the maximum limit of size for an external feature, such as a shaft, or the minimum limit of size for an internal feature, such as a hole. When a feature is within the size, it is in the “maximum material condition“ 9.1.2. Least materi
22、al size (LMS) It is the minimum limit of size for an external feature, such as a shaft, or the maximum limit of size for an internal feature, such as a hole. When a feature is within the size, it is in the “minimum material condition“ 9.1.3. Virtual size (VS) It is the size limit determined by both
23、the maximum material size and geometric tolerance. For an external feature, it is the maximum material size + geometric tolerance, and for an internal feature, it is the maximum material size - geometric tolerance. When a feature is within the size, it is in the “virtual condition“ 9.1.4. Envelope p
24、rinciple (EVP) It refers to a principle that when the cylinder or an individual feature made of two parallel planes is in the maximum material condition, it must be the complete form. To indicate this condition, is affixed to the dimensional tolerance. 9.1.5. Maximum material principle (MMP) The exp
25、ressed geometric tolerance is indicated when a feature is in the maximum material condition. When a feature is deviating from the maximum material condition to the least material condition, the deviated portion may be added to the expressed geometric tolerance. When this principle is applied, is aff
26、ixed to the dimensional tolerance. in feature control frame and after datum letter. 9.1.6. Functional gauge Gauges mainly to inspect the maximum material side of parts where MMP is applied. These also include plug gauges and cylinder gauges used for inspecting the least material side. 9.2. General 9
27、.2.1. The maximum material principle is applied mainly to cases where allowance of size may be added to the orientation or location tolerance in consideration of inter-dependency between dimensional tolerance, orientation tolerance and location tolerance for each feature when two features need to be
28、 assembled simply 9.2.2. The maximum material principle is applied to related features having axis or center plane. It includes orientation tolerance (angularity, perpendicularity, parallelism), location tolerance (position, concentricity, symmetricity) and straightness. 9.2.3. Where this system is
29、applied, the value of orientation or location tolerance in drawings is determined when EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 21/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology the toleranced feature is in the maximum material conditio
30、n. 9.2.4. When a feature is finished deviating from the maximum material size within the permissible limits, adding the corresponding portion to the orientation or location tolerance is allowed. 9.2.5. This added tolerance is allowed within the range not exceeding the virtual condition. In other wor
31、ds, the virtual size represents size of functional gauge for inspection. 9.2.6. When the orientation or location tolerance is applied to features related to datum having the dimensional tolerance, the maximum material principle may be applied to the datum feature, as with the toleranced features. 9.
32、2.7. In case of 9.2.6, floating of the datum axis or datum center plane is allowed to the amount corresponding to deviation of the datum feature from the maximum material size. (Note) Deviation of the datum feature from the maximum material size does not mean increased tolerance of the toleranced fe
33、ature. 9.3. Tolerance diagram It is the schematic diagram of the MMP (Fig. 9.1). As a feature moves from MMS to LMS, the hatched geometric tolerance increases. If the VS values of the shaft and hole are the same, the two must always stick together. Fig 9.1. Tolerance diagram Using this diagram helps
34、 easily determining the form dimension of the feature whose geometric tolerance is indicated. Ex: procedure of getting dimension of shaft from the mating hole (1) Get : VS= MMS of hole - geometric tolerance of hole center (*) (*) In case of multiple geometric tolerance (2) Determine geometric tolera
35、nce of shaft axis (3) Get : MMS = VS - geometric tolerance of shaft axis (4) Get standard diameter and dimensional tolerance of shaft EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 22/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology (a) Example
36、 of indication (b) Explanation of (a) (c) Tolerance diagram of (a) Fig 9.2 (d) Size determined by (a) A1A3 = actual size = 19.820.0mm MMS = 20mm ti = designated perpendicularity tolerance = 0.2mm VS = MMS + ti = 20.2mm t = permissible perpendicularity tolerance = 0.20.4mm EDS-A-1105METHOD OF INDICAT
37、ING GEOMETRIC TOLERANCE PAGE: 23/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology (a) Example of indication (b) Explanation of (a) (c) Tolerance diagram of (a) Fig 9.3 (d) Size determined by (a) A1A3 = actual size = 20.420.6mm MMS = 20.4mm ti= designated
38、 perpendicularity tolerance = 0.2mm VS = MMS - ti= 20.2mm t = Permissible perpendicularity tolerance = 0.20.4mm EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 24/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05. 31 VERSION: 3 GM DAEWOO Auto & Technology 10. METHODS OF INDICATING MMP Whe
39、n applying the MMP, include the symbol immediately after the tolerance value in the feature control frame as follows. While MMP is applicable to position, symmetricity, parallelism, angularity, perpendicularity and straightness where axis and center plane is indicated, only position, which is most f
40、requently used, will be shown here. Indication method Description Indication of position where MMP is applied Fig 10.1. When applied to tolerance When MMP is applied to geometric tolerance, include immediately after the tolerance value. 4 Hole size method Max. position tolerance = = Indication of po
41、sition where MMP is applied Fig 10.2. When applied to datum When MMP is applied to datum feature, include immediately after the datum latter. 4 Hole size method Max. position tolerance = = EDS-A-1105METHOD OF INDICATING GEOMETRIC TOLERANCE PAGE: 25/25 ISSUED DATE: 1996. 04. 10 REVISED DATE: 2008. 05
42、. 31 VERSION: 3 GM DAEWOO Auto & Technology Indication method Description Fig 10.3. When MMP is applied to tolerance and datum When MMP is applied to geometric tolerance and datum feature, include immediately after the tolerance value and datum letter. 4 Hole size method Max. position tolerance = =
43、Indication of position where MMP is applied Fig 10.4 When datum is expressed simply When datum is expressed simply, omit the datum letter and, include just in feature control frame. 11. RELATED STANDARDS KS B 0608 Method of indicating geometric tolerance JIS B 0021 Method of indicating geometric tolerance JIS B 0022 Datum of geometric tolerance JIS B 0023 Maximum material principle JIS B 0024 Basic principles of tolerance indication
