Group 16 - Black & Decker Drill/Gate 3
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Gate 3
Causes for Corrective Action
Overall the group has worked together very well together for this part of the project. Everyone finished their aspects of the project in the time frame allotted and expected. Although everything was done on time there was some confusion within the group throughout gate three. This confusion was due to illness and other miscellaneous circumstances as group members have had a difficult time making it to meetings during this stage of the project.
To eliminate the confusion encountered in gate three the group has established some guidelines to follow if a group member cannot make a meeting.
- All group members are responsible for getting the work allotted to them in the time frame requested no matter if the meeting can be attended by that group member. All work that needed to be done for the meeting should be given to the group via email before the meeting that cannot be attended by the individual.
- If a group member cannot make a meeting due to illness at least six hours notice before the meeting must be given to the group leader.
- If a group member cannot make a meeting due to traveling or another reason the group requires at least three days notice to be given to the group leader.
As long as everyone in the group follows these guidelines gate four should go very smoothly without the confusion encountered in gate three.
Component Summary
Table 1
Table 1 lists the part name, quantity required, model number, component function, material, manufacturing process and picture for each component.
| Part Name | Quantity | Model # | Component Function | Material | Manufacturing Process | Picture |
|---|---|---|---|---|---|---|
| Housing and Cover | 1 | 614262-00 | The main function of the housing and cover is to hold all internal components in an ergonomically designed way. | Plastic and Rubber | This component was manufactured through injection molding. The housing is manufactured as one half that all of the parts fit into. The cover is manufactured as the other half that attaches to the housing using screws. The rubber coating is then molded over the plastic housing and cover. |  |
| Spindle | 1 | 387870-01 | The function of this component is to attach the bit holder with the motor/gears of the drill. | Steel | The component was machined to size on a lathe. |  |
| Gear | 1 | 391710-00 | The main function of the gear is to help deliver power from the motor to the spindle. | Steel | This component was manufactured through hobbing. |  |
| Washer | 1 | 330016-09 | The main function of the washer is to create space in between the gear and the front bearing plate. | Steel | Metal stamping was used to manufacture this component. | |
| Front Bearing Plate | 1 | 385681-00 | The main function of the front bearing plate is to keep the gear, gear and pinion, washers, and spindle in place. | Steel | Metal casting was used to manufacture this component. |  |
| Keyless Chuck | 1 | 330075-49 | The main function of the keyless chuck is to hold the bit and to rotate. | Steel and Plastic | This component was manufactured through metal casting of the steel and injection molding of the plastic. |  |
| Rear Bearing Plate | 1 | 620285-00 | The main function of the component is to hold together the gear, gear and pinion, spindle, washers, and armature. | Steel | Metal casting was used to manufacture this component. |  |
| Gear and Pinion | 1 | 385988-00 | The gear and pinion transfers torque from the armature to the gear providing mechanical advantage. | Steel | This component was manufactured through hobbing. |  |
| Armature | 1 | 385537-02 | The armature rotates from magnetic forces and delivers torque to gear and pinion and fan. | Copper, steel, and Teflon. | The central shaft was machined, the copper wiring was drawn, the copper plates were formed, and the teflon shell was manufactured through injection molding. |  |
| Retaining Ring | 1 | 607888-00 | The retaining ring prevents the washer (plain), heat sink, and washer from sliding off of the armature. | Steel | Sheet Metal Forming was used to manufacture this component. |  |
| Washer (plain) | 1 | 148902-00 | The washer (plane) provides a buffer between the retaining ring and the heat sink. | Steel | Sheet Metal Forming was used to manufacture this component. |  |
| Heat Sink | 1 | 158478-00 | The heat sink dissipates heat to keep the drill cool. | Iron | Die Casting was used to manufacture this component. |  |
| Washer | 1 | 37381-00 | The washer provides a buffer between the heat sink and the armature. | Steel | Sheet Metal Forming was used to manufacture this component. |  |
| Field | 1 | 385849-00 | The field accepts the electricical energy to generate a magnetic field to rotate the armature. | Plastic, Copper Wiring, Cardboard Insulator, Steel, Brass | Injection Molding, Metal Stamping and Drawing were used to create this component. |  |
| Reverse Ring | 1 | 385995-01 | Keeps brushes in contact with armature with magnetism. | Plastic, Brass, Aluminum | Injection Molding and Metal Stamping were used to manufacture this component. |  |
| Reverse Lever | 1 | 611278-00 | The reverse lever changes the direction in which the keyless chuck rotates. | Plastic | Injection Molding was used to manufacture this component. |  |
| VS Switch | 1 | 611719-01 | The VS switch allows the user to operate the drill by appling varying pressures proportional to the desired speed of the keyless chuck's rotation. | Aluminum, Copper, Plastic, Steel | Injection Molding and Metal Stamping were used to manufacture this component. |  |
| 8 ft Power Cord | 1 | 330073-98 | The power cord provides electrical power to the field. The rubber is used for shielding of the copper wiring to provide safe transfer of electricity without harming the user. | Rubber, Copper | Extrusion was used to manufacture this component. |  |
| Cord Protector | 1 | 611721-00 | The cord protector takes stress off the wiring and helps keep the wires in a steady place. | Rubber | Injection Molding was used to manufacture this component. |  |
| Cord Clamp | 1 | 380414-00 | The cord clamp secures the wires inside the handle of the housing. | Aluminium | The manufacturing process for this component is stamping. |  |
| Screws (Clamp) | 2 | 330019-08 | The screws fasten the cord clamp inside the handle. | Stainless Steel | The manufacturing process for this component is thread rolling. |  |
| Screws (Housing) | 9 | 330019-03 | The screws fasten the two shells of the housing together. | Stainless Steel | The manufacturing process for this component is thread rolling. |  |
| Brush | 2 | 385733-01 | The brushes conduct electricity between the wires from the power supply and the motor. | Carbon | The manufacturing process for this component was powder metallurgy. Powdered carbon was placed in a mold along with a binder and then compressed by force (weight) so that the powder takes the shape of the mold and solidifies. |  |
| Felt Washer | 1 | 389818-00 | The felt washer ensures smooth movement between the spindle and the front bearing plate and reduces friction between them. | Felt | Felt is first manufactured by compressing fibers and then machined to give it the circular shape with a hole in the center. |  |
| Cap | 1 | 612596-00 | The cap helps in ventilation and also holds the spirit level in place. | Plastic | The manufacturing process for this component was injection molding. |  |
| Spirit Level | 1 | 611723-00 | The spirit level helps the user to maintain horizontal or vertical level of the drill while using it. | Plastic and ethanol | The spirit level was manufactured in multiple machined steps. Flat sheets of plastic were cut and stuck together after filling it with precise amount of ethanol, leaving behind a small bubble. |  |
| Bit Holder | 1 | 612861-00 | The bit holder keeps the bit secure when the drill is not in use. | Hardened rubber | The manufacturing process for this component was injection molding. |  |
Table 2
Table 2 lists the part name and complexity, as well as various information regarding the materials and manufacturing choices pertaining to the components.
| Part Name | Why were different materials selected for different components? | What forces are applied to the components? | Does material choice affect the manufacturing process? | Does the shape affect the manufacturing process? | Why was each manufacturing process chosen for that component? | Do any components have a particular shape? Why? | Is the component functional, comestic, or a combination of the two? | How complex is the component? |
|---|---|---|---|---|---|---|---|---|
| Housing and Cover | Plastic is used to create the housing and cover because it is inexpensive to mold into whatever form desired. Rubber is used for a coating to give the user a better grip when using the product. | A force is applied using the hand of the person using tool. Average force applied ranges from 10 pounds to about 150 pounds (most of a person’s body weight). Also, to keep all internal components inside and in place together 30 lbs of torque are applied b | The material choice does affect the manufacturing process as all materials cannot be used in an injected molding. | The shape affects the manufacturing process since many grooves and compartments are needed in the housing for every piece to fit. Also, openings are needed in the housing for ventilation. For these reasons injection molding provides the easiest solution. | The manufacturing process of injection molding was chosen for this product because it is easy to mass produce and easy to use with the materials selected. | The component has its particular shape so it is easy for a user to hold. | This component is functional as it houses all of the internal components and helps keep them in place. It also has a cosmetic aspect as this component gives this drill its appearance and color. | 2 |
| Spindle | Steel is selected for this product because it is a very strong material that can withstand a great amount of force. | The forces applied on the spindle are the friction from the front bearing plate and the torque coming from the attached gear which is 150 in-lb. | The material choice does affect the manufacturing process as the lathe is used to form the steel. | The shape affects the manufacturing process as the lathe was used to get a precise size of the spindle. | The manufacturing process of being machined to size using a lathe was chosen because it is a precise way to form a spindle. | The component has its particular shape so the bit holder can be attached to the spindle with ease. | This component is functional as it delivers the power generated from the motor to the bit holder. | 3 |
| Gear | Steel is used for this component because the teeth of the component have to be strong and steel is the best option for that feature at a low cost. | The forces applied on the gear is the torque and friction applied from the gear and pinion which is about 150 in-lb. | The material choice does affect the manufacturing process as hobbing is one of the most common choices for shaping a gear made out of steel. | The shape affects the manufacturing process since the many teeth needed on the gear make hobbing a logical solution. | The manufacturing process of hobbing was selected because it is one of the easiest ways to put teeth into a gear. | The component has its particular shape so it can interact with other gears to produce power to the spindle. | This component is functional as it helps to deliver power to the spindle. | 4 |
| Washer | Steel is used for this component because it is a strong material which is good for creating the space necessary. | The forces applied to the washer are the normal forces applied by the gear and the front bearing plate. | The material choice does affect the manufacturing process as metal stamping is an efficient way to produce strong metal washers. | The shape affects the manufacturing process since a washer has a hole in the middle of it making metal stamping a smart choice. | The manufacturing process of metal stamping was selected because it is one of the easiest ways to produce a washer. | The component has its particular shape so it can fit over the spindle and separate the gear and the front bearing plate. | This component is functional as it separates the gear and front bearing plate. | 1 |
| Front Bearing Plate | Steel is used for this component because it is a strong material which can withstand holding the gear, gear and pinion, and spindle in place. | The forces on the front bearing plate are the friction and normal forces from the spindle, gear and pinion, and two washers. | The material choice does affect the manufacturing process as metal casting works very well with steel. | The shape affects the manufacturing process as the shape of the part is complex making metal casting an easy solution to achieve the form desired. | The manufacturing process of metal casting was selected due to the shape of the part making metal casting the easiest solution for manufacturing the product. | The component has its particular shape so it can fit and hold the gear, gear and pinion, washers, and spindle. | This component is functional as it holds the gear, gear and pinion, washer, and spindle. | 3 |
| Keyless Chuck | Steel is used for this component because it is a strong material which can hold a bit in place. Plastic is used on the outside of the steel for ease of turning the chuck and for grip. | The forces on the keyless chuck are the torque and friction from the spindle which is about 150 in-lb and the normal force from the bit when pushing on a surface which varies. | The material choice does affect the manufacturing process as metal casting works very well with steel. Also injected molding works very well with shaping the plastic into any form desired. | The shape affects the manufacturing process as the shape of the part is complex making metal casting an easy solution to achieve the form desired of the steel components. Also injected molding is the best solution for manufacturing the plastic components | The manufacturing process of metal casting was selected due to the shape of the part making metal casting the easiest solution for manufacturing the steel parts. The manufacturing process of injected molding for the plastic components was chosen due to th | The component has its particular shape so it can fit a drill bit and be turned easily by the user when changing drill bits. | This component is functional as it holds the drill bit and rotates. Also this function has a cosmetic component as the black plastic used in the chuck gives it eye appeal. | 4 |
| Rear Bearing Plate | Steel is used for this component because it is a strong material which can hold the armature, gear, gear and pinion, spindle, and washers. | The forces on the rear bearing plate are the torque and friction forces from the gear and pinion, gear, and armature. | The material choice does affect the manufacturing process as metal casting works very well with steel that needs to be shaped into a complex form. | The shape affects the manufacturing process as the shape of the part is complex making metal casting an easy solution to achieve the form desired of the steel component. | The manufacturing process of metal casting was selected due to the shape of the part making metal casting the easiest solution for manufacturing the steel part. | The component has its particular shape so it can fit the spindle, gear, gear and pinion, washers, and armature. | This component is functional as it holds together the armature, spindle, gear, gear and pinion, and washers. | 3 |
| Gear and Pinion | Steel was selected because this component must bare and transfer the force that will be applied by the bit. | The Gear and Pinion is subjected to force applied by the armature, a resistant force from the gear, as well as frictional forces from the armature, the gear, and the plate on which the gear and pinion is mounted. | The material does not drastically affect the manufacturing process, as it is a fairly easy material to work with. | The shape of the part limits decided the manufacturing process, as it is a gear, and gears are commonly made through hobbing. | Hobbing was chosen as it is commonly used to manufacture gears. | The gear and pinion has differently sized toothed cylinders to create mechanical advantage. | The Gear and Pinion is a functional component; it does not require cosmetic appeal as it is concealed inside the casing. | 4 |
| Armature | The central shaft is made of steel because it must be durable to deliver torque to the Gear and Pinion. The wiring around the shaft and the plates are made of copper to efficiently conduct electricity. The shell is made of Teflon in order to insulate the electric current from the rest of the drill and contain the wiring. | A magnetic force is applied to the Armature which makes it spin. A resistant force from the Gear and Pinion is applied to the Armature. A frictional force from the Field is applied to the Armature. | The material does not drastically affect the manufacturing processes for the Central Shaft or Copper Wiring. The material of the Plates encouraged forging, as Copper is an easy material to forge. The material of the Shell decided its manufacturing process, as plastic parts are commonly manufactured by injection molding | The shapes of the parts do not drastically affect the manufacturing process. | Machining was used because it creates a strong part which is required. Drawing was selected because it is commonly used to manufacture wiring. Forging was selected because it is an efficient method to create the plates. Injection Molding was selected because it is commonly used to manufacture plastic parts. | The armature must be cylindrical in order to spin and provide torque for the rest of the drill. | The Armature is a functional component; cosmetic appeal is not required as the Armature is concealed inside the shell. | 4 |
| Retaining Ring | Steel was selected because a strong material is required. The material must also have elasticity to provide the normal and frictional forces. | A frictional force is applied to the Retaining Ring to prevent it from sliding up and down the Armature. A normal force is applied to the Retaining Ring from the Armature, which in turn creates the high frictional force. | The material does not heavily affect the chosen manufacturing process, as most metals would call for the same process. | The shape decided the manufacturing process, as it is a small and thin piece that can be cut from a sheet. | Sheet Metal Forming was chosen because the part can be cut from a sheet and maintain high strength and enough elasticity. | The Retaining Ring is in the shape of a C so that it can be clipped around a shaft with a smaller diameter. This enables the clip to hold its position on the Armature using frictional forces. | The Retaining Ring is a functional component; cosmetic appeal is not required as the Retaining Ring is concealed inside the shell. | 2 |
| Washer (plain) | Steel was selected because the washer must bare the forces of the Heat Sink and Retaining Ring without deformation. | The Washer (plain) is subjected to a normal force from the Retaining Ring, Heat Sink, and Armature. | The material does not heavily affect the chosen manufacturing process, as most metals would call for the same process. | The shape decided the manufacturing process, as it is a small and thin piece that can be cut from a sheet. | Sheet Metal Forming was chosen because the part can be cut from a sheet and maintain high strength and resistance to deformation. | The washer (plain) is round with a center hole in order to fit around the armature and fit inside the drill, while still creating a buffer. | The Washer (plain) is a functional component; cosmetic appeal is not required as the Washer (plain) is concealed inside the shell. | 1 |
| Heat Sink | Iron was selected because it will handle the heat that will be transferred to the Heat Sink. | The Heat Sink is subjected to a frictional force from the Armature. | The material does not heavily affect the chosen manufacturing process, as many metals can be die cast. | The shape decided the manufacturing process, as the Heat Sink has many small crevices which would be difficult and take time to machine, while die casting the Heat Sink is much more efficient. | Die Casting was selected because it can create the awkward shape of the Heat Sink efficiently. | The heat sink is shaped to create as much surface area as possible, to help heat escape. | The Heat Sink is a functional component; it does not require cosmetic appeal as it is concealed inside the casing. | 2 |
| Washer | Steel was selected because the washer must bare the forces of the Heat Sink and Retaining Ring without deformation. | The washer is subjected to a normal force from the Armature and the Heat Sink. | The material does not heavily affect the chosen manufacturing process, as most metals would call for the same process. | The shape decided the manufacturing process, as it is a small and thin piece that can be cut from a sheet. | Sheet Metal Forming was chosen because the part can be cut from a sheet and maintain high strength and resistance to deformation. | The washer (plain) is round with a center hole in order to fit around the armature and fit inside the drill, while still creating a buffer. | The Washer is a functional component; cosmetic appeal is not required as the Washer is concealed inside the shell. | 1 |
| Field | Copper is a good conductor for electricity. Steel reinforces the plastic casing and affects the electrical field . Plastic is to hold components in place, and it does not conduct electricity. The cardboard is a good insultor to help with the heating. | Magnetic forces are applied to the component when the field is on. | Yes, because there are many different parts for the field, making it more complex and expensive. | Yes, because each piece has a custom shape making it more complicated to produce. Also, all the pieces must fit together and function properly without issues. | Injection molding is used for the plastic casing because it is cheaper than to machine the cylidrical shape. Metal stamping is used to make the steel piece because machining the piece would take more time and cost more. The steel piece would need more pro | The field is in a hollowed out cylindrical shape because opposite sides of the field have copper wires that alternate charges to rotate the armature. | This internal component is functional because it converts the electrical energy to mechanical energy. | 5 |
| Reverse Ring | Plastic is used because it does not conduct electricity. Aluminum is used because it is malleable enough to make a coil. Brass is used because it is strong enough to hold the brushes against the armature while it spins at a high angular velocity | The brushes react back from the reverse ring keeping it against the armature. | Plastic does not affect the manufacturing process because it is a standard material for injection molding. Brass makes it a little more complicated with the metal stamping. | Yes, the shape in which the brass is makes it complicated because it must match specifications to make sure that the brushes fit and do not slip out. The plastic ring also affects the manufacturing process because a custom shape must be made for injection | Injection molding was used because it is the easiest method to make a complex shape in mass quantities. Metal stamping is used to produce the parts at an efficient rate | The reverse ring has a unique shape so it can connect to the reverse lever and fit around the armature while holding the brushes steadily in place. | This internal component is functional because it holds the brushes against the armature. | 3 |
| Reverse Lever | Plastic is used because it does not conduct electricity. | Approximately 5 lb of force are applied to switch the component left or right. | Plastic does not affect the manufacturing process because it is a standard material for injection molding. | Yes, because the shape is not simple and a custom shape must be made for the injection molding. | Injection molding is an easy process to produce a complicated shape at an efficient rate. | The reverse lever has a particular shape so it could reach into the drill and connect with the reverse ring, while also allowing the user the shift it left or right to change the direction in which the keyless chuck spins. The length of which it sticks ou | This component is a combination of both because allows the user to change the direction in which the keyless chuck spins and fits above the VS Switch for cosmetic reasons. | 2 |
| VS Switch | Plastic was used for the trigger because it does not conduct electricity. Copper was used because it is a great conductor for electricity within the VS Switch. Aluminum is used to help reinforce the switch mechanism. Steel is used for the spring because i | Spring forces are applied to keep the VS Switch from being broken by the compression force applied by the user. | Yes, because the different materials make it more complex by requiring more steps to make a complete product. | The shape does affect the manufacturing process because a custom shape needs to made to make the trigger and the box shape needs a special mold to be produced. | Injection molding were used because the shape of the trigger is complicated with curves and it is more efficient to produce the box rather than machining the piece. Metal stamping is used to produce the piece at an efficient rate | The trigger piece was designed to be ergonomic. The switch has its shape it protect its internal components and fit into the housing. | The component is a combination because it allows users to control the speed of the keyless chuck, and fits comfortably in a spot where fingers can easily press down on. | 3 |
| 8 ft Power Cord | Rubber is used because it is a good insulator to protect the user from the copper wires. | A maximum force of 45 lb can be applied vertical. | Rubber does not affect the manufacturing process because it is standard material for extrusion. | Yes, because the manufacturer needed to use a circular tube for extrusion. | Extrusion is a standard manufacturing process for power cords. | The cylindrical shape is the most efficient way to allow the copper wires run within the rubber tube without wasting materials. | The component is a combination because it transfers electrical energy into the drill and leaves through the bottom of the handle of the drill to help with the comestic appearance. | 2 |
| Cord Protector | Rubber is used because it is not brittle and is able to bend under forces without being deformed. | The cord protector puts compression on the power cord which creates friction to keep it in place. Also, the housing applies 30 lb onto the component to keep it in place. | Rubber does affect the manufacturing process because, it is a standard material used for injection molding. | Yes, because its complex shape needs to molded through injection molding. | Injection molding is an easy process to produce a complicated shape at an efficient rate. | Yes, the cord proctector has a unique shape to minimize forces on the cord and to make the drill look more pleasing to the eye. | This component is a combination of both because it reduces the forces on the cord to prevent it from being pulled out of place internally. | 1 |
| Cord Clamp | Aluminium is used to make the cord clamp as it is light in weight and very easy to machine. | The force applied due to the screws, but no other forces that affect or result from the use of the drill. | The material choice does affect the manufacturing process as machining is the cheapest and simplest process to cut out simple shapes from aluminium sheets. | The simple shape of the cord clamp does play a role in the choice of the manufacturing process as this shape holds the cords securely in place. | Machining is comparatively easy,cheap and simple compared to other manufacturing processes to make a simple clamp design. | The clamp holder does have a particular shape. It is small and flat as it has one simple function and so that it does not interfere with any other components in the drill. | The cord clamp is functional as it has to secure the cables inside the handle. | 1 |
| Screws (Clamp) | Stainless steel is used to make the screws as it is cheap and moderately durable. | Resistive force resulting from fastening the cord clamp inside the handle of the drill. | The material choice does affect the manufacturing process. Thread rolling would be the best choice for manufacturing screws from any metal. | The shape plays a vital role in the choice of manufacturing process used as the process of thread rolling was particularly designed for manufacturing metal screws in a cost-effective way. | The threading on the screw is the most important part of the design. And thread-rolling is one of the cheapest option for mass production. | The screws have a particular shape. Screws have threading so that they can fasten the cord clamp and a particular groove on top(corresponding to the screw driver to be used). | The screws are functional as it has to fasten the cord clamp inside the handle. | 1 |
| Screws (Housing) | Stainless steel is used to make the screws as it is cheap and moderately durable. | The resistive forces from the housing. Since screws are used to fasten the housing, there has to be a resistive force to oppose the fastening. | The material choice does affect the manufacturing process. Thread rolling would be the best choice for manufacturing screws from any metal. | The shape plays a vital role in the choice of manufacturing process used as the process of thread rolling was particularly designed for manufacturing metal screws in a cost-effective way. | The threading on the screw is the most important part of the design. And thread-rolling is one of the cheapest option for mass production. | The screws have a particular shape. Screws have threading so that they can fasten the two shells of the housing and also a particular groove on top(corresponding to the screw driver to be used). | The screws are functional as its sole purpose is to secure the two shells of the housing with no cosmetic aspect to it. | 1 |
| Brush | Carbon is used to manufacture the brushes due to its high resistance which ensures gradual shift of current between the wires from the power supply and the motor. | Frictional force due to the movement of the motor and electrical force as the current flows through them. | The material choice does affect manufacturing process as powder metallurgy helps in retaining the electrical characteristics of carbon. | The simplistic shape of the brush does play a vital role in choosing the manufacturing process. A complex shape would require the choice of a different manufacturing process. | The brush is fairly small and has a very simple shape and powder metallurgy does not affect the characteristics of carbon. | The brushes do have a particular shape. They cannot have an irregular shape as it would hamper the flow of current between the power supply and the motor. | The brushes are functional as they help in the smooth flow of current between the power supply and the electric motor. | 1 |
| Felt Washer | Felt is used for manufacturing the component as it does not tear easily,it is resistant to the heat created due to friction and it considerably reduces friction between the two components. | Compressive forces from the spindle and the bearing plate, when the drill is in use. | The material choice does affect the manufacturing process as machining is the cheapest process to cut out simple shapes. | The shape does affect the manufacturing process as machining proves to be the cheapest and simplest way to manufacture the felt washer. | It is a simple process of giving the felt washer a circular shape and punching a hole in it. Machining is the cheapest option available. | The felt washer does have a simple circular shape so that the spindle can go through the washer. | The felt washer is functional with no cosmetic aspect to it. | 1 |
| Cap | Plastic is used to manufacture this component as it is cheap and easy to mold. It also does not hamper the ventilation of heat generated in the motor. | The compressive forces exerted by the two shells of the housing. | The material choice does affect the manufacturing process as injection molding is the best way to mold plastic in a particular shape. | The shape plays a vital role in the choice of manufacturing process used as it is the best way to mold plastic with slits for ventilation and also to accommodate the spirit level. | Injection molding is the best choice to mold plastic with the slits and a circumference that fits perfectly in the housing. | The cap does have a particular shape as it has grooves to ensure proper ventilation, slot for the spirit level and a circumference that fits perfectly in the housing. | The cap is functional as it helps with the ventilation and it has to be cosmetic as it is on the housing of the drill. | 1 |
| Spirit Level | Plastic is used to to manufacture the casing as it is impact resistant compared to glass and easy to cut and form the rhombohedral shape. Whereas ethanol is used due to its low viscosity. | No external forces applied but buoyancy does help in making the bubble float on top of the ethanol. | The material choice does affect manufacturing process as machining is the simplest way to cut plastic in simple shapes. | The shape plays a small role in the choice of the manufacturing process. Due to its simplistic shape, machining is the best choice. | Machining is the smartest choice to cut up plastic sheets, assemble them in box-like shape after filling it up with ethanol. | The spirit level does have a particular shape. It is rhomohedral with external fins that fit in the slots provided in the cap. | The spirit level is functional as it specifies the level of the drill. | 2 |
| Bit holder | Rubber is used to make this component as it is flexible and the best way to secure the bit. | The compressive forces due to the housing and force exerted by the bit once placed in the holder. | The material choice does affect the manufacturing process as injection molding is the best way to mold rubber in the particular shape. | The shape plays a vital role in the choice of manufacturing process used as injection molding is the most efficient way to give rubber the particular shape, so that it can accommodate the bit and fit perfectly in the housing. | The peculiar shape and material choice makes injection molding the smartest choice to mass produce the component. | The bit holder has a peculiar shape so that it is secured properly and also to fit in the housing perfectly. | The bit holder is functional as it has to secure the bit. But since it is on the outer housing of the drill it has to be cosmetic too. | 1 |
Complexity Chart
This table defines the complexity ratings used in Table 1 and Table 2.
| Complexity (1-5) | Number of functions | Materials | Form/Figure (simple, moderate, complex) | Manufacturing time(low, average, extensive) | Design time (estimated days) |
|---|---|---|---|---|---|
| 1 | 1 simple function | 1 | simple/simple | low | 1 |
| 2 | 1 function | 1 to 2 | simple/moderate | low | 1 to 3 |
| 3 | 1 function | 1 to 3 | moderate/moderate | average | 3 to 10 |
| 4 | 2 functions | 1 to 4 | complex/complex | average | 5 to 15 |
| 5 | 2 or more functions | 1 or more | complex/complex | average to extensive | 5 or more |
Design Revisions
1. Reverse Lever
Using and taking apart the drill, the group has assessed that the reverse lever should be redesigned for better reliability and ease of use. The reverse lever is positioned above the trigger making it awkward and difficult for the user to use with ease. Also, the position of the component in the housing applies to much force onto the component making motion difficult. Another factor hindering the component’s motion is the limited area in which to pivot; to control the direction of the drill. The group’s main consensus on how to fix the problem is to eliminate the part as it is, and in its place put a lateral switch.
Lateral Switch: This lateral switch would replace the function of the reverse lever. The lateral switch would run under the reverse ring and be attached to it just as the original reverse lever was. Each end of the lateral switch would connect to buttons on the housing. Pushing one of the two buttons would decipher which direction the drill would turn. Using this lateral switch should eliminate most of the issues that came with the reverse lever as the housing would not put as much force on this new switch. The switch could also move freely enough to not hinder a user’s attempt to change the direction of the drill.
2. Magnetic Bit/Base
Magnetic Bit: One of the recommended design changes for the Black and Decker Drill would be a magnetic bit. This would help prevent the user from losing a screw once it is removed. This is a very common feature of many power drills, yet is missing from the DR202. Making the drill bit magnetic would marginally increase manufacturing costs, but would improve functionality without affecting any other aspects. This would keep the drill in the price range of the target audience (non-professionals).
Magnet in Handle: Another option is to add a magnetic pad to the base of the drill handle. This would allow users to temporarily store screws on the magnet. This magnetic pad would increase the weight of the drill slightly, but would not interfere with the operation of the drill. The cost to manufacture would increase slightly as well, but this would be offset by the new functionality. This change would not affect the maintenance, reliability, or ergonomics of the drill. The target audience (non-professionals) would appreciate the simple but useful magnet in the base, particularly when such an upgrade would cost so little.
3. Reverse Ring
The Black and Decker hand drill given to Group 16 for disassembly was non-functional upon arrival. Once the drill was disassembled, it was found that the reverse ring was broken. A functional reverse ring holds the brushes in contact with the armature and supplies current to the brushes from the power supply. Since the reverse ring in the drill was snapped in half it was unable to hold the brushes against the armature leading to no power being delivered to the rest of the drill. The failure of the reverse ring may have been due to the stress from use over time, or due to improper handling of the drill. In order to improve the durability of the reverse ring, a higher grade plastic could be used. Alternatively, the reverse ring could be reinforced with an aluminum ring with a rubber coating.
Higher Grade Plastic: Manufacturing the reverse ring from a higher grade plastic would increase the cost of the reverse ring, which in turn would increase the manufacturing price of the drill. This price change is nominal, but would increase reliability of the product greatly as this component is essential for the drill to function.
Aluminum reinforcement: Aluminum reinforcement could also be used to increase the durability of the reverse ring, but would consequently increase the weight of the reverse ring. If the reinforcement was made of aluminum the rubber coating would be needed so it would not interfere with the electrical function of the reverse ring. Both these modifications would increase the weight of the reverse ring, but the change would be small enough that it would not hinder the operation of the drill. Since the price change is nominal it would not drastically affect the final price of the drill to the consumer.
Solid Modeled Assembly
The gearbox was chosen to be solid modeled. It is made up of more separate components and is shown in the exploded view, however for clarity they are drawn together and because every part of the gearbox is held together by compression. The gearbox is the main component of a drill; it is where one can see the electrical energy that was converted into mechanical energy from the motor being used, its gearing increases the torque output of the motor and allows the drill to work in the many situations that it is used in. It is composed of the 4 main parts that are shown and the input shaft that transfers the power from the motor to the gearbox. The gearbox was also chosen to be solid modeled because a typical person does not think of a gearbox when picturing the main components of a drill, one thinks of the motor being connected straight to the chuck.
SolidWorks was used to create these models. SolidWorks was chosen because Group 16 is acquainted with a number of students with high levels of experience with the program. This resource made it much easier to learn the program and produce quality models. Had another program been chosen, it would have to be learned without any personal assistance, which would be much more difficult and time consuming.
Engineering Analysis
Engineering Analysis in the Design or Testing Stages
Engineering analysis is a very useful process. For the power cord of the Black and Decker power drill, this process can be used to determine the amount of force that the cord can withstand before failure. This would be useful during the design or testing stages, as it would allow the designers to determine how much force the cord can handle, and make the changes based on whether the results are adequate or not.
Analysis
Problem Statement: Find the force in which the power cord of the Black & Decker drill will pull out of the drill. This will be done by calculating the force that the rubber molded end, which is held in the housing by compression, will flex and pull out resulting in failure of the system.
Assumptions:
1. The drill is on earth and gravity is equal to 32 ft/s^2
2. The rubber mold will pull out before the cord snaps or the housing of the drill breaks
3. The factory compression force on each side of the housing is 30 lbs, the force holding the housing together is created by the 12 screws.
4. The cord will fail due to the vertical component of the applied force.
5. The drill is fixed and cannot move
Diagram:
Experimental Data/ Calculations:
The following data was collected/derived from this experiment and a maximum vertical force needed for the drill to fail was determined to be 45 lb.
Note: The weight was added in intervals of 5 lb; the actual force that it could have failed at is between 40.1 lb and 45.0 lb.
Solution Check: The force is in lb and the max force applied is reasonable.
Discussion:
By applying force to the cord in intervals of 5 lb the group found that when a vertical load of 45 lb is subjected on the cord it will fail. However the rubber molding did not pull through the housing as assumed; the cord pulled through the rubber molding when a weight of 45 lb was applied to it. This data is accurate however it is assuming that the cord will fail only from the force acting in the vertical (y) direction. If the necessary force for the drill to fail was calculated using the horizontal force (x) there would be many other factors that would have to be accounted for such as the housing cracking along with the internal forces in the materials and how they respond to forces acting at different directions. Overall one would agree that the force applied in order for the drill to fail is reasonable but a greater force required would most likely be beneficial to the user.
