T-FLEX Parametric CAD. Fundamentals. 2D Design

Fundamentals. Two-Dimensional Design
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You can do selective insertion of only necessary
elements from the fragment drawing into the
assembly drawing. This capability allows using
fully furnished part drawings in assemblies.
Fragments can be variable, meaning that one or
another fragment would be inserted in the
assembly drawing, depending on certain
conditions. This capability allows creating
assembly drawings and modeling products in
various configurations, when different parts are put in the same assembly, depending on the configuration.
Assembly drawings do not directly incorporate all fragment data. They only keep the necessary images and
references to fragment drawings. This helps achieving most compact representation of the drawings in the
memory and on the hard disk. Besides, if the same drawing file is inserted in different assemblies, then its
modifications will propagate on all documents that use it.
Specifics of Handling Assembly Drawings
This section describes main capabilities and design techniques of fragments and assembly drawings. Detailed
description of fragment-handling steps is provided in further chapters of this book.
Assembly Drawing Creation Techniques
Before starting with creation of an assembly drawing, think through its structure. Try to define requirements
to its parametric layout: what specifically will be subject to modifications in the future, what parts will make
up the drawing, what is the expected hierarchy of fragments. The conclusions made at this preliminary
analysis stage will define the preferable technique of the assembly model and fragment creation. Assembly
design techniques differ in the ways of creating fragment files:
• “Bottom-up” development. This technique implies creating part drawings first, to be inserted in the
assembly, in a conventional way in separate T-FLEX CAD documents. Assembly drawing creation in
this case implies subsequent assembling of the necessary fragments. In the course of development, one
has to accomplish the task of attaching part images within the assembly drawing.
• “Top-down” development. This technique implies that the part drawings originate from the assembly
drawing. This means, the fragments are created in the assembly context. In this case, development start
from creating the assembly drawing. Already created parts of the assembly drawing, including graphic
lines and nodes belonging to fragments, can be used for creating new fragments. This approach
simplifies creation of associative relations between the assembly fragments and the process of their
attachment. The created fragments are saved into separate documents for further refinement and/or use
in other assemblies.
The described techniques can be combined. For example, a fragment created and inserted in an assembly
according to the “Bottom-up” approach, can later be edited in the assembly context. Vice versa, a fragment
created in the assembly context, can later be used for creating other assemblies within the “Bottom-up”
framework.
Ways of Attaching the Fragment Image to the Assembly Drawing
For placing the fragment image at a desired place in the assembly drawing, in the system T-FLEX CAD
there are several different methods utilizing various tools depending on the problem being solved: