Reverse Engineering The title of this module is Reverse Engineering.

Reverse Engineering The title of this module is Reverse Engineering.
©2000 The Ohio State University

“Why would you want to do that?”
Reverse Engineering “Examining competitive or similar or prior products in great detail by dissecting them or literally taking them apart.” - Dym & Little “What does this do?” “How does it do that?” “Why would you want to do that?” The purpose of Reverse Engineering is to understand how and why a current design has come to be. Most often this task is completed on physical products that can be taken apart, examined and put back together for continued testing. These same Reverse Engineering procedures are also useful in deciphering chemical compounds, industrial procedures, manufacturing processes and computer programs. Reverse Engineering is often chosen by engineers or design teams who aim to build a competitive or superior product to one that is currently on the market. In the end, the goal is to save time and gain insight into how others have approached similar design challenges. There is no need to reinvent the wheel if a successful design already exists and can simply be improved upon. Dym and Little explain reverse engineering as, ‘examining competitive or similar or prior products in great detail by dissecting them or literally taking them apart.’ Questions to be asked would include, “ what does this do? How does it work? And Why would you want to do that?’

Reverse Engineering Gain insight into our own design problem by looking at how other people have addressed the same issues. Restrictions: Expensive designs Protected by patents May be the competitor’s design Design may not work very well Reverse Engineering can often times reveal ingenious solutions to current challenges and hurdles facing an engineer. An engineer should spend time, though, thoroughly investigating and testing the competitive solutions in order to avoid treading upon patents or rebuilding bad designs. This may involve extensive research of the legal attachments associated with a certain design or similar designs that exist on the market. And, although a design may solve the problem it may have certain material or manufacturing requirements that make its design quite expensive. Of course, the design may not be very robust and may not be the best solution for the given task after all. This usually opens the door for a redesign if an improved design or method can be determined. Reverse Engineering should serve as inspiration for, not just a solution to, a design challenge.

Reverse Engineering Methodology
Investigation, Prediction and Hypothesis Reverse Engineering Concrete Experience: Function & Form Design Models Modeling & Analysis Design Analysis Reverse Engineering is primarily used as a tool during the first stages of a complete design process. An engineer will often times investigate the marketplace for products similar to his/her new design that can be taken apart and examined inside and out for insight and time savings. This investigation may begin with general searches on the internet or in the Thomas Register for products with certain similarities to the new product. This first step begins the methodology behind Reverse Engineering. Once a product has been located, the product will be tested and attempts will be made to determine how exactly it functions. This will lead into disassembly and a concrete understanding of how and why a design works. These Reverse Engineering steps then lead the way to new designs, redesigns and hopefully successful solutions. Parametric Redesign Adaptive Redesign Original Redesign Redesign Adapted from Otto and Wood’s “Reverse Engineering and Redesign Methodology” UT Austin

1. Investigation, Prediction and Hypothesis Develop black box model Use / Experience product List assumed working principles Perform economic feasibility of redesign State process description or activity diagram The Reverse Engineering methodology has been broken down into detailed steps here that will become clearer and easier to navigate when the included Reverse Engineering project is completed. This overview illustrates the level of detail that should be maintained in order to successfully dissect a product or process especially as the complexity of the design increases. Reverse Engineering is much more than taking a product apart and looking at the internal components. It is just as important to understand why the components are where they are, what they are made of, how they perform, how they were made, etc. The first step of Reverse Engineering is Investigation, Prediction and Hypothesis. The engineer is taking a step back and looking at the product or process from a simple, consumer-oriented perspective. At this stage we want to understand the basics of how and why it works. Before cracking open the case, we want to begin predicting how the product is put together. This serves as a brainstorming process for the redesign and allows us to begin connecting engineering fundamentals with the consumer oriented view of the product. If a product is advertised as being “strong”, what exactly is this referring to? Does the product have a large, powerful motor or is there a gearbox involved? Why would one option be chosen over the other? Would one cost more than the other? How would this option be manufactured? What would the lead time be? These are just examples of questions that can be posed and ideally answered by the Reverse Engineering team. The black box model is a simple diagram of what goes in and what goes out. If power is required for a product, that’s considered an input. If exhaust fumes, movement or noise are created, that’s an output. The fundamentals of black box models will be discussed later in this presentation. We would also like to take a look at the complexity of the design and begin thinking about the economic reality of a redesign. It may be decided that an off-the-shelf part adaptation may be better than a complete redesign of a product once the design and manufacturing costs are estimated. At the same time, we may discover an easier and cheaper solution simply by studying this design. New material or manufacturing processes could significantly reduce component cost. Or, we may be able to eliminate redundant or unnecessary components to save on assembly costs.

2. Concrete Experience: Function and Form Plan and execute product disassembly Group defined systems and components together Experiment with product components Develop free body diagrams Identify function sharing and compatibility Transform to engineering specs. and metrics The second step of Reverse Engineering is gaining Concrete Experience with the product. The engineer will first use the product, as recommended by the manufacturer, to gain insight into the product’s ability to handle the advertised performance criteria. Can the photocopier truly reproduce color photographs without distortion and maintain the advertised quality, for example? Then, the engineer will begin to plan the product’s disassembly in such a way that it becomes clear how the product’s components interact with one another. How does the trigger turn the motor on and in turn drive the chuck, for instance? These components will be divided into defined systems and components with their interactions recorded as well. This process is known as System Level Design and will be discussed in greater detail later in the module. It is important to carefully illustrate the disassembly of any product or component with photographs or sketches in order to be able to reassemble the product at the end if further testing is required. Force flow diagrams can then be drawn to illustrate how power is transferred through the product. What is the interaction between piston, connecting rod and crankshaft during each stroke in a 4 cycle motor? Describe the conservation of energy in the system? Finally, an engineer can begin measuring and estimating actual values for the components and interactions that were previously investigated. How much force is required to turn on the blender? How fast is the motor spinning? What is the measured torque? Clearly only the measurements of interest need to be determined by the engineer based upon the design goal.

3. Design Models Identify actual physical principles Constantly consider the customer Create engineering models and metric ranges Alternatively or concurrently build prototype to test parameters Once the product has been completely dismantled, tested, and measured the process of designing or redesigning then begins. The design process itself is a wide open subject, with an infinite number of recommended pathways to take in order complete to the design process. In this case, though, an engineer is building upon the experience he/she has gained by Reverse Engineering products similar to or competing against their design. By now an engineer should have a good understanding of what processes are effective at completing a specific task, and those that can be improved upon. Three specific design models (Parametric, Adaptive, Original) are offered in the following slides. It is important to remember that the products that were dissected were developed to meet the specific goals and objectives of a particular client. The designer should exercise caution and remain focused on the current client’s needs at all times. In addition, the process of Reverse Engineering, though often times enlightening, can also be stifling. Simply because a design works does not mean that it cannot be improved upon or that another design will not be more efficient. Finally, intellectual property and ethical issues are directly tied to reverse engineering. It is inappropriate, and often times unlawful, to claim the design of another. Specific avenues for searching out patents will be discussed later in another module. The design process should begin by identifying the specific principles required for a product. How much temperature must it resist? How much liquid must it hold? How fast must the linkage rotate? A certain group of acceptable ranges can be determined based upon marketing expectations and customer feedback, for instance. The designer must also determine how accurately these values will be assigned. The cost of higher tolerances is exponential and must be considered in all new designs. Small models and prototypes are also part of the early design stages. These allow designers and engineers to test, on a small scale, how accurately their designs will function. Even non-functioning prototypes can provide valuable insight into the required size, weight or feel of a new product.

4. Design Analysis Calibrate model Create engineering analysis, simulation or optimization Create experiment and testing procedures Once a model has been designed the engineer should now begin to design simple experiments to test and calibrate the model. The advent of computer simulations has begun to offer unprecedented design advantages over the traditional build-test-fail-rebuild techniques of the past. It is now possible for an engineer to completely model a new design and measure stresses, strains, load bearing capabilities, center of gravity, etc., under given loading conditions and initial conditions. A testing procedure should be determined based on expected “real world” situations and conditions.

5. Parametric Redesign Optimize design parameters Perform sensitivity analysis and tolerance design Build and test prototype There are three basic redesign options once a product has been reverse engineered. A parametric redesign is defined as an evolution of the current design. New design variables are chosen in order to satisfy the designer’s needs such as a stronger case, more robust mechanism or faster motor. A list of acceptable design variable ranges should be determined. The new prototype should be tested in order to identify remaining areas for improvement.

6. Adaptive Redesign Recommend new subsystems Search for inventive solutions Analyze force flows and component combinations Build and test prototype Adaptive redesign traditionally leaves the current design unaltered, but rather builds upon it in order to satisfy a new function. New subsystems may be added to the current system during this process. A new subroutine may be added to a current MATLAB computer routine, for instance, in order to take advantage of the current routine while providing a new capability. A list of acceptable design variable ranges should be determined. The new prototype should be tested in order to identify remaining areas for improvement.

7. Original Redesign Develop new functional structure Choose alternatives Verify design concepts Build and test prototype An original redesign starts from scratch using the concepts, physical principles and results from the reverse engineering process to create a new product idea. New designs are often times inspired just from the knowledge of how another product truly functions, what it was made from, and how it was manufactured. Again, a list of acceptable design variable ranges should be determined. The new prototype should be tested in order to identify remaining areas for improvement.

System Level Design Reverse Engineering requires understanding the product or design as a system or set of systems that work and interact together. This concept is known as System Level Design. (Read slide)

System Level Design System = Components + Connections Components
Physical - pick-up, measure, draw on CAD Functional - flowcharts, difficult to define Connections Fundamental - intended design Incidental - created by physical proximity of components (vibration, heat transfer, etc.) A system is comprised of various components and the connections between them. Components should be investigated by two different methods. First, each component should be handled, dimensions measured, and drawn on CAD. Then its function needs to be identified. The use of a flowchart is recommended for complex components. Next, the connections between the components need to be established. These connections can be broken up into two types: fundamental and incidental. Fundamental connections are those that were intended while incidental connections are “side effects” such as vibration.

System Level Design Develop black box model avoiding bias.
Graphic representation of the system or object being designed, with inputs shown entering on the left and outputs leaving on the right. A black box breaks down the inputs and the outputs of the components. Developing a black box model helps to avoid any bias in the analysis. As seen here, the graphic representation of the system or object is placed in a “black box.” Inputs are shown as entering in the left and outputs are shown as leaving in the right side. Inputs Outputs System

Convert RF Signal To Sound At Desired Level
System Level Design Example: Radio Heat & Noise Power Convert RF Signal To Sound At Desired Level Sound RF Signal Status Indications (Volume, Freq.) For example, a radio has three inputs: electrical power, the RF signal, and user choices such as volume. The radio extracts the desired signal from the incoming RF carrier signal and then converts this electrical signal into sound at the desired volume. The fundamental outputs are sound and status indications such as volume, while the incidental outputs include heat and noise. User Choices (Volume, Freq.) RF=radio frequency

System Level Design Continue with the glass box approach.
Identify sub-systems Electrical Mechanical Task oriented Define interactions and flow of forces Intentional Unintentional Wires, signals, material, data, etc. The glass box approach identifies the sub-systems and defines the interactions and flow of forces within the black box. The subsystems may include the electrical, mechanical and task oriented functions. The interactions and flows of forces between these subsystems are then drawn to show the connection between each subsystem.

‘Glass Box’ Example Ink Jet Printer
Here is an example of the glass box analysis for an ink jet printer. (need explanation) Ink Jet Printer

System Level Design Final Breakdown For every piece or component of interest, discuss: 1) How was it made 2) Why it was made this way 3) Design issues 4) The material it is made out of 5) Complexity and cost 6) Ergonomic issues 7) Interaction with other components In the final breakdown, every component or piece of interest should consider: 1) How was it made 2) Why it was made this way 3) Design issues 4) The material it is made out of 5) Complexity and cost 6) Ergonomic issues 7) Interaction with other components

Reverse Engineering Example
Example Project Black and Decker Hedge Trimmer An example of the reverse engineering techniques will be demonstrated in this presentation. We will show an example of this process for hedge trimmer.

Investigation, Prediction and Hypothesis Reverse Engineering Concrete Experience: Function & Form Design Models Modeling & Analysis Design Analysis As shown earlier, the reverse engineering flow involves these steps. Parametric Redesign Adaptive Redesign Original Redesign Redesign Adapted from Otto and Wood’s “Reverse Engineering and Redesign Methodology” UT Austin

Reverse Engineering Example Project
1. Investigation, Prediction and Hypothesis Develop Black Box Model Assemble product and conduct a test What goes in? What comes out? (i.e. power, noise, heat, vibration) Electric Power Noise Finger Switch Hedge Trimmer Blade Movement In the first step, a black box model is created simply showing the system’s inputs and outputs. For the hedge trimmers, electrical power, the finger switch, and the safety switch all serves as system inputs. When in operation, the hedge trimmers produce blade motion, noise, vibration, and heat. Safety Off Vibration, heat

Conduct a single test of the performance of the product: Record product performance attributes Shearing speed 3300 strokes/min 5:1 Gear reduction = 16,500 RPM for the motor Next, the hedge trimmer is tested tested to determine the blade’s motional frequency. With 5:1 gear reduction, the speed of the motor is found to be 16,500 rpm for the motor.

What is the market for this product? “Suitable for small shrubbery” – Black & Decker Product Catalog Homeowners with small yards and limited budget For use only 3-4 times a year What are the costs associated with this product? Design - Manufacturing - Assembly – Packaging - Resale ($40.00) Next, the market for this product needs to be determined. According to the Black and Decker product catalog, the hedge trimmers are “suitable for small shrubbery”. Based on this information, it is determined that the hedge trimmers were aimed at homeowners with small yards whose use of the product would be limited to three to four times a year. The costs associated with this product include design, manufacturing, assembly, and packaging. The hedge trimmers resale value is $40.00.

How long will this product last? Assumed durability of each component (outdoor use, dirt) Availability of replacement parts and service shops What features does this product have that are important? Molded-in cord retainer Lock off switch prevents accidental start-up Lock on switch for continuous running Lightweight design for less fatigue (4.5 lbs.) The intended life of the hedge trimmers needs to be estimated next based on conditions of use and the design and material of each component. Also, if any parts fail, can they be repaired or replaced? These hedge trimmers have some important features including a molded-in cord retainer to reduce wear of the cord due to cyclic bending, a lock off switch to prevent accidental start-up, a lock on switch for continuous running, and has a lightweight design for less fatigue.

Additional Comments and Remarks -1
by: jenni796 (Fri Apr 7 '00) Pros: light weight, very durable Cons: none Trimming the bushes is my only contribution to our 2 acre yard. I bought my first Black & Decker hedge trimmer at Wal*Mart because it was very inexpensive compared to most other trimmers Black & Decker has an excellent reputation. The 13" seemed a little too small… The 18" seemed heavier I also wanted electric rather than gas because being a busy woman, I had no time to learn about mixing gas. Durability: Excellent Noise Level: Average Purchase Price: $25.00 Information about customer’s response can be found from surveys, interview, focus groups, etc. Here we found some customer response at a website REF:

by: dadof6 (Fri Apr 7 '00) Pros: Easy to handle and lite too! Cons: Electric and water never mix! While it may be a good trimmer it also has it's downside! The first problem with it being electric is that you need a drop cord. The second problem is that since it is electric and you use it outside, you run the risk of being electrocuted! Remember most people doing lawn work are also running sprinklers to water the lawn. I have had good friends killed simply by using these trimmers on wet grass. Over all this tool does a great job of trimming but the hazards to your personal safety far out weigh the pros of this tool. Durability: Good Noise Level: Average Purchase Price: $39.95 Here are additional comments and remarks from customers.

by: lpmiller (Tue Jun 27 '00) Pros: Cheap, powerful, lightweight Cons: Weak manual, requires an outlet. just about the cheapest thing you'll find on the market as usual the fine folks at B & D come through. As long as the cord reaches, I have the power I need. safety lock located at the top of the trimmer; release the trigger, the safety clicks on One of the safety tips that really amused me was, “Do not use in rain.” On the one hand, I’m just not that stupid, on the other hand...well, we all know someone, don’t we? Folks, it is an electric trimmer. Do Not Use In Rain. Or the bathtub. Really. Durability: Excellent Noise Level: Average Purchase Price: $29.99 Again, here are additional comments and remarks from customers.

Patent Search on Hedge Trimmers
After completing a search on the U.S. Patent and Trademark website: Patent # 5,778,649 (1998) Power Driven Hedge Trimmer Patent # 5,581,891 (1996) Hedge Trimmer with Combination Shearing and Sawing Blade Assembly Patents can be found at the US Patent and Trademark Website. Remember, patent searches must be complete to ensure that the product and technology is not legally protected. Here, there is a patent for the power driven hedge trimmer and with the combination shearing and sawing blade assembly.

Function and Form 2. Concrete Experience: Function and Form
Carefully begin Disassembly Document steps and components with photographs, sketches or video Now disassembly of the hedge trimmers was begun. Pictures were taken during this procedure so that the trimmers could be put back together and to document the connectivity of the system’s components.

Hedge Trimmer Sub-Systems and Interactions
Group defined systems and subsystems together. Switch Motor Blade Next the system’s components and connectivity are identified. The hedge trimmers consist of a switch, the motor, the blade, and a case to enclose these items. Case

Motor 120 V - 8 Amp Motor 350 RPM Why not batteries?
How important is size, speed? Was weight a consideration? Photo of Motor The motor specs are 120 V - 8 Amp Motor, 350 RPM. Questions to consider are: Why not use batteries? How important is size, speed? Was weight a consideration?

Switch Safety lock allows trigger action.
Is this a regulatory requirement? Ergonomic issues of size and lever force What type of spring mechanism is used? The switch has a safety lock allows trigger action. Is this a regulatory requirement? What are the Ergonomic issues of size and lever force? What type of spring mechanism is used?

Switch MOTOR V Sketch of Switch + -
Here is a sketch of the switch sytem. Sketch of Switch

Blades How fast do the blades need to move? Force?
Are the blades sharp? What are the blades made of ? Can we replace the blades? Considerations for the blades are:How fast do the blades need to move? Force? Are the blades sharp? What are the blades made of ? Can we replace the blades?

Transmission Pin for upper blade Input gear from motor
Pin for lower blade Output gear The transmission consists of two helical gears and two sets of pin in slot mechanisms. The two helical gears have a gear ratio of 1:15. The rotational motion is then converted into translation using pin in slot mechanisms. The pin that pushes the lower blade has a small diameter, while the pin pushing the upper blade has a much larger diameter. Slot for upper blade Blades Slot for lower blade

Case How was the case made?
Was the case designed to be esthetically pleasing? Why isn’t the case made out of metal? What sort of costs are involved in the manufacturing of this case? Consideration for the case include: How was the case made? Was the case designed to be esthetically pleasing? Why isn’t the case made out of metal? What sort of costs are involved in the manufacturing of this case?

Feature List Switch - Plastic Injection Molded Gear – Die Cast Steel
Case – Plastic Injection Molded Handle – Plastic Injection Molded Guard – Plastic Injection Molded The next step is to Develop a feature list for each component with associated definitions and figures. This list show how each part was manufactured.

Reassemble Product Once the analysis is complete, the hedge trimmer is reassembled.

Engineering Specifications
Transforming to engineering specifications Example - Motor-Blade Kinematics Helical gears Number of teeth: input = 4 output = 60 Motor speed = rpm Output speed = = 1520 rpm = 159 rad/s Maximum blade speed = 1 m/s In order to model the motor and blade connection, a kinematic model is first created. The gear ratio reduces the rotational speed from rpm at the motor to 1520 rpm. So the blade moves back and forth at the same frequency and has a maximum speed of 1 m/s.

This video demonstrates the kinematic action.

Transforming to engineering specifications Input gear from motor Output gear to blades A force analysis can be performed using basic kinematics formula. For a more detailed analysis, FEA can be used.

Design Models 3. Design Models Identify actual physical principles
Create engineering models and metric ranges Alternatively or concurrently build prototype to test parameters Design models identify actual physical principles and Create engineering models and metric ranges. Alternatively or concurrently, one can build prototypes to test parameters.

Design Analysis 4. Design Analysis Calibrate model
Create engineering analysis, simulation or optimization Create experiment and testing procedures Design analysis involve calibration of the model, creation of engineering analysis, simulation or optimization, and creation of experiment and test procedures.

Parametric Redesign 5. Parametric Redesign Optimize design parameters
Perform sensitivity analysis and tolerance design Build and test prototype Parametric redesign involve optimization of design parameters, performing sensitivity analysis and tolerance design, and building and testing the prototype

Adaptive Redesign 6. Adaptive Redesign Recommends new subsystems
Searches for inventive solutions Analyzes force flows and component combinations Builds and tests prototype Adaptive Redesign recommends new subsystems, searches for inventive solutions, analyzes force flows and component combinations, and builds and tests the prototype again

Another Reverse Engineering Example
Example Project Black and Decker Cordless Screwdriver We have another example of reverse engineering techniques for a Black and Decker cordless screwdriver. If you do not wish to view this next example, please click the “skip” button to proceed with the rest of the presentation. SKIP

1. Investigation, Prediction and Hypothesis Develop Black Box Model Assemble product and conduct a test What goes in? What comes out? (i.e. power, noise, heat) Electric Power Noise Cordless Screwdriver On/Off Switch Screwdriver rotation In the first step, a black box model is created simply showing a system’s inputs and outputs. For the cordless screwdriver, electrical power, an on/off switch, and a switch which allows the user to use the screwdriver manually all serves as system inputs. When in operation, the cordless screwdriver produces bit rotation, noise, vibration, and heat. Power/Manual Switch vibration, heat

Product Performance Conduct a single test of the performance of the product: Record product performance attributes No load Rotational speed: 150 rpm (claimed) 142 rpm (measured) 81:1 Gear reduction = 12,200 RPM for the motor Drove in 94 #6, ¾” self tapping screws into dry pine (not predrilled) Upon testing of the screwdriver it was found that the bit rotational speed was 150 rpm when unloaded. The transmission has a gear reduction of 5:1, meaning that, under no load, the motor’s speed is rpm. As a test of the screwdriver’s life after completely charging the battery, ¾”, #6 self tapping screws were driven into dry pine. The screwdriver was able to screw in and remove 94 screws before the battery needed recharging.

Product Market What is the market for this product?
“Great for Everyday Use” – Black & Decker Manual Homeowners with need for occasional use What are the costs associated with this product? Design - Manufacturing - Assembly – Packaging - Resale ($20.00) Next, the market for this product needs to be determined. According to the Black and Decker manual, the cordless screwdriver is “great for everyday use”. Based on this information, it was determined that the cordless screwdriver was aimed at homeowners with need for occasional use. The costs associated with this product include design, manufacturing, assembly, and packaging. The hedge trimmers resale value is $20.00.

Product Features How long will this product last?
2 year full warranty provided What features does this product have that are important? Cordless, rechargeable battery Reversible direction Power/manual switch Relatively high torque Relatively long battery life The intended life of the cordless screwdriver needs to be estimated next based on conditions of use and the design and material of each component. Also, if any parts fail, can they be repaired or replaced? The cordless screwdriver has some important features including a rechargable battery, reversible direction, a switch allowing the user to operate the screwdriver manually, relatively high torque output, and a relatively long battery life.

by Staceys1 (Nov 03 '00) Pros: Durable and easy to use Cons: none Recommended: Yes Owned for about 5 years and is still going strong. Easy to use: position the screwdriver on the screw and press a button. It has a switch that reverses the way the head spins depending on whether you are trying to remove or put in a screw. The tip is easily taken out to switch between a Phillips head and a flathead screwdriver. Very durable. It’s been dropped on concrete, and other than a few scratches, it still works fine. Amount Paid (US$): 20 (on sale) Information about customer’s response can be found from surveys, interview, focus groups, etc. Here we found some customer response at a website

By: YYvonne (Jan 19 '01) Pros: Makes tougher jobs a breeze for me Cons: none The Bottom Line: Makes screwing around a breeze! (Couldn't resist!) Recommended: Yes Not really designed for heavy duty jobs Saves me a lot of strain in my wrists Lightweight and easily held I like the directional buttons on the screw driver I've never had the rechargeable battery die on me in the middle of a job. The batteries recharge quickly Amount Paid (US$): 25 Here are additional comments from the customers.

By: Seeker1 (dec09’00) Pros: Easy to use, reversible heads, rechargeable Cons: none known Recommended: yes Best gift I ever bought my husband for myself!!! This is a tool we use constantly, for any household project, big or small Practically anyone could use, my daughter and myself included!! Has a battery pack which is rechargeable. When it loses it's charge, you simply plug it in, let it recharge and you're ready to go again. Has interchangeable bits, one on either end (phillips head and a slotted head). The feature that I really like is that it's reversible. You can either drive a screw in or back it out. Wonderful lifesaver of a tool. Amount Paid (US$): 19.95 Again, here are additional customer comments and remarks.

Function and Form 2. Concrete Experience: Function and Form
Carefully begin Disassembly Document steps and components with photographs, sketches or video Now disassembly of the cordless screwdriver was begun. Pictures were taken during this procedure so that the screwdriver could be put back together and to document the connectivity of the system’s components.

Cordless Screwdriver Sub-Systems and Interactions
Group defined systems and subsystems together. Battery/charger Switch Next the system’s components and connectivity are identified. The cordless screwdriver consists of a rechargeable battery, a switch, the motor, a transmission, a screwdriver bit, and a case to enclose these items. Motor Transmission Screwdriver Bit Case

Battery/Charger Diode Nickel Cadmium battery Jack
Wires to switch Jack Diode Nickel Cadmium battery Jack for connection to AC transformer Diode to half-wave rectify the AC signal (charging) The battery is a nickel cadmium battery. There is a jack to connect to the AC transformer. The Diode, set to half-wave, rectifies the AC signal during charging.

Switch rotation Rotation of switching device lines up the contacts for either forward or reverse directions Pushing the switching device creates contact between the upper contacts How important is size, speed? Was weight a consideration? Contacts to motor Rotation of switching device lines up the contacts for either the forward or reverse direction. Pushing the switching device creates contact between the upper contacts. Some questions to contemplate are: How important is size and speed? Was weight a consideration? Contacts coming from battery

Switch Sketch of Switch
Since the operation of the switch is difficult to see based on the photographs previously shown, a sketch of the switch is provided here. Sketch of Switch

Motor 2.4 V Motor 12200 RPM (no load) 3.567 Amps (no load)
Torque = .056 Nm (at stall) How important is size, speed? Was weight a consideration? The motor information are: 2.4 V Motor, RPM (with no load), Amps (with no load) and Torque = .056 Newton-meter (at stall) Again, the questions for consideration are: How important is size and speed? Was weight a consideration?

Transmission Sun gear: 6 teeth Planet gear: 19 teeth
Ring gear: 48 teeth Gear ratio = 81:1 The transmission data give: 6 teeth on the sun gear, 19 teeth on the planetary gears, 48 teeth on the ring gear. This gives a gear ratio of 81 to 1.

Transmission output to screwdriver bit Second stage of planetary gears
A sketch of the planetary gears is shown since their layout was not obvious in the previous photographs. Second stage of planetary gears First stage of planetary gears (Ring gear not shown)

Screwdriver Bit How fast does the bit need to turn? Torque?
What is the bit made of ? The screwdriver bit needs to be considered also. Some questions about the bit include: How fast does the bit need to turn? What is the torque that it can transmit? What is the material for the bit?

Case How was the case made?
Was the case designed to be esthetically pleasing? Why isn’t the case made out of metal? What sort of costs are involved in the manufacturing of this case? For the screwdriver case, questions include: How was the case made? Was the case designed to be esthetically pleasing? Why isn’t the case made out of metal? What sort of costs are involved in the manufacturing of this case?

Feature List metal leads – extruded and bent
plastic switch – injection molded plastic switching mechanism – injection molded plastic gears – injection molded casing – injection molding metal bit – extruded The next step is to Develop a feature list for each component with associated definitions and figures. This list show how each part was manufactured.

Reassemble Product Once the analysis is complete, the screwdriver is reassembled.

Transforming to engineering specifications Example - transmission Kinematics 1. Calculate gear ratio if carrier was fixed 2. Calculate carrier speed out of first set of planetary gears In order to model the motor and blade connection, a kinematic model was first created. The first step in calculating the output speed of the first set of planetary gears is to calculate its gear ratio if the carrier were fixed. This ratio is called r* and is the negative of the ratio of the number of teeth in the sun gear over the number of teeth in the ring gear. Then the carrier speed out of the first set of planetary gears can be calculated. Finally the speed out of the second set of planetary gears can be calculated. The motor rotates at rpm under no load and the predicted speed out of the entire transmission is 231 rpm. Note that this analysis does not take into account any loading on the motor due to friction or inertia. For this reason it is expected that the predicted speed will be higher than the actual speed. 3. Calculate carrier speed out of second set of planetary gears

Transforming to engineering specifications A force analysis may be performed for prediction of failure and to find the torque available at the screwdriver bit. Close to 1 Nm is available at the screwdriver bit.

Design Models 3. Design Models Identify actual physical principles
Create engineering models and metric ranges Alternatively or concurrently build prototype to test parameters Design models identify actual physical principles and Create engineering models and metric ranges. Alternatively or concurrently, one can build prototypes to test parameters.

Design Analysis 4. Design Analysis Calibrate model
Create engineering analysis, simulation or optimization Create experiment and testing procedures Design analysis involve calibration of the model, creation of engineering analysis, simulation or optimization, and creation of experiment and test procedures.

Parametric Redesign 5. Parametric Redesign Optimize design parameters
Perform sensitivity analysis and tolerance design Build and test prototype Parametric redesign involve optimization of design parameters, performing sensitivity analysis and tolerance design, and building and testing the prototype

Adaptive Redesign 6. Adaptive Redesign Recommends new subsystems
Searches for inventive solutions Analyzes force flows and component combinations Builds and tests prototype Adaptive Redesign recommends new subsystems, searches for inventive solutions, analyzes force flows and component combinations, and builds and tests the prototype again

Environmental Impact To determine the environmental impact of the existing design evaluate each step of the Product Life Cycle Pre-production Manufacturing Process Product Life The After Life Other considerations in reverse engineering are the environmental impact of the product and components. To determine the environmental impact of the existing design, one should evaluate each step of the Product Life Cycle. The product life cycle includes: Pre-production, Manufacturing Process, Product Life, The After Life

Pre-production Replaceability of natural resources
Availability of an alternative resource Energy required to obtain Energy to process Amount of waste created during processing Waste disposal method Factors of concern in pre-production include: Replaceability of natural resources Availability of an alternative resource Energy required to obtain Energy to process Amount of waste created during processing Waste disposal method

Manufacturing Process
Energy to produce Waste created during production Type of waste- solvents, emissions? Reuse of in-process material waste? Material yield During the manufacturing process, one should consider: Energy production Waste created during production Type of waste- solvents, emissions? Reuse of in-process material waste? Material yield

Product Life Energy consumption Waste production
Length of product life During the product life, one should contemplate the energy consumption, Waste production, and Length of product life.

The After Life Reuse Recycle- design for disassembly?
Neither- harmful pollutants? Discussion: Reuse vs. Recycle Finally, engineers need to also consider the product placement after the life of the product. Can it be reused or recycled? Can it be disassembled for reuse or recycling of the components? Is it harmful or a pollutant?

Summary Reverse engineering
Tool to understand current design solutions and technology Use dissection, experimentation and analysis Save time and gain insight on current design challenges and solutions After completing this presentation and the examples, one should have a detailed understanding of reverse engineering theory, strategy and application. The included examples in this module reflect mechanical and industrial engineering curriculum, but should in no way reduce the importance of reverse engineering as a tool for gaining insight into previous designs, solutions and ingenuity in all of the engineering disciplines. Reverse Engineering should serve as a useful tool. The purpose of Reverse Engineering is to understand current design solutions and technology using dissection, experimentation and analysis. In the end, the goal is to save time and gain insight into how others have approached similar design challenges. Reverse Engineering can often times reveal ingenious solutions and, thus, can be very useful to resolve design issues facing an engineer.

Credits This module is intended as a supplement to design classes in mechanical engineering. It was developed at The Ohio State University under the NSF sponsored Gateway Coalition (grant EEC ). Contributing members include: Gary Kinzel…………………………………….. Project supervisors Jim Piper and Rachel Murdell ……………….. Primary authors Phuong Pham and Matt Detrick ……….…….. Module revisions L. Pham …………………………………….….. Audio voice Reference: Otto and Wood’s “Reverse Engineering and Redesign Methodology” UT Austin

Disclaimer This information is provided “as is” for general educational purposes; it can change over time and should be interpreted with regards to this particular circumstance. While much effort is made to provide complete information, Ohio State University and Gateway do not guarantee the accuracy and reliability of any information contained or displayed in the presentation. We disclaim any warranty, expressed or implied, including the warranties of fitness for a particular purpose. We do not assume any legal liability or responsibility for the accuracy, completeness, reliability, timeliness or usefulness of any information, or processes disclosed. Nor will Ohio State University or Gateway be held liable for any improper or incorrect use of the information described and/or contain herein and assumes no responsibility for anyone’s use of the information. Reference to any specific commercial product, process, or service by trade name, trademark, manufacture, or otherwise does not necessarily constitute or imply its endorsement.

Reverse Engineering The title of this module is Reverse Engineering.

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Reverse Engineering The title of this module is Reverse Engineering.

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