Vac Attack. Final Report. Team #3: Adrian Baran, Matthew Murphy, Scott Novak, Doug Wissler 12/15/2014

Transcription

1 Vac Attack Final Report Team #3: Adrian Baran, Matthew Murphy, Scott Novak, Doug Wissler 12/15/2014

2 Executive Summary The Vac Attack portable vacuum is a response to the ACME tool company s need for a portable vacuum for their line of portable tools. The team was given the constraint of needing to reuse the motor and battery of one of their existing cordless drills. Customer needs were addressed early in the design process with the team including: effective removal of debris, ergonomic, easy to empty, and a durable design. Quality Function Deployment was used to transfer these customer needs into technical specifications necessary for the brainstorming phase, and the importance of various specifications was assessed using the Analytical Hierarchy Process. The team eventually chose the fourth concept proposed as the one which will continue on as the final product. Only one major change has occurred since then with the impeller design going from a conical design to a centrifugal one for the final product. The component and material selection of the product has been set with the housing, impeller, coupling and nozzle/canister being made from ABS plastic using plastic injection molds. Items such as the motor and battery will be carried over from the existing product line with the wiring and fasteners being purchased from vendors. The ergonomics of the product was always considered throughout the design processes with a comfortable handle designed along with an easily accessible on/off switch to promote ease of use. Section 5.9 shows the beta prototype used to conduct the tests, and how it is constructed. The testing procedure shown Section 6 can be replicated and describes the process which the team used to optimize the Vac Attack vacuum for optimal performance for the competition against the other design teams. Based off the specifications set by the team the product can be produced at $8.12 a unit, and retail for $30. In a four year period the product will produce a positive NPV of $4,127, for the firm showing that the product is a sound and profitable investment.

3 Table of Contents Introduction...1 Customer Needs and Specifications Identification of Customer Needs Design Specifications....2 Concept Development External Search Problem Decomposition Concept Generation Concept Selection...5 System Level Design Overall Description Preliminary Theoretical Analysis. 6 Detailed Design Modifications to Proposal Sections Final Theoretical Analysis Component and Material Selection Process (for Mass Production) Fabrication Process for Mass Production Industrial Design Detailed Drawings Economic Analysis Safety Construction of Beta Prototype Testing Test Plan

4 6.2 Test Results and Discussion of Results Conclusion References. 16 Appendices

5 1 1 Introduction 1.1 Problem Statement Team Vac Attack has been presented with the opportunity to develop a cordless vacuum cleaner based off the existing architecture of the ACME Tool Company s 18V cordless drill. The market for this product is current users of the ACME line of products, and other consumers in need of a light, portable, and affordable cordless vacuums. The team has been provided the following constrains for the project: a completed design by November 15, 2015, developing the product around the existing electronic system (batteries and motor), no components from competitor s products may be used. 1.2 Background Information Certain technical specifications are already available to the team due to the constraints in the project, including: battery specifications and charge time [1]. The motor type, from performing a dissection of the motor [Appendix A] and its specifications [2], and customer needs will be discussed later in the proposal. A substantial amount of information on centrifugal fans was used when determining the final fan design. In order to achieve maximum efficiency, the team went with an airfoil blade design. An airfoil fan has the highest efficiency of all centrifugal fans [10]. 9 to 16 blades of airfoil contour curve away from the direction of rotation [10]. 1.3 Project Planning The project has gone through a methodical design process as shown in the Gantt chart [Appendix D]. In the finalization of the design, members of the group were assigned specific tasks to complete while other members were given other tasks. Each member was selected for their specific task based upon their expertise in the task at hand whether it be theoretical analysis, creating the CAD files and machining to name a few. Meetings were recorded with deadlines set for the completion of tasks, which allowed the team to learn how projects are handled in the industry. 2 Customer Needs and Specifications 2.1 Identification of Customer Needs Early in the design process the team discussed possible customer needs and developed a list including: effectively remove debris, ergonomic, quiet, ease of emptying, cost effective, durability, battery life and ease of use. Also, by researching online customer reviews at cnet.com, the team found that customers where concerned with suction performance across a variety of material, portability and tendency to clog while operating. The customer needs the team established are primarily focused on the specific design objective of creating a portable vacuum to pick up rice. The reviews found online are for real manufactured vacuums, but some of the criteria still applies to our design project. After all research was

6 2 completed, the team established that suction performance, ease of use, and emptying were the most important customer needs based off of the AHP s [Appendix B]. 2.2 Design Specifications From the customer needs a proper list of design specifications was established. The design specifications include: force to move rice, handle design, decibel rating, canister size, cost, battery life, single speed and cycles per life. The customer needs were then related to these design specification by developing a Quality Function Deployment (QFD) [Appendix B, Table 7], illustrating the corresponding specification to each customer need. The design was broken down into three subsystems: suction, containment unit and body design. Within each subsystem there are particular specifications. These specifications were then weighted by importance. The most important features were found to be suction, ease of use, capacity of containment unit and reliability. From these weights all the specifications were arranged by using an Analytic hierarchy process. The tables illustrating the comparison of features within subsystems can be found in the Appendix B. 3 Concept Development 3.1 External Search In order to start the design process, an external search was performed. Patents and current products were researched to obtain information on the function and design of working vacuums. One of the patents that was researched is a rigid transparent dust collection apparatus (US B2). This apparatus was unique because it allows for quick and easy detachment, which would be preferred in the final design. A Dewalt DC515 wet/dry vacuum was researched and documented because it used common parts within the Dewalt family of tools using a 18V battery used throughout the product line similar to our intended product. Other features include a large on/off switch instead of a trigger for more comfortable use, and a large ½ gallon container for longer use between emptying the container. All of these features were taken into consideration for the initial design concepts. 3.2 Problem Decomposition The overall vacuum design was broken into three subcategories; body design, suction, and the containment unit. These were then broken down into further categories as shown below in the Problem Flow Chart.

7 3 Problem Flow Chart The flow chart allowed the team to develop designs to fulfill each problem. For instance, the problem of the containment unit is solved with either a detachable, internal, external, or a mix of more than one. Each of the different subcategories were included in at least one of the concept designs that will be shown in section 3.3 Concept Generation. 3.3 Concept Generation: The team developed multiple concepts via multiple brainstorming sessions for the problem, which will be tested to determine the best solution. Below are the concepts with hand drawn schematics of varying degrees of complexity, and their descriptions: Concept A With the following concept it is intended to be used as an alpha prototype mainly to test the fan/impeller design solution that the team wishes to implement on the product. A majority of the original drill s housing would remain intact with it only being shortened due to the loss of the transmission and chuck used on the original product. The impeller would be directly mounted to the DC RS550-18V motor to create the suction necessary for the vacuum. In this particular figure a gravity fed debris container (bottle) is shown where the debris would accumulate as it is moved through the nozzle. Concept A

8 4 Concept B Both of the following two concepts are fairly similar in how they are shaped. The main intention with these two concepts is to retain the lower handle design used on the original drill to minimize the overall housing redesign. The majority of the redesign would be done on the end where the motor and impeller is along with the debris containment unit(s). Concept B retains the same gravity fed container (canister) that was shown in Concept A above, along the inclusion of an on/off switch to simplify the use of the vacuum. Concept C With Concept C once again the design has many similarities to Concept B already described. The difference is the placement of the actual debris container (canister). In this concept the debris would be contained in the same area as the impeller. The impeller would be shielded from the debris by a shielding material that would allow for the fluid (air) to flow, while not allowing the debris to pass, and possibly damaging the impeller. A possible solution for this shielding would be a cone style air filter or even mesh. Concept B Concept C Concept C Concept D Concept D takes on a completely new housing with the only components that are retained from the original drill being the battery, the battery connectors, and the RS550-18V motor. The housing retains a very conventional design seen in many handheld/portable vacuum units. The on/off switch Concept D

9 5 shown in Concept B and C is retained to aid ease of use. A new handle will be designed to be as ergonomic as possible promoting ease of use and comfort. The debris container (canister) is once again similar to the one shown in Concept C above, and the impeller would be shielded by a material that would allow fluid flow, but not allow for debris to pass. The nozzle pictured is not a final nozzle design, but only a placeholder to show the location, with a more concrete design after alpha testing. 3.4 Concept Selection: Decision matrices were used by the team to determine which concepts would be used in the final design. An AHP table was created for each of the three subsystems; motor/suction, containment unit, and body design. For each subsystem, multiple categories were created and compared to each other to determine which aspects of each subsystem were most important. In order to explain how each table works, AHP 1 [Appendix B, Table 1] will be used as an example. First, each category was given an importance value, which the team decided together. In the first row, suction is compared to noise, vibration, durability, and reliability. The numbers are determined by dividing the importance of the row category by the importance of the column category. The first number, 4.00, was is the importance of suction, 8, divided by the importance of noise, 4. Once a row was filled, the total was determined by adding each number in the row together. To find the weight of each category, the total of each row was divided by the total of the total column. For suction, was divided by for a weight of.42. Each AHP was determined using the same aforementioned steps. AHP 1 [Appendix B, Table 1] determined weighted values for the subcategories of motor/suction. Suction ended with the highest weighted value, with reliability and durability coming in a close second. Vibration and noise were weighted as the least important. Next, AHP 2 [Appendix B, Table 2] determined the weighted values of the subcategories for the containment unit. It was determined that ease of use was the most important, followed by capacity, durability, and ergonomics. Finally, AHP 3 [Appendix B, Table 3] determined the weighted values of the subcategories for body design. It was determined that ease of use and durability were the most important aspects of the body design. Compactness and aesthetics were weighted as moderately important and mass was determined to be almost a non-factor. The determined weights were used to create a concept scoring matrix for three different design categories. Using these matrices, a concept design was chosen for the impeller, containment unit, and body. By using information from the external search, ratings were given based on data and observations of patents and similar products. The durability of the 2D impeller was ranked lower because of its thinner build, which wears quicker than the 3D impeller. It was determined from Concept Scoring Matrix 1 [Appendix B, Table 4] that the 3D impeller design will be taken further and the 2D impeller will not. Concept Scoring Matrix 2 [Appendix B, Table 5] has the internal unit barely beating out the external unit. The largest disparity was with ergonomics. An external canister is bulkier and in the way, while an internal canister is hardly noticeable. With such similar scores, either design could be considered in the future. A final decision will be made after testing of the alpha prototype.

10 6 A custom Housing was determined to be the superior design the body based off of Concept Scoring Matrix 3 [Appendix B, Table 6]. The custom design, shown in Concept D of Section 3.2, is more compact than Concepts A, B, and C. The team also determined that the custom body is more aesthetically pleasing than the designs using the original drill housing. 4 System Level Design: 4.1 Overall Description The chosen design incorporates six main components, as shown in Fig. 1. The vacuum is built around the electric motor which acts as the central element. A fan, filter, and nozzle all have a horizontal concentric alignment with the motor to allow for simplicity. This is possible because there is no gearing off of the motor and the fan is connected directly to the shaft. All of these parts are encased in or attached to a square like body that separates down the center for easy disassembly. The handle is part of the body and has a button located by the thumbs position when holding the vacuum for ease of use. The drills battery attaches to the back of the body staying away from the moving components in the front. The nozzle also doubles as the containment unit for the rice using gravity to keep it settled at the bottom. 4.2 Preliminary Theoretical Analysis Figure 1 This handheld vacuum cleaners most important component when it comes to performance is the fan. In order to determine what properties this fan needs, an existing vacuum must be compared. Two important specifications in fan design are volumetric flow rate and change in pressure. To estimate a

11 7 flow rate that our electric motor is capable of producing, we compared it to an existing vacuum cleaner whose specifications are shown in [Appendix C, Fig.4]. Using a ratio between motor input powers, estimation for flow rate can be obtained. These calculations are shown in [Appendix C, Fig.2]. A flow rate of around 4 ft^3/min is then used to determine the pressure change needed in order to create said flow rate. This is shown in [Appendix C, Fig.3]. All data used for our motor is listed in [Appendix C, Figure 5]. Equations are found from engineeringtoolbox.com, Fans Efficiency and Power Consumption. 5 Detailed Design: Figure 2: Exploded view of vacuum Figure 2 shows an exploded view of our handheld vacuum cleaner. This design incorporates a simple set up for ease of assembly and minimal part count. An electric motor, coupling piece, centrifugal fan, and nozzle/containment unit all sit concentrically within a two piece body. This body acts as the housing and supports for all components listed. All parts are sandwiched between the two pieces and require no other components to support them. 5.1 Modifications to Proposal Sections A prototype based on Concept A shown in the Section 3.3 was constructed and basic testing was performed. From testing a few design flaws and problems were found. The main issue was the ability to securely connect the 3D printed impeller to the metal gear at the end of the motor shaft. A couple of methods were attempted with the best being hot glue to fit the pieces together, but at high rpm the impeller rotation was very unstable. The new design will now include an aluminum adapter piece that will fit over the gear and be secured using two set screws. The other end of the adapter will connect to a high quality 3D printed fan by means of an axial screw with a washer providing compression on the fan. This design will restrict movement of the fan in all directions, while still allowing free rotation. Another

12 8 change to the originally proposed design is the shape and type of fan being used. The new design is a flat centrifugal fan with air foil blade profiles. An updated Gantt chart [Appendix D] shows the upcoming project schedule that was updated to include beta prototype, submission of detailed design report, design refinement and final testing. 5.2 Final Theoretical Analysis In order to calculate the inlet pressure of the cordless vacuum, Bernoulli s Principle and the Conservation of Energy equations were used. A simplified equation is found below, considering compressible flow due to air being the analyzed fluid. Vinlet 2 2 Pinlet ( ) 1 inlet Voutlet 2 2 Poutlet ( ) 1 outlet The equation can be simplified even further to the one below. At the inlet the velocity is considered zero which creates high pressure. The inlet velocity terms are canceled out. Pinlet ( ) 1 inlet Voutlet 2 2 Poutlet ( ) 1 outlet The specific heat ratio of air: The outlet will have a high velocity created by the impeller which creates low pressure. The high pressure from the inlet will rush towards the area of low pressure to even it out, creating suction. The outlet velocity created by the impeller with a radius of.0889 m and spinning at 6400 rpm is solved for below. The rpm value is found from the table in [Appendix C, Figure 5]. rad min m Voutlet R ( 6400rpm)(2 )(1 )(.0889m) sec 60sec s Rearranging the simplified Bernoulli s equation, the inlet pressure is solved for below. m 2 kg (59.58 ) (1.229 ) Pinlet ( ) s m Pinlet 63.84Pa. 0093psi During the competition, 1 cup of rice will have to be removed from a plate. The weight of 1 cup of rice is defined as Wr below. The area of plate is defined by Aplate, and was found by using a typical paper plate radius of 4.5 inches.

13 9 Wr. 46lbs Aplate 2 2 ( 4.5in) 63.62in Finally, the force required to pick up one cup of rice spread evenly over the area of a plate is solved for below by dividing the weight of one cup of rice by the area of the plate. (0.46lbs ) Fp psi 2 (63.62in ) 5.3 Component and Material Selection Process (for Mass Production) The proposed product will use a combination of available off the shelf components as well as custom components. Our custom components include: two housing halves, impeller, canister/nozzle, and coupling. All of the custom components will be made with plastic injection molding, with the material of choice being ABS plastic. ABS was chosen because the material s properties make it a very impact resistant and tough, which is ideal for a vacuum cleaner. The plastic is also widely used throughout the industry making it readily available to purchase as a raw material. The main concern with this material is to have a well-ventilated work space due to the fumes that may be harmful to potential factory workers. The material can be easily recycled allowing for the reuse of scrap material in manufacturing, and once the product reaches the end of its life [6]. The remain components for the product come off the shelf either from vendors or are already in used in other products in the Drill Master line. The reuse of the motor and battery /charging system come from other Drill Master products, which will allow the firm to lower costs across the whole line due to the ability to purchase these parts at a bulk discount. The remaining components such as the toggle switch/soldered wiring and fasteners can be purchased from vendors as specified by the design requirements. 5.4 Fabrication Process The fabrication process for the product will require an initial investment for 5 new molds necessary to create the custom components outlined in Section 5.3. The molds required will be made out of aluminum and will require machining to produce the desired shapes for each mold. After the molds have been produced the actual parts can be made with each molded part needing some post processing to remove any flash left after the molding process. Once that is completed the molded parts may e nter the assembly line. Another necessary process is the joining of all of the electrical components: motor, wiring, switch, and battery connector into one assembly by soldering any necessary connections. Once this electrical sub assembly is complete the impeller may be attached to the motor. Afterward, the impeller along with the electrical assembly may be placed into the housing and secured with the other housing half. Finally, the canister and nozzle maybe be snapped on, and the product can be sent to packaging.

14 Industrial Design The design features a comfortable handle with an easy to use switch located on the spine of the handle exactly where a user s thumb would naturally lie. This enables the user to easily switch the vacuum on and off with little effort. The weight of the vacuum is also evenly distributed so that independent of how the user holds the vacuum there will no difference of how easy it is to support vacuum. The vacuum also features flat surfaces on the both the sides and rear faces. This allows the user to set the vacuum down without really needing to worry about how the vacuum is oriented. The vacuum is made primarily of light weight ABS plastic ensuring that the overall weight is manageable and easy to use by all users regardless of strength or body composition. ABS is also resistant to high impact ensuring that product maintains its integrity through all common operations. The product is also symmetrically designed so that it can be operated by either right or left handed users. The overall body design is rather compact and in generally a rectangular shape, so that it can be used in most common vacuuming situations. 5.6 Detail Drawings Figure 3: Side view of vacuum with all internal components The detailed drawing shown in Figure 3 above shows the relative position of all of the components for the vacuum. Complete design drawings are in Appendix E, which can easily be replicated to reproduce the Vac Attack vacuum. 5.7 Economic Analysis The bill of materials [Appendix F, Table 1] breaks down the cost for one production unit of the Vac Attack vacuum. The break down includes how many of each component is necessary for the vacuum, the cost of the raw material/part, the labor costs incurred, and the total cost for that part. A unit production cost for one unit of $8.12 was calculated with a 13.5% overhead cost to help cover

15 11 marketing, development, and support costs for the product (one unit). All part, and material costs were assumed to at a bulk discount rate as a result the cost to produce 100,000 units annually is $812,000. The NPV (net present value) of the proposed product over 16 quarters is $4,127, at a 10% discount rate. All of values presented above are based off a proposed price of $30 per unit. The NPV was created by the team based of the estimations of various expenses including: development, production, and ramp up costs. The full spreadsheet for the calculations can be seen in [Appendix F, Table 2]. Based off the positive NPV calculation the Vac Attack vacuum is sound investments for the firm. 5.8 Safety Our design features a two part housing which encloses the motor and all wiring. The two halves of the body assembly are mounted together using screws which will allow the design to experience some collisions and wear, without breaking apart and risking injury. This design will allow the user to operate the product without the risk of being electrocuted by the electrical components. If an internal failure where to occur all the components would be contained within the housing, eliminating the risk of shrapnel injuring the user. The design also features rounded edges to ensure that the user does not injure themselves or other with potential sharp corners of the vacuum while operating. The designed vacuum is in compliance with UL1017 [7] standard for Vacuum Cleaners, Blower Cleaners, and Household Floor Finishing Machines under 250 V. The designed product also complies with the UL60745 [8] standard for Hand-Held Motor-Operated Electric Tools as long as the product is not used on any type of explosive or bio-hazardous material. The designed vacuum also complies with the IEC60312 [9] standard for House Hold Vacuums particularly dealing with dry materials. This design is only safe to operate on dry, non-explosive and non-hazardous materials operating with a power supply of less than 250 V. 5.9 Construction of Beta Prototype The construction of the Vac Attack beta prototype (Figure 4) deviated from the mass production mainly due to the inability to fabricate a housing unit such as the production model. Production techniques used to produce the beta prototype differed as well due to the fact that a majority of the components are plastic injection molded parts for the production model. On the beta prototype the components produced were constructed using: a milling, lathe, laser cutter, band saw, belt sander, drill press, hot glue gun, soldering iron, wire cutters, knife, duct tape, and a 3D printer. Addition construction photos can be viewed in Appendix G. Figure 4: Completed Beta Prototype

16 12 The housing on the beta was made out of a 4 diameter PVC pipe at 7 in length to allow for the packaging of the rest of the components, 16 exhaust holes were drilled to allow air to exit, and an opening for the electrical switch. To fit the motor onto the PVC pipe housing securely two.1 thick acrylic mounting brackets were cut out that would slide over the motor, with the motor being hot glued in place. After the motor was glued in place an aluminum coupling was attached to the gear on the motor by tightening two set screws on the coupling, which would for a stable mount for the impeller. All of this is shown in Figure 5 to the right. The wiring that was used on the hand drill was lengthened, re-soldered and a toggle switch replaced the trigger. Also the team reused the lower portion of the drill where the battery was attached, and glued that piece onto another.1 thick acrylic plate at the rear of the vacuum. Figure 5: Aluminum coupling and acrylic motor mounts The team then began final assembly of all of these components into the PVC pipe housing. The motor mounts were adjusted with the impeller on the coupling to get the proper alignment with the exhaust holes that were drilled earlier. The motor mounts were then hot glued into place to prevent the motor from shifting, and damaging the impeller. The 3D printed impeller was then finally mounted to the coupling and secured by a bolt and washer. A shield was placed in front of the impeller where it acted as a mount for the canister which a soup container and an inlet for air to the impeller. At the shield inlet a fine wire mesh was also added to prevent debris from damaging the impeller. The container had the nozzle permanently attached on the opposite side with hot glue. Finally, a handle was also glued on to aid with the handling of the beta prototype. The overall form of the beta resembles that of the production model, and allows the team to simulate how the production model would operate. 6 Testing: 6.1 Test Plan The first test to be conducted will determine the most efficient nozzle design. Two nozzles were 3d printed with identical bases and different diameter circular openings. Nozzle one has an opening with a inch diameter and nozzle two has an opening with a 1 inch diameter. Both nozzles fit identically to the current beta prototype. A flat plate taped to a surface will have 1 cup of uncooked rice evenly distributed over it. Nozzle one and two will be attached to the vacuum on a series of separate runs. These runs will be timed from when the vacuum is turned on to when the entire plate of rice has been removed from the plate. Up to 15 pieces of rice can remain on the plate and still be considered a completed run in order to promote accurate results. Five runs will be performed with each nozzle and their times will be averaged. The nozzle with the fastest average time will be used for the final

17 13 competition. Items needed include paper plate, duct tape, 1 cup of uncooked rice, 2 nozzles with varying diameters, stop watch, and vacuum prototype with interchangeable nozzle slot. Test number two will focus on the flow rate of the vacuum. The exit ports for the flow of the vacuum are placed radially on the housing being concentric with the fan blades inside. There will be a total of 16 evenly spaced 0.25 inch diameter holes in this pattern. To begin the test all but two of the holes, which are spaced 180 degrees from one another, will be covered with scotch tape to prevent flow. The vacuum will be placed vertically on each run for consistency and a flow meter will be placed flush on the nozzle. The fan will be turned on and the air speed will be recorded after it has stabilized on the meter. This process will repeat after the tape is removed from two more holes spaced 180 degrees from each other. The last run will consist of all 16 holes being open. These 8 data points will be graphed and a line of best fit will be attached. The amount of holes used in the final design will be determined by the peak of this graph. Items needed include scotch tape, flow meter, paper, pencil, and vacuum prototype. 6.2 Test Results and Discussion of Results After performing the first test involving nozzle design, nozzle 2 with the larger diameter performed 79% better than the other nozzle based on the average of the recorded times. Nozzle 1 averaged 7.77 seconds a run and nozzle 2 averaged seconds. The data for individual runs is available in Appendix H, Table 3. Going into this test, our team was not sure if our fan was producing a big enough pressure drop for the larger diameter to work efficiently. The results proved that our original inch diameter nozzle design was more conservative than it needed to be with respect to its opening area. Because of these results our final prototype will be using the 1 inch diameter nozzle. The second test was conducted in order to optimize the flow of our vacuum. It had to be performed two separate times due to concerns with the charge of the battery. The second time performing the test, with a fully charged battery, produced larger overall air speeds so we chose this curve to base our findings off of. This graph is shown below as Figure 6. The two data tables and original graph are in Appendix H. Our data shows that the air speed rose with each set of holes being opened up. Right around the point where all 16 holes are opened, our line of best fit levels off. Because of this we chose to use all 16 holes opened up for our final design. Due to the graph leveling we came to the conclusion that adding more holes would do nothing the performance of the vacuum.

18 14 Flow Speed Test 2 Flow Speed (mph) Number of Open Holes Figure 6: Flow speeds vs number of exhaust openings 7 Conclusion and Recommendations: The Vac Attack portable handheld vacuum is a multi-part assembly featuring lightweight plastic materials making it both easy to use, cost efficient, and eco-friendly. The design features airfoil fan technology in order to maximize flow rate from the provided battery and motor (of a handheld drill). The fan is mounted to the motor through a durable plastic coupling utilizing set screws to properly secure the fan. A toggle switch is wired to the motor and battery, and all connections are soldered to ensure reliability while operating at different orientations. The wire, fan and motor assembly are encased in lightweight plastic housing with an attached ergonomic handle for customer ease of use. The battery simply slides into place on the rear of vacuum and is easily removable. A fine mesh screen is used to separate the fan and the containment unit to prevent debris from striking and destroying the fan. The nozzle is permanently attached to the containment unit, which is easy to remove from the housing, empty and clean. The key features of this design are the centrifugal fan and the mounting coupling. The centrifugal fan is able to produce massive suction to handle any type of household cleaning. The mounting coupling is also key to the design because it allows the vacuum to reliably operate at maximum rpm s without chance of the fan disconnecting from the motor. Since the majority of the vacuum is produced through injection molding using ABS plastic the vacuum is able to retail at $30, which is relatively inexpensive for such a high performance device. From a manufacturer perspective investing in and producing this vacuum is a high profit venture. The vacuum only costs $8.12 to produce and would retail for $30, which in a four year period would produce a positive NPV of $4,127,053.

19 15 The design could be improved further through the development of detachable nozzles, to adapt to the many different cleaning needs of the customer base. Minor improvements could also be made to the handle to improve ergonomics as well as placing the power switch in a more convenient location for ease of customer use. Another improvement could be to the containment to make it easier to ope n and empty, maybe by implementing a latch to open a door to release debris. Finally, the overall aesthetics could be improved to make the product more stylish and pleasing to the customer s eyes. Through this entire design process the team has learned a wealth of information about product design, as well as gained experience working as a design team. The team also learned about various manufacturing processes and the advantages/disadvantages that each one possesses. The team utilized 3D printing while producing prototypes of the product, which proved to be a very efficient and easy process to produce multiple functional models to test. The team also learned how successfully manage a project by designating each member to a specific role suiting their strengths to ensure maximum time and work efficiency. However the biggest lesson that the team learned from this design process is that the first idea is never the best. Many prototypes were produced and were either scrapped or damaged, allowing the team to address flaws that were unforeseen prior to actual building the prototype(s).

20 16 References 1. Drill Master Owner s Manual available on Angel 2. Motor specs: 3. Vacuum comparison: series-electric-carbon-brush-ac-motor-for-vacuum-cleaner html 4. Motor vendor: 5. Household Vacuum Market: Household-Vacuum-Cleaners-Market#.VEG40vnF-Lk Understanding Centrifugal Fans by Tom Gustafson

21 17 Appendix A Drill Dissection: Transmission to be removed RS v Motor Trigger to be removed for on/off switch Battery contacts Figure 1: Dissected Drill

22 18 Appendix B Motor/Suction Suction Noise Vibration Durability Reliability Total Weight Importance Suction Noise Vibration Durability Reliability Table 1: AHP1 Table 2: AHP2

23 19 Table 3: AHP3 Table 4: Concept Scoring Matrix 1 Table 5: Concept Scoring Matrix 2

24 20 Needs / Specs Effective Rice Removal Ergonomi cs Noise Ease of Waste Disposal Cost vs. Performan ce Durable Force to Move Rice X X Handle Design X Table 6: Concept Scoring Matrix 3 db Rating Canister Size X X X Budget/C ost Battery Life Run Time X X Simple to use X X One Speed X Cycles per Life X Table 7: QFD

25 21 Appendix C Figure 2: Flow Rate Estimations Figure 3: Net Pressure Change

26 22 Figure 4: Electrical Specification Chart Reference [3] Figure 5: RS 550 Motor Specifications; Reference [4]

27 23 Appendix D Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 Week 16 Team Contract External Search Concept Generation/Selection Drill Test Presentation 1 Proposal Alpha Prototype Testing/Design Refinement Beta Prototype Detailed Design Report Write Final Report Beta 2 Prototype Gantt chart

28 24 Appendix E Figure 6: Housing Half Figure 7: Impeller/Fan dimensions

29 25 Figure 8: Nozzle/Containment Unit drawing Figure 9: Coupling part drawing

30 26 Appendix F Bill of Materials and Production Cost Parts Qty Material Cost Labor Total ABS Molded Parts Housing 2 $0.70 $0.40 $2.20 Impeller 1 $0.15 $0.10 $0.25 Canister 1 $0.20 $0.10 $0.30 Nozzle 1 $0.05 $0.10 $0.15 Coupling 1 $0.04 $0.05 $0.09 Motor 1 $0.80 $0.10 $0.90 Wiring/Switch 1 $0.60 $0.10 $0.70 Battery + Charger 1 $1.50 $0.10 $1.60 Fastners 8 $0.05 $0.05 $0.45 Packaging 1 $0.60 $0.10 $0.70 Unit Production Cost $7.34 Overhead 13.5% $0.99 Total Cost 1 Unit: $8.33 Table 1: Bill of Materials

31 27 Year1 Year 2 Year 3 Year 4 Values Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Development Ramp up Production cost Production volume Unit Production cost Sales Revenue Sales Volume Unit Price Cash Flow PV Year 1, r = 10% Project NPV Table 2: Project NPV

32 28 Appendix G Figure 10: PVC pipe housing with 0.25 exhaust holes, hole for switch, and 3D printed handle. Figure 11: Exhaust hole locations

33 29 Figure 12: Impeller on coupling relative to motor. Figure 13: Impeller secured on coupling with bolt and washer.

34 30 Figure 14: Wiring from switch to battery mount. All connections are soldered. Figure 15: Wiring inside the PVC housing

35 Figure 16: 3D printed nozzle and PVC pipe extension attached to soup container that acts as the debris container. 31

36 32 Appendix H (seconds) Nozzle 1 (0.375 in.) Nozzle 2 (1 in.) Run Run Run Run Run Average Table 3: Nozzle Run Test Data Holes Closed Flow Speed (mi/h) Test 1 Flow Speed (mi/h) Test Table 4: Air flow Test Data

37 Air Speed (mph) 33 Flow Speed (mi/h) Test Number of Open Holes Figure 17: Test 1 Air Flow Plot