Meadows, JD. ASME Press, ISBN: No. Sign In or Create an Account. Sign In. Advanced Search. Skip Nav Destination. James D. Meadows James D. This Site. He addresses functional requirements and manufacturing techniques, measurement, inspection, and gaging procedures. The book illustrates how symbology is best utilized, in what order it should be applied, and how each geometric control anticipates, integrates, and complements all other geometric controls on a part and in an assembly.
This book clearly organizes geometric dimensioning and tolerancing fundamentals into small, logical units for step-by-step understanding. Measurable performance objectives help you and your students assess their progress. Discussion questions promote interaction and higher-order thinking, and practice problems ensure thorough understanding of the concepts presented.
Important Notice: Media content referenced within the product description or the product text may not be available in the ebook version. The text is organized in a logical sequence and covers introductory topics in depth to help ensure a full understanding of basic concepts before building to more advanced applications.
Topics covered include general tolerancing practices, geometric tolerancing practices, types of controls applied with geometric tolerances, and calculating and applying tolerances. The text is extensively illustrated with detailed examples that enhance learning and provide in-depth analysis. Review questions and print reading problems at the ends of chapters enable students to reinforce learning, apply concepts, and problem-solving skills.
When the feature deviates from the least material condition larger shaft, smaller hole the geometrical deviation may be larger without violating the least material virtual condition LMVC cut-out contour. The least material virtual condition has the size of 50 least material size minus position tolerance , is perpendicular to the datum A and 60 apart from the datum B.
The more the ridge thickness deviates from the least material size, the more the actual median surface may deviate from the theoretical exact location. In the example, the smallest actual local size is In this case, the position deviation of the actual median surface can be 1,5, which corresponds to a position tolerance of 3. Here the least material virtual condition has least material size. The maximum geometrical ideal cylinder contained in the material possible to cut out may have a diameter smaller than the least material size.
A prerequisite is that the surface of the datum feature does not violate the least material virtual condition which is geometrically ideally positioned in relation to the geometrical ideal position of the toleranced features. Around this boundary, the datum feature may take, if possible, the position where the requirements of the toleranced features are fulfilled.
In the centre, both surfaces features have least material size and therefore are coaxial. On the right are shown the extreme permissible coaxiality deviations with maximum material sizes. In all cases, the same least material virtual conditions boundaries to be entirely contained within the material apply. In the case on the left, the whole tolerance is indicated at the size.
The tolerance may be utilized by size deviations and by coaxiality deviations in an arbitrary way. In the case in the centre, the tolerance is distributed on size and coaxiality.
The coaxiality tolerance will be enlarged by the size tolerance not utilized, but not vice versa. The size tolerance cannot be enlarged by the non-utilized coaxiality tolerance. In the case on the right, the size tolerance can also be enlarged by the non-utilized coaxiality tolerance. Thus the reciprocity requirement provides a communication between production planning and the workshop manufacturing-related tolerance.
In this case, the manufacturer must reduce the size tolerance at the minimum material side by the maximum geometrical deviation to be expected on his machine tool: in the case of a cylinder, two times the cylindrical deviation. With this supposition, it is most unlikely that an assembly contains only parts with actual sizes equal to the limits of size Fig.
The single tolerances are chosen larger than in arithmetical tolerancing. Here it is assumed that the actual sizes are normally distributed, their standard deviation is one-sixth of the statistical single tolerance, the distribution is centred in the tolerance and the dimensions of the parts are independent of each other. In Ref. In order to stipulate and to verify the assumptions of statistical tolerancing, properly defined terms are needed.
An international standard on this subject does not yet exist. Dimension chain: geometrical representation of several cooperating dimensions that are independent of each other Figs 4. Closing dimension: result of arithmetic addition of an independent single dimension within a dimension chain.
Single tolerance Ti: tolerance of a single dimension. Statistical tolerance Tsi: single tolerance with specifications regarding the distribution of the actual sizes within the tolerance zone. Arithmetical closing tolerance Ta: sum of the single tolerances within a dimension chain. Statistical closing tolerance Ts: closing tolerance, smaller than Ta, specified according to the actual size distribution.
Side zones and central zone: for the specification of statistical tolerances, the tolerance zone is divided into zones. In general, three zones predominantly symmetrical with respect to the mean size C are sufficient Fig. The lower side zone Bl is the zone adjacent to the minimum limit of size. The upper side zone Bu is the zone adjacent to the maximum limit of size. The central zone Bm is the zone between the upper and the lower side zone.
Side content Pl and Pu: percentage of actual sizes more precise: mating sizes or related mating sizes of a manufacturing lot within the side zone Figs. From this it follows that, with an asymmetrical distribution of the actual sizes where there is no lower side zone, the content that would go into this zone actually goes into the central zone Fig.
Mean dimension C Total tolerance Central zone Min. The left side zone is contained within the central zone. Dimensional and locational tolerances: From, orientation, run-out tolerances: Mean dim. The upper three examples specify central Size tolerancing Chapter 4 zones and central contents.
The other examples specify process capability parameters Cp, Cpk, Cc, Cpu, Cpm which have to be defined in referenced specifications and which determine limits of the distribution of the specified property. In many cases, this results in a gain in manufacturing economy. Because of the current trend to greater miniaturization and to more precise products, statistical tolerancing has become more important.
Sometimes the smaller arithmetical tolerances are not even achievable. Statistical tolerancing is more advantageous: — the larger the number of members in the dimension chain, — the larger the manufacturing lot, — the better manufacturing and inspection can satisfy the prerequisites for statistical tolerancing form and location of the distribution; see previous.
Size tolerancing Chapter 4 Sizes produced by punching usually have very small variability within a delivery lot, i. For example, regarding the size of punched holes, when the tool is new the distribution starts near the least material size of the hole. Due to the wear of the tool over the years, the distribution drifts towards the maximum material size of the hole.
As for a delivery lot, normally it is not known where within the tolerance the distribution is located, so the whole tolerance must be taken into account for the statistical line-up calculation Fig. These programs use methods of assembly simulation Monte Carlo method or convolution of distributions.
These programs facilitate statistical tolerancing considerably. In mass production, statistical tolerancing allows more realistic tolerance calculations, leading to larger tolerances with lower production costs without loss of product quality. The , e. For more information see ISO The two-line angular size of a cone is defined within a section plane containing the axis of the associated cone according to Gauss. The last operation is to associate straight lines according to minimax Chebyshev to the two extracted section lines.
In order to tolerance the cone completely, it is recommended to use profile tolerancing. See 6. See also 3. ISO deals with tolerancing of groups patterns. In the method of position tolerancing for the location of derived features , theoretically exact dimensions TEDs and position tolerances determine the location of features points, axes, median surfaces relative to each other or in relation to one or more datum s.
The tolerance zone is defined by the envelope in spheres of diameter of the tolerance and located at the reference feature at the theoretically exact location. Due to this definition, position tolerances do not accumulate where theoretically exact dimensions are arranged in a chain Fig. However, the following theoretically exact dimensions, that determine the theoretically exact locations of position tolerance zones, are not to be indicated: a theoretically exact angles between features e.
Formerly, when the position-toleranced features were drawn on the same centre line, they were regarded as related features having the same theoretically exact location Fig. When different position tolerances related to the same datum system e. When more simultaneous groups are concerned, SIM shall be enumerated, e. When the requirements of both patterns FIG.
It was former practice to consider multiple features, position toleranced, as if CZ were indicated the tolerance zones consider the relation of the features relative to each other. It is planned for the future to also apply the independency principle to position-toleranced features. This then is the opposite. During this intermediate period, according to ISO and ISO , with position tolerances for patterns, it shall always be indicated whether CZ combined zones or SZ separate zones applies.
When the position tolerances are related to a complete datum system, locking all degrees of freedom of the workpiece, CZ may be omitted, because the positions are fixed; see Fig.
Position tolerancing Chapter 5 FIG. It is unclear what the centres of the holes are maximum inscribed cylinder axes, centre of two-point sizes and from what to measure real surface of the FIG. Instead, position tolerancing shall be used for both distances between the holes and location in the datum system; see Fig.
Each requirement shall be met independently. For example, the actual axis of each of the four holes in Fig. The position tolerance zones are located in their theoretically exact positions in relation to each other and perpendicular to datum A. These position tolerance zones are located in their theoretically exact positions in relation to the datums A, B and C. It should be noted that datums, drawn perpendicular to each other, are not necessarily perpendicular to each other when they are not in the same datum system.
This applies to all datums of any geometrical tolerancing. Figure 5. Tolerancing a is mandatory; without this tolerance, the part is not completely toleranced. The tolerances a and f are mandatory; without these tolerances the part is not completely toleranced. With this practice, it was unclear which workpiece surface determined the direction. According to the current standard ISO , the direction of the width of the tolerance zone shall be specified by the tolerance zone plane indicator; see Fig.
Position tolerancing Chapter FIG. If this indication is missing, it means the median surfaces of the rectangular holes. The tolerance zones are then defined by two parallel planes a distance of 0,3 and 0,1 apart along the entire holes. For cylindrical features the tolerance zone is normally cylindrical, because the function permits the same deviation in all orientations.
Position tolerances can have cylindrical tolerance zones. This is in contrast to size tolerances, which permit only tolerances in two directions perpendicular to each other.
For floating fasteners Fig. Dmax limited by pressure min. See Table 5. The indicated position tolerances tce and tcd in Table 5. If necessary, the values are to be decreased accordingly. For head screws the under-head fillet may require chamfered holes or washers. Table 5. Accordingly, for the position tolerances tc the values tcd and tce are to be decreased by t. Inspected with plain measuring instruments, e. Then the mating size of the hole may be smaller than the lower limit of size, although the measurement results are within the size tolerance.
In the extreme case Fig. The external projection has the length of the Geometrical Dimensioning and Tolerancing for Design, Manufacturing and Inspection through-hole in the case of head screws Fig.
The projected tolerance zone applies only to these lengths, not to the length of the axis within the workpiece. From a practical point of view, the following definitions of the axis may be applicable: — for plain holes e. The simplified drawing indication is shown in Fig.
In the cases shown in Figs 5. The projection extension of the horizontal axis must be contained between two vertical planes 0,1 apart, between two horizontal planes 0,05 apart, over the length of The case b shows an additional restriction constraint for orientation. For example, in Fig. Position tolerancing, however, provides the possibility of allocating different tolerances to the different features Figs 5.
The slots are toleranced by a position tolerance 0,1 relative to their holes, but independent for each hole two independent groups K. The position tolerances shown in Fig.
With machines e. In such cases the housing base or housing flange may be indicated as the datum Fig. In case a , the surface B must contact the gauge according to the minimum rock requirement. The diameter of the gauge is equal to the maximum material size of the datum feature A. Position tolerancing Chapter 5 In case b , the gauge must enclose the datum feature A with the least possible diameter mating size of datum feature A.
The datum feature is oriented according to the minimum rock requirement. The surface B contacts the gauge on one point only. In case c , the surface B must contact the gauge according to the minimum rock requirement.
In this orientation, the gauge must enclose the datum feature A with the least possible diameter. The maximum possible cylinder perpendicular to the gauge surface A must enclose the datum feature B. The slot C must be enclosed by the maximum possible parallelepiped plane pair perpendicular to the gauge surface A. The median plane of the parallelepiped contains the axes of the gauge cylinder B.
The gauge cylinder B and the gauge parallelepiped C are perpendicular to the gauge surface A, and the symmetry plane of the gauge parallelepiped contains the axis of the gauge cylinder B. On the right, the relevant inspection or gauge is shown. In the case below, the hinge will be adjusted in the assembly. The maximum material virtual condition is perpendicular to the datums A and B minimum rock requirement.
In this case, the coaxiality deviation eccentricity of the two holes is 0, The bolt is guided without clearance by the right hole, and must deflect when entering the left hole. The maximum material requirement would allow larger coaxiality deviations with larger holes. Inspection can be performed with two mandrels that fit into the holes without clearance. The total tolerance is indicated at the nominal size.
The limitation at the maximum material limit go gauge is the same as in Fig. At the minimum material limit, the geometrical ideal form and orientation apply according to Fig. According to Fig. This may be an unnecessary restriction and could be avoided. Tolerancing according to Fig. At the frame is a minimum clearance of 0,5, that is the difference between the maximum material sizes. The position tolerance does not depend on the actual sizes of the slots and the hole.
With this requirement the position tolerance depends on the actual sizes and actual forms of the slots and of the hole. In the worst case, when the hole axis has the largest position deviation, the remaining wall thickness is 2, Fig. Then, also, in the worst case the remaining wall thickness is 2, Fig. Between the least material virtual cylinder and the recesses, there remains a minimum wall thickness of 2, Fig. The permissible position deviation of the inner cylinder increases when the diameter of the inner cylinder decreases.
The permissible position deviation of the outer cylinder increases when the diameter of the outer cylinder increases. D10 is the position tolerance; see Fig. P9 is the position tolerance, see Fig. Then the key has the largest distance from the shaft centre. The smaller the slot width the larger is the position tolerance.
This corresponds to the least material requirement. Then the clearance between shaft and hub allows additional position deviation. Here all geometrical deviations lead to deformations of the parts. Compare this with Fig. The maximum possible form deviation is twice as much as with profile tolerancing. With profile tolerancing, a distinction must be made between tolerancing of the form of section lines symbol and of the form of surfaces symbol.
The nominal theoretically exact, geometrically ideal, true form is to be defined by theoretically exact rectangular framed dimensions with Fig. Then the size TED, reference feature is defined by the minimax Chebyshev criterion, with or without reference to datum s Figs 6. Therefore the zone is equally disposed on either side of the nominal profile reference feature. Clearly, the envelope shall alter its form in a smooth manner.
Figure 6. The upper tolerance 0,3 related to the complete datum system ABC, locking all degrees of freedom of the part, is mandatory. Without this tolerance the part is not completely toleranced. The upper tolerance 0,6 related to the complete datum system RST, locking all degrees of freedom of the part, is mandatory.
Profile tolerancing Chapter FIG. Positive values mean offset outward and negative values mean offset inward of the material. When the values are negative and of half the tolerance, part and counterpart have the same CAD model unilateral tolerance zones ; see Fig. The offset is defined by spheres along the TEF. With VA, the angle of the tolerance zone is variable and defined by the Chebyshev criterion minimax. The width varies in a proportional variation, i.
On the right is shown tolerancing with restricted length. The reference feature is oriented according to Chebyshev. This is in contrast to CZ, which unites the tolerance zones. The difference is that the outer corners of the tolerance zone are rounded.
Further, possible additional constraints are indicated. The tolerance 0,1 is a combination of orientation related to A and location related to B and C specification. The tolerance 0,05 is a form specification. The tolerance 0,02 is a specification for section lines in section planes parallel to datum B. A clear indication is using the future symbol [-] for datums only for the definition of secondary or tertiary datums; see Fig. However, the difference between the intersection lines of intersection planes of different order is very small.
The upper tolerancing does not limit the deviation of the side faces, but the lower tolerancing does. The first CZ or SZ refers to the first order group group of two rectangular holes and the second to the second order group group of four planes.
The tolerancings b and c are allowed, but not recommended. The theoretically exact position is determined by the datums A and B. CZ includes the TED The limit dimensions depend on the distance from the datum B. The figure shows the formulae for the calculation. The maximum FIG. Both parts have the same CAD model. The space between centred contours is between 0, and 0, They are no longer the state of the art.
Even when large tolerances are permissible, geometrical tolerances profile, position shall be used. They are correct and fit into the current tolerancing system with general profile tolerances; see 7. Inspection can still be executed with plain measuring instruments, e.
Exceptions to this rule are two-point sizes for the lower limit of size with external features of size e. For example, see Figs 5. See for example Figs 5. Figure 7. For example, measurements with step gauges may be oriented according to the upper or lower surface, outside material.
With CMMs, the orientation may also be according to the upper or lower surface, inside material. It is also possible to measure the distance between two parallel median planes, according to Chebyshev minimax or according to Gauss. As the ambiguities depend on the geometrical deviations of the surfaces, it is without geometrical tolerancing not clear what the workpiece might look like. Therefore, geometrical tolerancing shall be used; see Fig.
However, this indication is not standardized and requires the explanation on the drawing near the title block , as shown in Fig. Because of the tolerance accumulation, very small expensive tolerances were indicated.
However, this was not functional, because when all but one chain member were at the limit, the last member exceeded the limit. However, even when this small tolerance was respected, the part often could not be assembled, because the pair of opposite holes was eccentric in relation to the other holes. It was not clear what the centre was centre of the horizontal or vertical local diameter, centre of the maximum inscribed cylinder, centre of the minimum circumscribed cylinder and from where to measure real surface, associated plane, and whether from primary, secondary or tertiary datum plane.
Geometrical tolerancing is unique and correct. It was not clear where the zenithal line of the angle was located horizontal: median plane of the outer surfaces or median plane of the inner surfaces or centre of the hole distance; vertical: associated plane of the two horizontal surfaces, median plane of the two hole median lines. There are at least five possible locations for the zenithal line, resulting in five different measurement results. Then this small tolerance applies to all centre distances, and also for the chamber.
This is expensive in production. The real form deviates from the ideal form. According to ISO 14 they should no longer be used. Instead, profile tolerancing should be used. It has a defined tolerance zone. The correct choice according to the design intention is profile tolerancing. However, although the tolerances are so small, the workpieces may not fit, because there are orientation deviations which have not been taken into consideration. The correct choice is profile tolerancing.
When, with profile tolerances, UZ with half of the tolerance is used, the part and the counterpart can have the same theoretical contour. Theoretically, the tolerances accumulate between the first and the last member of the chain. However, the accumulation practically does not happen, because the pattern for the casting contains the chain members approximately at the exact location. In machining, the CNC machine tool goes approximately to the correct location.
The correct dimensioning and tolerancing with profile tolerances related FIG. Therefore, these general tolerances shall no longer be used, as they are no longer state of the art; see ISO 14 Instead, a profile surface tolerance, related to a general datum system RST, that locks all the degrees of freedom of the workpiece and is rated to the size of the workpiece space diagonal, diameter of smallest enveloping sphere , ISO 20 , shall be used for surfaces without dimensional or geometrical tolerance indication.
The datum features shall be toleranced properly form tolerance for primary datum, secondary datum toleranced in relation to the primary datum, tertiary datum toleranced in relation to the primary and secondary datum. With that, the workpiece is already completely toleranced. It should be noted that the general tolerance applies only to surfaces without tolerance indication. When there is a tolerance indication, a tolerance directly or indirectly related to the general datum system is to be indicated, even when it is equal to the general tolerance.
It is also possible to indicate general tolerances individually when they are necessary for the main function. The general tolerance shall be large enough to be respected without any additional effort and with a high probability. This can be derived from past measurement results. Then manufacturing and inspection can focus on the individually indicated tolerances.
The tolerances are derived from ISO They are rated to the Dp dimension; see Table 7. This is the nominal maximum special distance of the toleranced surface from the datum system origin Fig.
This distance is important for the following reason. Plastic parts deform when cooling after the manufacturing process warping, distortion. In order to reduce this deviation from the nominal shape, the die is designed deviating from the nominal shape. The more the surface is away from the datum system origin, the more deviation from the nominal shape is needed for the die.
TABLE 7. There are 15 tolerance grades, each rated to the size of the casting diameter of the smallest envelope sphere ; see Table 7. It applies only when indicated see, e. Without this constraint, the wall thickness may become too small for the function. See also The surface texture symbols give the information on which general tolerance applies; see Fig. However, in the most functional cases, size tolerances are to be complemented by geometrical tolerances specifications, e.
Therefore it is not recommended to use general size tolerances. See also 5. Instead, general position tolerances can be used; see Fig. Further they could only be used when the dimensions are indicated on the drawing. In 3D CAD systems, when no 2D drawing exists and no dimensions are shown in the model, these tolerances cannot be used.
The general geometrical tolerances according to ISO When the features are too short, they are not inspection appropriate and the general tolerances cannot be used. Further the workpiece was not totally toleranced.
Furthermore there was no datum system involved, and it was difficult or impossible, to assess, which permissible total shape was allowed to the workpiece. Therefore the general tolerances according to ISO should not be used anymore.
Instead, general profile tolerances should be used, as described before. This page intentionally left blank Chapter 8 Recommended Procedure for Tolerancing 8. It is recommended to use the indications as shown in Fig. First, the CAD model is established.
Then an analysis of the main function is conveyed with establishment of the main datum system. This datum system shall be complete, i. Next, the datum features are toleranced, the primary datum feature with a surface profile tolerance without datum, and the secondary and tertiary datum features with surface profile tolerances related to the primary and to the primary and secondary datum.
Then, a surface profile tolerance is indicated as a general tolerance. With that, the part is then completely toleranced. However, it should be investigated whether surfaces should be toleranced for functional reasons with a smaller or perhaps in special cases with a larger Geometrical Dimensioning and Tolerancing for Design, Manufacturing and Inspection.
These tolerances overrule the general tolerance. With that, the combination with , , , may be necessary. Finally, it should be investigated whether, in addition to these tolerances, further tolerances as constraints are necessary for functional reasons. The integral features shall be profile toleranced and derived features position toleranced.
All these individually indicted tolerances overrule the general tolerance. The symbol SZ defines separate tolerance zones without relation to other features , e. For surfaces with individually indicated tolerances, the general tolerance does not apply. They must have a tolerance directly or indirectly related to the main datum system; see Fig. It is possible to indicate the general tolerances individually for features that have a main function. The first cutting process starts at the right end, as well as the second.
The dimensions correspond to that. The tolerances have become much smaller in order to meet the functional requirement at the step. Designers should use the function-related dimensioning and tolerancing. All other dimensionings and tolerancings derive from this. When manufacturing-related drawings are necessary, they may be provided in addition. When the tolerance of the manufacturing-related drawing is exceeded, with the functionrelated drawing it can be investigated as to whether the workpiece is still functioning.
However, the contractual drawing, whatever it is, is decisive for the acceptance or rejection of the workpiece. Chapter 9 Tolerancing of Edges 9. Edges are intersections of two surfaces.
Edges always exhibit deviations from the ideal geometrical shape burr or undercut or passing Fig. It may be necessary to tolerance the size of these deviations for functional reasons e. An undercut is a deviation inside the ideal geometrical shape of an internal or external edge Fig.
A passing is a deviation outside the ideal geometrical shape of an internal edge Fig. The edge deviation is illustrated in Fig. The tolerances for the deviations from the ideal geometrical shape of edges within cross sections are to be indicated by the symbol shown in Fig.
The indication at the symbol means only deviations inside the material of geometrical ideal form are allowed undercut permitted, burr or passing not permitted Fig. When necessary, the upper limit of the size of the deviation or the upper and lower limit of the size of the deviation is to be indicated following the sign Fig. A sharp edge is an edge with an indication of a very small edge tolerance e. When it is needed to specify the direction of the burr on an external edge or the undercut on an internal edge, this indication shall be placed in areas a2 or a3 as shown in Fig.
Tolerancing of edges Chapter FIG. When the symbol points to a line, this edge is meant; if only one view is represented and the outlines of both front and back are the same, the edges of the front and back are meant Fig. In case of ambiguity, the indication may be used at corners. The edge tolerance indication may be applied — as an individual indication for a single edge Figs 9. According to ISO , without an indication of the state of the edges, the parts may be delivered direct from the machine without an additional edge treatment.
When the symbols and rules according to ISO described previously are applied, it is recommended that reference be made to ISO — either within or near the title block or within allocated documents, in the manner shown in Fig. Figure 9. TABLE 9. The transition specifications according to ISO are limited to edges between two planes and between a plane and a cylinder perpendicular to each other; see Fig.
The edge transition tolerance defines the tolerance for a section line line profile tolerance in a section plane. This section plane is perpendicular to the section ideal line of the associated ideal features to the adjacent real features.
The association is according to Gauss total least squares. According to ISO , in each section plane, the dimensions start from the specification origin point; see Fig. The straight lines are to be found by an iteration process. In the first association iteration, a least squares Gaussian straight line is associated to each adjacent feature line profile Fig.
If the lengths of the features allow, the length of the profile shall be 3D; see Figs 9. The intersection between the bisector and the real workpiece is the separation point between the two adjacent features for further association purposes; see Fig. After the first iteration, the piece of the profile between the first separation point and the first intersection is disregarded and the association is repeated.
In some types of form deviations, there are always form deviations to be disregarded, e. In these cases, it is recommended to abort after the third iteration. The intersection of the associated lines of the adjacent profile lines is the specification origin; see Fig.
In both cases, the straightness of the edge perpendicular to the section FIG. The datums F and B in Fig. By default, the adjacent reference sections are fitted individually. If one shall be fitted first and the other constrained by it to be in theoretically exact orientation similar to a primary and secondary datum at the nominal angle between the two features, a triangle shall be indicated either above or below the transition symbol to indicate which reference section shall be primary; see Fig.
According to ISO , various nominal shapes of transitions are possible; see Table 9. The definitions of the transitions according to ISO are rather difficult and in some cases difficult to achieve in verification. Therefore it is recommended to use tolerancing according to ISO ; for example, see Fig.
The symbols apply to the most advanced condition of the drawing moulded, intermediate machined, final machined.
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