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ADVANCED MNFG > GD&T > Flashcards

GD&T Flashcards

(110 cards)

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1
Q

What does GD&T Stand for

A

Geometric Dimensioning & Tolerancing

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2
Q

What is Tolerancing

A

The total amount a specific Dimension is permitted to vary

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3
Q

Why do you need to tolerance?

A

Because every dimension cannot be perfect

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4
Q

What factors influence change in fit?

A

Temperature, humidity, atmosphere, dust, corrosion, wear, lubrication, etc

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5
Q

What are the two ways that a fit can be specified

A

Hole and Shaft basis

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6
Q

What are the 2 major fit systems?

A

ANSI and ISO

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7
Q

What are the 3 ISO general groups?

A

Clearance, Transition and interference fits

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8
Q

What are the 3 ANSI general groups

A

“RC”, locational and “FN” fits

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9
Q

“40H8” what does the first number mean

A

The basic size of the component

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10
Q

“40H8” What does the letter mean?

A

The letter indicates the class of fit (UPPER CASE FOR HOLES, lower case for shafts)

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11
Q

“40H8” what does the second number mean?

A

The second number indicates the international tolerance (IT) Grade

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12
Q

what kind of fit is “H11/c11”

A

a loose-running fit for wide commercial tolerances or allowances on external members

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13
Q

what kind of fit is “H9/d9”

A

free running fit not for use where accuracy is essential, but good for large temperature variation, high running speeds, or heavy journal pressures

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14
Q

what kind of fit is “H8/f7”

A

Close running fit for running on accurate machines and for accurate location at moderate speeds and journal pressures

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15
Q

what kind of fit is “H7/g6”

A

Sliding fit not intended to run freely, but to move and turn freely and locate accurately

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16
Q

what kind of fit is “H7/h6”

A

Locational clearance fit provides snug fit for locating stationary parts; but can be freely assembled and disassembled

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17
Q

what kind of fit is “H7/k6”

A

locational transition fit for accurate location, a compromise between clearance and interference

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18
Q

what kind of fit is “H7/n6”

A

locational transition fit for more accurate location where greater interference is permissible

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19
Q

what kind of fit is “H7/p6”

A

Locational interference fit for parts requiring rigidity and alignment with prime accuracy of location but without special bore pressure requirements

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20
Q

what kind of fit is “H7/s6”

A

Medium drive fit for ordinary steel parts or shrink fits on light sections, the tightest fit usable with cast iron

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21
Q

what kind of fit is “H7/u6”

A

Force fit suitable for parts which can be highly stressed or for shrink fits where the heavy pressing forces required are impractical

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22
Q

What does a metric limit tolerance value specified on one line look like

A

12.50±0.25

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23
Q

what does a stacked inch limit tolerance value look like

A

1.062
1.000

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24
Q

what’s the specified dimension of : 76±0.4

A

76

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25
what's the lower limit of : 76±0.4
75.6 (76-0.4)
26
Whats the upper limit of: 76±0.4
76.04 (76+0.4)
27
Whats the tolerance of 76±0.4
0.8 (76.04-75.6=0.8)
28
What type of dimension appears on a drawing in parentheses?
A reference dimension
29
What does an inch dimension with an equal bilateral tolerance look like?
0.750±0.005
30
what does ISO stand for
International standards organization
31
what does ANSI stand for
The American National Standards Institute
32
Why use GD&T?
Proper use guarantees the form, fit and function of a product without the need to make assumptions or interpret requirements
33
What is a feature?
a feature is a general term that applies to a physical portion of a part. (an edge, surface, vertex, etc)
34
What is a feature of size (FOS)
one cylindrical or spherical surface; a set of 2 opposed elements or parallel surfaces that are associated with a size dimension
35
When is MMC most often used?
when FOS is used in an assembly
36
When is LMC most often used?
LMC is often specified to ensure a minimum wall thickness on a part
37
When is RFS used?
RFS is often applied to ensure symmetry, and is the default if MMC and LMC aren't specified
38
What is basic dimensioning?
The basic dimension is the theoretical exact size that the feature of size should be
39
How are basic dimensions indicated on drawings?
Enclosed in rectangles
40
What are tolerance zones?
They're pictorial representation of the limits of size for a particular tolerance
41
What is the standardization of engineering drawing symbols controlled by
ASME Y14.5
42
What is this Symbol: Ø
Diameter
43
What is this Symbol: R
Radius
44
What is this Symbol: SR
Spherical Radius
45
What is this Symbol: SØ
Spherical Diameter
46
What is this Symbol: CR
Controlled Radius
47
What is this Symbol: X
Places or by
48
What is this Symbol: l_l
Counterbore
49
What is this Symbol: lSFl
Spotface
50
What is this Symbol: V
Countersink
51
What is this Symbol: a square
Square shape
52
What is this Symbol: ___ l V
Depth or deep
53
What is this Symbol: <-O
Dimension Origin
54
What is this Symbol: ()
Reference
55
Characteristics of FORM
Never has a datum associated
56
Characteristics of PROFILE
SOMETIMES has a datum associated
57
Characteristics of LOCATION
ALWAYS has a datum associated
58
Characteristics of ORIENTATION
ALWAYS has a datum associated
59
Characteristics of RUNOUT
ALWAYS has a datum associated although datum may not be obvious
60
Material Condition: (M)
At maximum material condition
61
Material Condition: (L)
at least material condition
62
Material Condition: (P)
Projected tolerance zone
63
Material Condition: (F)
free state
64
Material Condition: (T)
tangent plane
65
Material Condition: Ø
Diameter
66
Material Condition: SØ
Spherical diameter
67
Material Condition: R
Radius
68
Material Condition: SR
spherical radius
69
Material Condition: CR
Controlled Radius
70
Material Condition: ()
Reference
71
Material Condition: {ST}
Statistical Tolerance
72
Material Condition: <-->
Between
73
What is a datum
a datum is a reference from which measurements are made (assumed to be perfect)
74
What is a datum feature?
An actual feature that is used to establish a datum, like a face, bore or shaft
75
What are datum symbols?
Symbols that are used to identify datum and in situations where more than 1 datum is used, their order of precedence is shown in the feature control frame
76
What is a datum centre plane?
A plane that splits a symmetrical feature such as a slot or tab (needs a leader)
77
What are the 6 degrees of freedom
The two rotational directions around the each of the xyz axis
78
What is the symbol for coplanar surface datums?
L-M in the control frame
79
What does A mean in the feature control frame?
Primary datum reference
80
What does B mean in the feature control frame?
Secondary Datum reference
81
What do letters connected by '-' in the feature control frame mean?
'A-B' multiple datum reference
82
When do coaxial features exist?
When more than 1 features share a common axis
83
for an external datum feature, how is the datum centre plane created?
Its established by 2 parallel planes at the minimum separation
84
for an internal datum feature, how is the datum centre plane created?
its established by 2 parallel planes at maximum separation
85
A parts tolerance should be as liberal as possible to be?
Consistent with the parts function
86
The limits of the size of a feature controls?
the amount of variation in both size and form
87
What is the "envelope rule"?
if the feature is at MMC its geometric form must be perfect
88
What does RFS mean
Regardless of feature size
89
What does RMB mean
Regardless of material boundary
90
What features are applied only on a RFS basis
Circularity, cylindricity, profile, circular runout, total runout, concentricity & symmetry
91
What are the exceptions to rule #1 Extreme form variations
*parts that have stock sizes: sheet metal, gaskets, tubing, etc *a feature of size of a non-rigid part (rubber)
92
What can override rule #1 Extreme form variations
*apply a straightness control to the FOS *By adding a special note to the FOS *By means of the "independency" symbol (I)
93
What does FOS mean?
Features of Size
94
What is the symbol for RFS?
It doesn't have one, its assumed when no other condition is specified
95
What is Rule #2 "all applicable geometric tolerances"
RFS applies, unless MMC or LMC is specified
96
What is Bonus Tolerance?
It allows the tolerance available to vary with the actual size of the part
97
When is Bonus Tolerance permissible
When a MMC or LMC modifier is used in the tolerance portion of the feature control frame
98
What is a bonus tolerance derived from?
from the FOS tolerance
99
What is flatness
a form of tolerance and it controls the whole surface by means of 2 planes specifying the tolerance
100
Flatness Independency
defining size tolerance as independent of form tolerance
101
What is circularity?
the control of "out-of-roundness"
102
How is circularity measured?
it is measured at any/each cross section perpendicular to the axis
103
Does circularity reference a datum?
No, it controls form
104
How large can the circularity tolerance be?
It must be less than a tolerance of size
105
How is circularity show in the control frame?
a circle followed by a dimension
106
Where does Free State Variation exist?
Where a part distorts when manufacturing forces are removed
107
How is parallelism gauged?
Its gauged relative to a datum or another feature (Face A is parallel to face B)
108
Parallelism geometric tolerance is defined by?
Parallel planes or cylindrical zones that are parallel to a datum plane
109
Theoretically what is a tangent plane?
Its an exact plane that is considered to "lie" on the high points of the feature surface
110
How can perpendicularity be specified?
Its always specified RFS and a datum is required

ADVANCED MNFG (2 decks)

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