Windshield wiper assembly 2
From DDL Wiki
(→Major Post-Production Stakeholders) |
|||
Line 608: | Line 608: | ||
== FMEA == | == FMEA == | ||
- | {|class="wikitable" border ="1" cellspacing="0" align=" | + | {|class="wikitable" border ="1" cellspacing="0" align="center" |
|- | |- | ||
Line 626: | Line 626: | ||
|- | |- | ||
- | | ''' | + | | '''DC Motor''' |
- | | | + | | Gear teeth stripped from excessive wear |
| Costly repair<br />Temporarily inoperable | | Costly repair<br />Temporarily inoperable | ||
| 7 | | 7 | ||
- | | | + | | Excessive torque<br />Obstruction on arm |
| 1 | | 1 | ||
- | | Durability | + | | Durability tests |
| 2 | | 2 | ||
| 14 | | 14 | ||
- | | | + | | Fail-safe built into motor control to shut-down motor when excessive torque is detected |
|- | |- | ||
| '''Linkages''' | | '''Linkages''' | ||
- | | Misalignment<br />Shearing | + | | Misalignment in assembly<br />Shearing of steel tube |
- | | Costly repair<br />Temporarily inoperable | + | | Costly repair<br />Temporarily inoperable<br />Possible damage to components within the engine bay |
| 7 | | 7 | ||
- | | Improper installation<br />Environmental | + | | Improper installation<br />Environmental degradation |
| 2 | | 2 | ||
- | | Durability Tests | + | | Durability Tests |
| 1 | | 1 | ||
| 14 | | 14 | ||
- | | | + | | Clear markings or part geometry that only allows one assembly orientation |
|- | |- | ||
Line 656: | Line 656: | ||
| Debris<br />Linkage misalignment<br />Random forces | | Debris<br />Linkage misalignment<br />Random forces | ||
| 2 | | 2 | ||
- | | | + | | Dimension checks with gages<br />Dye penetrant to check for adequate lubrication |
| 2 | | 2 | ||
| 28 | | 28 |
Revision as of 19:03, 6 February 2011
Contents |
Report 1 - Product Analysis: Competitor Study
Executive Summary
Major Post-Production Stakeholders
A list of the major stakeholders of the competitors product was generated as long as a listing of their primary concerns with regard to the product. The benefit of this process is the expansion it has on our own awareness of the product since the redesign will be focused on benefiting these stakeholders and addressing their concerns in the most effective manner. Additional stakeholders or stakeholder concerns, along with a more quantitative understanding of the importance of these concerns, will be generated after more market research has been completed.
- User (Car-owner who used the product to clean their windshields)
- Effective: Effective removal of water, debris, and snow (light and heavy); Wide-cleaning motion; Leaves no streaks; Wide fluid dispersal
- Long-lasting components and structure: Durable and resistant to corrosion
- Easy and cheap replacement
- Safe: No sharp edges, would not injure the user, does not damage windshield
- Aesthetically appealing
- Must work under various climates extreme conditions: Especially - does not ice over or must be easy to de-ice
- Should not obstruct visibility both during operation and during storage
- Option to store replacement blades
- Broad selection of wiper blades – Ability to customize or upgrade
- Transporter (Concerned about the ease and safety of handling)
- Light-weight
- Durable in case of rough handling
- End-assembly automotive plant (Purchases sub-assemblies from separate manufacturer)
- Cheap, light-weight, durable, long-lifetime components and structures
- Simple and quick installation/assembly
- Safety, No VOC
- Efficient packaging within the engine compartment
- Minimize power usage and aerodynamic drag
- Repair mechanic (Concerned with ease of access and failure modes)
- Standardized
- Difficult to replace, but easy to repair
- Modular
- Safe: No sharp edges, would not injure the mechanic
- Other cars on the road (Concerned with other drivers being safe)
- Effectiveness of cleaning: Water, debris, snow, or ice is not flung in a dangerous way
- Does not fail (break) catastrophically
- Safe failure mode in case of collision
- Parking police (Wipers are needed to dispense traffic tickets)
- Wiper is safe and easy to lift so as to slide ticket underneath
Product Usability Study
Assembly
Product Operation
Dissection Exercise
Dissection Write Up
This section highlights the process used to reverse engineer the competitor’s windshield wiper shown in figure 1. This reverse engineering exercise dual objectives; first, it helped give an understanding of the function of the product and the manufacturing process used to create this product, secondly, it helped identify weaknesses in the design that may be developed into opportunities for design improvement.
Based on function, we disassembled the product into the following # sub-assemblies; Base substructure, large and small vibration mounts, 4 arms, gear casing, motor and the wiper. By taking a higher level view and observing these sub-assemblies and their interactions, we were able to fully develop the function structure diagram that is displayed in our usability study. By taking a closer view by dissecting and analyzing each component of the sub-assembly, we were able to create an assembly process for the entire structure.
Dissection Table
Bill of Materials | ||||||||
---|---|---|---|---|---|---|---|---|
Part Number | Sub-Assembly | Part Name | Quantity | Weight (in g) | Function | Manufacturing Process | Material | Image |
Base Structure |
| |||||||
1 | Driver Side Wiper Casing | 1 | 111 | Protect Arm 3 (driver side) wiper mount linkage | Cast | Aluminum | Image:.jpg
| |
2 | Passenger Side Wiper Casing | 1 | 212 | Protect Arm 3 (passenger side) wiper mount linkage | Cast | Aluminum | Image:.jpg | |
3 | U-Shaped Connection Bar | 1 | 259 | Connect driver and passenger side wiper mount casings | Stamping | Steel | Image:.jpg | |
Vibration Mount (large) | ||||||||
4 | Metal Grommet Insert (large) | 2 | Stabilizes vibration mount by holding onto chassis | Extended and expanded | Steel | Image:.jpg | ||
5 | Rubber Mount (large) | 2 | Vibration dampening | Molding | Rubber | Image:.jpg | ||
Vibration Mount (small) |
| |||||||
6 | Metal Grommet Insert (small) | 1 | Stabilizes vibration mount by holding onto chassis | Extended and expanded | Steel | Image:.jpg
| ||
7 | Rubber Mount (small) | 1 | Vibration dampening | Molding | Rubber | Image:.jpg
| ||
Arm 1 |
| |||||||
8 | Arm 1 Linkage (w/ plastic ball-in-socket joint) | 1 | 53 | Transfers drivetrain's rotational motion 90 degrees to linkage mechanism's plane | Steel tube crushed and welded. Hole drilled, ball-in-socket joint stamped in. | Steel | Image:.jpg
| |
9 | Lock Washer | 1 | 2 | Distribute nut pressure | Steel | Image:.jpg
| ||
10 | Nut | 1 | 3 | Attach Arm 1 to drivetrain | Tapping | Steel | Image:.jpg
| |
Arm 2 | ||||||||
11 | Arm 2 Linkage (w/ plastic ball-in-socket joint) | 1 | 149 | Transfer motion | Steel tube crushed and welded. Hole drilled, ball-in-socket joint stamped in. | Steel | Image:.jpg
| |
Arm 3 |
| |||||||
12 | Arm 3 linkage (w/ plastic ball-in-socket-joint) | 2 | Transfer motion | Steel | Image:.jpg | |||
13 | Wiper Mount Pin | 2 | Transfer motion | Steel | Image:.jpg
| |||
14 | Plastic Cover | 2 | 2 | Prevent fluid from seeping into linkage area | Injection Mold | Plastic | Image:.jpg
| |
15 | Screw-On Cap | 2 | 11 | Protect Wiper Mount Pin | Cast and Threaded Die | Steel | Image:.jpg
| |
Arm 4 |
| |||||||
16 | Arm 4 linkage [Length: 20.5" (52 cm) | 1 | 177 | Transfer motion | Image:.jpg
| |||
Other |
| |||||||
17 | Top Washer | 1 | 1 | Steel | Image:.jpg
| |||
Gear Casing |
| |||||||
18 | Gear Casing Cover Screws | 4 | <1 | Attach cover to casing | Die | Steel | Image:.jpg
| |
19 | Drivetrain Mounting Bolts | 3 | 5 | Mount drivetrain to base | Die | Steel | Image:.jpg | |
Motor |
| |||||||
20 | Motor Mounting Bolts (w/ Lock Washer) | 4 | 5 | Mount motor to base | Die | Steel | Image:.jpg
| |
21 | Motor Mounting Nuts | 4 | 3 | Mount motor to base | Tapping | Steel | Image:.jpg
| |
22 | Motor | 1 | Convert electric current via EMF to rotation of a linear worm gear | Standard purchased part | Image:.jpg
| |||
Windshield Wiper |
| |||||||
23 | Wiper | 2 | Rotate about pin and sweep across windshield | Plastic | Image:.jpg
| |||
24 | Blade | 2 | Remove water or other debris from windshield | Rubber | Image:.jpg |
DFMA
Manufacturing
Design for Manufacturing | |
---|---|
Guideline | Comments |
Minimize Part Count Eliminate fasteners, part consolidation | One motor Remove extra bolts Complex linkage can be replaced by another motor
|
Standardize Components Take advantage of economies of scale & known component properties | Different bolt sizes Different sized grommets that performed similar functions Standardized C-channel and tube size Standardized motor Standardized cast housing |
Commonize Product Line Economies of scale and minimum training and equipment | Same wiper assembly can be used in different vehicle models because of adjustable base length Cast parts remain the same; mold can be reused |
Standardize Design Feature Common dimensions for fewer tools and setups | Different screws all have the same head; only requires one type of screwdriver head |
Keep Designs Simple Simplest way to achieve needed functionality | Utilizes a constant, forward rotation of motor to achieve cyclic motion |
Multifunctional Parts e.g.: fingernail clipper | Four-bar linkage both achieves desired motion & connects the wipers |
Ease of Fabrication Choose materials easy to work with | Uses common metals (aluminum & steel) Uses common rubber for vibration isolation |
Avoid Tight Tolerances Causes exponential cost increases | Ball joints at ends of linkages allow for twisting & other non-planar motion within assembly without stressing parts Four-bar linkage arms have enough phase offset to allow for looser tolerance in linkage arm lengths |
Minimize Secondary & Finishing Operations Only where needed | Assembly is typically hidden, so aesthetic finishes are unnecessary |
Take Advantage of Special Process Properties e.g.: color in injection molding | Cast parts have ribs & optimized shape - does not add much complexity to casting process Text on cast parts(?) |
Assembly
Design for Assembly | |
---|---|
Guideline | Comments |
Minimize Part Count Eliminate fasteners, part consolidation | Three-piece housing can be cast as one Two motors can eliminate the need for a four-bar linkage
|
Minimize Assembly Surfaces and sequence them | Motor + gearbox are mounted on reverse side of linkages Grommets must be installed from sides of the assembly |
Use Subassemblies can be assembled and tested separately, can be outsourced | Motor + gearbox are preassembled Three-piece housing can be preassembled |
Mistake-Proof unambiguous, unique assembly orientation | Linkage arms are not labelled; their different lengths can lead to confusion during assembly No way to orient the cast housings |
Minimize Fasteners snap fits and part consolidation | Staked ends on pins Ball joints are staked in linkage ends |
Minimize Handling position for insertion or joining is easy to achieve | Fasteners are not all accessible from one side |
Minimize Assembly Direction ideal - add each component from top to base | |
Provide Unobstructed Access consider assembly path (e.g.: oil filter) | Motor housing screws are difficult to access |
Maximize Assembly Compliance chamfers and radii help assemble parts with variance | |
Features for Assembly Features that have no functionality in use but support assembly |
FMEA
Failure Mode and Effects Analysis | |||||||||
---|---|---|---|---|---|---|---|---|---|
Item & Function | Failure Mode | Effects of Failure | S | Causes of Failure | O | Design Controls | D | RPN | Recommended Actions |
DC Motor | Gear teeth stripped from excessive wear | Costly repair Temporarily inoperable | 7 | Excessive torque Obstruction on arm | 1 | Durability tests | 2 | 14 | Fail-safe built into motor control to shut-down motor when excessive torque is detected |
Linkages | Misalignment in assembly Shearing of steel tube | Costly repair Temporarily inoperable Possible damage to components within the engine bay | 7 | Improper installation Environmental degradation | 2 | Durability Tests | 1 | 14 | Clear markings or part geometry that only allows one assembly orientation |
Ball Joints | Ball becomes detached from joint Ball seizes in joint | Costly repair Temporarily inoperable | 7 | Debris Linkage misalignment Random forces | 2 | Dimension checks with gages Dye penetrant to check for adequate lubrication | 2 | 28 | |
Wiper Arm | Deformation | Reduced effectiveness | 5 | Impact from flying debris User error Weather Damage from carwash | 4 | Recess arm beneath car hood Increase plastic strength | 4 | 80 | |
Mounting Assembly | Loosening from body Grommet failiure | Damage to other components in the engine bay Reduced effectiveness | 8 | Loosened from body vibrations Bad installation Corrosion | 1 | Specify correct materials Durability Tests Allow for maintainance Electrical sensor Progressive, controlled failure | 4 | 24 | |
Wiper Blades | Tearing | Reduced Effectiveness | 5 | Material failure | 5 | Second blade Easily replaced | 1 | 25 | |
Wiper Arm Spring |
DFE
Design for Environment | |
---|---|
DFE Guideline | Suggestions for Improvement |
0. New Concept Development De-materialization, Functional optimization | -hydrophobic windshield -blowing a film of air -heated windshield/wipers/fluid |
1. Select Low Impact Materials Avoid toxics and ozone depleters, Use renewable, recycled, recyclable materials | - toxicity of the ethanol or methanol mixture of wiper fluid may be harmful when breathed in or ingested - disposal of fluid may lead to air or water pollution - fluid may corrode paint, rubber, wax, or plastic components |
2. Reduce Material Amount Reduce weight, transport volume | - depending on model of car, one wiper may clean effectively - designing system with two separate motors for each wiper would remove body connection and additional linkages |
3. Eco-Manufacturing Alternate production processes, reduce production waste | |
4. Optimize Distribution Less/cleaner/reusable packaging | |
5. Reduce Use-Phase Impact Lower energy consumption, reduce consumables | - maximize the efficiency of the wiper fluid pressure and spray pattern to reduce amount of fluid used while maintaining effective cleaning |
6. Maximize The First Life Increase durability, easy maintenance and repair | - design rubber vibration mounts to last lifetime of car
- since linkage assembly may be hidden underneath chassis, design structural components to last throughout lifetime |
7. End of Life Recycling, Design for Disassembly, Reuse of product, Re-manufacturing | - system can be easier to disassemble to make recycling of metal and rubber more desirable |
EIO-LCA | ||
---|---|---|
Life Cycle Stage | Inputs | Outputs |
Material Extraction | Natural resources (iron ore, aluminum) | Steel, Rubber, Plastic, Aluminum Environmental Damage (GHG like CO2) |
Production | Materials, Energy, Labor, Facilities (Machinery and Storage0 | Parts, Assemblies, Packaged goods |
Use | Fuel to run motor Wiper Blades & Replacement parts Washer fluid | Used/damaged wiper blades Disposed washer fluid Environmental Damage (GHG like CO2) |
End of Life | Windshield wiper assembly Washer fluid and its plastic container Replacement blades | Recyclable Components: Steel, Rubber, some Plastic Landfill waste |
Transportation | Packaging Diesel fuel Labor | Packaging Environmental Damage (GHG like CO2) |
Team Member Roles (Report I)
For Report 1, the team member roles were assigned as follows:
Role | Team Member |
---|---|
Team Leader | Justin Whaley |
DFMA Lead | Mike Lin |
FMEA Lead | Max Gustafson |
DFE Lead | Andrew Socha |
The roles were assigned based on preference and expertise in an area. Each team member was present for the usability study, the dissection, and the in-class exercises. While the write-ups for the analysis sections of the report were contributed by the individual analysis leads, the team leader completed the write-ups for the usability study, the conclusions from the dissection exercise, compiled the Powerpoint presentation, and scheduled weekly team meetings.
References
[1] Dieter, George Ellwood., and Linda C. Schmidt. Engineering Design. Boston: McGraw-Hill Higher Education, 2009. Print.