8/18/2019 General GDT Information
1/33
Geometric Dimensioning
and Tolerancing
Course Number
Instructor’s name
Planchard Copyright 2013
8/18/2019 General GDT Information
2/33
hat is Geometric Dimensioning
and Tolerancing !GDT"# It is a system o$ symbols% rules and de$initions
used to de$ine the shape &Roundness,
Flatness, Cylindricity% etc'( and design Intent
¶llel, perpedicular, concentric% et'( o$ themodel'
Planchard Copyright 2013
8/18/2019 General GDT Information
3/33
)b*ecti+es o$ GDT
# De$ine parts based on $unction
# Include geometric as ,ell as si-e
tolerances
# .acilitate inspection and /uality control
# educe need $or notes
# Capture design intent# Clari$y tolerances $or international use
# liminate tolerance stacup
Planchard Copyright 2013
8/18/2019 General GDT Information
4/33
)b*ecti+es o$ GDT)rthogonal Datum Planes !321" ule
3 points o$ contact
1 point o$ contact
4 rule that de$ines the
minimum number o$ contact
points necessary to properly
locate a part ,ithin the datum
re$erence $rame' The primary
datum re/uires three
points% the secondary datum
t,o points% and the tertiarydatum one point'
2 points o$ contact
Planchard Copyright 2013
8/18/2019 General GDT Information
5/33
5imple Part ,ith GDT
Dimension tolerance does not say anything about the shape o$ the part6
GDT controls the shape and the initial design intent'
Tolerance o$ the
$eature
Design Intent
oundness symbol o$
the $eature
Primary datum5econdary datum
Tolerance o$
the dimension
Design Intent
Perpendicularity
symbol o$
$eature
Planchard Copyright 2013
8/18/2019 General GDT Information
6/33
5imple Part ,ith GDT
Tertiary datum
5econdary datum
Primary datum
.latness symbol
o$ the $eature
Perpendicularity symbolo$ the $eature
Position symbol
o$ the $eature7 8ole
Dimension tolerance does not say anything about the shape o$ the part6
GDT controls the shape and the initial design intent'
Tolerance o$
the dimension
Tolerance o$ the datum
$eature
Planchard Copyright 2013
8/18/2019 General GDT Information
7/33
5imple Part ,ith GDT
oundness7 &459 :1;'
8/18/2019 General GDT Information
8/33
5imple Part ,ith GDT
oundness7 &459 :1;'
8/18/2019 General GDT Information
9/33
5imple Part ,ith GDT
:esNo
Perpendicularity symbol
o$ the $eature
Perpendicularity symbol
o$ the $eature
.latness symbol
o$ the $eaturePrimary Datum plane
Planchard Copyright 2013
8/18/2019 General GDT Information
10/33
5imple Part ,ith GDT
4ngularity symbol
o$ the $eature
?ie, the selected Datum
planes% the angularity symbol
,as added a$ter,ards6
Perpendicularity symbol
o$ the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
11/33
5imple Part ,ith GDT
Note7 The di$$erent Datum planes selected
to display the 4ngularity symbol
o$ the $eature $rom the pre+ious slide6
4ngularity symbol
o$ the $eature
.latness symbol
o$ the $eature
Perpendicularity symbol
o$ the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
12/33
5imple Part ,ith GDT
Dimension tolerance does not say anything about the shape o$ the part6
GDT controls the shape and the initial design intent
Datum C is the $ace o$ the $eature7 5imple 8ole
Position symbol
o$ the $eature
.latness symbolo$ the $eature
)$$set% arro,s ,ill not $it'
Planchard Copyright 2013
8/18/2019 General GDT Information
13/33
5imple Part ,ith GDT
Dimension tolerance does not say anything about the shape o$ the part6
GDT controls the shape and the initial design intent
Position symbol
o$ the $eature
.latness symbol
o$ the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
14/33
5imple Part ,ith GDT
Parts Do Not Have Center Lines - Features Have Axes
Center lines are a dra$ting con+enience' 4ssociate the datum $eature symbol
,ith datum $eatures6
Total runout symbolo$ the $eature
No !.or Construction" Centerline6
Planchard Copyright 2013
8/18/2019 General GDT Information
15/33
5imple Part ,ith GDT
Coaxial Diaeters T,o &or more( diameters that are sho,n on the
dra,ing as being on the same centerline &a@is('
e+ol+ed Aase .eature 7 4@is o$ re+olutions?s' @truded Aase .eature'
Circular runout symbol
o$ the $eature
Circular runout symbol
o$ the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
16/33
5imple Part ,ith GDT
Pro$ile o$ a 5ur$ace symbol
o$ the $eature
Tertiary Datum
Primary Datum
5econdary Datum
Planchard Copyright 2013
8/18/2019 General GDT Information
17/33
GDT 5ymbols
http7BB,,,',isconline'comBob*ectsBinde@t*'aspob*IDENG1FF0;
Planchard Copyright 2013
8/18/2019 General GDT Information
18/33
De$ault Document Datum
Tolerances &Dimpert(
Planchard Copyright 2013
8/18/2019 General GDT Information
19/33
9aterial Condition 5ymbols
# 9a@imum 9aterial Condition &99C(
H largest sha$t% smallest hole
# east 9aterial Condition &9C(
H smallest sha$t% largest hole
# egardless o$ .eature 5i-e &.5(
9
5
Planchard Copyright 2013
8/18/2019 General GDT Information
20/33
Tolerance Jones ,ithout GDT
9eans this6
The tolerance area or boundary ,ith that $orms the
.eature may +ary ,hen no tolerance o$ the $eature is pro+ided
Planchard Copyright 2013
8/18/2019 General GDT Information
21/33
GDT ule 1
# Indi+idual .eature o$ 5i-e
H here only a tolerance o$ si-e is speci$ied%
the limits o$ an indi+idual $eature prescribe the
e@tent to ,hich +ariations in its geometric$orm% as ,ell as si-e% are allo,ed'
Planchard Copyright 2013
8/18/2019 General GDT Information
22/33
ocation Controls
# Position
# Concentricity
# unout
Planchard Copyright 2013
8/18/2019 General GDT Information
23/33
GDKT True Positioning
Note circular tolerance -ones
Planchard Copyright 2013
8/18/2019 General GDT Information
24/33
5traightness
Planchard Copyright 2013
8/18/2019 General GDT Information
25/33
.latness
The sur$ace must be ,ithin the
tolerance o$ si-e and must lie bet,eent,o parallel planes7 0'2< apart &$eature
tolerance(
5ymbol
Tolerance o$
the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
26/33
oundness
ach circular element o$ the 5ur$ace in any
plane perpendicular to 4 common a@is must
be ,ithin the speci$ied tolerance o$ si-e' It also
must lie bet,een t,o concentric circles H one
ha+ing a radius o$ 0'2< larger than the other6
5ymbolTolerance o$
the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
27/33
Cylindricity
The cylindrical sur$ace must be ,ithin the
speci$ied tolerance o$ si-e% in this e@ample 0'2<and must lie bet,een t,o Concentric cylinders H
one ha+ing a radius o$ 0'2< larger than the
other'
5ymbol
Tolerance o$
the $eature
Planchard Copyright 2013
8/18/2019 General GDT Information
28/33
)rientation Controls
# Perpendicularity
# Parallelism
# 4ngularity# ine Pro$ile
# 5ur$ace Pro$ile
Planchard Copyright 2013
8/18/2019 General GDT Information
29/33
Parallelism $or Planes
The sur$ace must be ,ithin the speci$iedTolerance &0'12( o$ si-e and must lie
bet,een t,o planes &0'12( apart ,hich are
parallel to Datum Plane 4'
5ymbol
Tolerance o$ $eature
Datum Plane
Planchard Copyright 2013
8/18/2019 General GDT Information
30/33
Parallelism $or 4@is and Plane
The $eature a@is must be ,ithin the speci$ied
tolerance &0'12( o$ location and must lie bet,een
t,o planes &0'12( apart ,hich are parallel to the
datum plane &4( regardless o$ the $eature si-e6
Planchard Copyright 2013
8/18/2019 General GDT Information
31/33
Parallelism $or T,o 4@es
The $eature a@is must be ,ithin the speci$ied tolerance&0'0
8/18/2019 General GDT Information
32/33
Perpendicularity o$ 4@is +s'
Plane
The $eature a@is must be ,ithin the speci$ied
tolerance&0'0
8/18/2019 General GDT Information
33/33
4ll parts are not created e/ual
Pro$ile o$ a line is a $unny control' It ,ors ,ell $or parts lie e@trusions ,here
indi+idual slices ,ill be checed' 8o,e+er% ,hen you start adding datum
re$erences% it can turn into a pro$ile o$ a sur$ace control
CNC issues6
Planchard Copyright 2013