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Using Sketch Driven Assemblies for Design Automation & Re-Use

Patrick BarrettSherpa Design, Inc.Portland, OR

2www.sherpa-design.com

Sketch Driven Assemblies

Why use it? When?

Advantages

How to get started

NX Tools involved

WAVE, IPE’s, Cloning

Skeletons

How we’ve used it with some of our clients

Casting inspection fixtures

Nano / Semi tool

Vehicle structures


Who Am I? What’s a Sherpa?

Engineering Design Services: ‘get there’

Multi-CAD firm

Have the privilege of working with a lot of great companies

NX Mentoring

TCT Article: “Accelerating Design of Complex Products”


Why Do It?

Sketches are visual: easy to see what you’re doing/changing

Capture ‘Tribal Knowledge’

Standardize

Build in Flexibility

Save Time

Even 20% faster is still faster

1 day per week, 1-2 months a year…

Go kayaking


When To Use This Approach

Designs that are changing WRTSize

Position

Configuration

Assemblies that will probably have a long, evolutionary development cycle

Déjà Vu Design (2 or more: automate it!)

Not every design is a good candidate for thisWhere’s the ROI?

Focus on the PROCESS


Make a Model Plan

“Most people don’t plan to fail; they fail to plan”

Model Plans

Identify Key Drivers of the design/assembly

Layout the sketch, expressions, etc. on paper first

Allow you to troubleshoot (easier) your fundamental assumptions when you encounter road blocks

After you have the design programmed on paper, you CAD faster

Example Model Plan


NX Tools Used

Sketcher

WAVE Geometry Linker

IPE’s

Cloning (for re-use)

‘Skeletons’

Geometry that serves to constrain or locate assembly components (or features in linked parts)

Basic NX Applications


Skeletons

Can be whatever geometry makes the most sense to drive your assembly

Assy Solids, Curves, Datums, C-Sys, etc

Lighter the better

Can be inside Master part or it’s own component

Consider how these play with

BOM & Drafting

Teamcenter & your part number system

Cloning


WAVE Geometry Linker

Wave is powerful: use it sparingly*

Updates can take some time on large assemblies

Link the whole Sketch vs. Individual Curves

Smaller feature tree

Can add/delete from the sketch and not have to re-parent anything

*If you do a lot of WAVE consider the full-blown package. Easier to find/troubleshoot

broken links


IPE’s

Share important expressions between parts

Have a plan to where you want the user to update the expressions (Skeleton, TLA, etc). Keep it simple and consistent.

Basic construct: “part_file” :: expression

(Cloning maintains the link, Save-As will point to original

part)


Cloning

The “Intelligent Save-As” for Assemblies

Allows you to Create/Edit Assemblies

Works on file saved on disk, not open session

Maintains inter-part relationships

Re-names Linked Expressions

Maintains relationships between assemblies and their components

Part Number

Scheme is important


Internal Training/Documentation Is Key

Test your process and try to break the model

If someone can’t easily figure it out they will break it or make their own. Period.

Develop internal SME’s

Review the process and evaluate how well this is capturing the design intent. (Things change)

Take big automation tasks in phasesDon’t try to do it all at once

Don’t wait until the post-mortem to do a retrospectiveFind and fix problems as you go


SDA’s In Action

Inspection Fixture for Investment Castings

70% of the assembly design is done in a few hours

Consistent things changing from part to part

Started this 8 years ago (still paying for itself)


SDA’s In Action, 2

Turret Assembly Development

Lot’s of pieces that shifted around during development

Flexible layout

Tried multiple arrangements to get optimized design

Rules pertaining to interpart locations


SDA’s For Fast Conceptual Layouts

Program Manager/Lead could generate skeleton layout model

Add PMI, key notes, etc. to the model

Hand-off to design engineers for detailed design and component placements

Review what had to change to make it work


SDA’s In Action, 3

Vehicle Chassis Structure Tool

‘Standards’ that dictate position of members and sub-components

Vary with overall chassis length & wheel base

Many prismatic components

Get the bulk of this automated and leave room for design/customs


Chassis Sketch Layout

Using established standards.

Experimented with a Part Family at first


The Rear View Mirror

Select candidates based on anticipated ROIDoesn’t make sense for all projects

Make a Model Plan

Design on Paper Program It

Evaluate/Break It Improve It

Document it

Share it and train people

Benchmark your improvement

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Thanks!

Questions/CommentsContact me:[email protected]

Documents

Sketch Driven Assemblies - sherpa-design.com · fNX Mentoring fTCT Article: “Accelerating Design of Complex ... fLayout the sketch, expressions, etc. on paper first fAllow you to