Windshield wiper assembly 2

From DDL Wiki

Revision as of 15:13, 6 February 2011 by Jwhaley@andrew.cmu.edu (Talk | contribs)
Jump to: navigation, search

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)
    1. Effective: Effective removal of water, debris, and snow (light and heavy); Wide-cleaning motion; Leaves no streaks; Wide fluid dispersal
    2. Long-lasting components and structure: Durable and resistant to corrosion
    3. Easy and cheap replacement
    4. Safe: No sharp edges, would not injure the user, does not damage windshield
    5. Aesthetically appealing
    6. Must work under various climates extreme conditions: Especially - does not ice over or must be easy to de-ice
    7. Should not obstruct visibility both during operation and during storage
    8. Option to store replacement blades
    9. Broad selection of wiper blades – Ability to customize or upgrade
  • Transporter
    1. Light-weight
    2. Durable in case of rough handling
  • End-assembly automotive plant
    1. Cheap, light-weight, durable, long-lifetime components and structures
    2. Simple and quick installation/assembly
    3. Safety, No VOC
    4. Efficient packaging within the engine compartment
    5. Minimize power usage and aerodynamic drag
  • Repair mechanic
    1. Standardized
    2. Difficult to replace, but easy to repair
    3. Modular
    4. Safe: No sharp edges, would not injure the mechanic
  • Other cars on the road
    1. Effectiveness of cleaning: Water, debris, snow, or ice is not flung in a dangerous way
    2. Does not fail (break) catastrophically
    3. Safe failure mode in case of collision
  • Parking police
    1. 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
Gearbox Stripped teeth Costly repair
Temporarily inoperable
7 Extra stress
Obstruction on arm
1 Durability Tests 2 14
Linkages Misalignment
Shearing
Costly repair
Temporarily inoperable
7 Improper installation
Environmental degredation
2 Durability Tests
Easily repairable
1 14
Ball Joints Ball becomes detached from joint
Ball seizes in joint
Costly repair
Temporarily inoperable
7 Debris
Linkage misalignment
Random forces
2 Sheleltered 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.

Personal tools