Reverse Engineering

By Niraj M Wanikar, Chief Editor, CNCTimes.com, 2013-09-14 07:33:27

By Paresh Panchal

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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