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Geometric Dimensioning and Tolerancing Chapter 1, Introduction.
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Transcript of Geometric Dimensioning and Tolerancing Chapter 1, Introduction.
![Page 1: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/1.jpg)
Geometric Dimensioning and Tolerancing
Chapter 1, Introduction
![Page 2: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/2.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 2
History
• during the early period of manufacturing there were seldom any drawings
• one-off manufacturing• ~1798 – concept of interchange parts
– Eli Whitney won a contract to supply musketsto the United States government. The firearmsmanufacture were based on the concept ofinterchangeable parts.
– He made a presentation to congress by building10 guns and assembling and disassemblingthem claiming the same exact parts andmechanisms.
• specifying tolerances became veryimportant
Eli Whitney 1765 - 1825
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EML 2023Department of Mechanical and Aerospace Engineering 3
Tolerances
• All dimensions require a tolerance.
• A tolerance should be as large as possible without interfering with the function of the part to minimize production costs.
• Consider how your part will be checked to see if it meets the tolerances.
![Page 4: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/4.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 4
Tolerance Notes
![Page 5: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/5.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 5
Plus/Minus (Limit) Tolerancing
• Plus/minus tolerancing seemed to work well for many applications.
![Page 6: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/6.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 6
Plus/Minus (Limit) Tolerancing
![Page 7: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/7.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 7
Plus/Minus (Limit) Tolerancing
![Page 8: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/8.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 8
Limit Tolerancing
• Is the .620-.630 hole horizontal position measured from a true vertical plane or from the as built face?
• A .005” tolerance on the horizontal and vertical position of the hole means that the position could be off by as much as .007”.
+.005
+.005
.007
perfect locationfor hole center
max allowed errorfor hole center
![Page 9: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/9.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 9
Limit Tolerancing
• Limit tolerances don’t have an origin or any orientation or location relative to datums.
• The datums are usually implied.
• The drawings are subject to different interpretations.
• Plus/minus tolerancing works well for individual features of size (ex. diameter of a shaft), but does not control the relationship between individual features very well.
![Page 10: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/10.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 10
Limit Tolerancing
![Page 11: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/11.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 11
Limit Tolerancing
![Page 12: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/12.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 12
Limit Tolerancing
![Page 13: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/13.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 13
GDT
• Limit tolerancing can give the size of individual features.• GDT can provide:
– relationships between features– circular tolerance zone for hole placement
• GDT removes any ambiguity from the drawing specification
![Page 14: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/14.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 14
Mil Std 8 1950’sMil Std 8AMil Std 8B
Mil Std 8C-1963
ASA-Y14.5-1957
USASI Y14.5-1966
ANSI Y14.5-1973
ANSI Y14.5M-1982
ASME Y14.5M-1994
ASME Y14.5-2009
History of Dimensioning and Tolerancing Standards in the USA
![Page 15: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/15.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 15
Geometric Dimensioning and Tolerancing (GDT)
1. establish a reference coordinate system by defining datums
2. provide basic dimensions (perfect dimensions) relative to the datums
3. specify allowable tolerances
![Page 16: Geometric Dimensioning and Tolerancing Chapter 1, Introduction.](https://reader033.fdocuments.in/reader033/viewer/2022061423/56649f325503460f94c4db86/html5/thumbnails/16.jpg)
EML 2023Department of Mechanical and Aerospace Engineering 16
communicationsymbols
ASMEclarity
replace
totalform
size & location
function & relationship
tolerances & interchageabilitytolerance
plus/minussize