Upload
yogesh-naik
View
242
Download
0
Embed Size (px)
Citation preview
8/3/2019 GD&T01 Introduction60
1/60
Chapter1 1
Geometric Dimensioning &
Tolerancing
42 Slides ~1h
8/3/2019 GD&T01 Introduction60
2/60
Chapter1 2
Chapter 1. INTRODUCTION
8/3/2019 GD&T01 Introduction60
3/60
Chapter1 3
OBJECTIVE OF THIS PROGRAM:
Understand & use of Geometrical
Dimensioning & Tolerancing as specified by
ASME Y14.5-1994
For smooth integration into engineering
design systems (Specification)
Modern inspection
systems(Interpretation)
8/3/2019 GD&T01 Introduction60
4/60
Chapter1 4
Prerequisite for the Program:Adequate knowledge of reading of production
drawings
GD&T NTTF
8/3/2019 GD&T01 Introduction60
5/60
Chapter1 5
Introduction:
Geometric dimensioning and tolerancing (GD&T) is
a method for stating and interpreting design
requirements.
GD&T is an international system of symboliclanguage, and is simply another tool available to
make engineering drawings a better means of
communication from design through manufacturingand inspection.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
6/60
Chapter1 6
GD&T NTTF
Advantages of GD&T:Uniformity in design practice
Fewer misinterpretations
Interchangeability Ensured
Design requirements specified explicitlyLatest gaging techniques accommodated
Lower production costs
Maximum tolerance allocationHigher production yields
Less rework or scrap
8/3/2019 GD&T01 Introduction60
7/60
Chapter1 7
Structure of Presentation:
Begins with basic principlesBuilds with applications-oriented concepts.
Complex material is presented
in a building-block approach with examplesillustrating each concept.
End-of-chapter evaluations further
reinforce the explanations given in each section..
Completely covers the material in ASME
Y14.5M-1994
(Some drawing examples are dimensioned and
toleranced in inches and some in millimeters)
GD&T NTTF
8/3/2019 GD&T01 Introduction60
8/60
Chapter1 8
GD&T NTTF
Structure of Presentation:Does not
Prescribe design or engineering practices
State design requirements
Specify inspection techniques
8/3/2019 GD&T01 Introduction60
9/60
Chapter1 9
GD&T NTTF
NOTE:
Sometimes it is necessary to state how
something is to be manufactured or inspected
(Cylinder Bore)
Drawings in this presentation are not
complete production drawings, but onlyillustrate the principles / concepts.
8/3/2019 GD&T01 Introduction60
10/60
Chapter1 10
GD&T NTTF
DRIVERS OF GD&T:
Demand for Products
Demand for Accuracy
Interchangeability
Globalization(Design anywhere)
8/3/2019 GD&T01 Introduction60
11/60
8/3/2019 GD&T01 Introduction60
12/60
Chapter1 12
GD&T NTTF
.
GD&T:
Standardized Method for stating and
interpreting design requirements.
International system of symbolic language
Tool available to make engineering drawingsa better means of communication from design
through manufacturing and inspection.(Sri
Nagasamy)
8/3/2019 GD&T01 Introduction60
13/60
Chapter1 13
What is a Standard?
A model or Rule with which other similar things
are to be compared
Internationally applicable
To improve
CommunicationControl
Productivity
GD&T NTTF
8/3/2019 GD&T01 Introduction60
14/60
Chapter1 14
GD&T NTTF
Change:The most constant thing in society
Updation to make the standard useful to theindustry
8/3/2019 GD&T01 Introduction60
15/60
Chapter1 15
GD&T NTTF
WHY GD&T?Adds clarity to our coordinate system of
dimensioning
In Coordinate System, a part of the designer's
intent was always left to interpretation by the
craftsman (i.e., dimension origin, form profile and
orientation).
8/3/2019 GD&T01 Introduction60
16/60
Chapter1 16
WHY GD&T?
Most significant difference between the two
systems is the location of round features
Coordinate system had a square tolerance zone,
which allowed some good parts to be rejected
GD&T NTTF
8/3/2019 GD&T01 Introduction60
17/60
Chapter1 17
GD&T NTTF
GD&T IS NOT A REPLACEMENTThe coordinate system is not being replaced
entirely with GD&T.
GD&T is specified to enhance the coordinate
system as required by design.GD&T symbols, provide a means of completely
specifying uniformity and describing the designer's
intent.
8/3/2019 GD&T01 Introduction60
18/60
Chapter1 18
GD&T IS NOT A REPLACEMENT
Symbols eliminate most of the drawing
misinterpretation by not having notes in drawingmargins and by not having complete textual
descriptions of features and design requirements.
(Poka-Yoke)(XT - Brake part design)
GD&T NTTF
8/3/2019 GD&T01 Introduction60
19/60
Chapter1 19
GD&T NTTF
COMPLETE SPECIFICATION:
Complete specification of design requirementspossible with symbols
Symbols allow the designer to specify maximum
tolerances for parts that must assemble with otherparts.
8/3/2019 GD&T01 Introduction60
20/60
Chapter1 20
COMPLETE SPECIFICATION:
These maximum tolerances also ensure the
interchangeability of parts.
The use of symbols for complete specification is
becoming increasingly important with the
growing interrelated ownerships of companiesaround the world.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
21/60
Chapter1 21
GD&T NTTF
ADVANTAGES:
Two key principles for applying GD&TFunction
Relationship of parts in an assembly.
Method of specifying feature location.
8/3/2019 GD&T01 Introduction60
22/60
Chapter1 22
ADVANTAGES:
In the past, features were located with the
coordinate system.
The coordinate system is a method of
Tolerancing that uses a plus/minus tolerance.
Plus and minus tolerances are specified forlengths, widths, diameters, shapes, and locations.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
23/60
Chapter1 23
GD&T NTTF
Misinterpretation?
8/3/2019 GD&T01 Introduction60
24/60
Chapter1 24
GD&T NTTF
An illustration of how drawings
may be dimensioned and toleranced with thecoordinate system is shown in Figure 1-1.
This method of Tolerancing permits the length and
diameters to vary by a plus/minus value. It alsoallows the maker of the part to put the center hole
wherever he or she desires.
By looking at the drawing, we can only assume
that the hole is centered. This is an example of a
drawing being left open to misinterpretation by
anyone reading it.
8/3/2019 GD&T01 Introduction60
25/60
Chapter1 25
GD&T NTTF
8/3/2019 GD&T01 Introduction60
26/60
Chapter1 26
GD&T NTTF
An example of how holes are specified with the
coordinate system is shown in Figure 1-2.The tolerance as specified establishes a square
tolerance zone based on the plus/minus five
thousandths of an inch tolerance in the x and ydirections.
There is no consideration for the actual mating
size.
The tolerance zone is ten thousandths of an inch
on each side of square regardless of the actual
mating size.
8/3/2019 GD&T01 Introduction60
27/60
8/3/2019 GD&T01 Introduction60
28/60
Chapter1 28
GD&T NTTF
Zone of Tolerance
8/3/2019 GD&T01 Introduction60
29/60
Chapter1 29
GD&T NTTF
8/3/2019 GD&T01 Introduction60
30/60
Chapter1 30
Calculate the Loss of Tolerance field??
GD&T NTTF
Permitted zone of Tolerance
by Coordinate System
Permissible zone of Tolerance by Design Intent
8/3/2019 GD&T01 Introduction60
31/60
Chapter1 31
GD&T NTTF
Area of Square = (d / Sqrt2)**2
d
Area of Circle = ( / 4) d**2
150 %
8/3/2019 GD&T01 Introduction60
32/60
Chapter1 32
GD&T NTTF
An illustration of how the tolerance zone appears
is shown in Figure 1-3.
The axis of the hole or pin must be positioned in
that square zone in order for the feature to belocated properly.
The feature may lean or slant an uncontrolledamount as long as the axis stays within the square
zone.
8/3/2019 GD&T01 Introduction60
33/60
8/3/2019 GD&T01 Introduction60
34/60
Chapter1 34
GD&T NTTF
That .007 should be usable all around the desired
true position, as illustrated in the example in Figure1-5.
GD&T provides a method of specifying atolerance zone that takes the shape of the feature
into consideration if so desired by the designer.
GD&T also allows consideration for the
feature's actual local size for calculating total
tolerance.
8/3/2019 GD&T01 Introduction60
35/60
Chapter1 35
The symbolic method of specifying design intent
eliminates most misinterpretation of drawingnotes.
The proper application of geometric tolerancesensures the interchangeability of parts.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
36/60
Chapter1 36
GD&T NTTF
EXERCISE:
1. Drawings are the primary .tool
between designers and manufacturing.
8/3/2019 GD&T01 Introduction60
37/60
Chapter1 37
GD&T NTTF
ANSWERS FOR EXERCISE:
1. Drawings are the primary communicationtool
between designers and manufacturing.
8/3/2019 GD&T01 Introduction60
38/60
Chapter1 38
2. GD&T is a system made up of
...primarily
.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
39/60
Chapter1 39
2. GD&T is a system made up ofsymbolsprimarily.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
40/60
Chapter1 40
3. The GD&T standard is one of the standards
maintained by the .
GD&T NTTF
8/3/2019 GD&T01 Introduction60
41/60
Chapter1 41
3. The GD&T standard is one of the standards
maintained by the ASME.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
42/60
Chapter1 42
GD&T NTTF
EXERCISE:
4. GD&T adds to the coordinate dimensioning
system and ensures of mating when specific
...is required.
8/3/2019 GD&T01 Introduction60
43/60
Chapter1 43
4. GD&T adds to the coordinate dimensioning
system and ensured of mating
when specificclarityis required.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
44/60
Chapter1 44
5. GD&T does not . the
coordinate dimensioning and tolerancing system.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
45/60
Chapter1 45
GD&T NTTF
ANSWERS FOR EXERCISE:
5. GD&T does not replace the coordinate
dimensioning and tolerancing system.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
46/60
Chapter1 46
6. GD&T at best can be described as a
dimensioning and tolerancing
system.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
47/60
Chapter1 47
6. GD&T an best be described as a total
dimensioning and tolerancing system.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
48/60
Chapter1 48
GD&T NTTF
EXERCISE:7.GD&T is used to control the..
of a part feature and its relationship to other
features.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
49/60
Chapter1 49
GD&T NTTF
ANSWERS FOR EXERCISE:7.GD&T is used to control the form of a part
feature and its relationship to other features.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
50/60
Chapter1 50
8. GD&T is also used to control feature &
.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
51/60
Chapter1 51
8. GD&T is also used to control feature
size &
location
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
52/60
Chapter1 52
9. The key principles of GD&T are
. &
.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
53/60
Chapter1 53
9. The key principles of GD&T are
Function&
Relationship.
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
54/60
Chapter1 54
GD&T NTTF
EXERCISE:
10. Two advantages of the GD&T system aremaximum &
ensured of mating parts.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
55/60
Chapter1 55
GD&T NTTF
ANSWERS FOR EXERCISE:
10. Two advantages of the GD&T system aremaximum tolerances &
ensured interchangeabilityof mating parts.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
56/60
Chapter1 56
11. The total amount that a part size may vary isa size..
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
57/60
Chapter1 57
11. The total amount that a part size may vary
is a sizetolerance
GD&T NTTF
GD&T NTTF
8/3/2019 GD&T01 Introduction60
58/60
Chapter1 58
12. A common method used to specify a tolerance
for the nominal size of a feature is
.. values.
GD&T NTTF
8/3/2019 GD&T01 Introduction60
59/60
8/3/2019 GD&T01 Introduction60
60/60
THANK YOU