Difference between revisions of "*Gate 3: Product Analysis"

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(Engineering Analysis)
(Design Revisions:)
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A second possible design revision to the original Nerf Longstrike CS-6 would be an addition of a crank loading mechanism. This would replace the Paul and Ratchet mechanism currently implemented with the cocking bolt. Now, a crank with gears on it would be used to load the gun and pull the air chambers back.  This would involve the removal of the Cocking Bolt, the addition of a hand crank connected to a gear, and a slider connected to the air chamber with gears on the bottom. A picture of this design revision is shown below in Revision Two. An effect of this replacement of the Cocking Bolt with the crank system is that it would allow for a greater range. This is because a hand crank could create a larger force which would support a spring with a stronger spring constant to be used. This would then allow for a large return force on the foam dart. Thus, the darts that shoot out of the barrel will have a higher acceleration sending them further distances. The crank would also make it easier to load the gun as the Cocking Bolt currently uses two hands in order to pull the system back. Also, by removing the Cocking Bolt and adding a crank, it increases the safety of the product. The crank eliminates the potential safety hazard that the Cocking Bolt creates with the sliding of the rails where a small child could easily pinch their fingers before, during, and after the shooting of the dart. This design revision would meet global and safety standards around the world as well as be more appealing to the public due to the higher safety precautions. All of these factors show that a crank would be a beneficial change to the Nerf gun, causing a safer enjoyment by the user.
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A second possible design revision to the original Nerf Longstrike CS-6 would be an addition of a crank loading mechanism. This would replace the linear cam mechanism currently implemented with the cocking bolt. Now, a crank with gears on it would be used to load the gun and pull the air chambers back.  This would involve the removal of the Cocking Bolt, the addition of a hand crank connected to a gear, and a slider connected to the air chamber with gears on the bottom. A picture of this design revision is shown below in Revision Two. An effect of this replacement of the Cocking Bolt with the crank system is that it would allow for a greater range. This is because a hand crank could create a larger force which would support a spring with a stronger spring constant to be used. This would then allow for a large return force on the foam dart. Thus, the darts that shoot out of the barrel will have a higher acceleration sending them further distances. The crank would also make it easier to load the gun as the Cocking Bolt currently uses two hands in order to pull the system back. Also, by removing the Cocking Bolt and adding a crank, it increases the safety of the product. The crank eliminates the potential safety hazard that the Cocking Bolt creates with the sliding of the rails where a small child could easily pinch their fingers before, during, and after the shooting of the dart. This design revision would meet global and safety standards around the world as well as be more appealing to the public due to the higher safety precautions. All of these factors show that a crank would be a beneficial change to the Nerf gun, causing a safer enjoyment by the user.
  
 
[[File:Revision.png|thumb|center|caption|Revision Two: Replacing the Cocking Bolt with a hand crank and gears.| 350px]]
 
[[File:Revision.png|thumb|center|caption|Revision Two: Replacing the Cocking Bolt with a hand crank and gears.| 350px]]

Revision as of 04:02, 6 December 2012

Contents

Introduction

For this phase in the Nerf N-Strike Longstrike CS-6 project, the design team fully analyzed the components previously found in the disassembly phase of the project as well as recommended subsystem design revisions to the original Nerf gun. The team members began by first creating a component catalog containing each component of the Nerf gun. From here, seven of these components were chosen by the design team to be further analyzed on a more detailed and descriptive level. A major part of this analysis involved considering global, societal, economic, and environmental influences on design decisions. From here, the design team then chose four of these seven components. They then took these components and created them on a solid modeling CAD package which showed how they interacted with one another. Next, they chose one of the four components and described how engineering analysis was used in the testing stages as well as the design of it. Finally, the design team used all of the above analysis as well as their knowledge to recommend three design revisions to the Nerf N-Strike Longstrike CS-6 that would alter the design on a subsystem level. The design team then evaluated their work as a team. Throughout this phase of the team’s project, the group members were able to fully analyze and understand the functioning of the Nerf gun with respect to all of its components as well as gain insight on factors that go into the design of each component.

Project Management: Coordinate Review

Cause For Corrective Action

Since the submission of the last project by the design team, the members have figured out a correct timeline that best suits their needs as well as allows for the completion of all tasks to the best of their abilities. The meetings between Gate Two and Gate Three were as follows:

  • 10/25 : The extra assignment was finalized and completed. The group then rearranged their team meetings to suit everyone’s schedule especially with exams and the upcoming holidays. Information for the next gate was started and sections were divided up.
  • 10/30 : The component catalog was made. Components were chosen for the product analysis, solid modeling,and engineering analysis. Information was divided up.
  • 11/1 : The product analysis, engineering analysis, and design revisions were discussed as well as worked on.
  • 11/5 : The solid modeling portion of the assignment was started and completed.
  • 11/7 : The product analysis, engineering analysis, and design revisions were completed as well as finalized. All of the information was combined. The team manager then had the responsibility to finish uploading the gate.
  • 11/13 : The gate was individual reviewed before, altered at the meeting, and then group reviewed.

Over this time span before Gate Three, though the team’s time management went well, they came across a challenge. This challenge was that not all of team members were pulling their fair share of the project. These team members were contributing minimal work outside of the team meetings and though they agreed upon doing specific sections, they only put forth half the effort and instead relied upon others to pick up their share of the work. This problem was brought up at the November seventh meeting by two of the team members. Through a serious talk by all team members, each person was able to explain how they felt about the distribution of work throughout the project. Once the conversation was finished, each team member realized what they needed to improve on. Each person wasn't pulling their share in some way. From here, the group was then able to work together more efficiently and finish the rest of the gate with everyone's equal contribution. The team agreed that future problems will be handled the same way, through communication, honesty, and compromises. The project was then able to be finished to the best of every team member’s ability.

Product Archaeology: Product Evaluation

Component Summary

In the previous stage of the design team's project, the group members disassembled the Nerf Longstrike CS-6. Throughout this process, a component chart was made for each component found in the Nerf gun. This was done in order to better classify each part as well a to allow for a better understanding of the functionality of each component to its immediate subsystem and to the overall function of the Nerf gun. For each part,a number of identifying factors were recorded. First, the component name, the quantity of the component, and the specific material used was recorded. From here, the material used as well as the design of each component was analyzed in order to determine the best manufacturing process for each part. The reasons that correspond each component to its manufacturing process are the following:

  • Injection Molding:This manufacturing process is used to force liquid plastic into a mold in order to create small to medium sized parts. Key characteristics of this process are riser marks, draft, and parting lines. These are a result of the mold being taken apart from the plastic component once it is cooled and hardened. Components listed under this manufacturing process were chosen by the design team because they were made of plastic, had riser marks, and were of good detail that an injection mold has the potential to create. The following three pictures of the Base, the Base Divider, and Shoulder Stock, respectively, show examples of riser marks. Similar features were found in the remaining injection molded parts. Note: The rubber and foam components were injection molded with their corresponding materials.
Base Riser Marks: The circles in the picture outline examples of riser marks located on the inside of the Base showing injection molding.
Base Divider Riser Marks: The circles in the picture outline examples of riser marks located on the inside of the Base Divider showing injection molding.
Shoulder Stock Riser Marks: The circles in the picture outline examples of riser marks located on the inside of the Shoulder Stock showing injection molding.
  • Drawing:For this manufacturing process, a material is pulled through diet in order to form a specific profile. The key characteristic for this process is that the cross-sectional area remains constant throughout. Therefore, the components that were assessed to be made by this process were thin, delicate, and intricate in design. Drawing would be the most appropriate manufacturing process for such designs. The following picture of the sight hinge is a processed by drawing.
Sight Hinge: The wire shown is manufactured by drawing, or pulling steel through a diet.
  • Coiling:This process manufactures a thin delicate geometry into a spiral shape which cannot be achieved through die casting or other such manufacturing processes. This allows for no parting lines, riser marks, or draft. The components analyzed to be manufactured this way are dainty yet strong enough to withstand normal functionality. The Internal Air Shaft Spring shown is first drawed out and then coiled.
Internal Air Shaft Spring: The Internal Air Shaft Spring in the internal air shaft of the Nerf gun is an example of a coiling process that has no part lines, draft, or riser marks.
  • Die Casting:This is the manufacturing process of forcing or pouring liquid melt into a mold. It is extremely similar to injection molding only for a metal. Parting lines, draft, and riser marks are also characteristics that result from this manufacturing process. The following picture shows the cocking bolt axial which was processed by die casting.
Cocking Bolt Axial: The axial for the cocking bolt in the Nerf gun is processed by die casting.
  • Turning: The subtractive manufacturing process in which a part is fed into a stationary tool head. Turning is typically used for creating axially symmetric features or shapes, as well as for thread creation. The lathe is commonly used to perform this process. The Screw below is an example of this process.
Screw:the threading of the screw shows that the manufacturing process is turning

The component chart also classified each part's part number if it was applicable. This number contained number(s), letter(s), or a combination of both. This number is used during the assembly processed, often used to distinguish the left side from the right. The design team also determined the function of each component and any observations. Note: in the observations section, there is a sub-level, connection to major component, which describes where that component is in one of the five major components: Barrel Extension, Shoulder Stock, Quick-Reload Clip, Base, and Flip-Up Sight. A picture of each component was also taken. The following component catalog links each specific component to its chart information as follows:

Component Catalog
Parts of the Barrel Extension :
Barrel Extension Base Barrel Protective Cover Barrel Tube Ring Sight Aid Spring Support 1
Spring 1 Knob Spring 2
Parts of the Quick-Reload Clip :
Quick-Reload Clip Spring 3 Foam Dart
Parts of the Flip-Up Sight :
Sight 1 Sight 1 Attachment Spring Holder Sight 1 Springs Sight 2 Sight 2 Spring Holder
Sight 2 Springs Sight 2 Attachment Sight Base Spacer Sight Hinge Hinge Attachment
Parts of the Shoulder Stock :
Shoulder Stock Clip Storage
Parts of the Main Base :
Base Divider Main Base Clip Button Cocking Bolt Base Spacer Nozzle Divider
Internal Spring 1 Connection Internal Spring 1 Trigger Divider 1 Divider 2 Divider 3
Internal Spring 2 Connector Internal Spring 2 Internal Spring 3 Connector Internal Spring 3 Internal Spring 4 Connector Internal Spring 4
Internal Spring 5 Connector Internal Spring 5 Divider 4 Internal Air Shaft Spring Air Chamber 1 Air Chamber 2
Internal Air Shaft Base Connector 1 Base Connector 2 Internal Spacer Clip Hook
Hardware List :
Screws Nail

Product Analysis

After completing the overall analysis for every component, Group 5 chose seven components to analyze the engineering decisions that were made during the design of the product. The seven components chosen were the Major Spring, Barrel Tube, Trigger, Part Tube, Cocking Bolt, Barrel Tube, and Ring. Each of these components were chosen because each one is necessary for the transfer of energy throughout the system. The beginning input starts with the loading of the Cocking Bolt, which then pulls back Air Chamber 1 and Air Chamber 2 and compresses the Internal Airshaft Spring. The Trigger is then pulled which releases the air chamber and spring system and causes the dart to move through the Barrel Tube, which is held in place by the Ring. Each of the seven components chosen is directly related to the firing of the foam dart. Each component was chosen due to its importance to the user’s experience and product functionality or product failure. The component function, component form and the component’s manufacturing method are all assessed in the component analysis below. The component complexity is based on the function, component geometry, material, and manufacturing method, and are based on the following scale.

Component Complexity Scale:
Component Function:
Simple functions include the support of other components as well as physical connection between components.
Complex functions include energy flow.
  1. The component performs one or two simple functions.
  2. The component performs one or two simple functions, as well as some complex functions.
  3. The component performs complex functions.
Geometry:
  1. The component contains zero to three extrusions, cut outs, or alterations from the basic shape.
  2. The component contains four or more extrusions, cut outs, as well as some complex features such as mirroring.
  3. The component has many complex extrusions, cutouts, or alterations as well as more complex features such as coils and fillets.
Material:
  1. The component is made from a single material.
  2. The component is made from two different materials.
  3. The component is made from many different materials.
Manufacturing Method:
  1. The component requires one manufacturing process.
  2. The component requires two manufacturing processes.
  3. The component requires three or more manufacturing processes.
Interaction Complexity:
  1. Modular: Each component corresponds to exactly one function.
  2. Integral: Multiple components correspond to the functionality of multiple sub-assemblies.

When taking into consideration the material chosen for the following seven components, global, societal, economic, and environmental factors must also be considered. Economic factors influenced the decision of what material to use for this component such as the fact that steel and plastic keeps the cost of the component down. The use of steel, as well as plastic, meets the global safety standards when global factors are considered. Also, the societal factors considered when using these materials takes into account the fact that the product comes into contact and is used by children of young ages. All of these materials are safe for them to use as well as be in contact with the material for long periods of time.

1. Internal Air Shaft Spring:

Component Function: The function of the Internal Air Shaft Spring is for the storage of potential energy as well as the release of kinetic energy when the trigger is pulled. The component aids in the loading and the firing of the Nerf dart. The Internal Air Shaft Spring is compressed when the cocking bolt is pulled back, storing potential energy in the spring. When the trigger is pulled, the spring is released from its compressed position and kinetic energy is released, aiding in the shooting of the dart from its position of rest. The spring is meant to be in the protective covering of the base of the Nerf gun, coiling around the second air chamber where grease has been applied to allow for less friction between the two components and the loss of energy during the firing of the system.
Component Form: The component is in a spiral form with an axis of symmetry located at the center of the spring. The spring is primarily a three-dimensional shape with the following dimensions:
Length: 12.2 cm
Diameter: 2.7 cm
Pitch: 1.4 cm
Mass: 24.7 g
The shape of the spring allows for the spring to be compressed, thus allowing potential energy to be stored in the spring. When the spring is released from its state of compression, energy is converted to kinetic energy, causing the foam to dart to move. The material of the spring also plays a role in the components function. The spring is made of steel, which has the property of maintaining the desired shape allowing for a long life cycle. One factor that must be considered when manufacturing the spring is the desired spring constant. A greater spring constant allows for a greater force to be exerted on the foam dart, causing the dart to shoot farther. Because the spring is located inside the base of the Nerf gun, the component was not intended to be seen by consumers, thus no aesthetic properties were applied to the spring. Because the spring is made of steel, the color of the component is silver. The manufacturing process used to make the spring was drawing and coiling, leaving a smooth surface finish, causing less friction between the spring and the air chamber. The less friction between the two components leads to less energy loss during the firing of the bullet.
Manufacturing Methods: The manufacturing methods necessary to make the Internal Air Shaft Spring were drawing and coiling. First, the steel must be ductile enough to be pulled through a diet to obtain the desired profile of a wire. This wire is then coiled to the desired shape. Due to the spring’s thin and delicate quality, molding and casting cannot be used to manufacture the part. The manufacturing process of drawing allows for thin, intricate geometries to be created and coiling then shapes the wire into the desired spiral shape. When considering the application of this manufacturing process, an economic factor that influenced this selection is that drawing is economical for larger runs. This manufacturing process imparts good quality upon the product which allows for the manufactured product to be safe when used, thus taking into account societal factors. This manufacturing also allows for a long life span and functionality of the product; therefore, decreasing its long term environmental impacts. When global factors are considered, this process is the ideal choice because there is a large availability of steel to be used. The Internal Air Shaft Spring figure shows the result of coiling.
Internal Air Shaft Spring: The coiling shape shows the result of the coiling manufacturing process.
Component Complexity: The Internal Air Shaft Spring has a component function complexity of 3. The function of the Major Spring requires energy, making it a complex function. When the Cocking Bolt is pulled back, the spring is compressed, storing energy. This energy is necessary for the main funtion of firing the dart. Therefore, because of the Internal Air Shaft Spring's significance, it was given a greater complexity rating. The geometry of the component is also given a complexity rating of 3 because of its complex feature of coiling. Only one material is used in the manufacturing of the Internal Air Shaft Spring; therefore, it was given a material complexity rating of 1. Finally, when the manufacturing methods used to create the spring are analyzed, it is determined that two manufacturing methods are needed, drawing and coiling; therefore, the manufacturing method complexity is given a rating of 2. The interaction complexity for this component is given a rating of 1. This component only corresponds to one function which is the compression of the spring due to Air Chamber 2.

2. Barrel Tube:

Component Function: The main function of the Barrel Tube is to act as a tunnel to control the direction of kinetic energy as well as increase kinetic energy. When the Trigger is pressed, the Internal Air Shaft Spring, Air Chamber 1, and Air Chamber 2 are released, forcing air through the chamber and then forcing the bullet to move from its original position. The bullet is then forced through the Barrel Extension Tube. The inside of the tube is vertically grooved and coated with a layer of grease allowing for minimum friction and maximum kinetic energy. The tube aids in the energy flow of the system. The bundle of kinetic energy, also considered the foam dart, is forced through the tube by air pressure and released from the gun. The Barrel Tube can function in an indoor or outdoor setting and is built to withstand rough use.
Component Form: The basic shape of the Barrel Tube consists of a long cylindrical component with a symmetrical axis. The component is primarily a three-dimensional part that consists of the following dimensions:
Length: 34.6 cm
Diameter 1: 2.9 cm
Diameter 2: 2.4 cm
Mass:57.0 g
It is necessary for the Barrel Tube to be a cylindrical tube because the foam dart must be able to pass through the tube and remain in a straight path so as to direct the motion of the dart. The material of the tube also plays a role in the components function. The component is made of plastic. Because this Nerf Longstrike CS-6 is a toy, the material of the product had to be sturdy enough to handle rough use for the intended children ages 6 and older that are expected to use this toy. Plastic is also an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. The tip of the Barrel Tube is visible to the user; therefore, aesthetics were considered in the design of this part. The tube is made of orange plastic, maintaining the Nerf brands color scheme. The barrel tube is also rounded at the edges, as well as smooth, to increase aesthetic appeal to the user. A gloss coating has also been applied to this component to give the tube a finished look.
Manufacturing Methods: Only one manufacturing method, injection molding, was used in the making of the Barrel Tube. Molten plastic was forced into a mold to create this component. Riser marks can be found on the part, as shown in the Barrel Tube Riser Marks photo, which are main characteristics of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, injection molding was used to create the Barrel Tube which is a medium sized part with a smooth finish. The geometry of the tube is simple and symmetrical also allowing for the injection molding manufacturing process to be used to create the part. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. This process also produces parts that are in good detail as well as achieve a fine surface finish, which as a societal concern is a good quality part.
Barrel Tube Riser Marks: The riser marks on the Barrel Tube illustrate the injection molding manufacturing process.
Component Complexity: The functional component complexity of the Barrel Tube has a rating of 2 because the function of the tube consists of the complex function of assisting in the energy flow of the dart. However the Barrel Tube also has a simple function of connecting to the internal air shaft. The geometry of this component consists of four or more cutouts and extrusions as well mirroring; therefore, the geometry component complexity is given a rating of 2. The part is only made of one material, plastic, thus it can be given a material component complexity of 1. Lastly, the manufacturing method complexity of the Barrel Extension is given a 1 as well because only injection molding is necessary for the manufacturing of the part. The interaction complexity for this component is given a rating of 1. This component only corresponds to one function which is the direction of the foam dart.

3. Trigger:

Component Function: The main function of the trigger is to release the spring and air chamber system from its loaded position. The Cocking Bolt is pulled back, compressing the spring. When the Trigger is pressed, the spring is released, along with the two air chambers. Air is forced through the air chamber which then forces the bullet to move. The pulling of the trigger causes a “domino” effect inside the base of the gun. The trigger is pulled, releasing the spring, which then releases chamber 1 and 2. The trigger can function in an indoor or outdoor setting and is built to withstand rough use. The trigger is necessary in order for the main function of the system to perform; therefore, the trigger must be able to function in any setting.
Component Form: The shape of the Trigger is complex consisting of a long stick attached to a semi-circle, where the user touches the trigger to fire the gun. The trigger is not symmetric; however, symmetric shapes are located throughout the component. At the end of the stick, a rectangular hook is attached which allows for a connection between the Trigger and Air Chamber 1. The component is primarily a three-dimensional part that consists of the following dimensions:
Length: 12.6 cm
Width: 1.1 cm
Height: 3.8 cm
Mass: 10.2 g
The semi-circular shape on the Trigger adheres to the form of a human finger, which is the part of the human body that applies force to Trigger. The material of the tube also plays a role in the components function. The trigger is made of a plastic material. Because this Nerf Longstrike CS-6 is a toy, the material of the product had to be sturdy enough to handle rough use for the intended children ages 6 and older that are expected to use this toy. Plastic is also an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. The semi-circular section of the Trigger is the only visible part of the component when the Nerf gun is fully assembled. Therefore, this part of the trigger is fileted and appeals aesthetically to the user. The Trigger is made of an orange plastic which goes along with the color scheme of the Nerf brand. The component is smooth and rounded with a glossy finish to create a finished look to the part and increase aesthetic appeal. This also allows for increased comfort of the user when pulling the trigger.
Manufacturing Methods: Only one manufacturing method, injection molding, was used in the making of the Trigger. Molten plastic was forced into a mold to create this component. Riser marks as well as parting lines, shown in the Trigger Parting Line photo, can be found on the part, which is a main characteristic of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, Group 5 concluded that injection molding was used to create the Trigger. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. This process also produces parts that are in good detail as well as achieve a fine surface finish, which as a societal concern is a good quality part.
Trigger Parting Line: Parting line illustrates the use of injection molding manufacturing
Component Complexity: The Trigger is a vital component to the overall function of the system. The Trigger must be pulled in order for the energy to be transferred throughout the system. Human energy is needed to pull the Trigger, which then allows for the internal energy of the system to flow and cause the dart to leave the base of the Nerf gun. Therefore, the component function complexity of the Trigger is rated a 3 due to complexity of the energy flow. The geometry complexity of the component is rated a 3 as well. There are many extrusions and cut outs on the Trigger as well as filets creating a complex geometric part. Also, the material complexity of the Trigger can be given a rating of 1 because only plastic is used to create the part. Finally, the manufacturing method complexity is rated a 1 because only injection molding is needed to make the part. The interaction complexity for this component is given a rating of 1. This component only corresponds to one function, the release of the bundle of kinetic energy.

4. Air Chamber 1:

Component Function: The main function of the first Air Chamber is to hold the foam dart when the Nerf gun is loaded and then aids in the direction of the bundle of kinetic energy. It also acts as half of the air chamber. The Cocking Bolt is connected to the Air Chamber 1; therefore, when the Cocking Bolt is pulled back and then forward again, the foam dart is forced into Air Chamber 1 where it remains stationary until the Trigger is pressed and Air Chamber 2 and the Internal Air Shaft Spring are released, forcing air through Air Chamber 1 and forcing the foam dart to move. Air Chamber 1 is not meant to be outside the base. The component functions only when it is connected to Air Chamber 1 and the Internal Air Shaft.
Component Form: The general shape of Air Chamber 1 is a long cylindrical tube with an axis of symmetry at the center of the chamber. This tube is then permanently attached to a rectangular base. The component is primarily three-dimensional with the following dimensions:
Length: 23.6 cm
Diameter: 2 cm
Height of Base: 4.8 cm
Width of Base: 3.6 cm
Mass: 50.7 g
The base of the air chamber allows for the stabilization of the tube. Air Chamber 1 must be stable so that the kinetic energy being transferred inside the chamber can be at a maximum. The material of Air Chamber 1 also plays a role in the components function. The chamber is made of a plastic material. Plastic is an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. The chamber is not visible to the user; therefore, aesthetics did not play a role in the design of this component. The color of the component is orange, staying with the noticeable color scheme of orange blue that all Nerf products have. The inside of the chamber is smooth and glossy with a layer of grease which allows for minimal friction between the chamber and the dart and thus allows the dart to move through the chamber at a faster velocity.
Manufacturing Methods: Only one manufacturing method, injection molding, was used in the making of Air Chamber 1. Molten plastic was forced into a mold to create this component. Riser marks as well as parting lines can be found on the part, shown in the Air Chamber 1 Parting Line photo, which is a main characteristic of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, injection molding was used to create the chamber which is a medium sized part with a smooth finish. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. This process also produces parts that are in good detail as well as achieve a fine surface finish, which as a societal concern is a good quality part.
Air Chamber 1 Parting Line: The parting line illustrates the use of the injection molding manufacturing process.
Component Complexity: The chamber is a vital component to the overall function of the system. Air Chamber 1 and Air Chamber 2 work together to force air through the tube and force the foam dart to move. Because Air Chamber 1 is necessary for the flow of kinetic energy, the component function complexity is rated a 3. The geometry complexity of the chamber is also rated a 3 because of the many extrusions, cuts, and filets found throughout the part. Also, because the part is only made of plastic, the material complexity of the part is given a 1. Finally, only one manufacturing process is used for the making of Air Chamber 1, thus the manufacturing method complexity is rated a 1. The interaction complexity for this component is given a rating of 2. This component corresponds to multiple functions, the inserting of the dart into the system, the release of the dart, as well as the direction of the force on the dart.

5. Air Chamber 2:

Component Function: Air Chamber 2 acts as the second half of the air chamber. The part provides a force on the dart, aiding in applying additional energy to the foam dart. The Internal Air Shaft Spring surrounds the second air chamber. When the Cocking Bolt is pulled back and the spring is loaded, the second air chamber is also pulled back. When the trigger is pulled Air Chamber 2 forces air through the Air Chamber 1 which then forces the foam dart to move. This component aids in the transfer of kinetic energy from the spring-piston system to the foam dart. Air Chamber 1 is located inside the Base of the Nerf gun. The user does not directly interact with the chamber; therefore, the chambers environment is located inside the base of the gun.
Component Form: The general shape of the second air chamber is a cylindrical tube with one end open and the other closed. The part has an axis of symmetry and is primarily three-dimensional with the following dimensions:
Length: 9.7 cm
Diameter: 2.2 cm
Mass: 5.0 g
Because one end of the cylindrical tube is closed, the air is allowed to be forced into the chamber and thus into Air Chamber 1 which then causes the dart to move. The cylindrical shape is also important because it must cover Air Chamber 1. The material of Air Chamber 2 also plays a role in the components function. The chamber is made of a plastic material. Plastic is a strong and durable material that can handle the air pressure inside the chamber. It is also an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. The air chamber is not seen by the consumer; therefore, aesthetics did not play a large role in the design of this component. The color of the chamber is bright orange, which follows with the color scheme of the Nerf brand. Air Chamber 2 has a smooth surface finish and is also layered with grease on the outside and the inside of the chamber. This decreases the friction between Air Chamber 1 and the Internal Air Shaft Spring as well as between Air Chamber 1 and Air Chamber 2.
Manufacturing Methods: Only one manufacturing method, injection molding, was used in the making of Air Chamber 2. Molten plastic was forced into a mold to create this component. Riser marks as well as parting lines can be found on the part, as shown in the Air Chamber 2 Parting Line photo, which is a main characteristic of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, injection molding was used to create the chamber which is a small sized part with a smooth finish. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. A societal concern of this manufacturing method is that a good quality part must be made. Injection molding produces parts that are in good detail as well as achieve a fine surface finish, addressing societal concerns.
Air Chamber 2 Parting Line: The parting line illustrates the use of the injection molding process.
Component Complexity: The function complexity of Air Chamber 2 is given a rating of 3 because of the complex function of aiding in the energy flow of the system. The air chamber forces air through the first chamber thus forcing the foam dart to move. The geometric complexity of the air chamber can be given a rating of 3 because many complex features, such as extrusions, cut outs, filets, and mirroring are found on the part. The component is only made of one material; therefore, the material complexity of the component is given a rating of 1. Finally, because only injection molding is used in the manufacturing of the component, the manufacturing method complexity is given a rating of 1. The interaction complexity for this component is given a rating of 2. This component corresponds to multiple functions; it acts as a chamber of air which converts to a force on the dart and it applies a force on the spring before release.

6. Cocking Bolt:

Component Function: The main function of the Cocking bolt is to load the gun by pulling the air chamber and the spring back, allowing for potential energy to be generated. When human energy is applied to the cocking bolt, the bolt is pushed back which directly causes Air Chamber 1 to be pulled back and compress the Internal Air Shaft Spring. Potential energy is then stored in the spring. The Cocking Bolt is located on the outside of the base of the Nerf gun and is directly used by the user. Therefore, this component can be used in an outdoor or indoor environment.
Component Form: The general shape of the Cocking Bolt consists of two rounded knobs with a central axle holding the two together. The component is primarily three-dimensional with the following dimensions:
Length of Axle: 7.8 cm
Length of Knob: 4.2 cm
Diameter 1: 3.2 cm
Diameter 2: 2.4 cm
Mass: 40 g
The rounded knobs of the Cocking Bolt are gripped and can easily fit in an average hand allowing for easier motion of the component and thus allowing the Nerf gun to be loaded. The rounded knobs are made of an orange plastic, while the central axle is made of steel. Plastic is a strong and durable material that can handle human force on when applied. It is also an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. Also, steel is a strong and durable material that can withstand a large amount of force which is necessary to successfully pull the entire chamber and spring system back into the loaded position. The rounded knobs of the Cocking Bolt are located on the outside of the base and are directly used by the user. Because the knobs can be seen by the user, aesthetics played a role in the designing of the Cocking Bolt. The color of the component is bright orange, which follows with the color scheme of the Nerf brand. The surface finish of the Cocking bolt is gripped to allow for better handling of the bolt when being used to load the gun. The grip is designed in a pleasing way so as to increase aesthetic appeal.
Manufacturing Methods: Two manufacturing processes were used in the making of this component. Injection molding, as well as die casting, were used to make the Cocking Bolt. Molten plastic was forced into a mold to create the knobs of this component. Riser marks as well as parting lines,illustrated in the Cocking Bolt Parting Line photo, can be found on the part, which are main characteristics of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, injection molding was used to create the knobs of the Cocking Bolt, which are small parts with smooth surfaces. For the steel axle of the Cocking Bolt, the manufacturing process of die casting was used to create the part. Molten metal was poured into a die to create this part. Parting lines are found on the axle which indicates the use of this manufacturing method. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. This process also produces parts that are in good detail as well as achieve a fine surface finish, which as a societal concern is a good quality part. When global factors are considered, this process is the ideal choice because there is a large availability of steel to be used. These factors are also true for die casting as this process creates good quality parts that are cheap on large economic runs, can be reused, are safe, and readily available.
Cocking Bolt Parting Line: The parting lines illustrate the use of the injection molding process.
Component Complexity: The component functional complexity of the cocking bolt is rated a 3 because of the complexity of the function. The cocking bolt is directly related to the loading of the gun, thus the storage of potential energy in the spring. It also pulls back the two air chambers. Because of these connections, the Cocking Bolts function is complex. The geometric complexity of the part is given a rating of 2. There are some simple features to the component, such as a simple extrusion of the axe and knobs; however, the grip on the knob creates more complex features that must be cut and fileted. Because the Cocking Bolt is made of two different materials, plastic and steel, the material complexity of the part is given a rating of two. Finally, the knobs of the Cocking Bolt are created by injection molding, while the axle is created by die casting. The interaction complexity for this component is given a rating of 2. This component not only allows for the dart to be inserted, but also allows for potential energy to be built up.

7. Ring:

Component Function: The main function of the Ring is to allow for the attachment of the barrel extension to the base of the Nerf gun as well as to stabilize the Barrel Tube. The ring is attached to the Barrel Extension Base and supports the Barrel Tube held inside the Barrel Extension Base. The Ring also has grooves on its surface which allow it to twist into place and connect the Barrel Extension and the Base. The Ring is located outside the base of the Barrel Extension; therefore, it can function in indoor or outdoor environments.
Component Form: The general shape of the Ring is a small circular cylinder. The part has an axis of symmetry at the center of the Ring and is primarily three-dimensional with the following dimensions:
Depth: 1.2 cm
Diameter: 4.4 cm
Mass: 6.1 g
The circular shape of this component is necessary so that it will align with the circular shape of the tip of the base and allow for attachment. The component is made of a plastic material. Plastic is a strong and durable material that can handle the air pressure inside the chamber. It is also an inexpensive material that can be used to mass produce this product and keep the price of the product affordable for consumers. A strong material is necessary to allow for a strong a durable connection between the Barrel Extension and the Base. The Ring is made with orange plastic which goes with the color scheme of Nerf products. The surface finish of the component is smooth and glossy to allow for a smooth attachment between parts as well as to continue the aesthetic appeal of the entire product.
Manufacturing Methods: Only one manufacturing method, injection molding, was used in the making of the Ring. Molten plastic was forced into a mold to create this component. Riser marks, illustrated in the Ring Riser Mark photo, as well as parting lines can be found on the part, which is a main characteristic of injection molding. The material of the part is plastic which is also used for the injection molding process. Injection molding is good for small to medium sized parts and creates a fine surface finish; therefore, injection molding was used to create the Ring which is a small sized part with a smooth finish. When considering the application of this manufacturing process, an economic factor that influenced this selection is that injection molding is economical for larger runs. Also, plastic can be melted down and reused in this process, almost eliminating its negative effect on the environment. This process also produces parts that are in good detail as well as achieve a fine surface finish, which as a societal concern is a good quality part.
Ring Riser Mark: The riser mark illustrates the use of the injection molding manufacturing process.
Component Complexity: The Ring aids in the connection and support between the Barrel Extension and the Base of the Nerf gun; therefore, the component function complexity of the part is given a rating of 1. The part also consists of one to two simple features, such as extrusion and cutting, thus the geometric complexity of the part is given a rating of 1. Because the Ring is only made of plastic, the material complexity of the component is also given a 1. Finally, only one manufacturing process, injection molding, is used in the making of the Ring; therefore, the manufacturing method complexity is given a rating of 1. The interaction complexity for this component is given a rating of 2. This component corresponds to two functions; stability of the Barrel Tube and the connection between the Barrel Extension and the Base. If this component fails, neither of these functions can be completed.

Solid Modeled Assembly

After completing a full analysis of the Nerf gun, four parts were chosen as the most important components to the overall function of the system. These components include the Trigger, the first Air Chamber, the second Air Chamber, and the Internal Air Shaft Spring. These parts all have a high level of physical interaction with one another. Group 5 had an extensive history of using the CAD program Autodesk Inventor in previous classes as well as in high school courses. Therefore it was determined that through the use of Inventor, Group 5 would be able to create the best 3D drawings with the greatest level of detail and interaction to create the most realistic assembly. These four components are shown below as an Inventor drawing next to their real life component along with the assembly drawing for the Inventor model. Each component was changed to a orange color to allow for better contrast between the background and the part.

Component Name Real Component Picture Autodesk Inventor Model Assembly Drawing
Trigger
Triggergroup5.JPG
Triger2.png
Trigger1.png
Air Chamber 1
071.JPG
Air4.png
Air3.png
Air Chamber 2
068.JPG
Air2.png
Air1.png
Internal Air Shaft Spring
134.JPG
Spring1.png
Springpp.png

After creating the four components individually in Autodesk Inventor, each component was brought into an assembly drawing and constrained to create the Internal Air Shaft Spring and Air Chamber system. Each step is shown below.

Step 1: Insert Air Chamber 1 into Air Chamber 2
Step 2: Insert Air Chamber 2 [with 1 inside] into the Internal Air Shaft Spring
Step 3: Connect the Trigger to the lip indent of the bottom of Air Chamber 1

The assembled drawing illustrates the Internal Air Shaft Spring in compression. When the trigger is released, Air Chamber 1 and Air Chamber 2 are also released, forcing air through the chamber. This is the main function of the system. Air must be forced through Air Chamber 1, which would then cause the foam dart to move if a bullet were placed inside the chamber.

Engineering Analysis

After completing a thorough analysis of the seven components and creating a solid model of four of those components, Group 5 then decided to analyze a specific function of the Nerf gun system using the Engineering Analysis Process. Using diagrams and governing equations, the first four steps of the process were set up to find the deformation in the spring needed to get the desired trajectory.
Problem Statement: Knowing the specific range, d, and the specific height of the ground, z, what deformation in the spring is needed to get the desired trajectory?
Given:
d= 35 ft
Angle from horizontal, θ=0
Diagram of the System:
Diagram5.png


x1= Original Spring Length
x2= Compressed Spring Length
d= horizontal distance
z= vertical distance
F= Force


Assumptions:
  • Energy is conserved, no loss due to friction
  • No air resistance
  • The gun is completely horizontal
  • The initial velocity when released from the Nerf gun is horizontal
  • k is constant
  • Half of the kinetic energy comes from the spring and half from the pressure from the air chamber
  • No heat loss
  • The force of gravity is 9.81 m/s^2
Governing Equations:
(1) y= tanθ*x - g/(2〖v_0〗^2 〖cos〗^2 (θ)) x^2
(2) KE=1/2mv^2
(3) E=1/2 kx^2
  • The main goal of this engineering analysis is to computationally calculate the spring constant of the Internal Air Shaft Spring in the Nerf gun by making assumptions, such as ignoring friction and air resistance. However, the results of this computation are sensitive to the friction between the foam dart and the Internal Air Shaft of the Nerf gun, as well as the air resistance the dart encounters while in the air after being shot. Therefore, the spring constant could also be calculated experimentally, taking these two factors into consideration, resulting in a more accurate result.

Design Revisions:

Laser Sight

One possible design change for the Nerf Longstrike CS-6 would be the addition of a laser light pointer instead of a Flip-Up Sight located on top of the Base. The addition of this laser light sight would not alter the product in any way. Instead rails would be added to the bottom of the laser light just like the current Flip-Up Sight has. This would allow the laser light sight to be removable as well as versatile, allowing it to be attached to any Hasbro Nerf gun. The addition of this product to the existing design would not change the cost of the Nerf gun either. Instead this new design revision would allow for an increase in accuracy or performance and has the potential to be more desirable to purchasers. This new design revision also has the potential to increase the target audience as this technology could appeal to older/other children than the original design. Since, the economic circumstances in today’s age is more towards electronics and technology than it was ten years ago, this design revision could attract a whole new audience as well as sales similar to more electronic devices. Therefore the addition of a laser light sight to the Nerf Longstrike CS-6 could be extremely beneficial to the Hasbro Company and its purchasers.

Crank

A second possible design revision to the original Nerf Longstrike CS-6 would be an addition of a crank loading mechanism. This would replace the linear cam mechanism currently implemented with the cocking bolt. Now, a crank with gears on it would be used to load the gun and pull the air chambers back. This would involve the removal of the Cocking Bolt, the addition of a hand crank connected to a gear, and a slider connected to the air chamber with gears on the bottom. A picture of this design revision is shown below in Revision Two. An effect of this replacement of the Cocking Bolt with the crank system is that it would allow for a greater range. This is because a hand crank could create a larger force which would support a spring with a stronger spring constant to be used. This would then allow for a large return force on the foam dart. Thus, the darts that shoot out of the barrel will have a higher acceleration sending them further distances. The crank would also make it easier to load the gun as the Cocking Bolt currently uses two hands in order to pull the system back. Also, by removing the Cocking Bolt and adding a crank, it increases the safety of the product. The crank eliminates the potential safety hazard that the Cocking Bolt creates with the sliding of the rails where a small child could easily pinch their fingers before, during, and after the shooting of the dart. This design revision would meet global and safety standards around the world as well as be more appealing to the public due to the higher safety precautions. All of these factors show that a crank would be a beneficial change to the Nerf gun, causing a safer enjoyment by the user.

Revision Two: Replacing the Cocking Bolt with a hand crank and gears.
Sniper Stand

Another design change for the Nerf gun that would positively affect its performance is the addition of a Sniper Stand. It would not be necessary to remove any part of the current Longstrike CS-6 gun for the addition of a sniper stand. The stand and gun would need to have rails built in so that they can be attached to one another yet easily removed when need be. The rail on the stand would be compatible with any Nerf blaster in the N-Strike series, allowing for the stand to be used amongst the product family. The legs of the stand would be foldable so that the stand would become small, portable, and easily stored. The Sniper Stand would increase the accuracy of the Longstrike CS-6 or any other Nerf gun that it was used with. It would also allow the gun to have versatility and be used in more than just one way. These factors would increase the sales, marketability, and user enjoyment by improving the accuracy of the Longstrike CS-6. These adjustments and additions to the gun affect both societal and economic concerns.

Related Information

Main Page : Group 5 - Nerf N-Strike Longstrike CS-6

The Introduction : The Project Proposal

The Planning : *Gate 1: Project Planning

The Dissection : *Gate 2: Product Dissection

The Reassembly : *Gate 4: Product Explanation

The Conclusion : *Gate 5: Delivery