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A FORM TOLERANCES FORM TOLERANCES LOCATION TOLERANCE LOCATION TOLERANCE GDT PROBLEMS GDT PROBLEMS.

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Presentation on theme: "A FORM TOLERANCES FORM TOLERANCES LOCATION TOLERANCE LOCATION TOLERANCE GDT PROBLEMS GDT PROBLEMS."— Presentation transcript:

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2 A FORM TOLERANCES FORM TOLERANCES LOCATION TOLERANCE LOCATION TOLERANCE GDT PROBLEMS GDT PROBLEMS

3 Are all of these auto parts made in the same factory by the same company?

4 What is the purpose of GDT? It is used on mating parts in order to assure that they are ‘interchangeable’.

5 Where did GDT come from? ASME Y14.5-2009 THE A MERICAN S OCIETY OF M ECHANICAL E NGINEERS (ASME) CREATED A GLOBAL STANDARD TITLED ASME Y14.5-2009 FOR DIMENSIONING AND TOLERANCING.

6 What does this sign mean?

7 zone. Any speed in between the limits is within the acceptable range or zone. What are the LIMITS? SPEED LIMIT 65 40 MINIMUM UPPER LIMITLOWER LIMIT MAX. MIN. zone What happens if you go out of that zone?

8 SPEED LIMIT 65 40 MINIMUM 25 Tolerance The difference between the upper and lower limit equals the Tolerance zone. 65 UPPER LIMIT -40 LOWER LIMIT 25 = TOLERANCE ZONE What is the TOLERANCE?

9 TOLERANCE 12.7 5 12.25 12.50 + 0.25 LIMITS SPECIFIED DIMENSION What are the LIMITS?

10 MMCLMC MMC & LMC MAXIMUM MATERIAL CONDITION AND LEAST MATERIAL CONDITION

11 W hat is the difference between these two glazed doughnuts? Both of these doughnuts cost 90 cents. Which one is the best buy? Why? maximum Which one was made with the most or maximum amount of dough? MMC MMC = Maximum Material Condition LMC LMC = Least Material Condition M L

12 MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9) MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9) 1. 75 1. 73 0. 75 0. 73 n n M Look at the limits of the O.D. and the I.D. of the washer. Which ones represent the washer at MMC?

13 1. 75 1. 73 0. 75 0. 73 MMC OF THE O.D. n n MMC OF THE I.D. M MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9) MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9)

14 1. 75 1. 73 0. 75 0. 73 n n Look at the limits of the O.D. and the I.D. of the washer. Which ones represent the washer at LMC? L LEAST LEAST MATERIAL CONDITION (LMC) = IS WHERE A FEATURE CONTAINS THE LEAST AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE EXAMPLE 1-10, 1-11) LEAST LEAST MATERIAL CONDITION (LMC) = IS WHERE A FEATURE CONTAINS THE LEAST AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE EXAMPLE 1-10, 1-11)

15 1. 75 1. 73 0. 75 0. 73 LMC OF THE O.D. n n LMC OF THE I.D. L LEAST LEAST MATERIAL CONDITION (LMC) = IS WHERE A FEATURE CONTAINS THE LEAST AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE EXAMPLE 1-10, 1-11) LEAST LEAST MATERIAL CONDITION (LMC) = IS WHERE A FEATURE CONTAINS THE LEAST AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE EXAMPLE 1-10, 1-11)

16 1. 75 1. 73 0. 75 0. 73 MMC OF THE O.D. n n MMC OF THE I.D. M MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9) MAXIMUM MAXIMUM MATERIAL CONDITION (MMC) = IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. (SEE BOOK EXAMPLE 1-8 & 1-9)

17 MMCLMC Sometimes a geometric tolerance will be applied to a dimension at its MMC or it LMC. However……….. REGARDLESS OF FEATURE SIZE (RFS) = IS THE TERM USED WHEN A GEOMETRIC TOLERANCE OR DATUM APPLIES AT ANY INCREMENT OF SIZE WITHIN ITS UPPER OR LOWER LIMIT. (SEE EXAMPLE 4-7) RFS

18 Review ASME Y14.5-2009 1. What does ASME Y14.5-2009 stand for? IT IS A GLOBAL STANDARD FOR DIMENSIONING AND TOLERANCING. 2. What is tolerance? IT IS THE TOTAL AMOUNT THAT A DIMENSION IS PERMITTED TO VARY. 3. What are limits? ARE THE LARGEST AND SMALLEST (THE MAXIMUM AND MINIMUM) NUMERICAL VALUE THAT A FEATURES DIMENSIONS CAN BE. 4. How do they differ? TOLERANCE IS THE DIFFERENCE BETWEEN A DIMENSIONS UPPER AND LOWER LIMITS. 5. What is meant by Maximum Material Condition? IS WHERE A FEATURE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. 6. What is meant by Least Material Condition? IS WHERE A FEATURE CONTAINS THE LEAST AMOUNT OF MATERIAL PERMITTED WITHIN THE STATED LIMITS. 7. What is meant by RFS? REGARDLESS OF FEATURE SIZE

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20 Geometric Chacteristic Symbols

21 Feature Control Frame A SYMBOL MADE UP OF COMPARTMENTS CONTAINING THE GEOMETRIC CHARACTERISTIC SYMBOL AND THE TOLERANCE. (SEE PAGE 44, EXAMPLE 2-10) A SYMBOL MADE UP OF COMPARTMENTS CONTAINING THE GEOMETRIC CHARACTERISTIC SYMBOL AND THE TOLERANCE. (SEE PAGE 44, EXAMPLE 2-10)

22 DATUMS A

23 Locate the projector Projector Screen Plan View If we wanted to mount our projector from the ceiling what three dimensions would we need……. and in what order?

24 Locate the projector Projector Screen Plan View

25 Locate the projector Projector Screen Floor Elevation View A B C Mounting Bracket

26 DATUMS A DATUMS = ARE PLANES, SURFACES, POINTS, LINES OR AXES FROM WHICH MEASUREMENTS ARE MADE. THEY IDENTIFY SURFACES OR AXES THAT ARE IMPORTANT TO THE FUNCTION OF THE DESIGN.

27 A Datum Planes

28 A

29 A

30 A

31 A Datum Placement on Drawings DATUM FEATURE SYMBOLS ARE PLACED ON THE EDGE VIEW OR ON EXTENSION LINES. ORDER OF PRECEDENCE THE ORDER IN WHICH THE DATUM REFERENCE LETTERS ARE PLACED IN THE FEATURE CONTROL FRAME SIGNIFY THEIR IMPORTANCE. THIS IS CALLED THE ORDER OF PRECEDENCE.

32 .25 B Datum Axis Placement on Drawings DATUM AXIS A

33 Datum Axis Placement on Drawings A ON THE OUTSIDE SURFACE (THE EDGE) OF A CYLINDRICAL FEATURE. ON THE LEADER LINE SHOULDER THE SYMBOL CAN ALSO BE PLACED ON THE EXTENSION LINE.

34 Datum Axis Placement on Drawings A THE DATUM SYMBOL CAN ALSO BE ATTACHED TO THE FEATURE CONTROL FRAME.

35 Datum Target Placement on Drawings A At times only a small area on a surface will be used as a datum. Datum Target Symbol To identify these areas a Datum Target Symbol is used. 12 X DATUM TARGET SYMBOL = ARE USED TO DESIGNATE POINTS OR A SPECIFIC SURFACE AREA. THEY ARE USED WHEN IT MAY NOT BE POSSIBLE TO ESTABLISH AN ENTIRE SURFACE AS A DATUM. (SEE EXAMPLE 3-12 PAGE 71)

36 12 X

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38 Review 1. Define Datum? Are planes, surfaces, points, lines or axes from which measurements are made. They identify surfaces or axes that are important to the function of the design. 2. Describe the Datum Feature symbol? 3. List three areas where datum symbols should be placed? Edge view Extension lines Leader line shoulder Feature control frame A

39 Review (cont.) 4. When are Datum Target Symbols used? They are used to designate points or a specific surface area. They are used when it may not be possible to establish an entire surface as a datum. 5. Describe the Datum Target symbol?

40 GDT Problems

41

42 Problem 1 Solution

43

44 Problem 2 Solution

45 FORM TOLERANCES

46 Objectives Identify form tolerance symbols, explain their purpose, and apply them to a drawing Identify form tolerance symbols, explain their purpose, and apply them to a drawing. Straightness Straightness Flatness Flatness Cylindricity Cylindricity Circularity Circularity

47 What are Form Tolerances? Form Tolerances are applied to single features and, therefore, are not related to a datum. They specify a zone in which the dimensioned feature must be controlled.

48 STRAIGHTNESS

49 Straightness a Form Tolerance A condition where an element of a surface or an axis is in a straight line.

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51 HOLE DIA. By requiring a.04 tolerance zone allowance is made for the imperfection of the rod while stating an acceptable range for it use in the assembly. What does this mean?

52 FLATNESS

53 A condition of a surface where all of the elements are in one plane. Flatness a Form Tolerance The problem is….

54 ….can any surface be made perfectly flat? ‘Flatness’ So the designer must establish a range or zone of allowable variation. The form tolerance ‘Flatness’ is used to control the amount of variation on a flat surface.

55 flatness Unlike straightness which controls the form of an object… flatness is used to control only a surface.

56 CIRCULARITY

57 Circularity a Form Tolerance ‘out-of-round’? What kind of ride would you get if the wheels on you car were ‘out-of-round’? Is it possible to make a wheel that is perfectly round? How do you control the amount of allowable variation?

58 cross-section Circularity is established by two concentric circles created by a cross-section thru a rod or the center of a sphere. Circularity a Form Tolerance The problem is…. 0.25

59 CYLINDRICITY

60 Cylindricity a Form Tolerance The problem is…. 0.25 concentric cylinders Cylindricity is established by two concentric cylinders within which the entire surface of the cylinder must lie.

61 OUT OF TOLERANCE Cylindricity a Form Tolerance

62 ORIENTATION TOLERANCES

63 Objectives Identify orientation tolerance symbols, explain their purpose, and apply them to a drawing.Parallelism Perpendicularity Angularity

64 What are Orientation Tolerances? Orientation Tolerances control the relationship of features to one another. One or more datum features shall be referenced. These Orientation Tolerances are total, meaning that all elements of a related surface or axis fall within the specified tolerance zone.

65 Parallelism an Orientation Tolerance Parallelismis a condition of a surface or center plane equidistant from a datum plane or axis. Parallelism is a condition of a surface or center plane equidistant from a datum plane or axis.

66 Parallelism an Orientation Tolerance A NOTICE THAT A DATUM IS REFERENCED

67 Perpendicularityis a condition of a surface, center or axis at a right angle (90 degrees) to a datum plane or axis. Perpendicularity is a condition of a surface, center or axis at a right angle (90 degrees) to a datum plane or axis.

68 PERPENDICULARITY an Orientation Tolerance A.312A

69 PERPENDICULARITY an Orientation Tolerance A. 312 A.312 WIDE TOLERANCE ZONE

70 ANGULARITYis a condition of a surface, center plane or axis at any specified angle from a datum plane or axis. ANGULARITY is a condition of a surface, center plane or axis at any specified angle from a datum plane or axis.

71 Angularity an Orientation Tolerance A

72 LOCATION TOLERANCES

73 Objectives Identify location tolerance symbols, explain their purpose, and apply them to a drawing.Position Concentricity Symmetry

74 What are Location Tolerances? Location tolerances are used for the purpose of locating features from datums. They are also used for establishing coaxiality or symmetry.

75 Positional Tolerance is used to define a zone in which the center, axis, or center plane of a feature is permitted to vary.

76 THINK OF THE ARROW AS THE CENTER OR AXIS OF THE DRILL. CONSIDER THE BULLSEYE ON THE TARGET AS THE ACCEPTABLE TOLERANCE ZONE. ANY HIT WITHIN THAT ZONE IS CONSIDERED TO BE A BULLSEYE.

77 Positional a Location Tolerance

78 TRUE POSITION AXIS

79 WHAT IS THE MEANING OF THE FEATURE CONTROL FRAME SHOWN BELOW? IT MEANS = THE IDENTIFIED HOLE IS TO BE POSITIONED WITHIN A 0.5 DIAMETER OF ITS TRUE (EXACT) POSITION, AT ITS MAXIMUM MATERIAL CONDITION. THE HOLE WILL BE PERPENDICULAR TO DATUM-A, AND LOCATED FROM DATUM-B AND DATUM-C.

80 Positional Tolerance Application

81 Concentricity Tolerance is used to establish a relationship between the axes of two or more cylindrical features of an object. When two or more cylindrical features share the same axis, they are said to be coaxial. Concentricity Tolerance is used to establish a relationship between the axes of two or more cylindrical features of an object. When two or more cylindrical features share the same axis, they are said to be coaxial.

82 Concentricity a Location Tolerance

83 Symmetry Tolerance is a center plane relationship of the features of an object establishing a median point to center plane control.

84 Symmetry a Location Tolerance

85 GDT Problems A M L

86 GDT Pin & Ring Problem

87 GDT Placement Problem 1 Top surface is to be a primary datum Top surface to be smooth within.002 Rear surface is to be a secondary datum Right-side surface is to be a tertiary datum.625 Dia hole in top to be positioned within.002.625 Dia hole in base to parallel to.625 Dia. at top within.002 Instructions: Instructions: Ortho sketch, model and detail the Tool Post. Add the required GDT shown below.

88 GDT Placement Problem 2 Bottom surface is to be a primary datum Right-side surface is to be a secondary datum Front surface is to be a tertiary datum The two 10 Dia holes in top to be positioned within.01, at maximum material condition The right-side surface is to be at right angles with the base within.02 Instructions: Instructions: Ortho sketch model and detail the Frame Guide. Add the required GDT shown below.

89 GDT Placement Problem 3 Axis of the 57.07 – 57.15 Dia is to be a primary datum The 44.37 – 44.45 Dia to be on the same center as the 57.07 – 57.15 Dia within.01 The 28.52 – 28.58 Dia to be straight within.01, at maximum material condition Instructions: Instructions: Model and detail the Roller Stud and add the required GDT shown below.

90 GDT Placement Problem 4 Axis of the 1.372 Dia hole is to be a primary datum Bottom surface is to be a secondary datum Bottom surface is to be flat within.002 1.372 Dia hole is to be 90 degrees to the bottom surface within.005 at LMC. Upper 4.750 Dia surface to be parallel to the bottom within.005. The three.375 Dia holes are to be positioned within.001 at MMC. Instructions: Instructions: Model and detail the Center Bushing and add the required GDT shown below.


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