GD&T for Body
1GD&T for Body Engineering
Course content
课程内容
• Introduction to GD&T
• GD&T介绍
• 5 Step Process
• 5步方法
2GD&T for Body Engineering
Introduction
介绍
• What is GD&T
• 什么是GD&T
• How it affects Ford Motor Company
• 它如何让影响福特汽车公司
3GD&T for Body Engineering
What is GD&T
什么是GD&T
• Geometric Dimensioning and Tolerancing is a technical data base
through which our Product Design and Manufacturing Organisations
can talk to one another via Product Data, whether on paper or the
computer graphics screen
几何尺寸公差是贯穿我们产品设计和生产制造的技术数据基础，无论是
通过图纸或者是计算机上的图表，我们都能通过产品数据与其他人沟通。
• It is the engineering product definition standard that geometrically
describes design intent and provides the documentation base for the
design of the quality and production system.
工程产品定义标准，几何尺寸描述设计意图，并为品质设计和产品系统
提供文件基准。
• It is a technique of communication between Product Engineering and
Manufacturing Engineering that promotes a uniform interpretation of the
requirements for making a component.
• 它是一种在产品工程和制造工程之间的技术交流，并促成一种针对零部
件制造要求的唯一的解释。
4GD&T for Body Engineering
What is GD&T
什么是GD&T
• GDT provides the dimensions of the component and the
tolerances in a language that eliminates confusing and
inconsistent notes, datum lines, and location point
identifications, and replaces them with standard symbols that
refer to a universal code.
• GDT提供部件的尺寸和公差，用一种语言，它能够消除混淆和不
一致的注释，基准线，定位点辨认，并且用与一种通用的代码相
关的标准符号替换他们。
• This code describes the dimensions and tolerances of the
component with reference to the relationships of the features to
each other and their functional interfaces with mating parts,
assemblies, etc.
• 代码描述了关于部件间相互关系的特征的尺寸和公差，和他们匹
配的部件的功能界面，总成等。
5GD&T for Body Engineering
Authorisation
批准
6GD&T for Body Engineering
Application
• The application of GDT is initially the responsibility of the
relevant Component Engineer, however teamwork is the key to
the correct application through the component Core Team.
• This provides the opportunity for all disciplines to contribute their
part of the total design package.
• It ensures part data will satisfy design intent as well as
manufacturing and inspection requirements based on function,
machine capability and available technology.
7GD&T for Body Engineering
Application
• It provides the opportunity for proper Datum selection and has
the potential to significantly reduce product changes, especially
those changes following final product release.
• The Core Team should consist at a minimum of representatives
from Product Engineering, Design Engineering, Manufacturing
Engineering, and Quality Engineering.
8GD&T for Body Engineering
More information
9GD&T for Body Engineering
How GD&T Relates to Ford
The correct application has the potential to;
• Influence Fit and Finish
• Reduce Reworks
• Increase Reliability
• Affects Assembly Process
• Reduce cost
10GD&T for Body Engineering
The 5 Step Process
1 2 3 4 5
11GD&T for Body Engineering
5 Step Process
1 Utilise the new Design Concept
2 Establishment of the Datum Reference Frame
3 Establish GD&T Controls
4 Establish Tolerances
5 Final Approval of GD&T on Cad Data
12GD&T for Body Engineering
Step 1
Utilise new design concept
13GD&T for Body Engineering
Utilise new design concept
• The 1st step involves making decisions at the basic design
stage that will ultimately effect the design, manufacture and
verification of the final component.
• This can only be successfully achieved by the relevant PD
representative attending the Master Control Plan (MCP)
Meetings.
14GD&T for Body Engineering
Master Control Plan
What is the purpose of the MCP meeting in relation to PD
• To establish a common understanding for the verification process
of the major panels, . Bodyside, Hood, Deck Lid, Door, Roof,
Underbody, etc.
• To obtain agreement at an early stage of the design for the datum
reference frame, die approach, etc.
Who attends the Meeting
• PD and Manufacturing, . Body Engineering, DCD, Stamping,
Body and Assembly.
15GD&T for Body Engineering
Master Control Plan
When should the Meeting take place.
• Initial design concept stage, knowing the components
parameters such as size and function
Current methods use;
• Past evidence, past experience, can sometimes hinder rather
than assist the new design concept
Result of meeting
• May be documented in CAD, or paper form
16GD&T for Body Engineering
Step 2
Establish Datum Reference Frame
17GD&T for Body Engineering
Establish Datum Reference
Frame
• As part of the Master Control Plan (MCP) Process meeting,
Body Engineering and Manufacturing agreed to the definition of
the Datum Features and their location.
• PD have Ownership of the Datum Features.
18GD&T for Body Engineering
Datum Reference Frame
(Reference Pocket Guide, Page 8)
Consists of a set of three mutually
perpendicular planes
The reference frame exists
in theory only and is not on
the part
Sufficient datum features
are used to position the
part in relation to the
Datum Reference Frame.
19GD&T for Body Engineering
Datum Features
• An actual feature of the part used to stage/position the part in
the equipment for purposes of relating its geometry to the Datum
Reference Frame.
20GD&T for Body Engineering
Primary Datum Plane
• Achieved by establishing a minimum of three Points to define a
plane
21GD&T for Body Engineering
Primary Datum Plane
• Primary Datum Plane should be Parallel to Die Plane
22GD&T for Body Engineering
Primary Datum Plane
• When Datum Target Areas defining Primary Datum Plane are
not on one single planar surface, they must be controlled one to
another using the PROFILE of a SURFACE geometric control.
23GD&T for Body Engineering
Supporting a panel only on the designated Datum Target
Areas, effectively removes 3 degrees of freedom, . 1 Linear
and 2 Rotational.
24GD&T for Body Engineering
Datum Target Areas
• Datum Target Areas should wherever possible be planar and
parallel to the die plane.
Primary Datum Plane
25GD&T for Body Engineering
Datum Target Areas
• Dedicated Datum Target Areas makes both the part, and
gauge/fixture more robust, cost effective and Improves
repeatability
26GD&T for Body Engineering
Secondary Datum Feature
• Generally a Datum Feature of Size is used , . Single circular
Hole, positioned on a surface that is parallel to the Primary
datum Plane, and is ultimately used as a four way locator.
27GD&T for Body Engineering
Secondary Datum Feature
• Controlled relative to the Primary Datum Plane using the
Geometric control PERPENDICULARITY.
28GD&T for Body Engineering
Secondary Datum Feature
• The intersection of the derived axis of the feature perpendicular
to the Primary Datum Plane, and the design side of the
component is the local origin of all basic dimensions; 0,0,0
29GD&T for Body Engineering
Supporting a panel on the designated Datum Target Areas,
and using the four way locator removes another 2 Linear
degrees of freedom, resulting in all 3 Linear, and 2 Rotational
degrees of freedom constrained.
30GD&T for Body Engineering
Tertiary Datum Feature
• Generally the width of a
Slotted Feature of Size
is used as a
two way
locator.
31GD&T for Body Engineering
Tertiary Datum Feature
• To eliminate tolerance of Datum Shift on one of the theoretical
axis of the cartesian coordinate system, the orientation of the
slot (length) should point to the axis of the Secondary Datum
Feature.
32GD&T for Body Engineering
Tertiary Datum Feature
• The slotted feature’s
width must be
positioned on a surface
with the slot width axis
parallel to the primary
datum plane, and
controlled using the
geometric control of
POSITION and
nominated as the
Tertiary Datum Feature.
33GD&T for Body Engineering
Supporting a panel on the designated Datum Target Areas,
using the four way, and two way locators removes all six
degrees of freedom.
34GD&T for Body Engineering
Step 3
Establish GD&T Controls
35GD&T for Body Engineering
Common Terms and
Definitions
Reference Pocket Guide
Page 2
36GD&T for Body Engineering
Material Conditions
• MMC Maximum Material Condition
• LMC Least Material Condition
• RFS Regardless of Feature Size
• Virtual Condition
37GD&T for Body Engineering
Maximum Material Condition
• The condition in which a feature of size contains the maximum
amount of material within the stated limits of size.
• The Heaviest Part
• Minimum Hole Diameter ()
• Maximum Shaft Diameter ()
M
+
0
38GD&T for Body Engineering
Least Material Condition
• The condition in which a feature of size contains the least
amount of material within the stated limits of size.
• The Lightest part
• Maximum Hole Diameter ()
• Minimum Shaft Diameter ()
• To date no application in the Feature Control Frame for this
symbol has been identified in Body Engineering.
L
+
0
39GD&T for Body Engineering
Regardless of Feature Size
• There is no symbol for Regardless of Feature Size. If a material
modifier is not used then Regardless of Feature Size is
assumed.
• The term used to indicate that a geometric tolerance or datum
reference applies at any increment of size of the feature within
its size tolerance
• Regardless of Feature Size is expensive to verify, and rarely
reflects the relevant feature function, and therefore should not
be used in a Body application without the agreement of the
entire core team.
+
0
40GD&T for Body Engineering
Virtual Condition
• A constant Boundary generated by the collective effects of a
size feature’s specified MMC or LMC material condition and the
geometric tolerance for that condition.
• The VIRTUAL CONDITION of features of mating parts must be
matched, guaranteeing component features at their worst case
for assembly will always assemble.
• The Virtual condition envelope is the worst condition offered to
the mating part.
41GD&T for Body Engineering
Virtual Condition (Shaft)
Virtual condition (Shaft) =
MMC + Tolerance zone value
=
MMC
LMC
+
- 0
=
=
Virtual Condition
42GD&T for Body Engineering
Virtual Condition (Hole)
MMC
LMC
+
- 0
=
=
Virtual Condition
Virtual condition (Hole) =
MMC - Tolerance zone value
=
43GD&T for Body Engineering
Geometric Controls
Reference Pocket Guide
Page 1
44GD&T for Body Engineering
Feature Control Frame
(Reference Pocket Guide, page 3)
M A M C M
Geometric characteristic symbols, the tolerance
value, Material Modifiers, and Datums of Reference,
where applicable, are combined in a feature control
frame to express a geometric tolerance.
45GD&T for Body Engineering
Geometric
Characteristic
Symbol
Material Condition Symbol
Where applicable
M A M C M
Tolerance
Tolerance Zone
Shape where
applicable
Datum Reference Letters
46GD&T for Body Engineering
Geometric Controls
• Each feature of the component must be controlled for SIZE,
FORM, ORIENTATION and LOCATION.
• In the American National Standard there are fourteen geometric
controls.
• Body Engineering use just three;
1 PERPENDICULARITY
2 POSITION
3 PROFILE
47GD&T for Body Engineering
PERPENDICULARITY
Reference Pocket Guide
Page 29
48GD&T for Body Engineering
PERPENDICULARITY
• The main Application for PERPENDICULARITY within Body
Engineering is to control a single Secondary Datum Feature of
size (a hole) to be perpendicular to the Primary Datum Plane.
• Generally used only once within each component to define the
secondary datum feature.
• Any other use of this control
for other features would be an
additional requirement, because
PERPENDICULARITY does not
imply any location
49GD&T for Body Engineering
LMC
The
Cylindrical
Tolerance
Zone diameter
is dependant
on the actual
feature size
B
A
PERPENDICULARITY
M A0
+
0
A cylindrical tolerance zone
perpendicular to a datum plane
within which the axis of a feature
must lie.
50GD&T for Body Engineering
POSITION
Reference Pocket Guide
Page 33
51GD&T for Body Engineering
POSITION
• Definition
• Position Tolerance Zones
• Zero at MMC Concept
• Boundary Concept
• Composite Tolerance Zones
• Projected Tolerance Zone
52GD&T for Body Engineering
• The term to describe the
perfect (theoretical exact)
location of individual
features in relationship with
a datum reference or other
feature(s).
• In general the POSITION
control is used to locate
uniform features of size, .
holes, shafts, slots etc.
POSITION
53GD&T for Body Engineering
Verification
As with all Features of Size;
• First to be verified is that the top and bottom limits of size have
not been violated (Taylor’s Principle). A full form check at the
MMC and a two pointed instrument check at the LMC.
• Secondly the feature’s “Position” must be verified.
• GD&T does not dictate the method of verification. The decision
on the gauging technique employed is the responsibility of the
core team.
54GD&T for Body Engineering
Position Tolerance Zones
55GD&T for Body Engineering
Positional Tolerance Zone 1
(Cylindrical)
+ 0
To specify a Cylindrical Tolerance
Zone, a diameter sign must precede the
tolerance value, followed by the
material Modifier MMC unless
Regardless of Feature Size is intended.
A cylindrical zone within which
the centre axis of a feature of
size is permitted to vary from its
true (theoretically exact) position.
56GD&T for Body Engineering
Positional Tolerance Zone 2
(Non Cylindrical)
A zone within which the centre,
axis, of centre plane of a feature of
size is permitted to vary from its
true (theoretically exact) position.
+ 0
The tolerance value is followed
by the material Modifier MMC
unless Regardless of size is
intended.
To specify a total width Tolerance
Zone, No diameter symbol
precedes the tolerance value.
57GD&T for Body Engineering
BOUNDARY
Reference Pocket Guide
Page 37
58GD&T for Body Engineering
BOUNDARY
• In Body Engineering controlling the centre plane of a slotted
feature is rarely a priority.
59GD&T for Body Engineering
As no Diameter
symbol precedes
the positional
tolerance, a non
cylindrical zone is
inferred.
BOUNDARY
BOUNDARY
BOUNDARY
What we are interested in is controlling the
BOUNDARY of the feature.
+ 0
M
M
+ 0
60GD&T for Body Engineering
BOUNDARY
MMC Width of Hole
Positional Tolerance
Wide Boundary
4
BOUNDARY
M
BOUNDARY
+ 0
Virtual Condition
MMC Width of Hole
- Positional Tolerance
Wide Boundary
10
M
+ 0
61GD&T for Body Engineering
BOUNDARY
No portion of the
slot surfaces are
permitted to lie
within the area
described by the
Virtual Condition
when the part is
positioned within
the Datum
Reference Frame
The POSITION control + BOUNDARY
controls both Location and Orientation
+ 0
M
BOUNDARY
M
BOUNDARY
+ 0
62GD&T for Body Engineering
BOUNDARY
+ 0
M
BOUNDARY
M
BOUNDARY
+ 0
If the same
Positional Tolerance
value applies to
both the Length and
Width limits of size,
then the Feature
Control Frame is
separated from the
Limits of Size, and
points directly to the
slotted feature.
63GD&T for Body Engineering
BOUNDARY
+ 0
M
BOUNDARY
+ 0
If the same
Positional Tolerance
value applies to
both the Length and
Width limits of size,
then the Feature
Control Frame is
separated from the
Limits of Size, and
points directly to the
slotted feature.
64GD&T for Body Engineering
BOUNDARY
• The BOUNDARY note only applies to non cylindrical features.
• The POSITION control + BOUNDARY controls both Location
and Orientation
• In this case the word BOUNDARY must be added below the
FCF and the material Modifier MMC specified after the
POSITION tolerance value.
• No diameter symbol precedes the tolerance value in the Feature
Control Frame
• The positional tolerance specified for the length may differ from
that specified for the width.
To Summarise
65GD&T for Body Engineering
Zero at MMC concept
Reference Pocket Guide
Page 44
66GD&T for Body Engineering
Zero at MMC concept
• The Zero at MMC concept applies only to features who’s sole
function is CLEARANCE
67GD&T for Body Engineering
M
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
+
0
What is the smallest diameter hole
permissible?
Question?
10
Answer
Example of current specification
A M MB C
68GD&T for Body Engineering
Example of current specification
Yes
Answer
Question?
If a feature of the part was
measured, and the hole was
found to be Dia , would this
part be reject?
M
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
+
0
A M MB C
69GD&T for Body Engineering
Example of current specification
But, would the rejected part be
functional?
Question?
Answer
To make the part acceptable we would need to change the data
specification.
+
0
If the part meets the functional gauge requirements, we know the part
is functional.
The part has been rejected because of feature size alone.
Therefore it must have been manufactured to a tighter specification
than that stated on the data.
A M MB C
70GD&T for Body Engineering
Example of current specification
What needs to change?
Question?
The specification for the hole
needs to change, by adopting the
“Zero at MMC” concept
Answer
M
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
+
0
A M MB C
71GD&T for Body Engineering
Zero at MMC concept
+
Example:
To comply with the “Zero at MMC” concept for clearance holes;
The Specified value of the Feature of Size is modified to equal
the Virtual Condition, . (MMC-Positional Tolerance).
The geometric tolerance value is incorporated into the features
limits of size
+
0
A M MB C
A zero tolerance is specified in the Feature Control
Frame, and the material modifier MMC MUST follow
the zero tolerance value.
M 0 A M MB C
72GD&T for Body Engineering
M
0
Zero at MMC concept
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
The Zero at MMC concept gives
Manufacturing the FULL range of
tolerance available, and since the MMC
size is now equal to the VIRTUAL
CONDITION, no separate MMC feature
size verification is required. (Taylors
Principle)
The LMC feature size must still be
functionally derived and verified
+ 0
M 0 A B C
73GD&T for Body Engineering
The specified Feature of Size is
not the target size for
manufacturing.
Zero at MMC concept
The tolerance available is
dependant on the Feature of Size
M
0
The nearer the actual punch size
is to the LMC, the larger the
Tolerance of Position
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
M 0
+
0
VIRTUAL CONDITION & MMC
LMC FEATURE SIZE
74GD&T for Body Engineering
Standard Punch Size
M 0
+
0
Punch diameter will be LMC minus
rounded up or down
M
0
L
Actual Mating
Envelope
Tolerance
Zone (Dia)
Virtual
Condition
LMC
Example
Punch Dia.
75GD&T for Body Engineering
Composite Positional
Tolerances
Reference Pocket Guide
Page 45
76GD&T for Body Engineering
Composite Positional Tolerances
(For groups of holes)
M
+
0
MB MC
A
3 x FIX HOLES
The upper segment is referred to as the “Pattern Locating
Tolerance Zone Framework” (PLTZF)
The lower segment is referred to as the “Feature Relating
Tolerance Zone Framework” (FRTZF)
77GD&T for Body Engineering
Composite Positional Tolerances
Actual Hole Feature Relating
tolerance Zone
M
MB MC
A
Pattern Locating
Tolerance Zone
78GD&T for Body Engineering
Composite Positional Tolerances
M
MB MC
A
79GD&T for Body Engineering
Composite Positional Tolerances
M
MB MC
A
The control requires that each actual
feature axis must lie within the specified
tolerance zones of both the upper and
lower segments simultaneously
80GD&T for Body Engineering
Composite Positional Tolerances
M
MB MC
A
The control requires that each actual
feature axis must lie within the specified
tolerance zones of both the upper and
lower segments simultaneously
81GD&T for Body Engineering
Composite Positional Tolerances
• Its application is supported by the entire core team.
• The control reflects the part feature manufacturing process.
• It will be verified in full down stream.
• The added-on cost to the verification process is justified by the
required feature function.
Before specifying this control verify that;
82GD&T for Body Engineering
Projected Tolerance Zone
Reference Pocket Guide
Page 43
83GD&T for Body Engineering
Projected Tolerance Zone
The projected tolerance
zone principle should
be applied to
assemblies that contain
mating parts of
substantial thickness
and are constrained
with fasteners such as
screws in tapped holes,
studs or dowel pins
(termed fixed
fasteners).
84GD&T for Body Engineering
Followed by the dimension indicating the
minimum height of the tolerance zone
Projected Tolerance Zone
The PROJECTED Tolerance Zone is invoked by
using the symbol in the Feature Control FrameP
DIRECTION OF PROJECTED ZONE
P A B M C M
M12 x
MINOR
85GD&T for Body Engineering
Projected Tolerance Zone
The Projected
Tolerance Zone
effectively transfers
the tolerance zone
from inside the tapped
hole/dowel hole out
into the space
occupied by the body
of the bolt/dowel pin
after assembly
86GD&T for Body Engineering
PROFILE
Reference Pocket Guide
Page 20
87GD&T for Body Engineering
PROFILE
• Profile is the most versatile and probably the most powerful of
the geometric Controls.
88GD&T for Body Engineering
PROFILE
• The true profile is defined by the theoretically exact CAD model
(basic dimensions).
89GD&T for Body Engineering
PROFILE
Can be specified with or without a datum of reference
If the control has no datum of
reference then the tolerance
value applies to the features
true basic profile and no
orientation or location is
implied.
If the profile control is
referenced to the datum
features of the component
then the considered feature is
fully controlled for size, form,
orientation and location
90GD&T for Body Engineering
PROFILE
• Profile is separated into two types of controls
– Profile of a Line
– Profile of a Surface
• There are three methods of establishing the tolerance zone
– Bilateral (Default unless otherwise stated)
– Unilateral
– Special Case
91GD&T for Body Engineering
Profile of a Line
The Tolerance establishes a uniform
two-dimensional zone limited by two
parallel zone lines extending along
the length of the considered feature.
The Tolerance is applied
Normal/Perpendicular to the true
profile at all points along the profile.
The actual line element must lie
within the Specified Tolerance Zone.
(Bilateral)
92GD&T for Body Engineering
Profile of a Surface
The Tolerance establishes a
uniform three-dimensional zone
contained between two envelope
surfaces separated by the specified
tolerance.
The zone extends along the length
and width, or circumference of the
considered surface.
The tolerance is applied normal to
the true basic profile of the
considered surface.
93GD&T for Body Engineering
Unilateral Tolerance
TOL. APPLIES IN DIRECTION LMC
HOLE
TOL. APPLIES IN DIRECTION MMC
HOLE
BASIC PROFILE
94GD&T for Body Engineering
Unilateral Tolerance
TOL. APPLIES IN MATERIAL DIRECTION
MATERIAL DIRECTION
Tolerance Zone
95GD&T for Body Engineering
Unilateral Tolerance
TOL. APPLIES IN OPPOSITE MATERIAL DIRECTION
Tolerance Zone
MATERIAL DIRECTION
96GD&T for Body Engineering
Special Case
TOL. SPLIT: IN DIRECTION MMC
BASIC PROFILE
HOLE
97GD&T for Body Engineering
Special Case
TOL. SPLIT: IN MATERIAL DIRECTION
Tolerance Zone
Tolerance Zone
MATERIAL DIRECTION
98GD&T for Body Engineering
Element Lines
If, as a result of the relevant surface function it is necessary to
control the surface form with a tighter tolerance than the
tolerance of SIZE, FORM, ORIENTATION and LOCATION,
then the following method is recommended
99GD&T for Body Engineering
Element Lines
A M C M
This Represents two separate controls;
The upper FCF is the PROFILE
of the Surface, for SIZE, FORM,
ORIENTATION and LOCATION
controls
The Lower FCF is the ELEMENT Lines of the surface FORM
control. No LOCATION or ORIENTATION is implied (No Datums
of Reference)
100GD&T for Body Engineering
Element Lines
A M C M
True Basic Profile
PROFILE of a Surface 3D
tolerance Boundary for SIZE,
FORM, ORIENTATION and
LOCATION
Actual Surface must lie
within Tolerance
Boundary
101GD&T for Body Engineering
Element Lines
A M C M
PROFILE of a Line 2D
Tolerance Boundary located
and oriented anywhere within
the 3D Tolerance boundary
Actual Element Line of the
Surface must lie within
both tolerance boundaries
102GD&T for Body Engineering
Element Lines
A M C M
PROFILE of a Line 2D
Tolerance Boundary located
and oriented anywhere within
the 3D Tolerance boundary
Actual Element Line of the
Surface must lie within
both tolerance boundaries
103GD&T for Body Engineering
Element Lines
• Both profile controls contain an infinite number of points to be
verified.
• The core team should agree the number of points and their
location to ensure consistency and repeatability in the
verification process.
• This information is documented on the Control Plan.
• More information can be found in the CAD Methods web site,
under the title Significant/Critical Characteristics
To summarise
104GD&T for Body Engineering
Step 4
Establishing Tolerances
105GD&T for Body Engineering
Establishing Tolerances
• Tolerances should be derived based on the following;
– Function
– Cost
– Manufacturing Process
• From agreed generic tolerance data (see Cad Methods)
• Do Not “pick tolerances out of the air”, without documented data
with which to supports your decision.
• Do not copy tolerances blindly from previous data
106GD&T for Body Engineering
Diametral Features
• Clearance Holes
• Holes with specific function
107GD&T for Body Engineering
Clearance
Holes Tolerance of feature size should be derived from the generic tolerance
specification, unless otherwise
required, and stated on the 3D model
+ 0
Zero at MMC
concept applies
M A B0 CM M
108GD&T for Body Engineering
Holes with specific function
The tolerance of POSITION should
be derived from generic tolerance
specification unless otherwise
required
M A CM M
+?
Feature Size and Tolerance of
Feature Size to be functionally
derived and stated on the 3D
model
109GD&T for Body Engineering
Slotted Features
• Clearance Slots
• Slots with specific function
110GD&T for Body Engineering
Zero at MMC concept applies
Tolerance of feature width and
length should be derived from the
generic tolerance specification,
unless otherwise required, and
stated on the 3D model
The word BOUNDARY must be added under
the Feature Control Frame
Clearance
+ 0
BOUNDARY
M A B0 CM M
111GD&T for Body Engineering
Feature size and tolerance of feature
size to be functional derived and
stated on the 3D model
The tolerance of
POSITION should be
derived from generic
tolerance specification
unless otherwise required.
The word BOUNDARY
must be added under the
Feature Control Frame
Slots with specific function
+?
0
M A CM M
BOUNDARY
112GD&T for Body Engineering
Step 5
Final Approval of GD&T on the CAD
Data
113GD&T for Body Engineering
Final Approval of GD&T on
the CAD Data
• Verification required from the core team for Steps One to Four.
• The goal of this process should be to prevent any changes
associated with incorrectly specified PMI after engineering
release.
• This process allows input and participation from all activities
affected by the data.
114GD&T for Body Engineering
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115GD&T for Body Engineering
