ch16 gd&t overview cmp-nice
TRANSCRIPT
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
1/35
Chapter 16
EngineeringDrawing and DesignSeventh Edition
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
2/35
GD&T stands for GeometricDimensioning & Tolerancing
DIMENSION is a geometriccharacteristic the size of which is
specified such aslength,angle,location,or center distanceTOLERANCE on a dimension is the total
permissible variation in its size, which isequal to the difference between thelimits of size.
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
3/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
DIMENSIONS OF A PART
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
4/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
TOLERANCE SIZES
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
5/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
TYPE OF TOLERANCE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
6/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
SIZES OF MATING PARTS
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
7/35
Deviations
The difference between the basic sizeand the maximum and minimum sizes
are called the UPPER & LOWERdeviations.The BASIC DIMENSION represents the
theoretical exact size or location of afeature.
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
8/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
DEVIATIONS
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
9/35
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
10/35
Datum
A DATUM is a theoretical exact feature from whichdimensions may be taken.
A DATUM is generally chosen as an edge or featurewhich has the greatest influence in a specificmeasurement.
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
11/35
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
12/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
EXAMPLES OF DEVIATION OF FORM WHEN PERFECT FORMAT THE MAXIMUM MATERIAL CONDITION IS REQUIRED
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
13/35
Geometric Tolerance
A geometric tolerance is the maximumpermissible variation of form, profile,orientation, location, and runout from thatindicated or specified on a drawing.Feature control frame for an individualfeature is divided into compartments
containing, at the least, the geometrictolerance symbol and the geometric tolerancevalue
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
14/35
Feature control frame (fig.16-16)
Geometric characteristic symbolGeometric toleranceDatums (if used)Modifiers as required (*MMC forexample)
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
15/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
GEOMETRIC CHARACTERISTIC SYMBOLS
16-216-5
STRAIGHTNESSFORMINDIVIDUALFEATURES
SEEUNITSYMBOLCHARACTERISTIC
TYPE OFTOLERANCEFEATURE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
16/35
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
17/35
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
18/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
GEOMETRIC CHARACTERISTIC SYMBOLS
16-9PROJECTEDTOLERANCE
ZONE
SUPPLEMENTARYSYMBOLS
SEEUNIT
SYMBOLCHARACTERISTICTYPE OFTOLERANCE
FEATURE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
19/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
GEOMETRIC CHARACTERISTIC SYMBOLS
16-916-11
BASICDIMENSION
SUPPLEMENTARYSYMBOLS
SEEUNIT
SYMBOLCHARACTERISTICTYPE OFTOLERANCE
FEATURE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
20/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
GEOMETRIC CHARACTERISTIC SYMBOLS
16-6DATUMFEATURE
SUPPLEMENTARYSYMBOLS
SEEUNIT
SYMBOLCHARACTERISTICTYPE OFTOLERANCE
FEATURE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
21/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
GEOMETRIC CHARACTERISTIC SYMBOLS
16-11DATUMTARGET
SUPPLEMENTARYSYMBOLS
SEEUNIT
SYMBOLCHARACTERISTICTYPE OFTOLERANCE
FEATURE
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
22/35
Form Tolerances
FORM TOLERANCEScontrol the straightness,flatness, circularity and cylindricity
Form tolerances apply to individual featuresand as such do not require locatingdimensions.ORIENTATION TOLERANCEScontrolangularity, parallelism, and perpendicularity
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
23/35
More on FORM TOLERANCES
Straightness -a condition in which theelement of a surface or a median line is
a straight lineFlatness of a surface is a condition inwhich all surface elements are in one
plane
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
24/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
FEATURE CONTROL FRAME
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
25/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
APPLICATION OF FEATURE CONTROL FRAME
ATTACHEDUSINGA LEADER
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
26/35
MMC, RFS, LMC applies to features subjectto variations in size
MMC (Maximum Material Condition) is when a featureor part is at the limit of size, which results in itscontaining the maximum amount of material.
LMC (Least Material Conditon) refers to the size of afeature that results in the part containing theminimum amount of material. Thus it is theminimum limit of size for an external feature.
RFS (Regardless of feature size) indicates that ageometric tolerance applies to any size of a featurethat lies within its size tolerance.
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
27/35
Datums and the 3-plane concept(16-5)
Datum is a theoretical point, line, plane,or other geometric surface fromwhich
dimensions are measured when sospecified or to which geometrictolerances are referenced
Datum feature is a feature of a part,such as a surface, that forms the basisfor a datum or is used to establish itslocation
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
28/35
3-plane system
The three planes constitue a datumsystem from which measurements can
be taken. They will appear on thedrawing.Datum feature symbol is used on the
drawing to identify these surfaces
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
29/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
THE DATUM PLANES
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
30/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
THE DATUM PLANES
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
31/35
GEOMETRIC DIMENSIONING
AND TOLERANCING
THE DATUM PLANES
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
32/35
Orientation tolerancing (16-6) Angularity, parallelism and perpendicularity are
orientation tolerances applicable to related features Angularity is the condition of a surface or axis at aspecified angle (other than 90 or 0 ) from a datumplane or axis
Perpendicularity is the condition of a surface at 90
toa datum plane or axis. *A perpendicularity tolerancefor a flat surface specifies a tolerance zone definedby two parallel planes perpendicular to a datum plane
or axisParallelism is the condition of a surface equidistant atall points from a datum plane. Parallelism for a flatsurface specifies a tolerance zone defined by twoplanes or lines parallel to a datum plane or axis.
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
33/35
Datum Targets (16-11)
Datum target symbols are used to locate specificreference positions to be used on large datumsurfaces*
the surface of a feature may be so large that a gagedesigned to make contact with the full surface maybe too expensive or cumbersome to useFunctional requirements of the part may necessitate
the use of only a portion of a surface as a datumfeature
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
34/35
-
8/12/2019 CH16 GD&T Overview Cmp-NICE
35/35
CAD APPLICATIONS
TOLERANCE SYMBOL DIALOG BOX