Bike lock

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| align="center"|'''Minimize Fasteners'''
| align="center"|'''Minimize Fasteners'''
| Strengths:
| Strengths:
 +
* Simple roll pins, a number of snap fit components, and a heavy reliance on press fit components are used to reduce the number of fasteners
 +
* A number of bumps and depressible plastic extensions are used to fix removable parts in place
|-
|-
| align="center"|'''Minimize Handling'''
| align="center"|'''Minimize Handling'''

Revision as of 17:43, 2 February 2014

Contents

Executive Summary

Product Stakeholder Analysis

Product Usage Study

U-Lock

First, the user will place their bike next to a locking structure. The user will unlock the U-Lock, place the U around the locking structure and the bike frame, then they will return the base to the U-Bar and remove the key. The bike frame is now secured to the locking structure.

Place bike next to locking structure
Place bike next to locking structure
Unlock base from U-Bar with key
Unlock base from U-Bar with key
Place U-Bar around locking structure and bike frame
Place U-Bar around locking structure and bike frame
Attach base to U-Bar and turn the key to secure the lock
Attach base to U-Bar and turn the key to secure the lock

Possible User Issues

Lock can only secure one part of the bike, most commonly the frame. The wheels are still unprotected with this. This constraint is due to the geometry of the U-Bar. It must be small enough to not be a burden to carry around, but must also be large enough to easily fit around most structures and the bike frame.

Some users do not use the included clamp, as it may not fit around every bike. They must find some other method of securing the lock to the bike.

Puck Lock

First, the user will place their bike next to a locking structure. The user will then unravel the chain around the puck lock. User will wrap the chain around the locking structure and as many parts of the bike as possible. (eg. frame and wheel) The user will then resecure the chain to the central lock cylinder and lock the lock.


Use key to unlock the tubular tumbler lock and disengage the locking pin.
Use key to unlock the tubular tumbler lock and disengage the locking pin.
Free the end of the last link from this plastic retainer and unravel the lock.
Free the end of the last link from this plastic retainer and unravel the lock.
Secure the last link to the main cylinder and depress the pin to lock
Secure the last link to the main cylinder and depress the pin to lock


Possible User Issues

Small chain makes it hard to connect multiple bike components. May leave some parts unsecured.

Bill of Materials

U-Lock

Exploded View of U-Lock
Exploded View of U-Lock


The following table contains information about each part labled in the above image.

Part # Name Quantity Subassembly Mass [g] Function Material Manufacturing Process Image
1 Rubber Shielding 1 N/A 68 Provides weatherproofing for the U-Bar. It keeps dirt and grime out and prevents scratches. In comparison to the U-Bar it is plush and nice to the touch. Rubber Extrusion
2 U-Bar 1 N/A 330 Can be placed around the chosen locking surface and the bike frame. This is then inserted into the base of the U-Lock and secures the bike to the locking surface. Steel Extruded, Bent, Cut
3 U-Bar Clamp Attachment 1 Bike Frame Clamp 15 Provides nice mating surface for U-Bar and bike frame bracket. Plastic Injection Molding
4 Frame Attachment Screws and Nuts 4 Bike Frame Clamp 1 Screws and nuts used to press clamp edges together around the U-Bar. Steel Off the Shelf
5 U-Bar Frame Attachment Clasp 1 Bike Frame Clamp 13 Nicely holds onto the U-Bar and connects to a base piece that can be attached to a bike frame. Plastic Injection Molding
6 U-Bar Frame Attachment Locking Tab 1 Bike Frame Clamp 4 Tab presses over edge of Clamp attachment on the U-Bar to secure it to the bike frame. Plastic Injection Molding
7 U-Bar Frame Attachment Spring 1 Bike Frame Clamp <1 Spring sits under clasp and provides force on clasp to keep Lock attached to frame attachment. Steel Off the SHelf
8 Frame Attachment Joining Screw 1 Bike Frame Clamp <1 Fastens the two major parts of the frame bracket together Steel Off the Shelf
9 Frame Bracket Base 1 Bike Frame Clamp 17 Holds clasp. Has specific points of rotation so one can change the orientation of the clasp as it connects to the bike. Represents half of the frame bracket clamp. Plastic Injection Molding
10 Mating Pad 2 Bike Frame Clamp 2 Snap in part is smooth and offers a nice mating surface between the clamp and the bike frame (Not Pictured), and the U-Lock and clamp. Plastic Injection Molding
11 Bike Frame Bracket Clamp 1 Bike Frame Clamp 18 Part is placed around bike frame and fastened to the rest of the bracket via screws. Second half of frame bracket clamp. Plastic Injection Molding
12 Locking Bars 2 Locking Mechanism 26 Bars fit into notches cut into the U-Bar. When they are in place they secure the U-Bar in place and prevent its removal. The hooks on either edge sit on nubs that rotate when the key is turned, sliding the locking bars back and forth. Typically coating is used on parts that slide around. Steel Forged and Coated with Titanium Nitrate
13 Lock Component Housing Cylinder 1 Lock Mechanism 28 Neatly holds all the parts necessary to actually lock the lock. It has slots cut such that one cannot insert the lock upside down, tracks for the lock bars to slide on, and is designed such that all force imparted to the lock in an attempt to shock it open are directed around the lock bars. Plastic Injection Molding
14 Lock Housing 1 Lock Mechanism 15 Housing is made to nicely keep the lock in place inside of the component housing cylinder. It has a tab to prevent incorrect insertion of lock. Brass Off the Shelf
15 Rubber Grommet 2 N/A <1 Acts as both a seal to prevent dirt or water from entering the lock component housing cylinder, as well as a cushion to protect the cylinder from rubbing directly against the U-Bar Rubber Stamping
16 Lock Stopper Pin 2 Lock Mechanism <1 Grooves in the lock housing fit around these spring loaded pins. When the key is concerned, These pins are compressed and allow the lock to turn. Brass Stamping
17 Pin Housing 1 Lock Mechanism 8 Housing has space for spring and pins as well as the stopper pins and springs. Has a slot for a key to be inserted. Pin Housing will rotate around inside the lock housing. Brass Off the Shelf
18 Pin Springs 12 Lock Mechanism <1 Pins sit on top of these springs. When the key is inserted and turned, these springs will compress or extend to get all the pins to the same height so the pin housing can rotate. They will return to their natural length after the key is removed. Steel Off the Shelf
19 Pins 8 Lock Mechanism <1 These pins are each individually made with notches at a different height. The height of the notch corresponds to the pattern on the key. The correct key will line up with the notches, allowing the pins to be moved out of the way, allowing the pin housing. Brass Off the Shelf
20 Plastic Endcap 2 N\A 13 Acts as a weatherproofing seal for the outer casing of the lock base. It also seals off the ends of the lock base via a tight fit, discouraging the user from tampering with the internals of the lock. Adds a stylistic element to the lock. Soft Plastic Molding
21 Rubber Shock Absorber 2 N\A 4 Part acts as a weatherproofing seal as well as a shock absorber. Cushions any force that is applied to the ends of the lock. This prevents the lock from being bumped open. Rubber Stamping
22 Lock Bar Actuator 1 Lock Mechanism 3 Slides into grove on back of pin housing. When pin housing rotates, this part rotates as well. The Lock Bars are attached to the nubs on top and turning the pin housing causes the lock bars to slide from unlocked to locked. Brass Off the Shelf
23 Outer Housing 1 Lock Housing 127 A powder coated outer case that neatly houses the entire lock assembly. Has holes in it to accomodate the U-Bar ans well as a small hole in it, presumably for assembly alignment purposes. Coating adds plesant feel in comparison to unfinished steel. Steel Stamping and Welding
24 Key 5 N\A 6 Key is specially made to line up with each of the pins in a specific lock. The track pulls the pins into the correct position, which allows the lock to rotate. Steel and Plastic Row 1, column 8

Puck Lock

Exploded View of Puck Lock
Exploded View of Puck Lock


The following table contains information about each part labled in the above image.

Part # Name Quantity Subassembly Mass Function Material Manufacturing Process Image
1 Chain Link 14 Chain 20 Multiple links connected by pins allow for folding and extending of chain. Chain can be put around a locking structure and the bike frame in order to secure the bike to that structure. Steel Stamping
2 Protective Plastic Cover 14 Chain <1 Provides weatherproofing for the links to reduce the likelihood of rust for each chain link. Plastic Injection Molding in 2 halves
3 Pins and Washers 13 Chain 3 Connects chain links. Allows for smooth rotation of the links about the axis of the pin. Steel Off the Shelf
4 Outer Plastic Cover 2 N\A 5 Covers outside of lock. Provides weatherproofing for the inner lock components. Provides a nice surface to the touch in comparison to the metal underneath. Plastic Two halves injection molded
5 Upper Lock Housing 1 Lock Housing 68 Provides a place for the chain to lock to the lock body in a compact manner. This part is powder coated to prevent rust and wear. It protects the inner lock mechanisms from the elements. Steel Injection Molding
6 Lock Actuator 1 Lock Housing 8 Spans the lock cylinder and holds everything together. This part is moved when the key is turned. Steel Off the Shelf
7 Lock Housing 1 Lock Housing 11 Holds the two parts of the lock in a nice case. Its hard to break into, to prevent tampering. Steel Off the Self
8 Pins 8 Lock Housing <1 Pins slide into the second pin housing. When they intersect the second pin housing, its impossible to rotate the pin housings. This is how the lock locks. Brass Off the Shelf
9 Upper Pin Housing 1 Lock Housing 4 Second part of pin housing. Does not rotate. When the pins are extended into this piece, the housing cannot rotate. Steel Injection Molding
10 Roll Pin 2 Lock Housing <1 Pins hold the two sides of the Metal lock housing together. These are very difficult to remove without advanced tools to prevent tampering. Steel Off the Shelf
11 Lower Pin Housing 1 Lock Housing 11 Houses the pins and contains keyhole for the locking mechanism. When the pins are extended, they intersect the second part of the housing and prevent the housing from rotating. Steel Off the Shelf
12 Lower Lock Housing 1 Lock Housing 64 Secures the lock parts and prevents tampering. Steel Injection Molding
13 Lower Outer Plastic Cover 1 N\A 7 Provides weatherproofing and a nice surface to the touch for the lock Plastic Injection Molded

DFMA

U-Lock

Design for Manufacture Guidelines
Design Objective Comments
Minimize Part Count Strengths:
  • Most parts fit together without the use of fasteners

Weaknesses:

  • The U-bar clamp assembly is not needed for the U-Lock to function properly as a bike lock and it is unnecessary if the attachment assembly is not used to attach the U-Lock to the bike
Standardize Components Weaknesses:
  • Most of the plastic components are unique and require separate molds
Commonize Product Line Strengths:
  • All of the plastic parts are manufactured through injection molding, minimizing job training
  • Holes on multiple components line up for easy alignment when assembling
Standardize Design Features Strengths:
  • Housing for the locking assembly is symmetric

Weaknesses:

  • Plastic components are unique and would each require their own molds
Keep Designs Simple Strengths:
  • Design is composed of two main parts: the locking assembly and the U-bar assembly

Weaknesses:

  • Attachment assembly, which increases the complexity, is not necessary for the U-Lock to function as a lock
Multifunctional Parts Strengths:
  • Outer metal casing acts as housing, weatherproofing, and protection for the locking assembly
Ease of Fabrication Strengths:
  • Components are mainly comprised of plastic and steel
  • Housing for the locking assembly is symmetric
Avoid Tight Tolerances Strengths:
  • Tolerances are not too tight because there is some slop between the U-bar and the locking mechanism

Weaknesses:

  • If tolerances are too tight, the U-bar/locking assemblies do not fit together rendering the lock useless
Minimize Secondary and Finishing Operations Strengths:
  • Injection molded plastic parts do not require any secondary operations
  • Metal coloring is done through powder coating

Weaknesses:

  • Locking bars are coated with Titanium Nitrate after being forged
Take Advantage of Special Process Properties Strengths:
  • Powder coating is used to color the steel
  • Plastic components are colored during the injection molding process


Design for Assembly Guidelines
Design Objective Comments
Minimize Part Count Weaknesses:
  • Clamping and attachment assemblies are not needed for the U-Lock to function as a bike lock
Minimize Assembly Surfaces
Use Subassemblies Strengths:
  • Lock housing assembly and the U-bar can be assembled and tested separately before being put together for the final product
  • The actual locking assembly, which is bought off the shelf, is assembled separately before being put into the lock housing assembly
Mistake-Proof Strengths:
  • In the lock housing assembly each component has holes that are used to align the components during assembly
  • Each component of the locking mechanism has its own unique groove/hole in a plastic housing cylinder
Minimize Fasteners Strengths:
  • Most parts fit together without the use of fasteners
Minimize Handling
Minimize Assembly Direction
Provide Unobstructed Access
Maximize Assembly Compliance

Puck Lock

Design for Manufacture Guidelines
Design Objective Comments
Minimize Part Count Strengths:
  • There are very few unique parts in the total assembly

Weaknesses:

  • There are fasteners and spacers between every link
  • There are a lot of custom links, not a standard chain or cable
Standardize Components Strengths:
  • Uses a standard roll pin size to hold the main housing together

Weaknesses:

  • Contains highly specialized lock body components
  • Internal locking mechanism requires special production techniques and tooling
Commonize Product Line Strengths:
  • Parts have features that prevents it from being assembled incorrectly which eliminates specialized training

Weaknesses:

  • The complex shape of the housing may require additional complex steps to produce essential features
Standardize Design Features Strengths:
  • Many parts used in the design are repeated in the same dimensions (chain links, chain pins, chain spacers)
Keep Designs Simple Strengths:
  • Repeated chain features and multiples of components within the lock are repeated

Weaknesses:

  • Complicated molds for multifunctional parts may result in higher initial production costs
Multifunctional Parts Strengths:
  • The outer casing acts as protection for the locking assembly, storage for the chain, and housing for the locking mechanism
  • Multiple parts have subassemblies have multiple functions within the overall design
Ease of Fabrication Strengths:
  • The chain links are stamped

Weaknesses:

  • Highly complex lock housing may be difficult to fabricate due to its high strength requirements and complex overall shape
Avoid Tight Tolerances Strengths:
  • Spacers on the chain links help stiffen lateral motions in the chain, allowing for much looser tolerances when attaching the links

Weaknesses:

  • A lot of press fit components in the lock requires tighter tolerances and additional features to simplify assembly
Minimize Secondary and Finishing Operations Weaknesses:
  • Multiple parts require coatings, insertion into plastic parts, or complex secondary operations
Take Advantage of Special Process Properties Strengths:
  • Powder coating for coloring metals
  • Coloring added during injection molding for plastics
  • Metal inserts are used in injection molded parts


Design for Assembly Guidelines
Design Objective Comments
Minimize Part Count Strengths:
  • Complex housing shapes and interlocking pieces allow for very few fasteners holding the lock housing together

Weaknesses:

  • Redundant worms gears in the bike attachment may function better and reduce overall part cost if replaces with a ratcheting feature in the mount iteslf
Minimize Assembly Surfaces Strengths:
  • Most of the lock subassemblies can be sequentially placed from one direction into the final assembly

Weaknesses:

  • Permanent fasteners and individual subassemblies require multiple directions and side operations for assembly or permanent attachment to the final assembly
Use Subassemblies Strengths:
  • Much of the lock can be broken down into a number of subassemblies that are stacked upon each other for final assembly
  • The chain links are a repeated four piece pattern for easier wrapping about the final lock body
Mistake-Proof Strengths:
  • Many parts, including the lock, have features the prevent assembly in an incorrect orientation

Weaknesses;

  • Not following the proper pattern for the chain links will prevent the lock from being wrapped around the central housing
Minimize Fasteners Strengths:
  • Simple roll pins, a number of snap fit components, and a heavy reliance on press fit components are used to reduce the number of fasteners
  • A number of bumps and depressible plastic extensions are used to fix removable parts in place
Minimize Handling
Minimize Assembly Direction
Provide Unobstructed Access
Maximize Assembly Compliance

FMEA

U-Lock

Column 1 heading Column 2 heading Column 3 heading
Row 1, column 1 Row 1, column 2 Row 1, column 3
Row 2, column 1 Row 2, column 2 Row 2, column 3

Puck Lock

DFE

This product has very minimal GHC emissions already due to the lack of energy or material consumption during product use. The primary contributer during the manufacturing to this is the production of steel followed closely by the energy consumption during manufacturing. While these are hard to reduce, considering lower energy machining processes or considering replacing some or all of the steel within the product with recycled aluminum could likely further lower the GHC emissions associated with product production.

A $30 CO2 tax would only effect product price by approximately 58 cents, a fairly insignificant cost change and would therefore be unlikely to effect product sales.

The one downside to these estimates is that they are not the most accurate representation of a bike lock manufacturing. While bike locks are similar in composition to the primary industries represented by Hardware Manufacturing, they are not one of the main representations within the category, dominated by furniture, builders' and motor vehicle hardware. Locks are represented in the second and third of those categories, but not specifically bike locks.


Bike Lock Production
Best Match economic sector number 332500: Hardware Manufacturing
Reference Unit 1 unit
Units consumed per product life 1 unit
Cost per unit (2002 $) $30.89
Lifetime Cost $30.89
Economy-Wide mtCO2e Released per $1M of Output 640
Implied mtCO2 per Product Life $0.0197696
CO2 tax @ $30/mtCO2e $0.593088


Image:mtCO2eGraph.png

Group

Team Leader and FMEA Lead - Jeremy Jiang

Bill of Material - Ryan Chang

DFMA Leads - Rachel Chow and Alex Munoz

DFE Lead - Melissa Mann

Sources

Retrieved from "https://wiki.ece.cmu.edu/ddl/index.php/Bike_lock"
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