Group 13 - Kawasaki 1/2 in Electric Impact Wrench (12 V)

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Project Management

Work Proposal

We plan on reverse engineering our product by simply using standard tools to disassemble it. Before we begin to disassemble the product, we will first analyze it to see how and where it should be taken apart.

Tools Needed

  • Screwdriver (both phillips and flat head)
  • Needle nose pliers
  • Knife

Disassembly Time

  • 30 Minutes

Specific Challenges

  • Not damaging the electric portion of the product

Group Capabilities

  • 1 Year of preparation in the engineering practice
  • Practical, hands-on application
  • AutoCAD experience
  • Construction experience
  • Problem Solving

Group Shortcomings

  • Time Management
  • Conflicting Schedules
  • Little to no electrical experience

Management Proposal

In order to stay organized and manage our group properly, we will evenly distribute the work load, and meet at least once per week (with more meetings if needed). As we have in the past, our once-weekly mandatory meeting will be held on Tuesdays at 3:30 in the Bert’s dining area (1st floor Talbert). Depending on the amount of time we have for the assignment, we will break up the weeks we meet into different subjects. We plan on having at least 3 meetings between assignments, which will be scheduled as following.
  • Our first meeting will be strictly informative. In this meeting we will discuss exactly what is being asked for out of the assignment, and what we have learned in lecture that relates to the topic. We will then discuss how we plan on approaching the task at hand. This discussion will involve dates and times of extra meetings as we see fit, what research will need to be done prior to the final project, and specific individual assignments that will need to be completed prior to the next meeting.
  • The next meeting will involve any hands-on work that needs to be done. Having all researched our specific topics as previously assigned, we should be well informed as to how we go about our task, what it is we are trying to accomplish, and the necessary steps to achieve this task. After doing whatever hands on work necessary, we will compile and discuss the information we obtained through our individual research. We will then assign specific parts of the assignment to be done by each group member. We will then assess the time needed to accomplish these assignments, and whether we need to meet again prior to our next scheduled meeting.
  • In our final meeting we will compile all of our individual assignments, forming the final assignment. We will all evaluate this final project, and make minor changes as we see fit. When the entire group is satisfied with the finished product, we will assign someone to print or upload the assignment if necessary.
Group attendance to these meetings is essential. Without everyone’s contribution, the project will lack in quality, quantity, and accuracy. For this reason it is mandatory that every group member attend every meeting, unless there is a serious, legitimate excuse. If a member is not contributing their share, or consistently not attending meetings, a note will be made on the upcoming assignment making the professors aware of the situation.


Project Manager: Jesse Dewey
  • Will be in charge of the material covered in meetings, insuring deadlines are met, and assignment is submitted complete and on time.
Technical Expert: CJ Tracey
  • Will be in charge of learning about the product to have a relative understanding of how it works, and disassembly of the product
Communication Liaison: Dale Kawa
  • Will be in charge of contacting group members about meetings, professor communication, and overall organization of project
Hardware Manager: Amadeus Astacio
  • Will be in charge of holding the product, bringing it to every meeting and ensuring it does not get lost or damaged
Assistant Technical Expert: Jacobus Leroux
  • Will assist the Technical Expert in learning about and disassembling the product

Preliminary Project Review

Addressed Challenges

  • After three weeks of group meetings, we found certain flaws that slowed down the project. We took immediate action to fix said flaws, and ended up with a slightly altered version of our former management plan. These changes include:
  • Meeting three times a week rather than one. This allows our group to get work done without feeling rushed. It also lessens the burden of the work load on the whole group. Having more meetings makes for easier sharing of information, and thus a more complete project.
  • Getting a bulk of the work done a week in advanced. This allows maximum time for formatting, proofreading, and editing the wiki page. It also lessens the stress as the deadline gets closer.

Challenges Needing Addressing

  • We also noticed a flaw that still needs addressing:
  • Meeting efficiency. While in a meeting, we must immediately get to work to use our time as efficiently as possible. We must ensure that everyone is participating, for maximum efficiency and accuracy of the material. This will result in a less stressful, ideally shorter meeting in which we get a significant amount of work done.

Critical Project Review

  • We managed to fix all of the kinks in our group management. We now meet regularly 3 times a week which lessens the burden on all members. While we were hit with a major change (one of our group members dropping the class and not notifying us until one day prior to the gate 3 due date), we managed to pull together and finish this member's part.

Technical Report

The following technical report contains detailed information about the 12 volt, ½ inch Kawasaki Drive Roadside Impact Wrench kit. This product takes the high-speed output from an electric motor and converts it into a low speed, high torque impact wrench. This impact wrench is used mostly on basic automobile wheels. An interesting aspect of the wrench’s component setup is that the hammer and anvil subsystems are opposite of what one might think, with the smaller output component being the anvil and the larger component being the hammer. The clutch setup is also very interesting. By using a type of centrifugal clutch it can disengage after initial impact, which then creates the desired high toque.
To analyze the impact wrench the entire product was taken apart piece-by-piece, documenting our analysis using both pictures and in a technical paper. Viewing the layout of the subsystems and doing further research on the product itself, we were able to understand how the product worked. Using these methods we were able to figure out how the switch and motor work, what the hammer and anvil components are and how they work and how it all fit together. We were able to track the flow of energy through the wrench and determine how the hammer and anvil setup creates the low speed and high torque required for the device.
Through various exercises given to us by our MAE 277 professors, we were able to generate different designs to make the impact wrench more useful and efficient. The main catalyst for our designs was the GSEE factors (Global, Societal, Environmental, Economic) taught in class. In the process of making our designs, we addressed each factor individually and tried to create designs that would take that factor into account. Some of the designs created were ways to make the impact wrench cheaper, ways to make its manufacturing process less harmful to the environment, and how to make it more efficient. Eventually we settled on designs that focused more on societal and global factors. Our designs made it possible for the impact wrench to be used easily, added more features to appeal to a broader audience, and added more features to improve the efficiency of the impact wrench.

Product Archaeology

Impact Wrench Pic.jpg

Development Profile

  • This Kawasaki 841337 12v DC Impact Wrench received its copyright in 2010, and is distributed through Alltrade Tools LLC, a private company established in 1983 and based out of Long beach CA. It is produced and desgined by Kawasaki, a Japanese company that has its roots in motors, mainly motorcycles, who in the recent years branched out to include power tools and power lawn care products.
  • This product was designed to be compact and reliable, for basic DIY (Do it Yourself) jobs that the average consumer would come across. Its main selling point is that it plugs into your vehicles 12v cigarette lighter, making it ideal for roadside emergencies. It’s grip was designed with a rubber coating, making sure your hold is secure and comfortable even in undesirable working conditions such as snow and rain. Since it was copyrighted in 2010, our economy was not doing so well and consumers needed affordable products they could count on for reliability and job performance.
  • Since this product is sold through many online websites, it can be assed that it was distributed to a global market, in areas where the consumer can afford to purchase powertools, i.e. not poverty stricken. All of the products come with a standard 3 year limited home use warrenty designed to ensure proper product support in case of failure.

Usage Profile

  • Impact Wrenches are power tools designed for speedy removal of lug nuts with minimal effort on the users behalf. Usually lug nuts are difficult to remove due to their necessary tightness, along with caked on rust and dirt. Normal removal consists on significant effort and leverage on the consumers part with a lever attached to a regular socket wrench. Impact Wrenches get rid of that by allowing for very high torque output with minimal exertion by the user, removing lug nuts in a matter of seconds with the simple pull of a trigger.
  • This current impact wrench is geared towards home use, due to its relatively low torque output compared to professional grade wrenches and power source. Ours has a max torque output of 280 ft-lbs, professional grade wrenches have between 700-1200 ft-lbs. Additionally, impact wrenches are made to be plugged into a standard 120v outlet. Our product uses a variation designed, which allows it to be plugged into your cars outlet.

Energy Profile

  • The Kawasaki Impact Wrench we were assigned uses a few different forms of energy, electrical, rotation, kinetic, human, and a small form of chemical energy. It starts out within the cars battery, where chemical reactions take place that allow for a discharge of electrical energy to be harnessed by the 12v outlet. Once the wrench is connected to the outlet, the electrical energy powers the motor which turns it into kinetic and rotational energy by spinning the mass at a high velocity, impacting it onto the shaft turns the socket head. The only human energy required is the strength to hold it level and squeezing the trigger.

Complexity Profile

  • From opening up the case, we can observe the components on the wrench itself, and additional ones that come as separate pieces. On the wrench we can see the casing, the socket bit, the 3 way switch, and the power cord. Separate components include 2 safety fuses and 2 different socket heads. The components on the wrench don’t seem terribly complex as they are mainly for protection and grip. The most complex part on the wrench itself is probably the power cord, because it contains a removable fuses that allows for current to flow from the 12v port into the wrench. Although the 3 way switch does had hidden complexity within the wrench. It doesn’t really interact with the components on the outside, but under the casing it switches the motors gears to allow for both forward and reverse operation.
  • Separate parts are very similar, with the 2 fuses having the most complexity, as they contain more components themselves. The 2 additional socket heads are solid steel , and have a different size on each end, allowing for versatility in the field.
  • The only reactions from the components that we can see are the connection of the socket heads onto the bit, and the replacing of the fuses. While these aren’t that complicated, they are vital to successful and proper operation. We suspect that within the wrench there are much more complex parts and interactions taking place when operated.

Material Profile

  • The impact wrench handle and body is made mostly of a heavy plastic and rubber. A rubber finger grip on the inside of the handle makes it easier to grip tightly. The socket bit on the end of the impact wrench is made out of some kind of metal, most likely steel.
  • At the other end, the plug is made out of a hard plastic shell, with a metal conductor at the tip. The conductor is most likely made out of brass (a Copper and Zinc alloy). The chord is most likely made out of a copper wire, surrounded by a rubber casing.
  • Without taking the impact wrench apart, we can only assume that the inside is also made out of some form of metal, plastic and rubber.

User Interaction Profile

  • The user interaction consists of 2 steps. Setup and Operation. Setup includes plugging it into your car outlet, switching it to forward or reverse, and selecting the proper socket head size. Operation is physically connecting it to the lug nut, squeezing the trigger, and removing the nut.
  • The design of this wrench is very intuitive; by just looking at it you can get a good feel as to how it operates. The switching of the socket heads is a simple push on pull off mechanism. And plugging it in and pulling the trigger is easily deduced as well. The most complicated procedure was changing a fuse, but by simple inspection of the plug head I was able to unscrew it and change the fuse rather quickly with minimal effort.
  • This product is designed to be easy to use, simple and effective. The whole selling point is that it can be kept in your trunk, and by simply plugging it into your vehicles cigarette lighter you can have a quick and easy removal of your tire. The only thing that I can currently see that may be an issue is that the cable is only 11 ft long, which if you’re driving a larger vehicle, may not reach the rear wheels. This is something that would have to be assessed in a real world test with various vehicles.
  • The only regular maintenance required is the periodic changing of a blown fuse. It is very easy to change, simply unscrew the plug head and switch them out. Screw it back on and your good to go. I imagine that this is a rare occurrence though, as it is designed for roadside emergencies. Even if it gets heavily used outside of emergency situations, that being periodic brake and tire work, it isn’t necessary to remove a tire often enough to blow a fuse. The spares are more of a precaution than actual maintenance.

Product Alternative Profile

  • Hand Wrench
    • Advantages
  1. Simple to use
  2. Somewhat versatile
  • Disadvantages
  1. Can be extremely labor intensive
  2. Time consuming
  3. Not much torque for amount of work put in
  • Socket Wrench
    • Advantages
  1. Simple to use
  2. Versatile
  3. Less time consuming than a wrench
  • Disadvantages
  1. Can be labor intensive
  2. Not much torque for amount of work put in
  • These alternatives really don’t compare. An impact wrench has an unfathomable torque in comparison, is equally as versatile, and takes mere seconds to finish the job. Impact wrenches are made to save time and effort by taking out the physically intensive part of a wrench. In essence, there is little comparison.
  • A cheap hand wrench set generally costs between $30-$60. A cheap socket wrench set averages between $40-$70. A cheap impact wrench set generally costs between $60-$70. The differences in cost are relatively small, with significant change in performance.

Product Dissection


  • We began dissection by taking the housing/plastic casing off the entire wrench. This was done by using a Phillips head screwdriver to remove all 9 screws from the outside. Inside it revealed that there was indeed a large motor, a forward/reverse switch, power indicator light, electrical assembly, a large anvil and hammer assembly. By handling the motor, we discovered the motor is detachable from the anvil, which is in turn detachable from the hammer. It all slides together, so to separate the 3 main parts no tools are needed. From here we can see that on the hammer is a small ball bearing allowing for smooth movement, and a further spring system, which causes the “impact” to the shaft. This spring subsystem is the heart of the impact wrench, and while it is a relatively simple design and assembly, it allows for very high torque output on the shaft with little effort on behalf of the user.

Overall Assembly.PNG

  • There are 4 main pieces, or systems that work together. The motor, the anvil assembly, the hammer assembly, and the electrical assembly.


Hammer Assembly


  • This assembly is primarily composed of a solid block of steel with a spring subsystem. It is first removed from the motor shaft by simply sliding if off the motor shaft. This was the most difficult to disassembled, mainly because of the torque required to remove screws by the user. There is a slide/spring mechanism that can be disassembled by taking out 2 black Phillips head screws. These screws however are rather difficult to remove. We needed a drill with a Phillips head bit to remove them. Once that is done, the entire Slide/spring mechanism simply comes off the hammer.

Anvil Assembly

  • The anvil is a relatively simple design consisting of the shaft which slides into the hammer. When the hammer spins around, it hits the anvil with a short impact, when the resisting force is too much, the spring system retracts, which allows it to rotate once again for the next impact. There is little disassembly needed, as it all slides apart and there are no tools needed.

Electrical Assembly


  • The electrical assembly is a small black box with red, green and blue wires coming out of it that is not meant to be disassembled due to the fact that it is so small, and there is really nothing to be gained by taking it apart. The parts inside aren’t meant to be replaced. It is just a subsystem of the trigger, which simply moves a slide that reverses the polarity of the magnets. There is a small tab that you can press down with your fingernails to open it up. Inside there is a spring that pulls the switch back and forth to select forward or reverse. No tools needed

Motor Assembly


  • The motor assembly is slightly more difficult to take apart. Using a set of pliers, we removed 2 nuts from the steel housing, and twisted the lid off to reveal the inside of the motor canister. A very small socket wrench could be used as well, but for us a set of small pliers was sufficient. Attached to the walls of the canister are 2 magnets, which are activated by electrical current. There is a shaft, surrounded by copper wires and a series of smaller magnets, also activated by electrical current through 2 bushings. When plugged in, there are opposite fields between the magnets on the housing, and the magnets on the core, which causes the core to rotate at high speeds.


Fuse Box

  • This is connected to the electrical assembly by signals, energy, and physically.
  • Electrical Energy is connected to the motor to activate magnets and by a signal, which is the user input when the trigger is pulled, completing the circuit.
  • Connected physically by wires.
  • This subsystem is connected in order to transfer electrical energy to the motor from the cars 12v outlet. Without it, there is no energy transfer.

Spring Assembly

  • The Spring assembly is connected by energy, and physically to the hammer assembly.
  • It is physically touching the hammer assembly, and is only connected by the transfer of mechanical energy, including rotational and kinetic.
  • This subsystem is connected to the hammer assembly in order to transfer rotational energy, to the shaft in order to turn the lug nut. Without this subsystem, the hammer simply spins around inside without turning the shaft.

Direction Switch

  • The direction switch is connected to the motor by energy, and physically by wires,
  • Electrical energy goes through the wires to the motor, activating magnets.
  • This switch is connected to the motor in order to select which way the metal core rotates. This allows the wrench to both remove and attach lug nuts for increased versatility.
  • All of these subsystems are placed in order to meet the confines of the plastic housing, and by the energy flow. It starts at the plug and handle, and flows through the body and out to the shaft. The only requirement is that the output shaft be on the exterior of the wrench. Other than that it seems that the subsystems and main systems were placed in the path in which they interact.

GSEE Factors

  • Globally, the only influence is that it has been adapted to run on a car 12v port, but the overall wrench design itself is pretty much universal. The subsystems are all globally universal as well, put together based on practicality.
  • The Societal factors that went into this design came down to ergonomics, safety, and lifestyle. The wrench is designed to be used in emergency situations, so picture an elderly person/young lady on the highway who needs to replace a flat tire, but doesn’t have the strength required to remove the lugnuts. This wrench had to be designed so that people of all sizes and strengths can use it effectively. In regards to safety it includes 2 extra fuses so that if one blows, you can still change a tire and get back to a safe situation and minimize your time spent dangerously on the side of the road. The final Societal factor is lifestyle, which seems rather obvious but really is the main idea behind the uniqueness of this product. It is designed for the lifestyle of the average car owner. It really has no value to someone who does not own a car.
  • Economically, this product is designed to be an inexpensive, reliable tool for a unfortunate situation. There is not much complexity to the design so it has less parts and subsystems that can break, and is made mostly of solid steel. The only predictable breakage is a blown fuse, and they provide you with backups. For a relatively cheap price it provides a reliable solution.
  • Environmentally it is designed to have a long life cycle, with lots of recyclable steel parts if one takes the time to separate them. Its carbon footprint is negligible as it runs off of 12v electricity power from your cars battery. The most harmful component of it is the plastic housing and wire insulation, as those are petroleum based and harm the environment in both formation and decomposition. Other than that it is made of earth metals that are easily recyclable and have little to no effect in formation or decomposition.

Product Analysis/Component Summary


Component Function

  • The anvil acts as the striking point for the hammer and turns the high speed of the motor into the desired low speed/high torque required for the tool.
    • This component only has two functions, transferring high speed/low torque from the motor into low speed/high torque and transferring that high torque energy to the nut or bolt.
    • The flow associated with this component is the flow of energy. Energy is passed from the hammer to the anvil. Then energy is passed from the anvil to the nut or bolt.
  • The environment that the anvil operates in is inside the plastic tool casing.

Component Form

  • The general shape of the anvil is cylindrical.
  • Two notable properties are a long aperture at one end that the hammer impacts and a square shape at the other end to accept driver heads.
  • The anvil is primarily 2 dimensional. Is main function breaks down into rotation which only requires 2 dimensions.
  • Approximately 10 x 1 x 1 cm
  • The anvil has to be able to rotate which accounts for its large cylindrical area. It also has to be able to accept driver heads which why is square at one end. The long aperture at the other end is to give the hammer something to strike against.
  • Approximately 16 oz.
  • The anvil is made out of steel.
  • It has to be able to withstand the impacts from the hammer and the torque from usage.
  • The only specific material property needed is to be very tough.
  • It’s a simple component made of a very common material so it can be made anywhere for little and meet necessary requirements to function.
  • There are no aesthetic properties of this component because almost all of it is unseen by the user.
  • The anvil has no aesthetic purpose.
  • Its color is grey because that is the color of the material used.
  • The anvil is lightly polished to remove any burs that might catch on something.
  • This is for functional reasons.

Manufacturing Methods

  • The anvil was made by turning to get the cylindrical shape and then machined to get the square end. The part that is struck by the hammer was forged then polished in its inside edges.
  • There are machine markings circling the component and a line can be seen around the part struck by the hammer
  • Material choice had little impact on the decision. Turning is the only reasonable way to get the desired shape.
  • Shape was the driving factor in deciding what method was used. Since they knew they needed a cylindrical shape they had to choose a method that could make that effectively.
  • These techniques are fairly easy to do in any machine shop so it can be made anywhere for relatively little cost

Component Complexity

  • This component is not very complex. It’s just a steel bar with an arm at one end.
  • A scale of a complexity could be defined as difficulty of manufacturing.
  • The more functions or how complex a function the component has to perform effects how complex the part will be. The material used could limit complexity as far as ability to manipulate the material. The type of manufacturing method affects how complex the component can be.
  • The interactions are not complex at all. There is a smooth cylindrical end that slides into the hammer and a square end for accepting driver heads.
  • A scale can be defined as how intricate the interactions are.


Component Function

  • The bearing provides a smooth, frictionless environment for the anvil to rotate in and not cause any damage to the casing or anvil.
  • The bearing only performs the one function.
  • There is some energy transferred to the bearing but it’s a very small amount.
  • It functions within the casing.

Component Form

  • The component looks like a cylinder with protrusions on either side to prevent the casing from rotating along with the bearing.
  • The bearing is much wider at one end and the two protrusions are radially symmetrical.
  • This part is primarily 2 dimensional. Its function is rotational which only requires 2 dimensions.
  • Approximately 3 x 3 x 3 cm
  • The component has to be able to fit on the anvil and fit inside the casing without moving.
  • Approximately 4 oz.
  • The material does not have to be as strong as the anvil or hammer but has to be able to dissipate any heat from continuous use, it is probably made of aluminum or iron/
  • The only manufacturing decision that would impact the component would be cost.
  • The only possible material property the component would require would be the ability to dissipate heat.
  • An economical factor would be that it would cost less to use a weaker metal when material strength is not a major factor.
  • There are no aesthetic properties to this component; it is not seen by the user.
  • The component has no aesthetic purpose.
  • It is light grey because that is the color of the metal used.
  • The surface is unfinished because it doesn’t need to be.

Manufacturing Methods

  • The method used was most likely die casting.
  • The only other logical method would be by turning but because of the two protrusions on either side that would be impossible.
  • I do not believe material choice impacted this decision.
  • I do not believe that material shape impacted this decision.
  • The component is made of cheap metal and by a common manufacturing style.

Component Complexity

  • This component is fairly complex. There isn’t much going on the outside but the interior houses the bearings and interior components that make it work.
  • A scale could be defined as how difficult it is to manufacture the part.
  • Only function has any effect on the component, as long as it works it doesn’t really matter what or how it’s made or what it looks like.
  • Its interaction with the rest if the anvil is slightly complex. It has to fit snugly on the anvil so that it doesn’t lose grip but the exterior has to be able to move freely.


Component function

  • The hammers job is to hit the anvil at high speed moving it only a little bit per strike creating a low speed/high torque output.
  • This component only performs one function.
  • Energy is taken in directly from the motor then transferred to the anvil. There is also centrifugal energy actin on the clutch.
  • This component functions inside the tool casing.

Component Form

  • The shape of this component is a large cylindrical shape with its sides flattened out. There is a smaller cylinder on top of the larger cylinder.
  • There is a type of centrifugal clutch mounted on the larger cylinder and a bearing on the smaller cylinder.
  • This component is 3 dimensional. There is the rotational movement and there is lateral movement from the pin clutch.
  • Approximately 4.5 x 4.5 x 3 cm
  • It is very large so there is a lot of momentum behind it and room for the clutch.
  • Approximately 32 oz.
  • This component is most likely made of steel
  • The component had to be tough enough to withstand multiple impacts over the tools life.
  • The material had to be very tough.
  • They needed a cheap and durable material.
  • There are no aesthetic properties to this component, it is not seen.
  • It has no aesthetic purpose.
  • t is gray because that is the color of its material.
  • It is polished
  • It is probably functional to remove any burs.

Manufacturing Methods

  • This component was most likely made by die casting.
  • No other option fits the parameters of this part as well as casting does.
  • They had to make sure that whatever method they chose could be used with steel.
  • Shape is a major factor in this process.
  • Casting is a fairly easy process that can be done anywhere.

Component Complexity

  • This component is quite complex. It has the centrifugal clutch mounted on it as well as its own bearing.
  • A scale could be how difficult it would be to manufacture the component.
  • It has to be able to perform its job under violent conditions as well as withstand repeated blows.
  • The interactions here are moderately complex. It has en end with a square hole that fits into the motor shaft. The other end has the pin that causes the impacts to the anvil.
  • A scale could be how much is going on between their interactions.

Wrench Casing

Component Function

  • Serves as an environment for all interior subsystems, flows, and components that make up the system as a whole, and gives the user a gripping point for which to start the energy flow.
  • The only flows associated with this component are human energy by the pushing off the switch and or trigger, and the grip of the user.
  • Functions in the external environment, that meaning that it is directly connected to the outside conditions. Interestingly enough it functions as an environment for the internal components. i.e-the motor’s element is the interior of the casing.

Component Form

  • Generally shaped ergonomically to fit into a user’s hand, representing a similar overall shape to that of a handgun.
  • It is indeed symmetric, you can see a break line directly down the middle of the casing where it actually separates when you take it apart. This is also an indicator as to its manufacturing method which will be discussed later on.
  • The casing is clearly in the 3D planes, with functionality acting on all 3 axes. In short it is designed to both hold internal components and to serve as an acting point for the user, and components of both of these elements can be seen in the x, y, and z axes.
  • Roughly (20 x 25 x 4)cm. it should be noted that for analysis purposes, we used half of the casing. The overall dimensions of the part will be 2x the above measurments.
  • The components shape largely reflects the 2 main functions it must carry out.
  • It must hold all interior components, and it does so in a manner that mimics the energy flow throughout the system. From the bottom up the casing holds subsytems in the order of energy flow.
  • It must provide the user with a point of interaction and hold, and it does so comfortably. The contoured grip fits easily into your hand, and much like a handgun, you point where you want the resulting energy directed.
  • The casing weighs less than a pound when you have both halves.
  • The casing is mainly made out of plastic, with rubber inlays that are both aesthetic, and have a surface that is easier to grip in rough conditions.
  • Manufacturing probably played a part in the materials used. We can see that it is made by injection molding (discussed below) for which plastic is the most common material used. The rubber is also probably done by injection molding as we can see when it was punched out of the mold.
  • It can function with almost any material. Granted the rubberized handle gives it a slight texture advantage for better grip, but any material is able to be used as long as it can handle the shaking from use.
  • Globally, the decision to use plastic and rubber is due to the fact that both materials are readily available to manufacturers around the world. Societally the main factor was the rubberized handle. It appeals to society as a advantage over competitors by providing a more stable grip as opposed to one made solely out of plastic. Economically both materials are cheap to mass produce, saving costs to both the manufacturer and the consumer. Environmentally plastic is easily recyclable, which allows the casing to have a minimal impact on the environment.
  • Aesthetically the rubber inlays provide a splash of color on an otherwise black product. The shade of green also increases brand recognition, as it is the “Kawasaki Green” that consumers are familiar with, allowing them to connect a successful product to a company for future purchases. The rubberized green inlays are not just aesthetic, they provide a more secure texture from which to grip the tool when in use.

Manufacturing Methods

  • Injection molding is the most likely case of manufacturing. We feel this is an accurate assumption because you can clearly see a parting line where the product seperates, as well as riser marks on the interior.
  • As stated above, plastic parts and injection molding go hand in hand. Plastic is easily melted down and forced into a mold to create an otherwise very complex work. The specific ridges and dimensions needed in this casing would be very hard and costly to attain if anything besides injections molding was used.
  • There is not really much of a global factor that goes into choosing injection molding for this component. It mainly pulls influences from the other 3 GSEE factors. Societally it creates an even, streamlined, modern look that consumers can enjoy aesthetically without sacrificing functionality. Economically it is very cheap to mass produce, because one mold can be used continuously, making it very efficient to do so. Environmentally it creates virtually no waste product, so it saves the manufacturer money while having a minimal impact on the environment.

Component Complexity

  • While this component looks very detailed and complex, it actually is a relatively simple design. Functionally it only has 2 jobs, and there are no moving parts to it. On a scale of 1-10, with 10 being the most complex part within the impact wrench, we would put this component at around a 2. It is very easy for the consumer to see the benefit from using a rubberized grip and contoured handle to increase functionality, as well as green aesthetics as soon as they pick up the tool.
  • The interactions are of slightly higher complexity, as a user cannot see how it interacts with interior subsystems unless they take apart the impact wrench.

Motor Housing

Component Function

  • This component serves as an environment to an internal component, as well as providing a location for which to fasten magnets to.
  • The component provides a secure and sturdy housing for the electric motor within, but also has notches where the necessary magnets can stay in place. So it provides a housing for the motor, and a secondary fastening function which is vital to successful motor operation.
  • This component has both electrical and mechanical flow associated with it. Electrically by a magnetic field generated by the magnets attached directly to its interior, and mechanically by the indirect rotation taking place inside of it.
  • This component functions within the casing environment as mentioned above.

Component Form

  • The motor housing is generally a cylinder with one end opened up.
  • It is symmetric around its axis of rotation.
  • Ventilation holes punched out in the back
  • Primarily 3D, with important housing and magnetic properties in each plane.
  • Approximately (7.5 x 4.5 x 4.8) cm
  • The housing has to contain a motor that is roughly a smaller cylindrical apparatus, with magnets a small amount away from the motor. This in turn leads this component to be of similar shape, with slightly larger dimensions to accommodate for the containment of the magnets.
  • Component weighs roughly ½ a lb.
  • Made of solid steel, while the magnets are most likely made of iron.
  • Manufacturing was probably done by investment casting, which is typically used for steel and other metals. Material choice was probably based on function rather that process.
  • Globally steel is a very common material within motor housings, largely because of its durability to protect the internal moving parts from being damaged. Economically it is cheaper to use than other metals, say titanium, while still providing the necessary protection capabilities. Environmentally, steel is not very demanding to make. It is highly recyclable and leaves minimal impact on the environment.
  • Aesthetically it is rather bland. It is designed for function, not for looks. Since most consumers don’t take apart their power tools, there is no need for aesthetic appeal internally.
  • It is a steel grey color.
  • polished to remove any impurities that may come in contact with the motor during operation.

Manufacturing Methods

  • Not entirely positive, but most likely investment casting.
  • Based mainly on the fact that there are no break lines
  • The shape is a rather unique one that would need to be achieved by casting.
  • Economically it is costly, but there is no other option to achieved desired shape.

Component Complexity

  • We rated this component at a 6 out of 10 on our complexity scale, because while it is not as complex as the mass of wires that make up the electric motor itself, it still warrants a second glance to appreciate the benefit of it. Most complex is probably its manufacturing method, but its form and function can clearly be seen
  • The interactions between this component and the rest of the system are not very complex, rated at 4 out of 10. Its main interaction with subsystems is housing the motor, and that is extremely easy to deduce. The complexity level is based on the fact that the magnets are included in it, and not as easily seen by the user.


Component Function

  • Allows the user to use the impact wrench by completing the energy transfer
  • The trigger component has only 1 function, to move the switch on the inside to complete the circuit. Once it does that, other internal functions are allowed to take place once the flow of energy is in place.
  • The flow starts from user interaction, and once the circuit is completed turns into mechanical, electrical, and thermal.
  • The trigger mechanism is unique in the it functions on both the internal and external environments of the wrench. The main part of it is on the outside of the wrench, where the users finger applies pressure, but it also extends inward into the wrench in order to move the switch internally.

Component Form

  • The general shape of the trigger component is that of an upside down boot shape.
  • It has a vertical axis of symmetry.
  • While it is primarily shaped in 3 dimensions, its functionality is in the x direction.
  • Approximately (5.5 x 2.8 x 1.5)cm
  • Its upside down boot shape contours to the shape of a finger as it pulls on it, allowing for comfortable use of the tool.
  • The weight of this component is almost negligible. Rough estimate is 1/8 of a pound
  • The component is made from plastic
  • Seems to be made by injection molding, which is mainly used for plastics.
  • Uniquely this component does not require a specific material property in order to be functional. It could be made from numerous materials and still perform adequately
  • Globally plastics are readily available to manufacture in most areas, Economically it is relatively cheap to mass produce injection molded parts, and produces little to no waste product so environmental impact is minimal.
  • Aesthetically it is designed to go with the black and green color scheme put over the rest of the wrench.
  • Is designed for functionality, not aesthetics. Has no outstanding looks or flashy features, has soft black finish on it to blend in with rest of the wrench.

Manufacturing Methods

  • Injection Molding
  • As can be seen by the clear riser marks, and the necessary complexity of the part
  • Plastic can easily achieve precise and complex shapes when used in injection molding, which is another clue as to its manufacturing methods.
  • The shape could be done with other materials by hand or by CNC, but its easiest and cheapest if injection molding is used to achieve the required dexterity of the component.
  • Globally it is easiest to mass produce injection molded products to a large consumer market. Economically it is cheapest to use this method for mass producing a small part. Environmentally has minimal waste product.

Component Complexity

  • On a scale of 1-10, we rated this product at a 1. It’s a very simple design with one function, and its extremely easy for the user to see the benefit of this function. By using this component, the wrench works. Very simple, very easy to comprehend.
  • Its simplicity comes from its function and form, it has 1 function, and its form is designed to accomplish that one task.
  • The interactions are very simple, once pushed, it completes the circuit which allows the wrench to create work.

Internal Pin-Clutch Spring

Component Function

  • This component allows for a metal pin to return to equilibrium within the wrench, allowing for continuous usage of the wrench.
  • It really only performs one function, by allowing a pin to move back and forth on the hammer part of the wrench. By allowing that pin to retract, it allows the hammer to get back up to full speed before the next contact is made.
  • Functions in the internal environment created by the wrench casing as mentioned above.
  • It is a simple spring shape that most everybody is familiar with. A winding, cylindrical, helical coil over a small distance.
  • While it in shaped in 3D it functions primarily in 1 dimension, in one that is parallel with its overall length.
  • Approximately 1 x 4 x 1 cm

Component Function

  • The components shape is that of a spring, and by creating a winding helix, it creates a spring constant which allows the component to perform its required function effectively.
  • Components weight is almost negligible, not more than a few ounces.
  • The component seems to be made from either steel or iron wire. Not sure of the metal compound used.
  • Wire is made by drawing a metal through a die to obtain a given shape. When that wire is being used for a spring, it then goes through an additional process called coiling which turns it into the helix. Because that is the most popular way to create a spring, it is safe to assume that the wire material was chosen to correspond to the manufacturing method.
  • It needs to have a certain spring constant as determined by the designing engineers. They ended up at a certain spring constant that it must have in order to hold and retract the desired forces.
  • Globally wire is a common material in mechanics, and is readily available to manufacturing in most parts of the world allowing for broader manufacturing opportunities. Economically wire is a fairly inexpensive piece to make, which in turn allows for lower cost of production than if a more complex retraction system was used. Environmentally metal is easily reused and recycled, especially springs. They can be used over for new applications or melted down and recycled.
  • Aesthetically it is not a very pleasing product to look at. It is a dark grey color, with no finish on it. Looks dirty and rugged.
  • This is an acceptable look though, because the spring serves no aesthetic purpose to the overall system of the wrench. It is a strictly functional part, and is not meant to be seen by consumers.
  • Its color and lack of a finish is left as it was when it was done being manufactured. This is because there is no need to make it look aesthetically pleasing, rather to make it function at the lowest cost possible.

Manufacturing Methods

  • This component was likely manufactured by drawing and coiling.
  • Because it is a wire, and wire is produced by drawing and coiling as the most efficient and inexpensive way.
  • It is shaped like a helix, which is best achieved through drawing an ingot through a dire to achieve the desired thickness, then coiling it to the desired diameter.
  • Economically it is cheapest and most efficient to produce this part by drawing and coiling. Environmentally it has little waste, because the ingot is just being re-shaped. Globally it offers a wide variety of manufacturing options because it is a fairly easy process to achieve.

Component Complexity

  • This component is not very complex. While it is an internal part, and not made to be seen by the consumer it is still relatively easy to see the benefit of having a spring mechanism on the pinclutch. We rated it at a 3 out of ten for just the spring part. The pinclutch system as a whole is much more complex, but this analysis is for the spring component only.
  • The above categories go hand-in-hand with each other, but don’t connect as directly to complexity. The functionality is the only clear connection to its complexity, and it has a very simple and direct function that is not very complex.

Solid Model Assembly

  • We made a 3D model of the anvil, hammer, and bearing. This assembly plays a huge role in the functionality of the impact wrench.
  • We used Autodesk Inventor 2012 to do said modeling.









Engineering Analysis/Design Revisions

A design revision that can be made to the impact wrench would be dual functionality. Instead of being used as only an impact wrench, certain tweaks can be made to the subsystems to allow for it to be used as a screwdriver as well. There can be a setting that reduces torque so that the screwdriver doesn't strip the screws and allows for the user to have more control over the product. The wrench can also come with interchangeable heads that will allow for the change from impact wrench to screwdriver. These changes will probably cost the consumer more money for this purchase, but it would save them money because they would not have to buy more then one power tool. The dual functionality would also attract more consumers to buy the product. The dual functionality complies with the societal concerns of GSEE because it is aimed more towards societies who enjoy high-tech gadgets and who have frequent construction products that call for then one tool.
One design revision that can be made has to deal with the component that charges the impact wrench itself. As it stands now, the impact wrench must be plugged into a 12 volt DC socket (mostly cigarette lighters in vehicles) in order to function. This type of impact wrench was designed for use on standard vehicle wheels. The design that can be implemented can get rid of the plug all together and instead, can either use batteries or a rechargeable battery pack. Though this revision may cost the consumer a little extra, it would be much more convenient to use and would have a broader range of capabilities and uses. Also, if in any case the vehicle battery dies and this tool is needed, it is rendered useless. Giving it a battery pack or allowing it to use batteries would allow the impact wrench to be used anywhere and at anytime. This design complies with the GSEE factor of global and societal concerns. This new source of power and maneuverability will allow for a more broad range of consumers from around the world who would be able to use the impact wrench for uses other then vehicle wheels such as heavy equipment maintenance and other construction projects.
Another design revision that can be made is to add a LED light or flashlight near the impact wrench head. If this impact wrench would need to be used at night, it would be very difficult to see and operate in the dark. Even if one had a flashlight it would be very difficult to operate both the flashlight and the impact wrench simultaneously. Creating an impact wrench with a light built in would maximize efficiency in the dark and would also increase the available times of uses. The label on the front of the package claims that the impact wrench is for roadside emergencies, yet operating it in the dark can be very harmful and unproductive for the user. Adding this light would help increase safety during nighttime usage. Adding this light for safety and availability complies with the global and societal concerns.
One component of the impact wrench that could undergo engineering analysis is the anvil. Since the anvil is one of the main components of the impact wrench and it is continually hitting and getting hit by the hammer, it must undergo a lot of testing to make sure that it complies with all of the specifications it must achieve. First, the engineers analyzing the anvil will come up with a problem that must solve. That may be what material to make the anvil out of, what size, what length, what shape, what kind of surface finish, how heavy it must be, its life expectancy, and how strong and sturdy the anvil must be to be able to perform its job. The second step would be to draw diagrams (either by hand or by using an online application) of all of the different kinds of designs that were created, and compare and contrast them until a final design is agreed upon. Next the engineers will state all of the assumptions that they should make, such as the weight and density of the material chosen. These assumptions will help the engineers with their equations as well as with solving the problem at hand. Next they will list any governing equations relevant to solving the problem at hand. These equations can include τ = F/A which measures stress on the anvil, τ = rFsinθ which measures the anvils torque output, and P= τω which measures power. Next the engineers would use these equations, and possibly more, to figure out the max torque, speed, and power that the anvil would need to perform its role. After these calculations are done, the anvil will go for testing to see if it complies with specifications and to see if the anvil fulfills all of its requirements and is safe and durable. Some tests that it will go for are tests to see if the anvil fits along with the rest of the components as well as within the casing of the product. They can test to see the strength and durability of the anvil. They can also test to see how smoothly the anvil operates. Lastly, the engineers will discuss and interpret the results of the solution, checking back to see if they are satisfied with that they have done and checking to see if what they have done satisfies the problem they were originally faced with.

Product Reassembly

The reassembly of the impact wrench was relatively simple. There are not many parts involved in the reassembly process, which makes the entire process very quick and easy. The only tool used in the reassembly process was a Philips head screwdriver. Due to the different size in the screws, two different sized Phillips head screwdrivers were used, one for the big screws and one for the small screws. The only challenge to reassembling the impact wrench was remembering where each of the parts belonged. However, the casing of the impact wrench clearly outlined where each part would fit, and using simple deduction it was fairly easy to reassemble the impact wrench by putting the parts into their respective places. Throughout the reassembling stages, there was only a single, slightly difficult step. This step would be the reassembling of the electromagnet because in order to reassemble it you must force the parts into place against a strong magnetic force. On a scale of one to ten, one being easy and ten being difficult, I would rate this assembly process a four out of ten. I would give it a low rating because the impact wrench has very few parts and where the parts belong is clearly indicated by looking at the casing. The few parts and clear locations make the entire assembly process quick and easy. The only tool necessary for the reassembly is a Phillips head screwdriver, which is easy to operate. The only challenging part was the reconstruction of the electromagnet. Any person with average strength, knowledge of screwdriver use, and simple deduction can easily reconstruct this impact wrench. The reassembly process was identical to the disassembly process in every way. The same steps taken to disassemble the impact wrench were just reversed to reassemble it. Seeing how easy and simple the impact wrench is assembled, it could be possible that the original assembly was done by hand. The first step in the reassembly process is reconstruction the electromagnet (motor). The only reconstruction necessary for this part is placing the motor shaft and copper coil into the center of the electromagnet, fighting the magnetic force as it is inserted. Then screw the back of the electromagnet (motor) closed. The motor is then placed at the very back of the impact wrench casing. The next part for reassembly is the trigger. This reassembly is very straightforward as a majority of the triggers electrical components are already connected. The only necessary step is pushing the triggers electrical components together and then placing them near the top of the handle of the impact wrench casing. Next the reverse switch is placed into the reverse switch socket and connected to the top of the trigger. The hammer assembly is very straightforward as well. Taking the bearing, you simply place the spring into the spring slot, slide the counter weight under the thick black bracket, then screw in the skinny bracket (using the small Phillips head screwdriver) on top of the area where the spring resides and the end of the counter weight is placed. The anvil does not require any reassembly of its own. The cylindrical end of the anvil is then connected to the hammers bottom and the entire combination is placed in the remaining spot in the impact wrench casing, with the head of the anvil protruding out of the casing. The leveler is also placed in its respective place. The power jack connected to the trigger is placed in its slot, allowing for the extension cord to be free and be placed into the power source. When all parts are in place, put the other half of the impact wrench casing on top of the half containing all of the parts. Using the big Phillips head screwdriver, screw the two casing parts together. When all of the screws have been screwed into the casing, the impact wrench reassembly has been finished.


While there is numerous mechanisms working in conjunction with each other within this wrench, for this section we will only be considering the ball-locking mechanism (US Patent 4480497) that holds the socket head in place. This is the mechanism that when you push the head onto the shaft with sufficient force, snaps it in place and holds it there securely. If we look at the drawing below, we can see the inner workings of this simple yet effective mechanism.


While this is an abstract drawing, the same principles and equations apply. Picture the rectangular piece (#3) as the shaft of the wrench with the locking mechanism, and the oval shape (#1 & 2) as the socket head with a small cavity (#9)being pushed into place. Originally, the ball (#11) is in the outer position and the spring and block (#7) is extended with no force being applied to it within a chamber (#4). When the socket head is first put on, the ball and the head walls are pressing against each other with no movement. The spring has a critical point when applied force reaches a numerical value high enough, the spring compresses. Pushing on the socket head applies a force to the ball, which in turn applies an equivalent force to the block and spring system. When the applied pushing force reaches the critical point, the spring compresses, and allows the ball to retract a small amount into the chamber. When this happens, the socket head slides freely into the shaft until the cavity is aligned with the ball. Because the cavity is an open space, it applies no force to the ball (or to the spring), which allows the spring to extend to its original position pushing the ball back to into the cavity. Due to the limited movement of the socket head to the left, it is now locked in place and will not slide off the shaft. Removal is a reversal of the process in which a pulling force is applied until the critical point is reached. For this mechanism to work successfully, the following equations must be considered: F=ma

Design Revisions

1) One thing we noticed in was that the trigger assembly seemed overly complicated. It looked like it could be simplified by using a 3-position switch instead of having these little components that if they break would be hard to replace. This could save money for the manufacturer because it would be easier to manufacture and get parts for.
2) The option of a battery pack should be included with the wrench. Since it runs of a 12 volt car jack, it is implied that it is supposed to be used with your car. If the cord is not long enough to get from the inside of your car to wherever you need it, the tool is useless. By giving it a battery pack the tools mobility is increased making it more appealing to consumers.
3) With all the torque that will be applied to this tool it seems that the thin plastic casing would wear out quickly and wouldn’t last too long. Making the case completely out of metal also isn’t a viable option. Putting in metal supports at certain locations to absorb and disperse some of that energy would increase the tools life and efficiency. These supports, mostly around the motor, could help eliminate wear on the plastic that repeated impact would create by creating a firmer hold on the specific part and dispersing the energy over a larger area so one location isn’t constantly taking all the force.