gd&t basics

7/25/2019 GD&T basics

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EML 2023Department of Mechanical and Aerospace Engineering

Geometric Dimensioning andTolerancing

Chapter 6, Form, Orientation,Profile, and Runout

Tolerances


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Geometric Characteristics

2

Form, Orientation, Profile, and Runout Tolerances


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Straightness

Straightness can be applied to a surface either flat orc!lindrical"#

Straightness can also be applied to an a$is#

%

straightness applied to aflat surface

straightness applied to ac!lindrical surface


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Straightness

&

's !ou measure along a line, the height must be bet(een )2 and )% mm and the *ariation ma! not be

more than +# mm from a straight line#


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Straightness

Straightness applied to a c!lindrical surface#


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Straightness

Straightness can also be applied to an a$is#

6

)2# +#2


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Flatness

Flatness is the condition of a surface (here all elementsare in one plane#

.


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Flatness

The surface could be chec/ed b! translating the partunder a dial indicator#

0


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Circularit!

Circularit! is roundness# 't an! cross1sectional measurement during one

complete re*olution of the feature, all points of thesurface are perpendicular at an e ual distance from acommon a$is#

))


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C!lindricit!

C!lindricit! is the condition of an entire feature surfaceduring one re*olution in (hich all surface points are ane ual distance from a common a$is#

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)&



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Perpendicularit!

Perpendicularit! is the condition of an entire surface,plane, or a$is at a right angle to a datum plane or a$is#

)


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Perpendicularit!

Perpendicularit! is the condition of an entire surface,plane, or a$is at a right angle to a datum plane or a$is#

)6


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)-



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'ngularit!

'ngularit! is the condition of an a$is or plane other than0+ degrees to another datum plane or a$is#

).


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)0



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Parallelism

Parallelism is the condition of a surface, center plane, ora$is that is an e ual distance at all points from a datumplane or a$is#

2+

bilateral tolerance 3one


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Parallelism

4$ample of a c!linder being parallel to another surface#

2)


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Parallelism

4$ample of a c!linder being parallel to another c!linder#

22


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2%



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Profile5 line , surface

Profile tolerance is specified for designs (here thesurface is to be controlled (ithin a gi*en basic shape#

Specified for irregular features that are difficult to control(ith other form or orientation tolerances#

2&


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Profile5 line , surface

2


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26



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Circular Runout and Total Runout

The (orst circular runout occurs at the slice (ith thegreatest *ariation +#+% mm in this case"#

Total runout is the difference bet(een the highest andlo(est readings found o*er the entire feature# +#)) mmin this case"#

2-


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EML 2023Department of Mechanical and Aerospace Engineering 2.


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Circularit! *s# Runout

Can an!one e$plain the difference bet(een the t(o and

can the! be used on a print interchangeabilt! http577(((#eng1tips#com7*ie(thread#cfm id8).6%00 tp577communities#ptc#com7message7)-%)0

20
http://www.eng-tips.com/viewthread.cfm?qid=186399http://communities.ptc.com/message/173195http://communities.ptc.com/message/173195http://communities.ptc.com/message/173195http://communities.ptc.com/message/173195http://www.eng-tips.com/viewthread.cfm?qid=186399http://www.eng-tips.com/viewthread.cfm?qid=186399http://www.eng-tips.com/viewthread.cfm?qid=186399


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Circularit! *s# Runout

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EML 2023Department of Mechanical and Aerospace Engineering %2


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EML 2023Department of Mechanical and Aerospace Engineering %%

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