Tips & Techniques
Top-Down Design Tools
Managing Complex Assemblies
Victor Remmers
Holland Engineering Consultants BV
Top-Down Design Philosophy
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© 2006 PTC
Traditional Design Approach
“Bottom-Up Design”

Design of individual components independent of the assembly

Manual approach to ensure that components fit properly and meet the design
criteria

Components and those placed in sub-assemblies are brought together to
develop the top-level assembly

Errors are manually identified and modifications to each component are made
to make the adjustment. As assembly grows, detecting these inconsistencies
and correcting them can consume a considerable amount of time
Top Level
Assembly
Component
Design
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Component
Design
Component
Design
© 2006 PTC
Possible example Bottom Up?
Mate
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© 2006 PTC
Top-Down Design Philosophy
“Top-Down Design”
 Method
of placing critical information in a high-level location
 Communicating
that information to the lower levels of the product
structure
 Capturing
the overall design information in one centralized location
Design
Information
Component
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Component
Component
© 2006 PTC
A more integrated approach….
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© 2006 PTC
Top Down Design Stages – It is a concept.
6-Stage Process
1.
Conceptual Engineering Phase
Layouts and Engineering Notebook
2.
Preliminary Product Structure Phase
Pro/INTRALINK, Model Tree
3.
Capturing Design Intent Phase
Skeleton Models
4.
Manage Interdependencies Phase
Reference Viewer & Reference Graph
5.
Communication of Design Intent Phase
Copy Geoms, Publish Geoms & Shrinkwrap
6.
Population of the Assembly Phase
Automatic Component Constraints & Component Interfaces
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© 2006 PTC
The Bobcat example
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© 2006 PTC
Stage 1
Conceptual Engineering Phase
Layouts and Engineering Notebook
Understand Existing Situation

High-level Requirements

Space Allocation
Define New Space and Motion

2D Sketches

3D Models

Rapid Iteration & Convergence

Animations
Capture Key Design Intent
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
Parameters

Notes

Spreadsheets

Proprietary Data
© 2006 PTC
Stage 2
Preliminary Product Structure Phase
Pro/INTRALINK, Model Tree

Quickly define product hierarchy
•

Before any of the components’ geometry is defined
Intuitive, automatic mapping to “start models”
•
Templates ensure all designs share the necessary common
elements such as layers, views & parameters

Foundation for efficient task distribution

Assembly Population Environments

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•
Pro/E menus and Model Tree pop-up menus
•
Pro/INTRALINK and PDMLink
Component Creation Methods
•
Empty Components; Copy from start models
•
Automatic assembly of default datums
•
Unplaced, Partially- & Over-Constrained Components
© 2006 PTC
Stage 3
Capturing Design Intent Phase
Skeleton Models
What needs to happen?

Capture conceptual design parameters within the context
of the assembly

Capture & control critical object interfaces in a single,
convenient location
How? Skeleton Models…
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
Centralized pathway for communication

Facilitate task distribution

Promote well-organized design environments

Enable faster, more efficient propagation of change

Special Treatment in BOMs, Simplified Reps, Drawings,
Model Tree & Mass Property Calculations

Uniquely supported Scope Control Setting
© 2006 PTC
Stage 4
Manage Interdependencies Phase
Reference Viewer & Reference Graph
Tools to Manage References

External Reference Control
• Ensures
Top-Down Design
methodology is followed
• Incorporate
design management rules
directly into the design
• Ensures
proper design reuse

Pro/INTRALINK

Model Tree

Global Reference Viewer

Reference Graph
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© 2006 PTC
Stage 5
Communication of Design Intent Phase
Publish Geoms, Copy Geoms & Inheritance
Publish Geometry Features

Provides ability to pre-determine the geometry to be referenced by a Copy
Geometry feature

Allows designers to define their interfaces to the rest of the design
Copy Geometry Features

Allows copying of all types of geometry

Surfaces, edges, curves, datums, quilts, copy/publish geometry

Retains copied geometry name and layer settings

Dependency on parent geometry can be toggled

Can be “Externalized”
External Copy Geometry

Build relationships on external models independent of an assembly

Useful for coordinate system assembly practices
Inheritance – Inherit model geometry for one-way associativity
Shrinkwrap (included in Foundation Advantage Package)
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© 2006 PTC
Stage 6
Population of the Assembly Phase
Automatic Component Constraints & Component Interfaces
What tools are available for populating the
assembly?


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Assembly Tools
•
Drag & Drop Placement
•
Component Interfaces
Component Creation
•
Within the context of the assembly
•
Mirror Parts or Subassemblies
© 2006 PTC
How does Top Down Design relate to company goals?
Four Goals from Upper Management
1) Cycle Time Reduction.
2) Increase User Satisfaction with Software.
3) Margin Increase.
4) Cost Reduction.
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© 2006 PTC
Why should you use it?
Benefits:
 Reduced design time
 Reduced errors (right the first time)
 Increased quality
 Better project management visibility
 Concurrent engineering
 Confidence in top-level regeneration
 Knowledge of how modules interface
 Top-level change control
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© 2006 PTC
Example: to design an alternator...
What information should a designer need to work with most times?
Complete Top-Level
Assembly
540 MB
Neighboring
Subassemblies
320MB
All Skeleton Models
in Top-Level
Assembly
70 MB
Subassembly,
with Skeleton Model containing
all required information ~ 20 MB
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© 2006 PTC
What does an example look like?
Three Phases
Pro/INTRALINK
Pro/CONCEPT
ISDX
Pro/ENGINEER
Pro/NOTEBOOK
CONCEPTUAL
DESIGN
CAPTURE DESIGN
CRITERIA
DETAILED DESIGN
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© 2006 PTC
Product Definition
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Product Definition: Engineering Layout
What it is:

First thing done in design cycle

Used to evaluate key interface points

Used to evaluate key components of project
What it is Not:
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
Three dimensional solids

Fully detailed
© 2006 PTC
Advantages of Using a Layout
 Document
design information in one centralized location
 Document
design information before creating solid models
 Investigate
design options without involving the entire assembly
 Easily
make design changes because all of the design
information is contained in one location
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© 2006 PTC
#2 Product Definition: Assembly Structure
What it is:

Virtual Assembly / BOM

Used to organize assembly & assigning of design tasks

Used to input non-geometrical data up-front
What it is Not:
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
Three dimensional solids

Fully detailed

Fully constrained
© 2006 PTC
Advantages of Defining Preliminary Product Structure

Defining the product structure prior to defining geometry can assist
you in organizing the assembly into manageable tasks that can be
assigned to design teams or individual designers.

Associate specific library parts (that are to be used on the project)
with the assembly at the start of the design, preventing confusion
later.
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© 2006 PTC
Advantages of Defining Preliminary Product Structure
Cont…

Submit the assembly to Pro/INTRALINK or PDMLink and assign
models to the appropriate vaults or folders.

Individual designers can focus on specific design tasks instead of on
how their design is going to fit into the overall structure.

Input non-geometrical information such as the part number,
designer’s name, etc., at a very early stage.
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© 2006 PTC
#3 Product Definition: Skeletons
What it is:

Zero-mass geometry

Exact location detail

Minimized geometric detail
What it is Not:
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
Three dimensional solids

Fully detailed
© 2006 PTC
And Definitely Not This!!
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© 2006 PTC
Advantages of Using Skeletons
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
Provides a centralized location for design data

Simplifies assembly creation / visualization

Aids in assembling mechanisms

Minimizes unwanted parent-child relationships

Allows you to assemble components in any order

Controls propagation of external references
© 2006 PTC
Central source for information
Benefits of Communicating Information From a Central Source

Task distribution

Concurrent Modeling

Managing External References
Tools
 Declaration

Publish Geometry

Copy Geometry
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© 2006 PTC
Hierarchy
Top_level.asm

Top_level_skeleton.prt

Sub_assy_1.asm
Sub_assy_1_skeleton.prt

Sub_assy_2.asm
Sub_assy_2_skeleton.prt






Sub_assy_x.asm
Sub_assy_x_skeleton.prt
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© 2006 PTC
3D Design … Finally!
 The
foundation is set … but topologically modifiable … it’s time
for 3D.
 With
Reference Control Manager, you are safe to create your
parts directly in the assembly.
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© 2006 PTC
More Than Meets The Eye!
Interchangeability:
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
Family of Tables

Interchange Assembly

Layout Declarations
© 2006 PTC
Power of Top-Down Design
To Achieve Advanced Automation, consider using:
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
Relations

Pro/Program
© 2006 PTC
Miscellaneous Tips
Separate Part Versus Assembly for Skeleton Features

Avoid constructing assembly-level skeleton features since the system
requires that you perform all edits of these features in Assembly mode.
• The
components can become an obstruction and degrade performance.
• Furthermore,
you cannot easily reuse skeleton features at the assembly
level in other subassemblies. By using a separate part file, you can edit the
feature in Part Mode and reassemble it into many different assemblies.
Geometry Features

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Place all static information in a skeleton as early as possible and place
all dynamic information later in the design process cycle.
© 2006 PTC
Miscellaneous Tips
Datums for Skeleton Models

Consider renaming skeleton datums to “sk_”
Visualization

Use simplified reps and transparency prolifically to make viewing easier

Use “display states” to highlight different items at different times

Use surfaces to clarify meaning of centerlines & axes
Conceptualization

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Don’t be afraid to use simple hand sketches before delving into complex
situations … it’s NOT illegal
© 2006 PTC
Pro/E Wildfire Enhancements
High-performance Assembly Modeling
Lightweight Components

Represent common components with lightweight
graphics for optimum display speed

Accurate mass properties and BOMs

Customizable symbolic representations
Flexible Components

Represent multiple states of a
single component in an assembly

Addresses critical need for consistency
between BOM and assembly model
Intelligent Regeneration

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Assembly regeneration is up to 80% Faster!
© 2006 PTC
Highlights of Top-Down Design
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
Capture knowledge, or design intent, allowing you to
concentrate on significant issues by making the software
perform tedious, repetitive calculations.

Enable the framework for interchangeability of components
allowing for high-velocity product development by supporting
rapid iterations of product variations.

Create a concurrent design environment by spreading project
design responsibility across many organizational levels.
© 2006 PTC
New in Advanced Assembly in Wildfire 3.0
Data Sharing Dashboard
The Data Sharing dashboard consolidates the Merge, Cutout, and Inheritance features in
a modern user interface.
Enhancements to Data Sharing features in a new dashboard offer many benefits:
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•
Allows changing of multiple feature types at any point
•
Offers a user-friendly user interface with easy access to commands
•
Supports object-action workflow for increased productivity
•
Consolidates Data Sharing features, such as Merge, Cutout, and Inheritance
© 2006 PTC
New in Advanced Assembly in Wildfire 3.0 (#2)
Top-Down Design with Mechanism Assemblies
You can now design a skeleton model that includes motion.
Motion skeletons are available in Assembly, allowing motion to be incorporated into the model
at the beginning of the design process. There is no longer a need to recreate an assembly to
include a mechanism analysis.
You can create mechanism bodies and connections as a motion skeleton, then run a simple
kinematic analysis to ensure that the skeleton provides the appropriate degrees of freedom.
You can then create and assemble components to the motion skeleton. Motion skeletons are
defined in the same way as normal assembly skeletons and include reference control settings.
They do not appear in the assembly bill of materials.
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© 2006 PTC
POWER OF
TOP DOWN
DESIGN!!!
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© 2006 PTC