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DIMENSIONS, TOLERANCES, AND ASSEMBLIES - Coggle Diagram
DIMENSIONS, TOLERANCES, AND ASSEMBLIES
DIMENSIONS
TYPES
. Parallel Dimensioning
. Superimposed Running Dimensioning
. Chain Dimensioning
. Combined Dimensioning
. Dimensioning Small Features
. Dimensioning Of Multiple Features
. Dimensioning Of Radius
. Dimensioning Of Circle, Arc, Hole
. Dimensioning Angles
RULES
. Neat
. Dimensions should not be
duplicated
. Avoid dimensioning to avoid hidden
lines and features
. Dimension lines, extension lines,
object outlines should not cross/overlap
-
TOLERANCE
-
IMPORTANCE
. In practices, parts cannot be manufactured exactly to dimensions stated in drawing due to manufacturing variations
. Tolerances are included with dimensions in engineering drawings to take into account these manufacturing
limitations
. Rejection rate will be very high and is not realistic
. Translate into manufacturing
method needed
. Different manufacturing methods has different degree of tolerance
. Ensures good quality control for parts from different companies
. Ensures mating parts of an assembly interface and fit well
TYPES
. Bilateral Tolerance:
vary in 2 directions,
directions need not vary by same amount
. Unilateral Tolerance:
vary in only one direction
. Limit Tolerance:
upper and lower limits of the dimension specified
ASSEMBLY MODELLING
WHAT
. Multiple parts brought together to define a larger, more complex product representation
. Facilitates collaboration among designers, engineers, manufacturing technicians and others to ensure a product assembly works
. Individuals in different disciplines can work concurrently, resulting in faster and less costly delivery of products to market
HOW
Constructing an assembly normally begins with bringing in a base component, selected because of its central role. Each component brought in needs to be oriented and located relative to other components in the assembly. Assembly joints are used between elements of components.