Group 9 2012 Product Analysis

From GICL Wiki
Jump to: navigation, search

Contents

Purpose

This gate consists of two main sections; the first section that we will mention is titled Project Management, and the second much larger section, Project Archeology. Within the Project Management section consists a section for the Cause for Corrective Action where our groups activities with one another are discussed. The Product Archeology section encompasses multiple parts. The parts include a component summary chart, a product analysis of seven different components, a solid model assembly of 4 component using inventor, an in-dept Engineering Analysis of 1 major component and 3 possible design revisions.

Cause for Corrective Action

We as a group have not had to deal with as many problems as we did coming from gate one. During gate two we were able to fix the problems that we had encountered originally when first coming together as a group to work on the previous gate. We now had better time management which eventually prevented many other issues that we had, such as becoming disorganized in our haste and not looking over the finished gate with the rubric in hand to be certain that all of the gate requirements had been meet before the gate was due. With this gate, we have a few more issues that we will need to be able to address. Firstly, we will have to deal with the ability to access modeling programs. We have all already tried to download the type of Autodesk Inventor that we are all familiar with off of the student section of Autodesk.com, and have not been successful in doing so up and until this point. We can now either try to make this program work, or find times that work during the week for our group to meet up and to go to the computer labs in Bell hall or Furnas Hall that have the software already installed on them. This is something that we will need to address early on individually based on our own personal preferences and availabilities during the week. This also seems to be the longest and most intensive gate out of the ones that we have completed so far, so we will need to stick to a strict schedule to make sure that we do not fall behind and end up rushing to complete it in the last minute possible. So if we stick to the plan that we had for gate one, and keep in mind the extra challenges that we will have to face on this gate, then we shouldn’t have any foreseen problems.

  • In just ending a team meeting, I will add that it has been discussed and our group has come to the decision that we will all meet up on Wednesday after MAE 277 lets out and go as a team to Furnas Hall to work on the CAD drawings on Inventor in the computer labs computers as we can not seem to get the program to cooperate with our laptops. We will all go as one to be sure that all of the dimensions that are measured be the same for interacting parts and so that the assembly model can be made that same day. Jeff will bring a flash drive for all of the drawings to be stored on so they can all be transferred onto one computer for this final drawing to be done. It has also been decided that the drawing will be of the magazine assembly as this is a relatively complex mechanism that is vital to how the gun operates as it is responsible for preparing the darts for firing. John is currently in possession of the Nerf gun so he is responsible for bringing the gun to the lab to take various measurements off of.

Product Archaeology: Product Evaluation

Component Summary
Part # Description Image
1 \'\'\'Axle Rod\'\'\'
    • Function: It is the center point for the Dart Advanced Drum. the axle allows for an axis of rotation for the Dart Advance Drum which allows feeding of darts into the firing chamber.
    • Materials Used: Plastic and Stainless Steel.
    • Manufacturing Process: Plastic- Injection Molding. Stainless Steel- Forming (Drawing).
AxleRod.png
2 \'\'\'Magazine Housing\'\'\':
    • Function: To provide protection from battle debris for the Dart Advanced Drum as well as provide rigidity for the magazine housing.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
MagazineHousing.png
3 \'\'\'Dart Advance Drum\'\'\':
    • Function: Holds the ammunition ready to be loaded into the firing chamber. This system is spring loaded which allows for the system to constantly force a new dart into the chamber.
    • Materials Used: Plastic and Stainless Steel (flat coil spring).
    • Manufacturing Process: Plastic- Injection Molding. Stainless Steel- Rolling.
DartAdvanceDrum.png
4 \'\'\'Rapid Feed Assist Knob Spring\'\'\':
    • Function: Provides pressure against the Rapid Feed Assist Knob to keep it from constantly engaging.
    • Materials Used: Stainless Steel.
    • Manufacturing Process: Forming.
RapidFeedAssistKnobSpring.png
5 \'\'\'Magazine Housing Cover\'\'\':
    • Function: Keeps dart from falling out of magazine. This component is made of a clear plastic which allows the user to see inside drum to see any problems with the magazine, such as jams.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding
MagazingHousingCover.png
6 \'\'\'Rapid Feed Assist Knob\'\'\':
    • Function: Allows the user to manually twist the Dart Advanced Drum, which allows the user to clear any possible jams that may occur during rapid fire.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
RapidFeedAssistKnob.png
7 \'\'\'Push Rod Lock\'\'\':
    • Function: Locks the firing mechanism on the push rod. Keeps the mechanism held at full potential as to be ready for fire upon trigger pull.
    • Materials Used: Plastic and Stainless Steel
    • Manufacturing Process: Plastic- Injection Molding. Stainless Steel- Forming.
PushRodLock.png
8 \'\'\'Firing Barrel\'\'\':
    • Function: Guides the dart out of the firing chamber. The rifling within the barrel puts an axially oriented twist on the dart, which allows for a more accurate, dependable shot pattern.
    • Materials Used: Plastic
    • Manufacturing Process: Injection Molding.
FiringBarrel.png
9 \'\'\'Muzzle\'\'\':
    • Function: Holds the firing barrel in place, while being a cosmetically pleasing accent to the exterior to the gun.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
Muzzle.png
10 \'\'\'Outermost Casing\'\'\':
    • Function: Holds inner components together and in their correct locations as there are tabs and screw locations on its interior to house the inner workings of the Nerf gun. The vibrant orange color provides a drastic contrast to the average environment, which allows for misinterpretation with real weapons to be impossible; as well as provides a fun colored toy for children to play with.
    • Materials Used: Plastic
    • Manufacturing Process: Injection Molding
OutermostCasing.png
11 \'\'\'Stock\'\'\':
    • Function: Provides an endpoint to the Nerf gun and provides protections for the shaft extending from the firing mechanism that extends back past the point of the outer casing when fully cocked. This part is also designed to accept Nerf approved aftermarket accessories such as firing stocks and other additional user modifications available at your local Nerf retailer.
    • Materials Used: Plastic
    • Manufacturing Process: Injection Molding
Stock.png
12 \'\'\'Firing Chamber\'\'\':
    • Function: The end of this mechanism guides the the firing spring into the center of the chamber, which then ejects the dart into barrel.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
FiringChamber.png
13 \'\'\'Firing Spring\'\'\':
    • Function: Is the main source of potential and kinetic energy for the firing of the dart. The compression and release of the spring is what fires the dart.
    • Materials Used: Stainless Steel.
    • Manufacturing Process: Forming.
FiringSpring.png
14 \'\'\'Holding Bracket\'\'\':
    • Function: Holds the firing mechanism at full potential until the trigger is pulled and this is the part of the gun that is responsible for releasing the spring, thus firing the dart.
    • Materials Used: Plastic and Stainless Steel.
    • Manufacturing Process: Plastic- Injection Molding. Stainless Steel- Forming
HoldingBracket.png
15 \'\'\'Trigger\'\'\':
    • Function: It ectenst out of the outer casing allowing for the user to be able to provide the user input needed to fire the dart. It is connected to the holding bracket on the firing mechanism, which allows for the dart to be fired. The user can also hold the trigger down and the gun will fire as fast as he/she can cock the gun, thus activating the Rapid Fire feature of the gun.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
FiringTrigger.png
16 \'\'\'Cocking Arm Pushrod\'\'\':
    • Function: Connects the Cocking Arm Foregrip and the Firing Chamber. It allows for the Firing Chamber to be cycled through; thus cocking the spring, and having a dart loaded into the firing chamber ready to be fired.
    • Materials Used: Plastic and Stainless Steel.
    • Manufacturing Process: Plastic- Injection Molding. Stainless Steel- Forming.
CockingArmPushRod.png
17 \'\'\'Cocking Arm Foregrip\'\'\':
    • Function: Allows for a hand placement that allows the user to pull back the Cocking Arm Pushrod. Also provides the user with stability when firing the gun.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
CockingArmForegrip.png
18 \'\'\'Drum-Magazine Holder\'\'\':
    • Function: Connects the Drum Magazine and outermost casing. It provides an easy release of the Magazine for an easy reload.
    • Materials Used: Plastic.
    • Manufacturing Process: Injection Molding.
DrumMagazineHolder.png
      • Each component used only one time as mentioned in table above.
    • Fabrication Methods:
    • Injection Molding: Process of forcing molten plastic into a mold and allowing it to harden within the mold producing a finished piece. The mold is reused and is typically composed of steel.
    • Forming: Process of heating and shaping a metal into designated shape.
Product Analysis

1. \'\'\'Dart Advance Drum\'\'\':

    • The dart advanced drum is located inside the magazine housing to form the subsystem of the Magazine for the Nerf gun. Its main objective is to feed darts from the magazine into the firing chamber. It does this by rotating around an axle, while attached to a self winding spring to keep pressure so that the next dart can be loaded into gun after a previous dart is fired. Energy flows from the tension in the self winding spring to torque that spins the drum.
    • The general shape of the component is a cylindrical drum with dart shaped depressions, surrounding its exterior. Via the self winding spring, the drum is connected to a hollow channel, which feed the darts and provides a locking point onto the gun. The outside cylinder is completely symmetrical around its center point. The dimensions of this cylinder is a 3.5 inch diameter with a 2.5 inch depth. The depressions which hold the darts have a .57 inch diameter. The component roughly weighs 4 ounces.
    • The dart advanced drum is made mainly from plastic, with the exception of the self winding spring. This material choice was made because injection molding is a relatively cheap process, while completing it\'s task without any issues. In order to function, the metal spring needs to be able to coil back to itself in order to perform the task needed. Therefore, the choice of metal is necessary for it to function. The material choice is an economical issue because injection molding is a relatively cheap process, keep the product price a at minimal for the consumer. A societal issue that relates to the material choice is that plastic is a relatively durable product, making it hard for children to break. This allows children to play with the product avoiding any serious injury. The vibrant orange color of the drum, making it aesthetically pleasing, which is important because this component, is located on the exterior of the gun. The vibrant orange color cannot be mistaken for a real gun by others. It has a smooth surface finish which is important because it will have minimal friction between darts. This allows for maximum performance. It also keep children safe because it has no sharp edges.
    • Since it the component is covered in injection marks, we know the component was made by injection molding. Since, it is a complex geometry, injection molding is the most pheasable option. Machining this part would be far too expensive. Since, its the cheapest method, it keeps the product cost at a minimal.

2. \'\'\'Outmost Casing\'\'\': Outermost Casing:

    • The Nerf N-Strike Rampage Blaster is a toy created to replicate a real weapon in a non-violent way for children and young adults to enjoy. With the components of the toy constantly undergoing movement from loading, reloading, and multiple user actions such as jumping, sliding, and running, the gun must be able to withstand a decent amount of abuse and be able to remain functional and in-tact. The casing that surrounds the toy not only is there for visual appeal, but also to maintain structural integrity and stability in multiple environments; hot, cold, wet, or dry.
    • The outermost casing is specifically designed to provide the user with a comfortable operating position while being used and to keep all of the inner components from moving around while the product is being used. The casing is not symmetric due to the side mounted magazine housing as well as having a slot which can be opened to prevent jams inside of the firing chamber. Given that the casing must be able to be both comfortable and practical for the user, the dimensions had to be made to fit users of all sizes and ages. The dimensions are 4”x21”x12.8” and is suitable for most ages and either left or right handed shooters. Individually, the casing weighs about 10 ounces, but when the toy is put together entirely, it weighs about 2.1 pounds.
    • In order to reduce weight for the entire system, the casing is made of plastic. With plastic being a very easy material to shape and color while retaining a light weight and rigid structure it is the perfect choice, especially since it is very cheap to manufacture in bulk. Aside from reliability that is naturally found in the plastic, no extra supports from different materials are needed to keep the casing functioning aside from the screws that hold both sides together when fully assembled. Since the gun is so light weight due to the plastic, a person of any age will be able to hold and fire the toy with ease and does not have to worry about any sharp edges due to the natural round edges found all over the outermost casing. Next to the appealing low price of the gun due to the choice of material, the aesthetic appeal of the toy is also something to take note of. With a vibrant color scheme of orange, blue, and silver, the toy appeals to all genders and all ages by maintain a sleek yet sophisticated look. When the user is holding the toy it is nearly impossible for them to injure themselves because the toy has a smooth, shiny finish that eliminates all possibilities for having sharp corners which eliminates scratching or puncture possibilities for the operator.
    • In order to maintain a low price for the toy, the method used to manufacture these parts in high volume is injection molding. With its complex design featuring slots for the magazine holder, the magazine, fore-grip, stock, and jam prevention slot, this method of manufacturing would prove vital for mass production without any serious flaws in the design. This manufacturing process allows for mass production which can lead to widespread distribution around the world for this particular toy and adds a new source of profit for the company.
    • By looking at the outside of the casing you would not think much of it aside from the visual appeal, but when the casing is removed and the inside can be seen, it is actually a very complex piece of engineering. All along the inside of the toy one can find brackets to hold each part in an exact position to avoid any undesirable movements that may interrupt the toy’s functionality. The casing can be viewed as one of the simplest pieces of the toy from the outside, but is actually one of its most complex.


3. \'\'\'Drum Magazine Holder\'\'\':

    • This component’s purpose is to attach the drum magazine to the outer most casing and hold it in a position that darts can be loaded from it into the firing chamber. It also needs to allow the release of the drum magazine only when the user pushes the release button, but keep it locked at all other times. It also needs to be able to take a certain amount of force and still remain attached to the side of the outer most casing. The flow in this part consists of constant force from the internal spring against the magazine release button, to ensure that the magazine stays locked in place when the button is not pushed. It also takes an input from the user which decides when the magazine will be released. This part needs to be able to function in all conditions because it is an exposed part of the gun. It needs to be able to fulfill its job whether it is hot, cold, wet or dry.
    • The general shape of this part is a rectangular prism with a rectangular shaped hole in the center of it, which is where the drum magazine is held. The center of the square hole is shifted slightly toward the muzzle end of the gun so that the magazine release mechanism can be placed inside of the back end side of the component. At this end, you can see the push button for the release of the magazine. When the part is turned, exposing the side that is flush with the outer most casing, you can see a hollow inner section, as well as symmetrically placed clips along the longer sides of the rectangle which hold the component to the side of the outer most casing. This is a three dimensional part, with a length of 3 inches, a width of ¾ of an inch, and a height of one inch, and a general weight of 2 ounces. This general rectangular shape was selected based on the shape of the end of the drum magazine, which is predominantly rectangular to accommodate for the shape of the darts. Because this part is solely to hold the magazine, this is the only impact on its shape.
    • This part is made mostly of plastic. The only parts that aren’t plastic are the screws which hold the four mounting clips, and release mechanism cover onto the part, as well as the spring within the release mechanism. The manufacturing of this part influenced the part material in the sense that they could make more of them faster and safer by using plastic rather than something like metal which would take longer to create and cost more. This part also relies on the flexible properties of plastic that allow its clips to flex and click into place as well as flex a small amount to be removed. The plastic also it able to work similarly in colder weather as well as hot weather which means there will be no change in performance because of the climate. Also the decision to make it out of plastic means it can be produced without any sharp edges. Because the gun is mainly used by younger children who will be running around and playing with it, it is important that there are no sharp edges exposed so that the child cannot hurt themselves. It is especially important on this part because a child will be constantly contacting this surface to reload the gun. The use of plastic and small amounts of metal allows the part to be made cheaply as well as allows for it to be completely recycled at the end of its lifetime which is essentially short.
    • Since this part is exposed on the outside, it needs to be generally aesthetically pleasing. So it has some stripes that are marked by differences in the texture finish on the outer side. This part is blue with the release button being orange. This is to match the color scheme of the rest of the gun. All of the surface finish colors and designs on the part are purely for aesthetic purposes.
    • This part was mostly made using injection molding, as well as some forming. All of the plastic components on the gun were made by injection molding, and the spring was formed. On all of the plastic parts, including the internal pieces of the release mechanism we can see ejector marks which are an indication of injection molding. The spring we assume is done by forming because that is the predominant way to make springs. The fact that most of the parts were to be made using plastic, injection molding was the best option. All other options such machining processes as well as additive processes would be too costly by comparison as well as take too long to produce. The fact that the component is made up of many small simple components, injection molding was a feasible choice. Had these been larger and more complicated in its geometry, it might have required a more complicated process. Considering a global standpoint in the production, these guns are made overseas, usually by several unskilled and basically trained workers, the production process needed to be simple enough for them to complete it. It would be difficult to train them to operate something complicated like a CNC machine or a type of 3-D printer, so injection molding would be the best option. From an economical standpoint, this is also the cheapest type of production for plastic parts as well as the fastest, so it allows each gun to be sold cheaper, as well as produce more of them to sell. It also proved to be a good production method because injection molding is a safe way to produce parts. This can be done with no more environmental damage than and other process of forming plastic since it needs to be melted in any case, so it proved to be a good method in that regard.
    • This is a generally complex part. It is comprised of several other parts that all need to be fit together in close quarters in the correct order. It has ten plastic parts as well as eight screws and one spring. So this component is one of the most complicated parts on the gun. Based on what the components function is, it needs to be generally more complicated, since it has several functions as well as several internal components. The manufacturing of this product also leads to the need for several different parts to be made separately, since injection molding can only shape the basic shells and small pieces, which then have to be assembled.

4. \'\'\'Firing Spring\'\'\':

    • The function of this component is to provide all of the energy to the firing mechanism that fires a dart forward. It needs to be able to be compressed a large distance to build up the most possible potential energy and then provide enough force to be able to fir a dart out of the barrel by converting the potential energy into kinetic energy. This component has user input in the form of the user cocking the gun, which compresses the spring. It also has a user input in the form of the user firing the gun, which is what releases the compressed spring. The energy flows in as potential energy and out as kinetic energy. This functions in a relatively stable environment inside the casing of the gun where it is kept protected from dirt and mud. The only variation in its work environment is the changes in temperature which would be based on where the consumer uses the gun.
    • The general shape of this component is a cylinder, which is made by a uniform coil of metal wire. When the spring is at rest, the coils are all equally spaced between one another. This is a three-dimensional part with an overall length of about six inches, and a diameter of one half of an inch. This general shape is absolutely crucial in the components function. This parts function is based on its ability to be compressed and released over and over without much variation in its overall performance. This shape allows this to happen. It also needs to be able provide a force when it is compressed to achieve its function. With this form, it is able to do that. This component weighs roughly one ounce.
    • This component is made completely out of stainless steel. This selection of material was based completely around its functionality. Stainless steel is a metal that is strong, but is also completely resistant to rusting. So this allows the spring to never break down. The flexibility of the metal allows it to complete its function constantly and have it always return to its original position. Its strength allows it to produce a large amount of force against the firing mechanism when it is released. The choice of this material was in no way influenced by the manufacturing of it. When looking at an overall global standpoint, this material was chosen because it is able to function in wet and dry environments. It can be used in Arizona where it is very dry, or in Seattle where it rains frequently. The choice or plain steel could have caused the spring to rust away if in was used in a pool or left out in the rain like it would possibly be used by a child. From a societal standpoint, the material does not leave any sort of residue that can be harmful if child were to lick it or get it on their skin, such as graphite or lead. Economically it is a relatively cheap metal when you compare it to other types of materials that can be used in springs like aluminum, or composites. Environmentally, this is a recyclable metal that never breaks down, so ensuring that it is recycled can mean no environmental damage can come from its use.
    • This component is a silver color with a mirror shine. Since this part is not seen by anybody, because it is covered by the outer casing, it was not designed to look at all aesthetically pleasing. All of its aesthetic features come from its function. So its silver color comes from the fact that it is bare metal. If it had been coated with chrome or paint, it would eventually crack off and fall away, so leaving it bare was easier and safer by not leaving any paint chips behind. The surface finish is a polished mirror shine. This is done so that there will be virtually no friction between the spring and anything that touches it.
    • This component was created by forming it around a round pole. This is most likely done by heating the material then wrapping it around the pole and letting it cool and form into its final shape. This seems to be the case because there are no indications of die casting such as riser marks. Also because the surface finish is of a high quality, we can infer that the material hasn’t been manipulated very much. Since forming on requires a slight change from the wire, it seems most likely. The wire itself was most likely formed by drawing it through a die. Since its cross sectional shape it so simple, drawing seems more likely compared to extrusion which is used for a more complicated cross section. These methods needed to be used because the component it made out of metal. Had the spring been made out of plastic, they could have made it using injection molding, which would have been a much cheaper and simpler process to complete. Had the shape been flat and overall simpler, die casting could have been used, but since its shape is so complicated, it need to be drawn and then formed. From a global standpoint, the process of drawing is very simple so an unspecialized worker anywhere in the world would be able to operate the machine easily. It would be the same for the forming process, which may have been a big factor in determining this method. It is a very safe form of making springs and wire. These are processes that are completed in massive amounts and it has proven to be a very safe method of production. From an economic standpoint, these are very cheap methods of production, which also allows for a very large production rate which means more sales possible. These methods also do not create any waste products and don’t release emissions, so choosing these made it an environmentally responsible choice.
    • This is an overall simple component. It is only made of one continuous piece of wire that is formed in concentric loops that are spaced at a constant distance away from each other loop. The entirety of this components complexity comes from the fact that it is created in a coil. Which means that the form of this component is the main responsibility for its complexity. Its function is what demanded that it is this shape, and the manufacturing is what produced it in that shape, so those are also responsible for it as well.

5. \'\'\'Barrel\'\'\':

    • The overall function of the barrel of the Nerf gun is to guide the dart out of the firing chamber and ultimately out of the gun. In addition the barrel is also rifled so when the dart travels down the length, it is provided with a twisting motion and the spinning of the dart allows for a more accurate flight path and I tighter grouping of shot trajectories down range at the designated target as opposed to if no rifling where to be used at all. The barrel is the final point for the dart to pass through in its mass flow through the overall system. This then means that the outermost end of the barrel is exposed to the outside so it is possible for dirt and debris to enter the barrel as well as that the barrel is then fully exposed to the outside weather conditions.
    • The shape of the barrel is a long cylindrical tube with a series of spirals cut into the interior surface to form the rifling in which is necessary to the overall functionality of the system. The barrel is 12” long with a diameter of .6” which is just large enough to house the darts but is still small enough that the rifling can still be useful because if it were made to large, then the twisting motion of the dart would not be made as dominant. The barrel is also a relatively light part of the gun weighing approximately 2 grams. This allows for the main mass of the gun to be held in the center of the overall geometry and keeps it from becoming front heavy and awkward to handle. The component is made entirely of plastic to make this low weight requirement possible. Keeping the barrel made out of plastic also serves as a cost cutting measure since plastic is cost efficient and is easy to work with. This aids to the Economic and societal features since plastics are affordable and don’t drastically increase price like some other synthetic materials out there while still remaining rigid and durable enough to not affect the performance of the gun.
    • The barrel is largely covered by the outermost casing but the end is slightly exposed and the inside of the barrel can be seen if the user looks down the barrel do it is only these aspects of the toy that need to be aesthetically pleasing. It is for this reason too why I feel as though Nerf decided to add the rifling to let the user know that he is buying a high quality product and brag to his fellow “Nerfers” that he/she has the higher quality product. The barrel is colored bright orange and this is because of the government’s laws about toy guns forcing them to wield a bright orange barrel tip to let bystanders know that the gun is in fact a toy and not a military grade weapon.
    • The manufacturing method used to produce this part I fell would be a complex extrusion process. I feel that a stationary circular die was used to form the outside surface while there was another ribbed die that was located in the center that rotated to create the rifling that continues the length of the barrel. This would be the most economical process to create the part because plastic can easily be extruded and in order to get the center rifling the only other method would’ve been to machine the center of every barrel produced and that would become extremely expensive and greatly increase production on time.
    • The complexity of this part is relatively complex in the way it must be manufactured to create the rifling inside the barrel but for the assembly complexity it is extremely straight forward and just sits up against the firing chamber ready to accept the fired darts with little to no added resistance as it is just a straight tube.


6. \'\'\'Stock\'\'\':

    • The function of the stock as-is is relatively straight forward and is just simply a knobby mechanical looking end for the end of the gun. The beauty of the stock is that it can also act as an adapter to accept aftermarket stocks for added user customer customization by you die hard “Nerfers” out there who would kill to have a highly custom Nerf N-Strike Rampage Blaster and with this stock Nerf has acknowledged that this is a reasonable addition for the gun to come with from the factory. Because of the fact that this stock must be able to accept aftermarket parts it must be strong enough to support the added load that would be put on the gun from both the weight of the aftermarket stock as well as the abuse that it could take in battle if the aftermarket part were to be struck.
    • The form of the part is basically a large plastic peg that sticks out the rear of the gun to act as an acceptor for custom parts that would connect via a sort of “peg and slot” connection. It sticks back .75” which allows for long enough area for the friction mount that would hold the aftermarket stock onto the gun adequately. This part is relatively dense because it needs to be made thicker to support the added load and shear force so it weighs along 3-4 oz and for such a small part that is a decent mass. This part could’ve been made of metal to give the needed strength but that would’ve added unneeded expense to the toy making it an economically smart decision to fabricate out of plastic as in normal circumstances it will be plenty strong enough.
    • The stock is located on the rear of the gun and is entirely exposed so the finish on the part needs to be one that is presentable and up to the high standards of the rest of the exterior of the gun. The part itself is gray and it is smooth with 5 depressed lines running the length of the part that serve as friction points for the aftermarket stock to slide into to impede rotational motion so that the stock stays put once applied and does not rotate freely while in use by the respective “Nerfer”.
    • The manufacturing process that would’ve been used to create this part would’ve been injection molding as it is the most cost effective way to mold plastics into unique shapes and there are seam lines within the plastic itself from where the front edges of the plastic began to cool while still being injected into the mold and when the two front edges of the pour met, the seam lines had been formed. This part could’ve been machined out of a solid piece of plastic to stop this from happening in the first place but that would’ve been extremely more expensive and not very cost efficient, thus raising sale price for a very minimal performance gain making this to be a very smart economic call in the manufacturing of the part.
    • As a whole this part is relatively simple in its makeup, while come thought had to be put in to make for this to become a universal fitment on to aftermarket stocks for the gun, the actual manufacturing of the part is simply just an injection molding process. For the assembly of this part on the gun, it is just help on to the rear of the gun by two screws making for a very straight forward assembly of the gun as well.


7. \'\'\'Cocking Arm Pushrod\'\'\':

    • The cocking arm pushrod’s only function is to cock the firing spring, which allows a dart into the firing chamber, which can then be fired. The component is connected to the firing chamber by a metal pushrod that rests around a cylindrical shell. The cylindrical shell is able to slide freely along the push rod. This shell is then connected to the cocking arm fore grip, which is how the user is able to cock the gun. This whole mechanism is located on the interior of the outermost casing.
    • The cylindrical shell is symmetrical about the push rod and acts primarily one dimensional along the x-axis resting on the push rod. The push rod is roughly 15 inches long and weighs about an ounce. The cylinder that rests on the pushrod is about 6 inches long by 4 inches wide and weighs roughly 3 ounces. The shell is made entirely from plastic, while the pushrod is made of stainless steel. The rod has to be made of steel because it needs to be durable because it takes a lot of abuse from the user. If the rod becomes disconnected from the firing chamber, the gun will not load. Plastic is sufficient for the cylindrical shell because its function is to simply slide along the smooth pushrod. The plastic is cheaper and keeps the gun at an affordable cost. This component does not have to be aesthetically pleasing because it is located on the inside of the gun and cannot be seen unless the gun is taken apart. Its smooth surface finish is important because it allows minimal friction between the cylinder and the push rod. This makes for a faster reload, which make the gun more enjoyable for the user.
    • The manufacturing process used for the plastics was injection molding. This is noticeable by simply analyzing the component because there are injection marks on the part. The shape impacts the manufacturers decision because, the cylindrical part would be had to machine, as well as making it much more expensive. This material choice keeps the gun at an affordable cost for the consumer. Forming processed the push rod, which was the most affordable option considering the necessity that the part was steel.
    • The complexity of the component was affected by the need of two different materials for maximum performance. Since, plastic and steel were needed, it made the component more expensive to assembly than other in the gun.
Solid Modeled Assembly
    • For our Solid Modeled assembly, we choose to draw four parts of the Drum Magazine. We felt this was a good choice because it was one of out two main subsystems of the gun and is responsible for accepting the ammunition to be fired and keeping it in a sorted order so that all the twenty five darts loaded in the magazine can be ready to fire whenever the user is ready for battle. This means that not only is this part vital to the operation of the gun as a whole, but it must also be made precisely so that it can operate in the cleanest manner possible and not become easily jammed up under heavy fire. We chose to draw these components with Inventor 2012 because we all had previous experience with Inventor 2010 from CAD class in high school and we felt we would have the best luck attempting to just learn the new layout of the new updated Inventor that we were previously familiar with, rather than attempting to learn a whole new program such as Solid Works. This allowed for the process to go very smoothly after we became acclimated with the new redesigned layout of the program. Pictured below are the solid models created by use of Autodesk Inventor 2012 in the order as follows: a Total Assembly of the Drum Magazine, the Axle Rod, the Dart Advance Drum, the Magazine Housing, the Magazine Housing Cover, and the Exploded View of the Drum Magazine.
AssemblyView.png
AxleRodView.png
Drum.png
BackCover.png
Cover.png
ExplodedView.png

Engineering Analysis

    • For this section, We choose to analyze the Firing Chamber of our Nerf Gun.
DartChart.png
Component Function
    • The Firing Chamber is the heart of the gun, every sub component somehow interacts with this piece. The overall function of this mechanism is to first take the user inference of the cocking action and store it as potential energy in the spring. Once the user pulls the trigger, it releases all of the potential energy in the spring at once, firing the dart through the barrel. This mechanism is located inside the outermost casing, thus protecting it from dust and debris,but it is vulnerable to extreme heat and cold of outside conditions.
Component Form
    • The general shape of this component consists of several concentric cylinders ceded inside one another. Connected to the end of the main cylinder is a long plastic push rod, where the firing spring sits. When activated, the spring will push the rod through the main cylinder forcing the dart forward. Below the main cylinder, there is a series of linkage that connect the push rod lock to the firing chamber, which allows for the overall component to function. The whole chamber is held into the outermost casing by two screws located at the upper right hand corner and lower left hand corner. When component is activated, the motion strictly one dimensional moving along the x-axis.
    • The cylindrical shape directly relates to the shape of the barrel in which it connects directly to. This allows for a clean fitment inside the outermost casing and allows for a clean flow energy through the system, allowing for a minimal loss due to friction when firing.
    • The component weighs roughly an ounce, completely out of of plastic. Since its made entirely from plastic, the weight of the component is kept to a minimum, compared to making it out of other materials, such as steel. This keeps the cost of materials as low as possible, keeping the overall cost of ownership of the product down for buyers. If this product were made entirely out of metal, it might see slight performance and durability improvements at the expense of a high market price, as well as an increased overall weight. This is a societal issue because an increase in production cost, increases sales prices, thus making it less affordable to the average family. In addition, the added weight might make it harder for smaller children ,the target audience, to handle safely, leading to some possible safety concerns for the user.
    • Since the component is hidden entirely by the outermost casing, its aesthetics are irrelevant. Since, the aesthetics are not a concern, surface finish does not have to be held to the high standard of that of the guns exterior.
Manufacturing Methods
    • The only manufacturing method used for this component is various injection moldings that are simply glued together at the seams and this is done because its made entirely out of plastic, meaning this is the most economical method that the manufacturer could use to keep cost down. This makes the component as light and as cheap as possible, while still completing it\'s job of maintaining a safe product for children to be playing with and ultimately abusing in everyday use.
Problem Statement

A possible question surrounding the firing chamber is determining the velocity of the dart as it leaves the chamber.

Governing Equations
  • Potential Energy of spring= k*change in distance of spring
  • Kinetic Energy =1/2*k*x^2
  • Force of Friction = coefficient of static friction * normal force
Discussion

In order to measure the velocity of the dart a number of steps would need to be completed for an accurate calculation. A reference point must first be established behind the barrel of the toy in order to determine the amount of time it takes to travel a certain distance upon exiting the barrel. This can give the user a general idea of where the velocity inside of the firing chamber will be. Once this velocity has been found, the user can then begin to add in factors that may change the speed during the firing stage such as friction. Once all of these disturbances have been found and are properly introduced to the velocity at the end of the barrel, calculations can be made to find both potential and kinetic energy inside of the firing chamber which will result in finding the velocity of the dart.

Design Revisions

  • When Nerf created the Nerf-N-Strike Rampage Blaster, they created it with the anticipation to appeal to a maximum number of people. Upon dissection, we discovered that there are a few modifications that can be made to the gun to make appealing for a greater range of consumers.

\'\'\'1. Firing Spring Improvement:\'\'\' Before dissection we had a test run with our gun to get baseline statistics of our gun fired. After this test, we found that our fired an average of 75 feet, with a rough standard deviation of dart distances being at 7 feet. Our group feels that for a small additional cost, a larger, more powerful spring could be added in place of the smaller, much inferior current firing spring. This simple addition would greatly increase the firing range of the gun. If the gun were to fire farther, it would attract a wider buyer base because not only would this gun have a high dart capacity with its current drum magazine but, its firing range would exceed that of most long range Nerf guns, making it a double threat. We feel that this alteration can be made for minimal addition of cost, with maximum addition of fun and performance for the user.

NerfGunSpring.jpeg

\'\'\'2. Stock Addition:\'\'\' Since our gun comes from the factory with an attachment ready to accept an aftermarket stock, we feel that Nerf should supply the user with a pre-installed stock straight from the factory. If this were to be on every gun it would produce better sales for Nerf because it gives the much more aggressive look of assault rifle to the average child, without making the gun any more dangerous. Manufacturing cost would increase slightly, but we feel the spike in sales would greatly out weigh this increase. During our test run we found it awkward to handle, as you hand to support the whole weight of the gun in your hands. It also made it difficult to aim because it is hard to look down the sights without being able to rest the gun on your shoulder for support. If the stock was to be a permanent part of the gun, these downfalls would be eliminated thus making for an all around better looking, better performing Nerf gun.

NerfGunStock.jpeg

\'\'\'3. Scope Addition:\'\'\' Upon first inspection, we found that our gun has rails on the top that appear to be set up to accept an aftermarket scope. We feel that the addition of scope to the weapon right out of the box would increase sales because it appeal to a wider audience. This would also increase the aesthetics, giving it a mean, more aggressive appearance and make the young boy firing the gun to feel that he is a real life sniper out fighting the bad guys. The scope addition would also make the gun much easier to aim, allowing for a much more accurate shot. If a scope were to be added it would make for even the most novice Nerfer to be able to shoot the gun like a trained professional with a very accurate shot pattern. We feel that this scope would be a smart addition by Nerf to the gun because it has such great increases in both the ascetics and performance.


NerfGunScope.jpeg