Vacuum cleaner

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Executive Summary

During our product analysis of a Dirt Devil Swift Stick we came across several notable observations. As we went through the uses of the product and used them for its main function a few basic problems occured. These problems ranged from small annoyances to major hazzards. This caused us to further look into customer needs and see how they can be addressed for this product. A vacuum cleaner is a common household appliance designed for cleaning purposes. It may be easy to design a vacuum for one of the many uses a customer buys a vacuum for, but to design a vacuum that can cover all of the uses is the challenge. Our customers need more than just a vacuum that picks up a mess off the carpet, they also want to be able to clean up a spill on a hard floor, or vacuum the steps with ease. Those are a few of the problems we will address in our product redesign. Once the product uses and customer needs were completely documented, the product was dissected and all of the parts were analyzed and documented in detail. This gave us a more complete understanding of how this product was manufactured and assembled. The dissection gave us a basis for further analysis. This further analysis included DFMA, FMEA, DFE, and Quantitative Mechanical Analysis. The DFMA for this product was well thought out and little or no improvements can be made for the product. The screw fastener design lend itself to making the vacuum robust and able to hold together through any bumps or vibrations of the vacuum, even though this manufacuring proceedure would take longer. There were also many times during our dissection where we noted places that the plastic was molded in such a way that the parts could not be put together incorrectly. Only one time did we notice that an improvement could be made at the spot where the electrical cord meets the motor housing. During further analysis of the failure modes we discovered that besides the power outlet, there was nothing dangerous with the product that could not be easily detacted by the user. Most problems, like clogging, motor failure, switch failure were all very detectable making the priority to change them very low. By performing environmental impact analysis, the power supply sector proved to be the most impactful both during the manufacturing process and life cylce. Analyzing the end-of-life cylce, the production of electrical power to operate the vacuum was found to be more even more affective when considering the cost for its life span, estimated to be about three years. A green design approach would focus on making a vacuum more energy efficient. From these analyses, decisions could be made to improve upon any areas of manufacturing that could be lacking or cause ill effects on the environment. These problems are conclusion are futher discussed in the body of the report.

Product Evaluation

During product evaluation our group used the vacuum cleaner in an everyday use situation. We noted things that worked well along with external problems that occured with everyday use.


A vacuum cleaner is common household appliance used for cleaning purposes. A vacuum cleaner cleans by creating suction. A pump creates a pressure difference inside the unit causing atmospheric air to be forced up through a tubing system. Most vacuum cleaners utilize a rotating brush at its entrance to help "sweep" dust and dirt into the suction path. Vacuumed particles are finally depostited in some collecting container that can either be removed or emptied after use.

Main Compnenets There are six main components to a standard vacuum cleaner:
-Intake port which may include attachments such as a brush
-exhaust port
-Electric motor
-Pourous bag or container

Diagram found at HowStuffWorks

How it Works A vacuum operates by creating a low pressure area inside the machine causing for air at atmospheric pressure to be forced or "sucked" into the system. What connected to a power supply, the motor uses the potential difference as energy for its work. Most commonly, the motor uses a fan; spinning the fan causes the low pressure region and therefore the suction. A spinning brush is often used to help sweep up dust, dirt or other particles into the air stream. Particles pass through the intake port and are deposited into some type of container. Air is forced out through the exhaust port to allow for the continuous flow of air. Finally, dirt and dust is removed by either removing the porous bag or emptying the removable container. A general diagram is seen above.
Information gathered from HowStuffWorks HowStuffWorks site

Product Uses

For normal use of a vacuum cleaner:

-Unwind power cord and connect unit to home outlet
-Power on unit
-Move unit in back and forth motion covering the vacuum area desired
-Turn off unit
-Wind power cord and store

The normal use of a household vacuum cleaner can be seen in the flow chart below.


Customer Needs

The traditional user needs for a vacuum cleaner are:
-Ability to provide suction
-Effective cleaning ability of carpet, hard wood and any other household surfaces
-Comfortable use while operater is standing
-Ability to transport easily (weight and bulk)
-Easy removal of dirt/dust container/bag
-Easy Storage
-Fair cost
-Quiet and smooth running

Bill of Materials

An extensive list of parts in the vacuum. Information includes part names, quantities, weights, function of use, process for manufacturing, and the material the parts are made from.

Part # Name Quantity Weight Function Manufacturing Process Material Image

A-001 Short Screw 4 < 1g Holds plastic cover on vacuum head Turned Steel
A-002 Long Screw 1 < 1g Holds plastic cover on vacuum head Turned Steel
A-003 Small Screw 2 < 1g Holds cover on vaccum channel Turned Steel
A-004 Swivel Connector 1 64g Attachment joint allowing multiple andgles and ranges of motion Injection molding Plastic
A-005 Attachment Cover 1 101g Asthetic cover to enclose the vacuum channel and wheels Injection molding Plastic
A-006 Vaccum Channel Cover 1 17g Creates a vaccum channel do direct vacuumed debris Injection molding Plastic
A-007 Main Wheel 2 14g Allows vaccum to roll on various serfaces Injection molding Plastic
A-008 Attachment Base 1 117g Creates vacuum channel and holds wheels Injection molding Plastic
H-001 Large Screw 1 5g Holds handle to main vacuum housing Turned Steel
H-002 Bottom Cord Hanger 1 12g Provides a place to wrap cord Injection molding Plastic
H-003 Small Screw 2 < 1g Holds handle and switch housing together Turned Steel
H-004 Handle (Left Half) 1 23g Creates a housing for the switch assembly and allows for a place to grasp Injection molding Plastic
H-005 Handle (Right Half) 1 23g Creates a housing for the switch assembly and allows for a place to grasp Injection molding Plastic
H-006 Shaft 1 63g Extension for handle to hold vacuum at comfortable height Extrusion Steel
H-007 Switch Activatior 1 20g Connects circuit to turn power on Extrusion Steel
H-008 Thumb Switch 1 4g Activated by user to turn power on or off Injection molding Plastic
H-009 Adjustible Cord Hanger 1 2g Place to wrap cord with quick release swivel to remove cord easily Injection molding Plastic
H-010 Cord Hanger Adjuster 1 <1g Piece that connects to cord hanger and allows hanger to be adjusted into two positions Injection Molding Plastic
H-011 Cord Hanger Adjuster Screw 1 <1g Holds adjustable cord hanger and cord hanger adjuster together Turned Steel
H-012 Thumb Switch Screw 1 < 1g Holds thumb switch in place and connects the switch activator Casting Steel
W-001 Spring Clip 1 5g Holds waste basket cover in place and provides a quick release Injection molding Plastic
W-002 Spring 1 < 1g Pushes back on spring clip to keep cover closed Extrusion, Forming Steel
W-003 Filter 1 57g Protects blower/motor for debris and keeps dust from being blown back out of the vacuum housing Injection molding Plastic and shear textile
W-004 Waste Basket Cap 1 20g Opens to empty waste basket Ejection molding Plastic
W-005 Waste Basket 1 270g Holds vacuumed debris Injection molding Plastic
V-001 Small Screws 7 < 1g Holds cover on motor assembly Turned Steel
V-002 Spring 1 < 1g Pushes back on spring clip to keep waste basket connected to the vacuum housing assembly Extrusion, Forming Steel
V-003 Spring Clip 1 5g Holds waste basket in place and provides a quick release Injection molding Plastic
V-004 Motor Assembly Cover 1 168g Housing for motor/blower and fuse Injection molding Plastic
V-005 Motor Assembly Holder 1 158g Housing for motor/blower and fuse Injection molding Plastic
V-006 Switch Screw 1 < 1g Holds power switch in place Turned Steel
V-007 Vibration Mount 2 < 1g Lowers vibrational forces and noise from the motor/blower Vulcanizing Rubber
V-008 Motor 1 459g Creates partial vacuum by spinning Winding, Extrusion, Injection molding Plastic, Copper, Steel, Aluminum
V-009 Fuse 1 < 1g Prevents electrical disturbances from reaching the motor Multiple Glass, Aluminum
V-010 Electrical Cord 1 262g Carries current to the vacuum Extrusion and Molding Rubber, Copper

Product Analysis

In depth analysis of the individual parts and function of the vacuum. This allowed for more discussion for possible improvement to the existing product. Improvements were found in the areas of manufacturing, failure, and environment.

Design for Manufacturing and Assembly

Design for Manufacturing and Assembly (DFMA) is a set a of tools and methods for analyzing the manufacturing process in order to develop a simplified process of reduced cost.

Current DFMA

The current product has most likely been through an extensive improvement process. Nearly all of the parts of the vacuum has only one possible fit so there is no opportunity for confusion or mistakes. Making the design even better is the inclusion of notches between fitting parts. The addition of notches allow for correct pieces to easily slide together into the correct position.

There are a few areas that could be improved.

Recommended Improvements

The current design requires many screws to be used for assembly. This process can be improved with a redesign utilizing snaps to fasten the product. Snaps would make assembly easier and faster but also more robust. A vacuum's operation experiences many vibrations. These vibrations can lead to eventual losening of the screws. The use of snaps would eliminate the potential for this problem.

Another problem with the current design is the process of attaching the power cord. The current design has multiple ambiguous positions for placement of the cord. It is the one part where this occurs. This process can be easily simplified by merely adding a color code or the elimination of the multiple choices.

Finally, there were a few different screws used in the assembly. There was not a major difference between the different types which could possibly lead to some mistakes or confusion when deciding which component to use. Making the screw types more identifiable with there correct position could further aid assembly. Elimination of screw elements would also solve this problem.

Failure Mode Effects Analysis

Although this product was designed to keep failures to a minimum, there are still many peossible ways in which this vacuum cleaner can fail. Most of these failure modes will affect the performance of the vacuum, but will generally not cause any harm to the user. The only situation where harm can occur is when the plug does not fit the outlet properly. Since the vacuum power will still be on even if the plug is partially removed from the outlet, the user would have no way of knowing that the dangerous situation is occuring. Anyone comming in contact with the exposed metal could be burnt to recieve an electric shock. Generally, all of the failure modes associated with this vacuum have a low occurance and are also very obvious to the user. Because of this, each has failure mode is given a relatively low priorty for change.

The table below shows the failures that could occur and the effect these failures have on the overall performance of the vacuum.

Item and Function Failure
Effects of Failure S Cause of Failure O Design Controls D RPN Recommended
& Deadline
Actions Taken S O D RPN
Vaccum Channel
*Creates channel for vaccum flow
Jams/Clogs No air flow 4 Objects jammed at inlet 5 Product testing in normal situations 3 60 Explore other inlet design options N/A N/A 4 5 3 3
*Allows vaccum to roll
Jammed/Stops turning Vaccum can no longer roll 4 Axel dammage 2 Quality control testing 1 8 Take no action N/A N/A 4 2 1 8
*Provides air flow
Blower stops turning Fails to produce suction 6 Missing filter/hole in filter causes debris to damage moter/blower 2 Test use when filter is damaged 2 24 Take no action N/A N/A 6 2 2 24
Electrical Cord
*Provides power to motor
Does not fit properly into electrical outlet No electrical connection can be made, Potential for electric shock 8 Tight fit around electrical outlet 5 Failure observed by user 1 40 Explore other cable/outlet design options N/A N/A 8 5 1 40
Switch activator
*Makes circuit connection to provide power turn on motor
Does not make connection Vaccum will not turn on 4 Shaft does not line up due to wear 1 Quality testing by pushing button
Extended life testing
3 12 Explore more durable materials N/A N/A 4 1 3 12

Design for Environment

Design for environment (DFE) is method for analyzing the environmental impact of a product. DFE considers a product’s manufacturing processes as well as its use throughout the product’s life cycle.

The environmental impact of a product can be determined through a process called EIO-LCA. This process takes into account all sectors of the econonmy affected by the manufacturing and distribution of the specified product. The EIOLCA software determines the impacts of economic activity, energy usage, greenhouse gas emissions, employment, etc.

For our analysis we found Power generation and supply to be the sector to have the most environmental effect. Power generation and supply was responsible for roughly 30% of the total greenhouse gas release and nearly 75% of total air pollutant release. We also found that the power supply to the manufacturing has the most effect on the environment of the vacuums various stages. The manufacturing stage was also responsible for over half of the toxic releases into the environment. Pie charts are show below.

Chart for Air pollutants Image:Airpie.JPG
Chart for toxic releasesImage:Toxicpie.JPG
Chart for grnhouse gasesImage:Greenhousepie.JPG

For our product we evaluated the economic impact as well as the energy usage for the products end-of-life cycle. Using the software we evaluated the economic impact of a household vacuum production for 1 million dollars of economic activity. It was determined that 2.3 million dollars total is needed for production. Using the price of a single vacuum, (30 USD,) we determined the per unit price of manufacturing to be 69 USD. The resulting table is shown below. .

Economic Activity

Sector Total Economic $mil Value Added $mil Direct Economic $mil Direct %
Total for all sectors2.300.9871.6270.4
335212 Household vacuum cleaner manufacturing1.000.3751.00100.0
420000 Wholesale trade0.0960.0640.05052.4
550000 Management of companies and enterprises0.0720.0510.039 53.9
325211 Plastics material and resin manufacturing0.0630.0150.04164.6
32619A Plastics plumbing fixtures and all other plastics products 0.0560.0230.05191.8

It is clear after our analysis that the power generation and supply of the manufacturing process has the most impact. There is certainly some uncertainty in our data. We could benefeit from further analyzing the environmental impact of the use of the product through the end of its life cycle. Still, even with our uncertainty, the power generation and supply sector is so much greater than all others that we can come to our conclusions with great confidence.

In addition to the evaluation of manufacturing impact, we evaluated the impact of electrical use. For our unit we estimated the use to be 100 hr/year. This value considers home use as well as use by cleaning professionals. With the vacuum rating and our electrical supplier’s kw-hr price, the cost for a year of operation is 117 USD/year. BAsed on the EIOLCA software, we determined that on yearly basis, the electrical power supply actually produces slightly larger amount of greenhous gases than does the manufacturing process. For air pollutants, the manufacturing of the vacuum and the production of the power supply provide similar amounts of pollutants. For our product we can assume that a vacuum will occur less than an annual basis, (a vacuum will not be bought every year.) Considering this, the environmental effect of the electric power production becomes very important.

For a green design, the power problem most be top priority; Although power supply for the production phase is clearly a problem, we would be most effective in a design that addresses the products energy consumption during use. Energy for operation has the most environmental impact over a products life span. Addressing the issue would benefeit both the end user, having to pay less operation costs, and the manufacturer, creating a more attractive product to market to the consumer.

Quantitative Mechanical Analysis

Air flows in the vaccum from the blower to the vaccume outlet. In between, the air flows through parts of the vaccum assembly with different cross sectional areas. The path of air is as follows:
1.) Air is pulled in through the initial vaccum channel (arrow point) (Fig. A, Part# A-006)
2.) Air travels through a rectangular cross-sectional channel
3.) Air flows through a circular swivel connector (Fig B, Part# A-004)
4.) From the connector, the air travels throgh the waste basket
5.) Air is pulled from the waste basket through a filter (Fig C, Part# W-003)
6.) Air is pulled in to the blower inlet
7.) Air pulled through impellar and exhaled out the vent on the motor housing

The airflow, Q, does not change at any point through the vaccum. Airflow for any given pneumatic circuit is dependent only on the fluid power of the motor/blower assembly. The velocity, however, does change at different points through the flow channels. As the cross-sectional area increases, the velocity of air decreases. As the cross-sectional area decreases, the velocity increases. Suction produced at the outlet is based on the dynamic pressure at that point. Dynamic pressure is directly proporational to the square of the velocity.

Airflow, Q, will change when there is a break in the circuit, such as a new opening or a leak. In the connection to the swivel connector (Fig. B), there is room for leak. When the vacuum handle is down close to the floor, the leak is the greatest. When it is standing upright, the leak is kept to a minimum. The suction pressure can be estimated using the formulas Q=VA where A is the cross-sectional area and V is the air velocity, and q=1/2 rho * V2 where rho is the fluid density and q is the dynamic pressure. If air is leaking at the swivel connector, less air flow will be traveling to the initial vacuum channel. With less air flow and the same exit cross-sectional area, the velocity will be smaller. Since the suction (dynamic pressure) is directly proportional to the air velocity, lower velocity will mean lower suction. This shows that the leak inside the air channels will result in a lower suction and therefore a poor performance.

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