Home
Subjects
Create
Search
Log in
Sign up
Upgrade to remove ads
Only $2.99/month
Video Lectures (exam 5)
STUDY
Flashcards
Learn
Write
Spell
Test
PLAY
Match
Gravity
Terms in this set (65)
tangent edge (double lines)
occurs when there is some intersection or a point of confluence between a flat surface and then a curved surface
can be visible or hidden
merely a choice by the draft person
automatic dimensions
automatically placed dimension and some make sense and some does not make sense
linear
(limits of size; plus/minus)
clearance fit
guarantee free - running operation
ASME Y14
Y14.1 drawing sheet size and format
Y14.2 line conventions and letterring
Y14.3 sectional view
Y14.4 pictorial drawings
Y14.5 dimension and tolerancing
Y14.6 screw threads
Y14.7 gears and splines
model- bade definition
is addressed in asme standard Y14.41 (2003) and MIL 31000A
represents a practice of embedding product manufacturing information data at the 3D model level
obsoletes the need for 2D drawings as the source of design authority
perpendicularity
distance between two planes that we know at an angle to the datum or perpendicularity
profile
specifies the allowable in theoretical surface
used for surfaces that have curvature or not
can be relative to a datum or surface
parallelism
two slanted lines
2 parallel planes
flatness
does not have a datum
only geometrical symbol and the size
related features
orientation
location
runout
individual or related
profile
orientation
individual features
form
feature control frame
geometrical characteristic symbol
diameter symbol indicating a cylindrical tolerance zone
tolerance
material condition modifier
primary datum
secondary datum
datum material condition modifier
tertiary datum
L
material condition modifier
least material condition
true position control
allowable deviation from both size and shape
basic dimensions
are referred to as datum
datum precedence 3-D
A: primary - largest surface, three points
B: secondary - next longest surface, two points
C. tertiary - one point
datum precedence
it matters in what order you line your datum
GD&T "technologies"
Datum/precedence
basic dimension
geometric description of tolerance
technical case for GD&T
ensure correct (ambiguous) part assembly and interchangeable
provide for proper manufacture and inspection
embody design intent
ANSI/ASME standards
1886 pipe sizes / threaded ends
1915 ASME boiler code (MA shoe factory)
B18.3 socket cap and set screws
Y1.1 drawing abreviations
Z25.1 rules for numerical round-off
Y32.3 symbols for welding
Y14.x drafting
GD&T
technology development to minimize ambiguity in graphical engineering communication
codified into a set of rules and symbols applied to machine drawings
these rules specify: size, location, orientation, shape, form of the featured
rules maintain through international standard
these standards then serve as source of authority for the correct drawings interpretation
using fit tables
decide which fit is required
identify row in fit table according to nominate
table will provide values to establish tolerance (limits of size for both shaft and hole)
ANSI B4.1 fit categories (Similar for ISO)
RC/LC ( guarantee clearance)
LT/LN ("mix" of clearance and interference (location/rigidity)
FN (force fit) guarantee interference (power transfer)
transitional fit
selective assembly
interference fit
guarantee position
provide for power transfer between two elements
shaft basis
basic size is the largest shaft (shaft can be smaller)
For mating applications where shafts "drives" the dimensions of mating components
hole basis
basic size is the smalls hole (hole can be larger)
most commonly used
allowance
minimum clearance or maximum interference (maximum material condition)
interference
negative space between a shaft and hole (press-fit)
clearance
space between a shaft and a hole (free- running)
table of fits
tabulated tolerance values for mating of cylindrical parts (shafts/holes)
translate "English Language" engineering requirements to specific tolerance numbers
ANSI B4.1 (US) - ISO Fits (metric)
rules for tolerance
baseline vs chain dimensioning (tolerance stack-up)
table of fits
geometric tolerancing
tolerance stack up
accumulate tolerance from an edge or from a datum
tolerance formats
uni/bilateral ( superscript or in line format +-)
limit (high (* always above) and the low number)
imperial (no leading zeros, match decimals)
metric (no +- , no trailing zeroes except on limit dims)
geometric
(location, shape, form, orientation; GD&T)
tighter tolerance ("tens")
done by abrasive removal
typical computer controlled machining
<5 mils
typical manual processes
10 - 50 mils
common tolerance ( inches)
part dimension ; Standard Tolerance
(x.x) .2
(x.xx) .01
(x.xxx) .005
(x.xxxx) .0005
sheet of paper
4 to 4 though
human hair
80 micrometer
cats whisker
4/1000 inch = 100 micrometer = 0.1mm
thousandth, thou, or mil (not mm)
1/1000 inch = 0.0254 mm =25.4 micrometer
1 inch
25.4 mm (exactly)
tolerance is learned through
intuitive understanding of small dimensions
study of fundamental rules
understanding of manufacturing processes
experience and experimentation
the curse of cad
software treats dimensions, which is hundreds of thousands upon hundred of thousands higher than anything we can achieve in the physical world
hole callout
gives you the information from the whole wizard
tolerance
the acceptable range of variability that will still guaranty that our design will perform as intended
to design is to manage uncertainty by
dimensioning right
from the right place
write the right tolerance
an imperfect world
there is no such thing as a feature, or location, that measures, say one inch
this is an abstraction; nothing in real life measures exactly one inch
every dimension carries with it some degree of uncertainty
introduction to tolerencing
single parts vs. assemblies
- complexity of tolerance increase
artisan vs. modern manufacturing
- no longer the same
the inexact nature of dimensions
reference
"REF"
dimensioning and tolerance
are at the very heart of great design
dimension rules (asme y14.5)
every feature shall be explicitly and fully dimensioned leaving nothing to assumption
each necessary dimension shall be shown; no redundant dimensions allowed
each dimension shall have a tolerance (exceptions: stock, ref). tolerance can be specified locally or globally.
dimension shall suit the function and mating relationship of a part, and be unambiguous in their interpretation
drawing shall not specify the manufacturing method
dimension should be readable and should be shown in true views referring to visible outline (avoid crossing extension lines)
dimensions should be applied in the view where the contour shape is best shown (contour line)
90 degree angles is implied in drawing
stock materials (wire, sheet, rod) shall have a linear dimension, optionally followed by its gage/code in parenthesis
all dimensions applicable at room temperature
all dimensions applicable in free state condition (unstress)
all geometric tolerance apply for full depth, length, and width of the feature
dimensions and tolerance apply only at the drawing level where specified
baseline dimensioning
vertical dimensions are relative to the top edge of that part
all the horizontal dimensions are relative to the right edge
chain tolerance
dimensions on top of one another
accumulate tolerance
design intent
is a long journey acquired through study, insight and experience. Veteran designers learn something new everyday
specify dimensions
that can be easily set up for manufacturing, and can be easily measured for inspection
Imperial
no leading zero for sub-inch dims, add zeros after decimal point as needed to indicate tolerance
metric
leading zeros for sub-millimeter dims, no trailing decimal zeros, no commas/spaces
dimensining standard
ASME Y14.5
great designs
do their job with the least precise (costly) components possible
"true" design
the least restrictive dimensions on said parts
that will allow the device to perform as intended
YOU MIGHT ALSO LIKE...
GD&T
54 terms
GC 120 Final
86 terms
Drafting 2
89 terms
OTHER SETS BY THIS CREATOR
menu
8 terms
soup & salad
5 terms
EXAM 5
94 terms
Design Test 4 reviews
107 terms