| Imagine
being asked to supply customers with accurate drawings
of their parts. This may sound ironic, but many companies
do not have up-to-date drawings of their parts and some
have never had part drawings of any kind.
Precision
manufacturers can offer part drawings to their customers
using a process called reverse engineering. Reverse
engineering is defined by the Military Handbook MIL-HDBK-115
(ME) as the process of duplicating an item functionally
and dimensionally by physically examining and measuring
existing parts to develop the technical data (physical
and material characteristics) required for competitive
procurement. Put more simply, reverse engineering is
the process of creating a part drawing by measuring
the part to determine dimensions and attainable tolerances,
when no formal specifications exist.
Tolerance development,
often the most difficult aspect of the reverse engineering
process, can be achieved only from a thorough understanding
of the part and how it is used.
Reverse engineering is
an ideal process to use in the following situations:
A physical model of a product has
been produced, but no drawings exist.
Drawings have been created, but
working prototypes have been modified.
Worn or broken parts, for which
there are no drawings, must be replaced and there is
no source of supply.
A 3D CAD system is introduced to
a company, and all existing products must be loaded
into the system.
A disaster destroys parts records.
Computer
Aided Reverse Engineering (CARE) also can be
useful in the redesign process, as well as in the introduction
of new products. In some cases, it may be easier to
develop drawings of an existing product and modify them
in a 3D CAD system than create drawings from scratch.
This is especially true for complex shapes that can
be difficult to conceptualize.
Computer Aided
Reverse Engineering (CARE) can be accomplished using
a variety of tools and technologies. Generally, the
complexity of the part being reverse-engineered will
dictate the type of equipment and software used.
The simplest reverse
engineering process is manual measurement and data collection
of a physical model's dimensions. In this process, hand
tools such as micrometers, vernier calipers and gages
are used to capture the critical dimensions needed to
generate a part drawing. A more sophisticated approach
is to use a hard probe and a manual Coordinate
Measuring Machine (CMM). The CMM operator maintains
contact between the hard probe and the surface being
measured to record as many dimensions as possible. The
most effective reverse engineering techniques minimize
measurement errors by gathering and processing data
electronically. In such a process, a physical model
is measured and the dimensions immediately digitized
and collected in a database. Next, this digitized data
is transferred to a CAD system, where surfaces are developed
and drawings are finalized. Besides reducing the risk
of measurement errors, processing data electronically
significantly reduces the time required for the overall
reverse engineering effort.
Digitizers can
range in complexity and accuracy from hand-held units
to rigid laser-based systems. Even traditional CMM machines
have software accessories to take measurements and translate
them into various CAD formats. Manual digitizers are
generally the least expensive and let the users work
in a free form manner. Users simply touch the model
with the sensing tip, and data is recorded. Laser and
white light digitizers are usually more costly, but
bring increased automation to the process and provide
more precise control of measurements. Laser and light
digitizers scan the profile of a model and automatically
generate a large amount of data points, or a series
of cross sections. As the need for reverse engineering
has grown, there has been an increase in the number
and types of commercial packages available. These packages
can be divided into two groups, stand-alone systems
and CAD integrated systems.
If you have the
ability to measure a part and create an accurate CAD
drawing, you can offer reverse engineering service to
your customers. Many companies have discovered the business
growth potential.
Computer Aided Reverse
Engineering (CARE) In Practice
As I described
reverse engineering as a process in which parts are
carefully measured and tolerances are developed prior
to generating CAD drawings. The most common application
for reverse engineering is the reproduction, or modification,
of an existing part for which there is no formal drawing.
We at CAM TOOLS
has reverse engineered many products for our customers,
we are using reverse engineering techniques to help
our customers for many years. In our reverse engineering
process, we has employed multiple scanning methods to
capture part geometry. Scanning methods is depend upon
accuracy requirements and geometrical shape of the components.
By using IMAGEWARE a high-end point cloud processing
software from SDRC, CAM TOOLS personnel convert scanned
data into Class-A surface model. The surface model can
be directly imported into I-DEAS a high end MCAD software
to generate 3D Solid model, base of solid model 2D drawing
are made in I-DEAS drafting setup. After conforming
3D model form our customers we start with 3D mould design
of article.
We have association
for digitizing facilities such as :-
a) White light
Scanner
b) Renishaw cyclone
series-2
c) Faro arm.
CASE STUDY
NO1:- Reverse Engineering & 3D Mould Design of
Grab of Scooter.
One of CAM TOOLS customers needed
to quickly Reverse Engineering and separation of Core
& Cavity of Scooter Grab that were designed without
CAD models. CAM TOOLS Engineers used Ranishaw Retro-Scan
digitizing technique to digitize part and obtain dense
point cloud. Based on point cloud class-A surface is
generated on IMAGEWARE, same surface is transferred
to I-DEAS to offset the surface and to add other engineering
details
Customer :- B.S.
Mould is one of the Leading Industrial Mould & Moulding
company in Mumbai.
Problem :- Development of Grab 3D Model
from upgraded Clay model.
The company required :-
1) Complete 3D CAD model of the GRAB
through scanning of physical model.
2) The surface
should be of high quality for aesthetics.
3) The surface
should be tangent continuous to avoid any design and
manufacturing problems.
Solution
Process ( Reverse Engineering ) :
A) Scanning
:-
The The scanning service was provided
by CAM TOOLS using Ranishaw Retro-Scan digitizing system.This
digitizing technique was chosen because it was easily
available in mumbai..The scanning process resulted in
raw data sets of several million data points.
B) Surface Modeling :-
Using this scanned data, high quality,
high accuracy surface model was then generated by CAM
TOOLS team of expert CAD engineers using Imageware Surfacer-LT
as the surfacer modeler.The final surface model of the
part was thoroughly checked and verified to meet the
quality requirements. The model was then finally modified
to facilitate efficient export into customer’s
CAD system for approval of the model.
C) 3D Solid Modelling :-
After conforming outer surfaces
from customer we started generating solid model by using
IDEAS Artisan Series 4 as a solid modeller, by using
shelling command we are able to quickly obtain solids
D) 3D Mould Design :-
After approving CAD model from
Customers CAM TOOLS team of expert Tool Engineers using
IDEAS Artisan-4 modeler started generating parting surfaces
& other mould details. Based on 3d solid models
of mould parts 2d drawing were prepared for manufacturing.
Digitizer :- Ranishaw
Retro-Scan digitizing.
Scanning time :- 20 hrs for complete
model.
Scan procesing software :- Tracecut,
Imageware surfacer LT .
Surface modeler :-
Imageware surfacer LT.
Accuracy of surface modeling :- 0.2
m.m.
Tangent Continuity :- 0.5 deg.
CAD Modelling :-
120 hrs.
Solid Modelling :- 40 hrs.
3D Mould Design :-
30 hrs.
Time Saving over older
processes :- 70 %
CASE STUDY
NO2:- Reverse Engineering & 3D Mould Design of
Car Reflector.
One of CAM TOOLS customers needed
to quickly Reverse Engineering and separation of Core
& Cavity of Scooter Grab that were designed without
CAD models. CAM TOOLS Engineers used Steinbichler Comet
400 scanner scann part and obtain dense point cloud.
Based on point cloud class-A surface is generated on
IMAGEWARE, same surface is transferred to I-DEAS to
offset the surface and to add other engineering details
Customer :- Sweet
Traders is supplier of automobile parts to general market
as spares.
Problem :- Development of Reflector
from existing Reflector.
The company required :-
1) Complete 3D CAD model of the Reflector
through scanning of physical model.
2) The surface
should be of high quality for aesthetics.
3) The surface
should be tangent continuous to avoid any design and
manufacturing problems.
Solution
Process ( Reverse Engineering ) :
A) Scanning :-
The scanning service was provided
by CAM TOOLS using Ranishaw Retro-Scan digitizing system.This
digitizing technique was chosen because it was easily
available in mumbai..The scanning process resulted in
raw data sets of several million data points.
B) Surface
Modeling :-
Using this scanned data, high quality, high accuracy
surface model was then generated by CAM TOOLS team of
expert CAD engineers using Imageware Surfacer-LT as
the surfacer modeler.The final surface model of the
part was thoroughly checked and verified to meet the
quality requirements. The model was then finally modified
to facilitate efficient export into customer’s
CAD system for approval of the model.
C) 3D
Solid Modelling :-
After conforming outer surfaces
from customer we started generating solid model by using
IDEAS Artisan Series 4 as a solid modeller, by using
shelling command we are able to quickly obtain solids
D) 3D
Mould Design :-
After approving CAD model from
Customers CAM TOOLS team of expert Tool Engineers using
IDEAS Artisan-4 modeler started generating parting surfaces
& other mould details. Based on 3d solid models
of mould parts 2d drawing were prepared for manufacturing.
Digitizer :- Ranishaw
Retro-Scan digitizing.
Scanning time :- 20 hrs for complete
model.
Scan procesing software :- Tracecut
,Imageware surfacer LT .
Surface modeler :-
Imageware surfacer LT.
Accuracy of surface modeling :- 0.2
m.m.
Tangent Continuity :- 0.5 deg.
CAD Modelling :-
80 hrs.
Solid Modelling :- 30 hrs.
3D Mould Design :-
30 hrs.
Time Saving over older
processes :- 70 %
Advantages
of Reverse Engineering :-
Some of the benefits of using advance reverse
engineering techniques are
1) Reduce time
& efforts for transferring CAD information from
shop floor to Parent CAD systems.
2) Reverse Engineering
products and tools fo which incomplete data is available.
3) Improve Quality
of the products by doing virtual to physical part comparison
and doing modification thus achive zero defects.
4) Finger print
the dies and moulds so as to maintain uniformity between
shop floor and CAD models.
5) Reduce the
complete cycle time within the Design and R & D
department.
6) Using software
as Data Bridge for transferring and cleaning the electronic
files from different CAD systems.
7) Implement
Corporate-wide quality awareness
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