reverse engineering- process document.ppt

AKUVA INFOTECH PVT. LTD. INNOVATE ENGINEER EXPERIENCE

Copyright Akuva Infotech Pvt. Ltd.

Reverse Engineering

Reverse engineering is defined as the process

of obtaining a geometric CAD model from 3-D points

acquired by scanning existing parts.

It also can be defined as

The process of redesigning an existing part, subassembly, or

product, without drawings, documentation, or a computer

model is known as reverse engineering.

Actually the reverse of the engineering process, going from a

finished product to design.

Used to digitize old parts and systems.

Reverse Engineering



Antikythera mechanism

A famous example of reverse engineering

Ancient mechanical computer

Discovered in wreck in 1900, dated around 150-100 BC

When it was discovered

After Reverse Engineering



Why Use Reverse Engineering?

To bring existing physical geometry into 3D record.

Benchmarking of the given product.

The original manufacturer no longer exists, but a customer needs the product.

The original product design documentation has been lost or never existed.

Inspection and/or Quality ControlComparing a fabricated part to its CAD

description or to a standard item.

Some bad features of a product need to be eliminated.

Might indicate where a product should be improved.

Strengthening the good features of a product based on long-term usage.

Analyzing the good and bad features of competitors products.

Exploring new avenues to improve product performance and features.



Reverse Engineering- Process Flow Chart

Scanning the physical part

Stage wise deviation

analysis and report CAD modeling procedure

Mesh data preparation



SCANNING THE PHYSICAL PART

Part to be scan

Scanner



Obtain multiple views from a 3D scanner

Register views to a single 3D point set

Triangulation

Point set Triangle set



MESH DATA PREPARATION

Usually when scanning, some unwanted data will be captured in the form of noise so cleaning of scan data is necessary before Meshing.

Unwanted data is removed. to reduce the scan data size and optimize the data for fast processing of model decimation is done.

Illustration

Before noise removal After noise removal

Noise



Healing of Mesh data

Mesh data will be exported as STL data. STL data will be imported for modeling. Healing of the STL data will help to remove unwanted holes and appropriate boundary preparation

Holes

Before Healing After Healing



CAD modeling includes mainly two approaches

1. Feature-based modeling or Non-parametric.

2. Parametric-based modeling or History-based modeling

CAD modeling procedure



1. Feature-based modeling or Non-parametric.

Hard to detect features free form surfaces and organic models

Mesh data Cad data Feature recognition Deviation



2. Constraint-based modeling or History-based modeling

Store the complete history of the model building operations. Edit object by changing the history and replaying it(or relevant part of it). Edit operations are simpler and more robust. But complete history often contains irrelevant information.



Constraint-based modeling or History-based modeling

Example: Coffee pod

STEPS

1. Align the scan data to a fixed plain.

2. Select a plane to obtain mesh sketch

3. All Sketches should be constrained.



Example for a fully constrained sketch.

Sketch Deviation



Stage wise deviation analysis

In each stage compare the scan data along with the constrained sketch and correct it

according to the deviation

When a feature is generate compare it with scan data and correct it according to deviation

in case if deviation is not clear in previous step.

This process will help to eliminate most of the mistake usually committed while

constraining a sketch And it will reduce the time taken for doing complete quality check



Stage wise deviation analysis

Before giving the fillet After giving the fillet



Physical Part Scan Data

CAD Model Deviation Report

SUMMERY: Reverse Engineering of a Coffee pod



Conclusion

Reverse engineering Interesting applications directly relevant to industry problems Involves many core issues

Reverse perspective provides new insights in process Design intent essential for working on high abstraction levels

Contact us, If you are interested on reverse engineering, CAD,

geometry, graphics and simulations.



Thank you

reverse engineering- process document.ppt

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