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GD&T Form Table of Contents Return to the Previous Slide Slide 1QuitMaster Table of ContentsGlossary Chapter3 Form and Position Tolerances 形位公差 TTTT eeee rrrr mmmm ssss 术术术术 语语语语 FFFF oooo rrrr mmmm t t t t oooo llll eeee rrrr aaaa nnnn cccc eeee 形形形形 状状状状 公公公公 差差差差 PPPP oooo ssss tttt iiii oooo nnnn t t t t oooo llll eeee rrrr aaaa nnnn cccc eeee 位位位位 置置置置 公公公公 差差差差

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GD&T Form Table of Contents Return to the Previous Slide Slide 2QuitMaster Table of ContentsGlossary Form Tolerance: is the variation of the true form of a single factor to its perfect form make a small shaft found to be distortion and not cylindrical, or the section is out of round, or the axes is bended, or make a plane found to be warp.

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GD&T Form Table of Contents Return to the Previous Slide Slide 3QuitMaster Table of ContentsGlossary Position Tolerance: is the variation of the actual position of related factors to its ideal position form. While machining a stepped shaft, the axial cord of each step may not be the same, namely, concentricity and coaxality error. Surfaces expected to be perpendicular are not perpendicular after it machined.

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GD&T Form Table of Contents Return to the Previous Slide Slide 4QuitMaster Table of ContentsGlossary Symbols of Form and Position Tolerances

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GD&T Form Table of Contents Return to the Previous Slide Slide 5QuitMaster Table of ContentsGlossary A verification setup, including a dial indicator. This type of setup is often used in the process of verifying form during the production of parts. FORM TOLERANCES

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GD&T Form Table of Contents Return to the Previous Slide Slide 6QuitMaster Table of ContentsGlossary Gages Used To Verify Form Dial indicators are often used to measure variation from dimensional limits on form tolerances. Note the spherical tipped probes of different size and flexibility.

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GD&T Form Table of Contents Return to the Previous Slide Slide 7QuitMaster Table of ContentsGlossary V blocks are often used to cradle cylindrical parts in the manufacturing and inspection processes. Gages Used To Verify Form

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GD&T Form Table of Contents Return to the Previous Slide Slide 8QuitMaster Table of ContentsGlossary A surface plate is vital in the processes of manufacturing and inspection. Made from solid granite, they vary in size and thickness. The surfaces are processed to a very smooth finish. They are used as datum plane simulators. Gages Used To Verify Form

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GD&T Form Table of Contents Return to the Previous Slide Slide 9QuitMaster Table of ContentsGlossary Additional tools and fixtures that are used in the inspection process. Gages Used To Verify Dimensional Accuracy

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GD&T Form Table of Contents Return to the Previous Slide Slide 10QuitMaster Table of ContentsGlossary FEATURE STRAIGHTNESS TOLERANCES OF FORM TOLERANCES OF FORM

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GD&T Form Table of Contents Return to the Previous Slide Slide 11QuitMaster Table of ContentsGlossary Straightness Applied To A Feature In this example, the feature control frame, specifying straightness of line elements, is applied to the top surface of the part. It is not associated with any dimension, therefore, it references its own true geometric counterpart—a perfectly straight line. This is the case with all form tolerances, datums are therefore never referenced in a feature control frame specifying form control. 16.0 15.4 0.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 12QuitMaster Table of ContentsGlossary Straightness Applied To A Feature The shape of the tolerance zone for surface element straightness is two parallel lines. Notice that the straightness specification is called out in the front view. Therefore, the control applies in that view only (in the orientation of the front view, from left to right or right to left). The straightness control from front to back (as shown in the side view) is equal to the size tolerance (0.6 mm). 0.2 16.0 15.4 0.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 13QuitMaster Table of ContentsGlossary Straightness Applied To A Feature 0.2 Size limit tolerance 0.6 mm (allowed by General rule #1) 16.0 Remember, the straightness tolerance control applies only in the orientation depicted in the view where the straightness tolerance symbol is shown. Straightness in the other (cross) orientation is controlled by the height (size) dimension tolerance. 15.4

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GD&T Form Table of Contents Return to the Previous Slide Slide 14QuitMaster Table of ContentsGlossary There is an infinite number of surface line elements (in the orientation or direction of the straightness control) that comprise the surface, and each line element must be verified independent of all others. Each line is inspected separately (the inspection device is reset after each segment). Enough passes must be taken to satisfy the inspector that the surface line elements are within the specified tolerance zone. Straightness Applied To A Feature 0.2 0.6

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GD&T Form Table of Contents Return to the Previous Slide Slide 15QuitMaster Table of ContentsGlossary Straightness Of Line Elements To further illustrate the principle of orientation, in relationship to straightness control, consider the drawing above. Two separate geometric tolerances for straightness have been applied to the same surface, albeit in different orientations; the front view represents a cross-horizontal orientation—left to right, whereas the right side view shows a longitudinal-horizontal orientation—front to back. 0.05 0.1

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GD&T Form Table of Contents Return to the Previous Slide Slide 16QuitMaster Table of ContentsGlossary Straightness Of Line Elements 0.05 0.1 Each line element on the surface must lie between two parallel lines 0.05 apart in the orientation depicted in the front view, and 0.1 when oriented as shown in the right-side view of the drawing.

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GD&T Form Table of Contents Return to the Previous Slide Slide 17QuitMaster Table of ContentsGlossary Straightness Of Line Elements 0.05 0.1 The illustration attempts to show the different tolerance zones that would result from the two geometric tolerances called out on the drawing. 0.1 Tolerance 0.05 Tolerance

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GD&T Form Table of Contents Return to the Previous Slide Slide 18QuitMaster Table of ContentsGlossary STRAIGHTNESS CONTROLLED BY DEFAULT—RULE #1

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GD&T Form Table of Contents Return to the Previous Slide Slide 19QuitMaster Table of ContentsGlossary Rule #1 (Default) Control of Straightness The dimension between the top and bottom of the object shown below, allows a size tolerance of 0.5 mm. All line elements, across the entire surface, must be straight within 0.5 mm. 12.5 12.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 20QuitMaster Table of ContentsGlossary 12.5 12.0 Rule #1 (Default) Control of Straightness 12.5 12.0 Straightness of all line elements (in all directions) must fall within the 0.5 mm tolerance zone defined by two parallel lines.

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GD&T Form Table of Contents Return to the Previous Slide Slide 21QuitMaster Table of ContentsGlossary STRAIGHTNESS CONTROLLED BY RULE #1 COMBINED WITH A GEOMETRIC TOLERANCE

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GD&T Form Table of Contents Return to the Previous Slide Slide 22QuitMaster Table of ContentsGlossary Rule #1 is never overridden by a straightness control that is applied to surface elements. The straightness control refines the allowable tolerance straightness error of the surface. 10.6 10.0 Straightness Controlled By Rule #1 Combined With A Geometric Tolerance 0.3 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 23QuitMaster Table of ContentsGlossary Tolerance zone (2 parallel lines, 0.3 apart) may float inside Rule #1 limits The geometric tolerance controlling the straightness of the line elements on the top surface must be smaller, and be contained within the larger size tolerance. However, the refining form tolerance may float within the larger size tolerance. Any line on the top surface (in the specified orientation) must be within 0.3 mm of perfect straightness. When form tolerances are called out on features, rule #1 is in effect, and all elements on the surface must be within the limits of size. Straightness Controlled By Rule #1 Combined With A Geometric Tolerance 10.6 10.0 0.3 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 24QuitMaster Table of ContentsGlossary At this checking location. the full range of tolerance for straightness is available, but remember, every line element is independent of all others. Straightness Controlled By Rule #1 Combined With A Geometric Tolerance Tolerance zone (2 parallel lines, 0.3 apart) may float inside Rule #1 limits 10.6 10.0 0.3 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 25QuitMaster Table of ContentsGlossary At the lower range of the size limits, the full tolerance for straightness is available. Straightness Controlled By Rule #1 Combined With A Geometric Tolerance Tolerance zone (2 parallel lines, 0.3 apart) may float inside Rule #1 limits 10.6 10.0 0.3 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 26QuitMaster Table of ContentsGlossary When departure from MMC is less than the straightness tolerance, as in this case, some of the tolerance for straightness is compromised, and therefore unavailable, Straightness Controlled By Rule #1 Combined With A Geometric Tolerance Tolerance zone (2 parallel lines, 0.3 apart) may float inside Rule #1 limits. Departure may be less than allowed, but actual surface elements cannot violate size limits. 10.6 10.0 0.3 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 27QuitMaster Table of ContentsGlossary Straightness of Surface Elements 0.04 14.93 - 15.00 Straightness of a feature is most often used to control the longitudinal surface elements of a cylinder or cone. An infinite number of longitudinal lines exist on the surface shown in the illustration above, and the specification implies that all surface line elements on the pin must be straight within a tolerance of 0.04 mm.

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GD&T Form Table of Contents Return to the Previous Slide Slide 28QuitMaster Table of ContentsGlossary Straightness Of Surface Elements 0.04 14.93 - 15.00 All longitudinal elements on the surface of the pin must lie between two parallel lines 0.04 mm apart. The two lines comprising the tolerance zone must also be in a plane that is common with the axis of the cylindrical pin.

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GD&T Form Table of Contents Return to the Previous Slide Slide 29QuitMaster Table of ContentsGlossary Straightness Of Surface Elements There are infinite possibilities for resulting feature form in the drawing displayed, but in no case can the size limits be violated. Three extreme form possibilities will be illustrated. 0.04 14.93 - 15.00

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GD&T Form Table of Contents Return to the Previous Slide Slide 30QuitMaster Table of ContentsGlossary Straightness Of Surface Elements Combined With Rule #1 The first example shows the pin curvature to the extent allowed by the geometric tolerance. Regardless of how much the diameter size varies, within the 14.93 – 15.00 mm diameter, the surface line elements must be straight within the specified tolerance. Perfect form is required at MMC. As departure from MMC occurs, out of straightness is allowed—up to 0.04 mm. 0.04 tolerance zone 0.04 14.93 - 15.00 15.00 MMC

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GD&T Form Table of Contents Return to the Previous Slide Slide 31QuitMaster Table of ContentsGlossary Straightness Of Surface Elements “Waisting” can occur on the part, and if so, some of the tolerance may be compromised at opposite points when at the lower limit of size. If the 0.04 tolerance was maximized all around the diameter, 0.08 mm would have to be subtracted from the upper limit (15.00 mm), leaving a total minimum diameter of 14.92 mm. The part would be out of tolerance. 0.04 tolerance zone 0.04 14.93 - 15.00 15.00 MMC

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GD&T Form Table of Contents Return to the Previous Slide Slide 32QuitMaster Table of ContentsGlossary Straightness Of Surface Elements Feature “barreling” could also result. But once again, some of the tolerance could be compromised at opposite points inasmuch as the full 0.04 mm tolerance could not be in effect all around the object without violating the overall size tolerance. 0.04 tolerance zone 0.04 14.93 - 15.00 15.00 MMC

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GD&T Form Table of Contents Return to the Previous Slide Slide 33QuitMaster Table of ContentsGlossary Straightness Of Surface Elements 0.04 14.93 - 15.00 15.00 MMC 0.04 tolerance zone In a feature-control application, the straightness tolerance must be less than the size tolerance.* In the case of barreling or waisting of the surface, the full straightness tolerance may not be available for opposite elements because the limits of size cannot be violated. REMEMBER *This general rule can be overridden by a note specifying that perfect form is not required at MMC.

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GD&T Form Table of Contents Return to the Previous Slide Slide 34QuitMaster Table of ContentsGlossary 0.3 10.8 10.0 0.3 10.6 10.0 The application of the feature control frame—whether associated with a feature or a feature of size—makes a significant difference in the interpretation of the control.The application of the feature control frame—whether associated with a feature or a feature of size—makes a significant difference in the interpretation of the control. In the illustration on the left, the control is on a feature; notice the resulting tolerance zone, controlling the surface line elements.In the illustration on the left, the control is on a feature; notice the resulting tolerance zone, controlling the surface line elements. The drawing on the right shows the application of the geometric tolerance in conjunction with the feature of size, thus controlling the median line or axis of the part.The drawing on the right shows the application of the geometric tolerance in conjunction with the feature of size, thus controlling the median line or axis of the part. Feature Control Frame Applications

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GD&T Form Table of Contents Return to the Previous Slide Slide 35QuitMaster Table of ContentsGlossary Rule #1 Default Straightness Control In this example, the maximum possible diameter the pin could be, within its size limits, is 10.6 mm. At that size (maximum material condition), the cylindrical form of the pin would have to be perfect, the axis would be perfectly straight, as would all the longitudinal line elements on the surface. As the pin diameter gets smaller in size, moving away from maximum material condition towards least material condition (LMC)—but still within the size tolerance limits—the axis of the pin is allowed to bow or deform in the same amount. 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 36QuitMaster Table of ContentsGlossary Pin diameter smaller than MMC, but within size tolerance. Rule #1 Boundary (Mating Envelope) 10.6 MMC Because rule #1 is in effect, the size envelope cannot be violated, and where there is no geometric tolerance applied to the dimension, the virtual condition is equal to the MMC of the pin, which in this case, is 10.6 mm. As the pin diameter decreases in size, but remains within the size tolerance, the straightness of the pin’s axis may be affected in an amount equal to the departure. Rule #1 Straightness Control 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 37QuitMaster Table of ContentsGlossary Tolerance Zone Diameter = 0.6 Pin Diameter at 10.0 10.6 MMC Rule #1 Straightness Control Shown at the worst case—the smallest diameter allowed by the size tolerance or least material condition—the tolerance zone for the axis would be equal to 0.6 mm, thus permitting the axis to be out of straightness by the same amount—the part could be cylindrical but bowed. Rule #1 Boundary (Mating Envelope) 10.6 10.0

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GD&T Form Table of Contents Return to the Previous Slide Slide 38QuitMaster Table of ContentsGlossary FEATURE OF SIZE STRAIGHTNESS AT RFS

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GD&T Form Table of Contents Return to the Previous Slide Slide 39QuitMaster Table of ContentsGlossary 12.6 12.0 0.2 Feature Axis Control RFS In this illustration, the feature control frame is associated with the size dimension—the diameter of the pin. Thus, the control is on the axis of the part, and applies at any increment of size within the specified diameter size tolerance. Because the geometric tolerance is applied to a feature of size, Rule #1 is overridden. The virtual condition, or mating part envelope of the pin is equal to the MMC of the pin, plus the geometric tolerance, or 12.8 mm.

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GD&T Form Table of Contents Return to the Previous Slide Slide 40QuitMaster Table of ContentsGlossary Pin Diameter--at any cross section, must be within the limits of size ( 12.0-12.6 mm). 0.2 tolerance zone, regardless of feature size. The smallest true cylinder (an adjustable gage), in contact with the high points on the surface. The maximum acceptable diameter would be equal to the virtual condition— the pin’s MMC plus the geometric tolerance ( 12.8 mm). 12.6 12.0 0.2 Feature Axis Control RFS The feature axis straightness is maintained regardless of feature size (RFS). The 0.2 axis tolerance applies at any increment of size within the stated diameter size tolerance. Rule #1 is overridden, and the virtual condition is 12.8 mm.

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GD&T Form Table of Contents Return to the Previous Slide Slide 41QuitMaster Table of ContentsGlossary Pin Diameter Straightness Tolerance Zone Diameter 12.6 12.4 12.2 12.0 0.2 12.6 12.0 0.2 Straightness Tolerance Applied to a Feature of Size RFS At any increment of size, within the size limits, the tolerance for straightness of the median line or axis is constant. Rule #1 is overridden because the control is applied to a feature of size.

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GD&T Form Table of Contents Return to the Previous Slide Slide 42QuitMaster Table of ContentsGlossary 12.0 - 12.6 0.2 Straightness Tolerance Applied to a Feature of Size MMC When it is important to modify a straightness control to a condition of MMC, the tolerance portion of the feature control frame must include the appropriate material condition modifier.

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GD&T Form Table of Contents Return to the Previous Slide Slide 43QuitMaster Table of ContentsGlossary StraightnessBonusTotal Diametral Pin ToleranceToleranceTolerance Zone 12.60.2 0.0 0.2 ToleranceZone VirtualCondition 12.8 0.2 M 12.0 -12.6 Pin Diameter, at any cross section, must be within the limits of size ( 12.0-12.6). This series of visuals illustrate the concept of bonus tolerance applied as the object departs from MMC. Straightness Tolerance Applied to a Feature of Size MMC

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GD&T Form Table of Contents Return to the Previous Slide Slide 44QuitMaster Table of ContentsGlossary StraightnessBonusTotal Diametral Pin ToleranceToleranceTolerance Zone ToleranceZone VirtualCondition 12.8 0.2 M 12.0 -12.6 Pin Diameter, at any cross section, must be within the limits of size ( 12.0-12.6). This series of visuals illustrate the concept of bonus tolerance applied as the object departs from MMC. Straightness Tolerance Applied to a Feature of Size MMC 12.40.2 0.2 0.4

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GD&T Form Table of Contents Return to the Previous Slide Slide 45QuitMaster Table of ContentsGlossary StraightnessBonusTotal Diametral Pin ToleranceToleranceTolerance Zone ToleranceZone VirtualCondition 12.8 0.2 M 12.0 -12.6 Pin Diameter, at any cross section, must be within the limits of size ( 12.0-12.6). This series of visuals illustrate the concept of bonus tolerance applied as the object departs from MMC. Straightness Tolerance Applied to a Feature of Size MMC 12.20.2 0.4 0.6

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GD&T Form Table of Contents Return to the Previous Slide Slide 46QuitMaster Table of ContentsGlossary StraightnessBonusTotal Diametral Pin ToleranceToleranceTolerance Zone ToleranceZone VirtualCondition 12.8 0.2 M 12.0 -12.6 Pin Diameter, at any cross section, must be within the limits of size ( 12.0-12.6). This series of visuals illustrate the concept of bonus tolerance applied as the object departs from MMC. Straightness Tolerance Applied to a Feature of Size MMC 12.00.2 0.6 0.8

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GD&T Form Table of Contents Return to the Previous Slide Slide 47QuitMaster Table of ContentsGlossary Advantages of Straightness Tolerance Applied to a Feature of Size MMC Applying straightness to a feature of size—especially if the control is modified to apply at maximum material condition—allows for additional tolerance as departure from MMC occurs. This added or bonus tolerance provides greater flexibility to manufacturing, and can have a positive affect on production costs. In those instances where the conditions are as described above, fixed gages that represent the worst case for assembly can also be used for verification, thus impacting overall costs. The next series of screens will illustrate this concept. The advantages of MMC control will be illustrated through the use of sketched parts in various configurations, in their respective receiver gages.

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GD&T Form Table of Contents Return to the Previous Slide Slide 48QuitMaster Table of ContentsGlossary Mating Part Boundary Verification The dimension and control frame are shown in the lower left corner of the screen. In the illustration, the part is shown at the maximum material condition. It is in the receiver gage is shown at the mating part boundary limits or virtual condition. There is adequate clearance for the parts to assemble without interference. 12.8 (VC) 12.6 (1) 0.2 M 12.0 -12.6

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GD&T Form Table of Contents Return to the Previous Slide Slide 49QuitMaster Table of ContentsGlossary (1) 12.8 (VC) 12.6 (1) 0.2 M 12.0 -12.6 Mating Part Boundary Verification Pin Diameter at MMC & perfectly straight. Gage at Virtual Condition

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GD&T Form Table of Contents Return to the Previous Slide Slide 50QuitMaster Table of ContentsGlossary Pin Diameter at MMC & perfectly straight. Gage at Virtual Condition (1) 12.8 0.2 12.6 (2) 12.8 (VC) 12.6 (1) 0.2 M 12.0 -12.6 Mating Part Boundary Verification Pin Diameter at MMC. Gage will accept with 0.2 variation in straightness

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GD&T Form Table of Contents Return to the Previous Slide Slide 51QuitMaster Table of ContentsGlossary 0.8 12.8 12.0 (3) Pin Diameter at MMC & perfectly straight. Gage at Virtual Condition (1) 12.8 0.2 12.6 Pin Diameter at MMC. Gage will accept with 0.2 variation in straightness (2) 12.8 (VC) 12.6 (1) 0.2 M 12.0 -12.6 Mating Part Boundary Verification Pin Diameter at LMC. Gage will accept with 0.8 variation in straightness

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GD&T Form Table of Contents Return to the Previous Slide Slide 52QuitMaster Table of ContentsGlossary 0.8 12.8 12.0 (3) Pin Diameter at MMC & perfectly straight. Gage at Virtual Condition (1) 12.8 (VC) 12.6 (1) 12.8 0.2 12.6 Pin Diameter at MMC. Gage will accept with 0.2 variation in straightness (2) 0.2 M 12.0 -12.6 Mating Part Boundary Verification Carefully review these concepts. (2) (3) Pin Diameter at LMC. Gage will accept with 0.8 variation in straightness

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GD&T Form Table of Contents Return to the Previous Slide Slide 53QuitMaster Table of ContentsGlossary TOLERANCES OF FORM FLATNESS

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GD&T Form Table of Contents Return to the Previous Slide Slide 54QuitMaster Table of ContentsGlossary TERMS AND DEFINITIONS Flatness: A condition where all of the elements of a given surface are in a single plane.Flatness: A condition where all of the elements of a given surface are in a single plane. Flatness tolerance: The total amount surface elements are permitted to vary from a true plane.Flatness tolerance: The total amount surface elements are permitted to vary from a true plane. Flatness tolerance zone: The distance between two parallel planes within which all of the elements of the controlled surface must lie.Flatness tolerance zone: The distance between two parallel planes within which all of the elements of the controlled surface must lie.

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GD&T Form Table of Contents Return to the Previous Slide Slide 55QuitMaster Table of ContentsGlossary Flatness Verification Flatness (A 3D tolerance zone) may be determined by a theoretical plane, established by the high points of the controlled surface in contact with a surface plate or gage.Flatness (A 3D tolerance zone) may be determined by a theoretical plane, established by the high points of the controlled surface in contact with a surface plate or gage. From the theoretical plane, a second plane is offset and parallel by a distance equal to the tolerance value. All elements of the controlled surface must lie between the two parallel planes.From the theoretical plane, a second plane is offset and parallel by a distance equal to the tolerance value. All elements of the controlled surface must lie between the two parallel planes.

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GD&T Form Table of Contents Return to the Previous Slide Slide 56QuitMaster Table of ContentsGlossary Second Plane Flatness Tolerance Zone Primary Plane Surface Plate Flatness Verification Neither the object nor the gage is perfectly flat. They will position themselves on the high points of contact. Once that is done, the second plane, parallel to the first, is established a linear distance—equal to the tolerance value—away from the theoretical plane. All of the elements on the controlled surface must lie between the two planes.

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GD&T Form Table of Contents Return to the Previous Slide Slide 57QuitMaster Table of ContentsGlossary Second Plane Flatness Tolerance Zone Primary Plane Surface Plate Flatness Verification Flatness may be verified with a dial indicator that extends through a hole in a surface plate. The indicator is made stationary, and the part is moved around on the surface plate to ensure that all elements of the controlled surface are checked.

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GD&T Form Table of Contents Return to the Previous Slide Slide 58QuitMaster Table of ContentsGlossary Feature Flatness 0.2 Size limit tolerance 0.6mm (allowed by General rule #1) 16.0 15.4 The flatness tolerance control applies to all elements on the surface to which the tolerance is applied. The flatness tolerance is allowed to float within the larger size tolerance. It can be oriented in any location or direction as long as it does not violate the size tolerance.

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GD&T Form Table of Contents Return to the Previous Slide Slide 59QuitMaster Table of ContentsGlossary All surface elements must be within the tolerance zone defined by two parallel planes, 0.2 apart. Enough passes in random directions must be taken to satisfy the inspector that all of the surface elements are within the specified tolerance zone. Feature Flatness 0.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 60QuitMaster Table of ContentsGlossary TOLERANCES OF FORM Flatness being verified using a surface plate, a height stand, and a dial indicator.

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GD&T Form Table of Contents Return to the Previous Slide Slide 61QuitMaster Table of ContentsGlossary TOLERANCES OF FORM Inspection/verification setup, comprised of a rotational surface plate, a height stand, and a digital indicator.

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GD&T Form Table of Contents Return to the Previous Slide Slide 62QuitMaster Table of ContentsGlossary Coordinate tolerances combined with the first fundamental rule, when applied to a feature of size (a distance between two parallel surfaces), provides an automatic flatness control for both surfaces. At MMC, both surfaces would have to be perfectly flat. As departure from MMC occurs, however, form variation equal in amount to that departure is allowed. (Form variation limits are equal to the difference between the upper and lower size tolerance, and apply equally for both surfaces). Because rule #1 is in effect, the size limits cannot be violated. Default Flatness Controlled By The First Fundamental Rule

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GD&T Form Table of Contents Return to the Previous Slide Slide 63QuitMaster Table of ContentsGlossary Flatness Application The feature control frame can be attached to an extension line as shown here. It may also be attached to a leader, with its arrow touching the surface (as shown on the next slide). However, it must always be associated with a view where the surface being controlled for flatness appears as a single line—an edge view. 0.2 14.0 - 14.6

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GD&T Form Table of Contents Return to the Previous Slide Slide 64QuitMaster Table of ContentsGlossary 0.2 14.0 - 14.6 The top surface is specified to be flat within a tolerance zone defined by two parallel planes 0.2 mm apart. The size dimension allows 0.6 mm of tolerance between the two surfaces. Flatness Application

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GD&T Form Table of Contents Return to the Previous Slide Slide 65QuitMaster Table of ContentsGlossary 14.6 MMC 14.0 LMC 14.0 - 14.6 Flatness Application The limits of size are illustrated on the drawing. Clearly, the part is within the size tolerance range. But the flatness tolerance must also be within the size tolerance, and contain all of the surface elements. 0.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 66QuitMaster Table of ContentsGlossary 0.2 Tolerance Zone 14.6 MMC 14.0 LMC 14.0 - 14.6 0.2 The surface elements are within the size tolerance but fall outside the prescribed flatness tolerance. Flatness Application

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GD&T Form Table of Contents Return to the Previous Slide Slide 67QuitMaster Table of ContentsGlossary 0.2 Tolerance Zone 14.6 MMC 14.0 LMC 14.0 - 14.6 0.2 As long as the tolerance zone for flatness is parallel to the theoretical plane established at the bottom, the elements will not fit within the tolerance zone. However, what has been stipulated is that the top has to be flat. There is no relationship to the bottom, other than the size dimension. So... Flatness Application

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GD&T Form Table of Contents Return to the Previous Slide Slide 68QuitMaster Table of ContentsGlossary 0.2 Tolerance Zone 14.6 MMC 14.0 LMC 14.0 - 14.6 0.2 Placing gage blocks under one end of the part creates an equalizing effect on the object. We can now verify whether or not, under such circumstances, the elements of the surface are within the prescribed tolerance zone. As can be seen in the illustration, with this adjustment, all of the elements fall within the tolerance for size and form. Flatness Application Gage Block

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GD&T Form Table of Contents Return to the Previous Slide Slide 69QuitMaster Table of ContentsGlossary 0.4 Tolerance Zone 7.2 MMC 6.0 LMC 6.0 – 7.2 0.4 The full range of the tolerance zone for flatness becomes available only after the departure from MMC exceeds the width of the tolerance zone for flatness. This is because the size limits cannot be violated. When the part is at the upper limit of the size tolerance, some of the form tolerance zone must be compromised. Flatness Application

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GD&T Form Table of Contents Return to the Previous Slide Slide 70QuitMaster Table of ContentsGlossary This blown up view may help solidify the concept. When nearly at maximum material condition, there may not be sufficient space to accommodate the entire form tolerance. The 0.4 tolerance range is compromised in this illustration because its limits extend beyond the size limits. At MMC the surface would have to be perfectly flat. All surface elements must be within the size tolerance zone, indicated by yellow phantom lines. Flatness Application 0.4 1.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 71QuitMaster Table of ContentsGlossary GEOMETRIC TOLERANCES CIRCULARITYCIRCULARITY

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GD&T Form Table of Contents Return to the Previous Slide Slide 72QuitMaster Table of ContentsGlossaryDEFINITIONS Circularity for a feature other than a sphere is a condition where all points of the surface intersected by any plane perpendicular to an axis are equidistant from that axis.Circularity for a feature other than a sphere is a condition where all points of the surface intersected by any plane perpendicular to an axis are equidistant from that axis. Circularity for a sphere is a condition where all points of the surface intersected by any plane passing through a common center are equidistant from that center.Circularity for a sphere is a condition where all points of the surface intersected by any plane passing through a common center are equidistant from that center. Circular tolerance: The amount which surface elements of a controlled diameter may vary from a theoretically perfect circle.Circular tolerance: The amount which surface elements of a controlled diameter may vary from a theoretically perfect circle. Circularity tolerance zone: Two concentric circles which are perpendicular to the diameter axis, or in a plane that passes through the center of a sphere, and separated by a radial distance equal to the tolerance value, and within which, at any cross section, each circular element of the surface must lie.Circularity tolerance zone: Two concentric circles which are perpendicular to the diameter axis, or in a plane that passes through the center of a sphere, and separated by a radial distance equal to the tolerance value, and within which, at any cross section, each circular element of the surface must lie.

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GD&T Form Table of Contents Return to the Previous Slide Slide 73QuitMaster Table of ContentsGlossaryDEFINITIONS Circularity for a feature other than a sphere is a condition where all points of the surface intersected by any plane perpendicular to an axis are equidistant from that axis. Circularity for a sphere is a condition where all points of the surface intersected by any plane passing through a common center are equidistant from that center. Circular tolerance: The amount which surface elements of a controlled diameter may vary from a theoretically perfect circle. Circularity tolerance zone: Two concentric circles which are perpendicular to the diameter axis, or in a plane that passes through the center of a sphere, and separated by a radial distance equal to the tolerance value, and within which, at any cross section, each circular element of the surface must lie. (Many cross sections must be inspected) Note: A circularity tolerance zone—two concentric circles—is conceptually easy to visualize. However, verification of a circularity form control is complicated enough that a separate ANSI standard (ANSI B89.3.1) is required to provide an expanded explanation of specification and inspection requirements. For example, the specification means that the roundness of the controlled surface shall be within.005 inches as determined by the least squares circle method with 150 cycles per revolution, using a.010 radius stylus tip. Note: A circularity tolerance zone—two concentric circles—is conceptually easy to visualize. However, verification of a circularity form control is complicated enough that a separate ANSI standard (ANSI B89.3.1) is required to provide an expanded explanation of specification and inspection requirements. For example, the specification.005 LSC 150.010 means that the roundness of the controlled surface shall be within.005 inches as determined by the least squares circle method with 150 cycles per revolution, using a.010 radius stylus tip.

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GD&T Form Table of Contents Return to the Previous Slide Slide 74QuitMaster Table of ContentsGlossary GEOMETRIC TOLERANCES Circularity being gauged in process of part production.

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GD&T Form Table of Contents Return to the Previous Slide Slide 75QuitMaster Table of ContentsGlossaryCircularity Circularity is a (2D tolerance Zone ) surface feature form control. When circularity is applied to an external feature such as the diameter of a pin or shaft, the outer boundary (larger tolerance band or circle) is first established by circumscribing the high points of the surface using a variable gage—one that will collapse around the external diameter while maintaining its circular shape.Circularity is a (2D tolerance Zone ) surface feature form control. When circularity is applied to an external feature such as the diameter of a pin or shaft, the outer boundary (larger tolerance band or circle) is first established by circumscribing the high points of the surface using a variable gage—one that will collapse around the external diameter while maintaining its circular shape. The inner boundary of the external feature can then be established as radially smaller than the upper limit of the size tolerance by the amount of the specified form tolerance. However, the actual feature, at any point of measurement, must be within the size envelope allowed by rule #1.The inner boundary of the external feature can then be established as radially smaller than the upper limit of the size tolerance by the amount of the specified form tolerance. However, the actual feature, at any point of measurement, must be within the size envelope allowed by rule #1.

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GD&T Form Table of Contents Return to the Previous Slide Slide 76QuitMaster Table of ContentsGlossaryCircularity When circularity control is applied to an internal feature, such as a hole, the inner boundary (smaller tolerance band or circle) is established by gage contact of the high points of the surface.When circularity control is applied to an internal feature, such as a hole, the inner boundary (smaller tolerance band or circle) is established by gage contact of the high points of the surface. The outer boundary is radially larger than the smaller size tolerance limit by the amount of the specified form tolerance. In this case also, the feature, at any point of measurement (perpendicular to the axis), must be within the limits of size.The outer boundary is radially larger than the smaller size tolerance limit by the amount of the specified form tolerance. In this case also, the feature, at any point of measurement (perpendicular to the axis), must be within the limits of size.

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GD&T Form Table of Contents Return to the Previous Slide Slide 77QuitMaster Table of ContentsGlossaryCircularity The specified circularity requires that within the tolerance limits established by the size dimension, the form tolerance (all circular cross-sections on the part) must not vary from true circularity beyond the amount permitted by the circularity tolerance, which consists of two concentric circles spaced apart by 0.4 mm radial distance. 0.4

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GD&T Form Table of Contents Return to the Previous Slide Slide 78QuitMaster Table of ContentsGlossary Two concentric circles establish the circularity tolerance zone. Circularity 0.4

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GD&T Form Table of Contents Return to the Previous Slide Slide 79QuitMaster Table of ContentsGlossaryCircularity Smallest true circle that circumscribes that circumscribes the high points the high points of the feature of the feature diameter—within tolerance diameter—within tolerance 0.4

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GD&T Form Table of Contents Return to the Previous Slide Slide 80QuitMaster Table of ContentsGlossary Smallest true circle that circumscribes that circumscribes the high points the high points of the feature of the feature diameter—within diameter—withintolerance. Circularity The outline of the actual part and its cross section are shown. After a measurement is taken at a specific location, the part is rotated slowly approx 30 deg. where another measurement is taken. This procedure continues all around the part. Note that all elements of the circular section are within the boundaries of the tolerance limits. 0.4 0.4 Offset of concentric circles

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GD&T Form Table of Contents Return to the Previous Slide Slide 81QuitMaster Table of ContentsGlossary Smallest true circle that circumscribes that circumscribes the high points the high points of the feature of the feature diameter—within diameter—withintolerance. Circularity Measurements are taken at many section locations along the part. The gauge is reset between each measurement. 0.4 0.4 Offset of concentric circles

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GD&T Form Table of Contents Return to the Previous Slide Slide 82QuitMaster Table of ContentsGlossary Diametrical features such as cylinders, cones, and spheres are the only features that circularity can appropriately be applied to.Diametrical features such as cylinders, cones, and spheres are the only features that circularity can appropriately be applied to. Circularity cannot be modified to apply at MMC or LMC. It comes under the control of size tolerances and general rule #1, which stipulates that the form must be perfect when the part is at MMC. Circularity, therefore, always applies regardless of feature size, and must be contained within the boundaries of the size limits.Circularity cannot be modified to apply at MMC or LMC. It comes under the control of size tolerances and general rule #1, which stipulates that the form must be perfect when the part is at MMC. Circularity, therefore, always applies regardless of feature size, and must be contained within the boundaries of the size limits. Circularity

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GD&T Form Table of Contents Return to the Previous Slide Slide 83QuitMaster Table of ContentsGlossary Circularity Indirectly Controlled by Other Geometric Tolerances If circularity is determined to be a necessary specification, care should be taken to ascertain the effects of other geometric tolerances that may also influence or indirectly control circularity. In addition to circularity, geometric tolerances controlling cylindricity, profile, and runout also influence the circular form of features.

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GD&T Form Table of Contents Return to the Previous Slide Slide 84QuitMaster Table of ContentsGlossary FORM CONTROLS CYLINDRICITYCYLINDRICITY

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GD&T Form Table of Contents Return to the Previous Slide Slide 85QuitMaster Table of ContentsGlossary FORM CONTROLS CYLINDRICITYCYLINDRICITY

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GD&T Form Table of Contents Return to the Previous Slide Slide 86QuitMaster Table of ContentsGlossaryCYLINDRICITY Cylindricity: A condition of a surface of revolution in which all points on the surface are perpendicular and equidistant from a common axis. Cylindricity can control straightness and circularity Cylindricity Tolerance: A 3D boundary defined by two theoretically perfect coaxial cylinders within which all the elements of the specified surface must lie. Cylindricity (3D) Tolerance Zone: The radial distance between the two coaxial cylinders defines the tolerance zone and represents the amount that surface elements are allowed to vary from a perfect cylinder. This numerical value (always less than one-half of the diametrical tolerance) is specified in the tolerance cell of the feature control frame. Note: As a surface form control, cylindricity is always considered RFS, and the physical limits imposed by size dimensions cannot be violated. Datums are neither proper nor allowed in the feature control frame, and the tolerance cannot be modified to consider additional tolerance as departure from MMC occurs. A diameter symbol zone descriptor cannot be used in the feature control frame. Tolerances Of Form—Cylindricity Definitions of Terms

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GD&T Form Table of Contents Return to the Previous Slide Slide 87QuitMaster Table of ContentsGlossary When cylindricity control is applied to an external feature, the outer boundary (larger cylinder) is typically established by circumscribing the high points of the surface. The inner boundary is radially smaller by the amount of the specified tolerance. The feature, at any point of measurement (a plane, perpendicular to the axis), must be within the limits of size.When cylindricity control is applied to an external feature, the outer boundary (larger cylinder) is typically established by circumscribing the high points of the surface. The inner boundary is radially smaller by the amount of the specified tolerance. The feature, at any point of measurement (a plane, perpendicular to the axis), must be within the limits of size. Tolerances Of Form - Cylindricity

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GD&T Form Table of Contents Return to the Previous Slide Slide 88QuitMaster Table of ContentsGlossary Tolerances Of Form - Cylindricity When cylindricity control is applied to an internal feature, the inner boundary (smaller cylinder) is typically established by gage contact with the high points of the surface. The outer boundary is radially larger by the amount of the specified tolerance. The feature, at any point of measurement, must be within the limits of size.

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GD&T Form Table of Contents Return to the Previous Slide Slide 89QuitMaster Table of ContentsGlossary GEOMETRIC CONTROL FOR CYLINDRICITY

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GD&T Form Table of Contents Return to the Previous Slide Slide 90QuitMaster Table of ContentsGlossary The geometric control for cylindricity is a feature form tolerance which controls circular, longitudinal, and parallel elements of the feature surface elements only. Because it is strictly a surface element control, datums are neither proper nor allowed. As is the case with all surface controls, cylindricity always applies regardless of feature size.The geometric control for cylindricity is a feature form tolerance which controls circular, longitudinal, and parallel elements of the feature surface elements only. Because it is strictly a surface element control, datums are neither proper nor allowed. As is the case with all surface controls, cylindricity always applies regardless of feature size. Because cylindricity can only be applied to features and cannot be applied to features of size, material condition modifiers cannot be used with a cylindricity specification.Because cylindricity can only be applied to features and cannot be applied to features of size, material condition modifiers cannot be used with a cylindricity specification. The size envelope imposed by dimensional limits and Rule #1 are never overridden by a geometric tolerance for cylindricity, and the geometric tolerance becomes the controlling factor only when departure from MMC exceeds the cylindricity tolerance value. Therefore, the virtual condition of the controlled feature is not affected.The size envelope imposed by dimensional limits and Rule #1 are never overridden by a geometric tolerance for cylindricity, and the geometric tolerance becomes the controlling factor only when departure from MMC exceeds the cylindricity tolerance value. Therefore, the virtual condition of the controlled feature is not affected. Tolerances Of Form - Cylindricity OVERVIEW

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GD&T Form Table of Contents Return to the Previous Slide Slide 91QuitMaster Table of ContentsGlossary 0.4 A feature control frame describing cylindricity control may be called out in either view and is applied by using a leader line, as shown. 0.4 OR Verifying Cylindricity Geometric Tolerance

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GD&T Form Table of Contents Return to the Previous Slide Slide 92QuitMaster Table of ContentsGlossary 0.4 Tolerance zone is two coaxial cylinders Verifying Cylindricity Geometric Tolerance Multiple-section measurements are taken just like the measurements for circularity, except the gauge is NOT reset between sections.

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GD&T Form Table of Contents Return to the Previous Slide Slide 93QuitMaster Table of ContentsGlossary 0.4 Smallest true cylinder that circumscribes that circumscribes the high points the high points of the feature of the feature diameter. diameter. 0.4 Radial Distance Tolerance zone is two coaxial cylinders Verifying Cylindricity Geometric Tolerance

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GD&T Form Table of Contents Return to the Previous Slide Slide 94QuitMaster Table of ContentsGlossary 0.2 10.5 9.5 The size tolerance zone consists of two coaxial cylinders, 0.5 mm apart. This tolerance defines the actual local size limits. Cylindricity Geometric Tolerance—Always RFS

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GD&T Form Table of Contents Return to the Previous Slide Slide 95QuitMaster Table of ContentsGlossary 0.2 10.5 9.5 The cylindricity tolerance zone consists of two coaxial cylinders, 0.2 mm apart. This tolerance can “float” within the larger size tolerance. Cylindricity Geometric Tolerance—Always RFS The size tolerance zone consists of two coaxial cylinders, 0.5 mm apart. This tolerance defines the actual local size limits.

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GD&T Form Table of Contents Return to the Previous Slide Slide 96QuitMaster Table of ContentsGlossary Coaxial cylinders establish the tolerance zone for feature cylindricity. Cylindricity Geometric Tolerance—Always RFS Feature size tolerance. (While surface elements are restricted to the refined tolerance zone, the actual local [measured] size of the cylindrical feature may vary within the larger boundaries.) 0.2

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GD&T Form Table of Contents Return to the Previous Slide Slide 97QuitMaster Table of ContentsGlossary Coaxial cylinders establish the tolerance zone for feature cylindricity (RFS). At any measuring position, all surface elements must be within the cylindricity tolerance zone. They may vary within the zone, and the entire zone may expand or contract within the larger size tolerance. Cylindricity Geometric Tolerance—Always RFS 0.2 Feature size tolerance. (While surface elements are restricted to the refined tolerance zone, the actual local [measured] size of the cylindrical feature may vary within the larger boundaries.)

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GD&T Form Table of Contents Return to the Previous Slide Slide 98QuitMaster Table of ContentsGlossary The cylindricity tolerance zone may extend beyond the lower limit of the size tolerance, but no elements on the surface can be located outside of those limits. That part of the tolerance would be sacrificed. Cylindricity Geometric Tolerance—Always RFS 0.2 Feature size tolerance. (While surface elements are restricted to the refined tolerance zone, the actual local [measured] size of the cylindrical feature may vary within the larger boundaries.)

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GD&T Form Table of Contents Return to the Previous Slide Slide 99QuitMaster Table of ContentsGlossary The geometric tolerance for cylindricity becomes the controlling factor only when departure from MMC exceeds the cylindricity tolerance value. Cylindricity Geometric Tolerance—Always RFS 0.2 Feature size tolerance. (While surface elements are restricted to the refined tolerance zone, the actual local [measured] size of the cylindrical feature may vary within the larger boundaries.)

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General Tolerance and Hole Fit

General Tolerance and Hole Fit

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