Lecture # 08 Reverse Engineering

BAHIR DAR UNIVERSITY
BAHIR DAR INSTITUTE OF TECHNOLOGY (BiT)
FACULTY OF MECHANICAL AND INDUSTRIAL
ENGINEERING
Rapid Prototyping & Reverse Engineering
[MEng6123]
Reverse Engineering

Reverse Engineering
Definition
• It is described in Wikipedia as:
• … the process of extracting knowledge or design information from
anything man-made. The process often involves disassembling
something (a mechanical device, electronic component, computer
program, or biological, chemical, or organic matter) and analyzing its
components and workings in detail.

Reverse Engineering
Definition
• A process of discovering the technological principles of a human made device,
object or system through analysis of its structure, function and operation
• Systematic evaluation of a product with the purpose of replication.
 Design of a new part
 Copy of an existing part
 Recovery of a damaged or broken part
• An important step in the product development cycle.

Importance
• To develop a systematic approach to think about the engineering
design of devices and systems
• We may not start from the very beginning to develop a new product
every time.
• We need to optimize the resources available in our hands and reduce
the production time keeping in view of the customers’ requirements.
• For such cases, RE is an efficient approach to significantly reduce
the product development cycle.

Why Reverse Engineering ?
The original manufacturer of a product no longer produces the product
The original manufacturer no longer exists, but a customer needs the
product.
The original design documentation has been lost or never existed.
There is inadequate documentation of the original design
Some bad features of a product need redesigned.
To strengthen the good features of a product based on long-term
usage of the product
To analyze the good and bad features of competitors' product

Why Reverse Engineering ?
To explore new avenues to improve product performance and features
To gain competitive benchmarking methods to understand competitor's
products and develop better products
The original CAD model is not sufficient to support modifications or
current manufacturing methods
The original supplier is unable or unwilling to provide additional parts
The Original Equipment Manufacturers are either unwilling or unable to
supply replacement parts, or demand inflated costs for sole-source
parts
To update obsolete materials or antiquated manufacturing processes
with more current, less-expensive technologies

• A three-phase process
• Scanning,
• Point processing, and
• Application specific geometric
model development.
Reverse Engineering–The Generic Process

• Reverse engineering strategy must consider the following
 Reason for reverse engineering a part
 Number of parts to be scanned–single or multiple
 Part size–large or small
 Part complexity–simple or complex
 Part material–hard or soft
 Part finish–shiny or dull
 Part geometry–organic or prismatic and internal or external
 Accuracy required–linear or volumetric

Phase 1–Scanning/ Digitization of the object/ Data Capturing
• This phase is involved with the scanning strategy–
• Selecting the correct scanning technique,
• Preparing the part to be scanned, and
• Performing the actual scanning to capture information that
describes all geometric features of the part such as steps, slots,
pockets, and holes.
• 3D scanners are employed to scan the part geometry, producing clouds
of points, which define the surface geometry.
• There are two distinct types of scanners, contact and noncontact

Phase 1–Scanning/ Digitization of the
object/ Data Capturing
Contact Scanners
 Employ contact probes that automatically
follow the contours of a physical surface
 Based on Coordinate Measuring Machine
(CMM) technologies, with a tolerance
range of +0.01 to 0.02 mm.

Phase 1–Scanning/ Digitization of the object/
Data Capturing
Contact Scanners
 The probes must deflect to register a point;
hence, a degree of contact pressure is
maintained during the scanning process. This
contact pressure limits the use of contact
devices for soft, materials such as rubber
cannot be easily or accurately scanned.

Data Capturing
Noncontact Scanners
 Capture data with no physical part contact.
 Use lasers, optics, and charge-coupled device
(CCD) sensors to capture point data
 Can capture large amounts of data in a
relatively short period of time,
 The typical tolerance of noncontact scanning
is within ±0.025 to 0.2 mm.
 Some noncontact systems have problems
generating data describing surfaces,
which are parallel to the axis of the laser

Data Capturing
Noncontact Scanners
 Employ light within the data capture
process. This creates problems when the
light imposes on shiny surfaces, and hence
some surfaces must be prepared with a
temporary coating of fine powder before
scanning.

Phase 2– Point Processing
• Involves
importing the point cloud data,
reducing the noise in the data collected, and
reducing the number of points.
• Allows us to merge multiple scan data sets.
Sometimes, it is necessary to take multiple
scans of the part to ensure that all required
features have been scanned.
• This involves rotating the part; hence each
scan datum becomes very crucial.

Phase 2– Point Processing
• Multiple scan planning has direct impact on the
point processing phase. Good datum planning for
multiple scanning will reduce the effort required
in the point processing phase and also avoid
introduction of errors from merging multiple
scan data.
• Software packages are generally needed for
point processing.
• Simplify the data
• Polygon meshing
• Polygon editing

Phase 3– Application Geometric Model Development
• The generation of CAD models from point data
• This phase depends very much on the real purpose for reverse
engineering.
• For example, if we scanned a broken injection molding tool to produce
a new tool, we would be interested in the geometric model and also in
the ISO G code data that can be used to produce a replacement tool in
the shortest possible time

Phase 3– Application Geometric Model Development
• One can also use reverse engineering to analyze “as designed” to “as
manufactured”.
• This involves importing the as designed CAD model and superimposing the
scanned point cloud data set of the manufactured part.
• The RE software allows the user to compare the two data sets (as designed to
as manufactured). This process is also used for inspecting manufactured parts.
• Defining surface boundaries
• Applying NURBS
• Exporting the data

Rapid Prototyping in combination with RE
• A group of techniques to quickly fabricate a scale model of a physical
part or assembly using 3D CAD data
• Integration of reverse engineering and rapid prototyping is being used
for getting product to the market quickly by resolving a long-standing
conflict between design and manufacturing

(d) Fabricated RP Model
(a) wooden pattern, (b) cloud of points (c) 3D CAD model
Rapid Prototyping in combination with RE

Levels of Analysis in Reverse Engineering
1. System-Wide Analysis
2. Subsystem Dissection Analysis
3. Individual Component Analysis

System-Wide Analysis
• Customer Requirements
• Engineering Requirements
• Functional Specifications
• Prediction of Subsystems and Components

Subsystem Dissection Analysis
• Document Disassembly
• Define Subsystems
• Determine Subsystem Functional Specifications
• Determine Subsystem Physical/Mathematical Principles

Individual Component Analysis
• Repeat Dissection Steps to Individual Component
• Define Component Material Selection and Fabrication Process
• Suggest Alternative Designs, Systems, Components, and Materials

Material Characteristics and Analysis
• Important for material identification and performance evaluation of a
part made using reverse engineering.
• One of the most frequently asked questions in reverse engineering is
what material characteristics should be evaluated to ensure the
equivalency of two materials.
• Theoretically speaking, we can claim two materials are “the same” only
when all their characteristics have been compared and found equivalent.
• This can be prohibitively expensive, and might be technically
impossible.

• Which material properties are relevant & need to be evaluated in a
reverse engineering project ?
• ultimate tensile strength,
• fatigue strength,
• creep resistance,
• fracture toughness……,
• In answering this question, the engineer needs at least to provide the
following elaboration:
1. Property criticality
2. Risk assessment
3. Performance assurance

1. Property criticality: Explain how critical this relevant property is to
the part’s design functionality.
2. Risk assessment: Explain how this relevant property will affect the
part performance, and what will be the potential consequence if this
material property fails to meet the design value.
3. Performance assurance: Explain what tests are required to show the
equivalency to the original material.

• The mechanical, metallurgical, and physical properties are the most
relevant material properties to reverse engineer a mechanical part.
• The mechanical properties are associated with the elastic and plastic
reactions that occur when force is applied.
• The primary mechanical properties include ultimate tensile strength,
yield strength, ductility, fatigue endurance, creep resistance, and
stress rupture strength.

• Many mechanical properties are closely related to the metallurgical and
physical properties.
Metallurgical properties
• refer to the physical and chemical characteristics of metallic elements
and alloys, such as the alloy microstructure and chemical composition.
Physical properties
• refer to the inherent characteristics of a material, such as the density,
melting temperature, heat transfer coefficient, specific heat, and
electrical conductivity.

Material Identification and Process Verification
• Material identification and process verification are essential to reverse
engineering.
• Involves analyzing chemical composition, microstructural characteristics,
grain morphology, heat treatment, and fabrication processes.
• The chemical composition of a material determines its inherent properties.
• The microstructural characteristics are closely related to a material’s
mechanical properties.
• Grain morphology reveals the grain size, shape, texture, and their
configuration in a material.

Composition Determination/Identifying alloying Elements
• Mass Spectroscopy
• Inductively Coupled Plasma–atomic Emission Spectroscopy
• Electron Specimen Interaction and Emission
• X-ray analysis

Microstructure Analysis
• The chemical composition shows what an alloy is made of.
• Microstructure is an alloy’s footprint that traces back its heat treatment
history and fabrication flow path, and shows how this alloy is manufactured.
• Light Microscopy
• Scanning Electron Microscopy
• Transmission Electron Microscopy

Manufacturing Process Verification
• The four primary parameters in manufacturing are temperature, time,
force, and atmosphere, such as
the solution heat treatment temperature,
aging treatment time,
force used in forging or press, and
atmosphere in which the part is cast or welded.
• .

• The macro-structural appearance, such as surface finish, and
microstructural features, such as grain morphology of the finished
parts, usually provide the first evidence of how they are made.
• Therefore, reverse engineering, a manufacturing process, often starts with
macrostructure examination and microstructure analysis to determine the
temperature, time, force, and atmosphere that the Original Equipment
Manufacturer (OEM) used to produce the original parts.

• The three most utilized manufacturing processes to produce mechanical
components are casting, product forming, and machining.
• To assemble individual parts together, many joint methods are used,
such as soldering, blazing, and welding.
• To improve the strength and performance of the product, many
engineering treatments, such as heat treatment and surface treatment,
ranging from coating to shot peening, are commonly applied.
……… ??? ……

Lecture # 08 Reverse Engineering

Recommended

More Related Content

What's hot (20)

Similar to Lecture # 08 Reverse Engineering (20)

More from Solomon Tekeste (11)

Recently uploaded (20)

Lecture # 08 Reverse Engineering