Introduction to Fundamentals of Assembly

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Introduction to Fundamentals of Assembly
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Bottom-Up Design (Modeling)
The components (parts) are created first and then
added to the assembly file. This technique is
particularly useful when parts already exist from
previous designs and are being re-used.
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Top-Down Design (Modeling)
The assembly file is created first and then the
components are created in the assembly file. The
parts are build relative to other components.
Useful in new designs
In practice, the combination of Top-Down and
Bottom-Up approaches is used. As you often use
existing parts and create new parts in order to
meet your design needs. Parts can be modified in
assembly or in part file.
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Assembly and Exploded View
Assembly View
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Degrees of Freedom
An object in space has six degrees of freedom.

• Translation movement along X, Y, and Z axis
  (three degrees of freedom)

• Rotation rotate about X, Y, and Z axis
• (three degrees of freedom)

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Assembly in NX5
Open a new file and call it an Assembly
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Assembly in NX Mate option
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Assembly in NX Mate option
Align Two selected surfaces become co-planar and
face in the same direction. Can also be applied
to revolved surfaces. This constrains 3 degrees
of freedom (two rotations and one translation).
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Assembly in NX Mate option
Parallel Two planar surfaces are made parallel,
not necessarily co-planar.
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Example
Select Add Existing Component ? select the file
containing the first component in the assembly
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Example
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Example
Then select the top face to mate the two surfaces
Select the bottom face
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Example
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Add the third component (bolt) and Mate the
bottom of the bolt head with the top surface of
the base
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Select Mate Component option ? select Center ?
select the bolt cylinder surface and the hole
surface
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Exploded Views
Select Exploded Views from the Assemblies menu
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After creating an explosion, select Assemblies
and choose Auto-explode Components
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Select components and specify the distance
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The Exploded View
This option may not produce a perfect exploded
view the first time it is intended to give you a
good start towards a perfect explosion. After
using Auto-Explode Components, you can follow up
and refine your explosion by choosing Edit
Explosion and editing the parameters with the
Explode Component dialog.
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Select Assemblies ? choose Edit Explosion ?
select the object to be moved
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Assembly in SW
Select to open an assembly file
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Assembly Inserting Components
Select Insert ? Component ? Existing Part
Rotate component
Move component
Assembly Toolbar
Mate positions components relative to each other
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Assembly
Select the first component to insert into
assembly..
Browse to find your component if it is not open.
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Assembly Mate Command
Insert the plate, click any place on the screen
to drop the plate
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Assembly Mate Command
Select Coincident
Options after selecting the Coincident Mate
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Assembly Mate Command
Coincident, two surfaces facing each other
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Assembly Mate Command
Two surfaces at a specified angle
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Assembly Mate Command
Use Concentric option to line up cylindrical
surfaces
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Exploded View
Select Exploded View option from the Insert menu
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Creating an Assembly Example
The example assembly requires three mates to
fully define it.
First constrain Mate between the hollow faces as
shown.
Hollow faces
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Example
Second Constrain Align the right faces of both
components.
Right side faces
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Example Switch Plate
Switch plate consists of two components, plate
and fasteners.
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Example Switch Plate
First Constrain Concentric select the
cylindrical face of the fastener and the
cylindrical face of the switch plate.
Two degrees of freedom remains, the fastener can
still move in and out and rotate inside the hole.
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Example Switch Plate
Second Constrain mate the flat circular back
face of the fastener and the flat front face of
the switch plate.
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Example Switch Plate
Parallel could be used to line up the slot on the
screw head with the flat top face of the switch
plate.
The assembly is fully defined