DFR Improve

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Georgia Institute of TechnologySystems Realization Laboratory

Recycling Guidelines




Design for Recycling Guidelines

• Most recycling guidelines are divided into three categories:

– Component design

– Material selection

– Fastener selection

• Most people agree that these issues, plus the choice of whichprocesses are employed for recycling, have the largest impact

on recyclability.• Mechanical and manual separation techniques can be

suggested for each of the above areas.

• Some also emphasize packaging.




Fundamental Lessons Learned

• As part of ongoing efforts in improving vehicle recyclability,a number of fundamental lessons have been learned from thedisassembly of vehicles and studies by the Vehicle RecyclingPartnership:

– The limiting factor in economic recycling of complex, integrated assemblies(such as instrument panels) is the separation into pure material streams.

– Both manual and mechanical separation have their advantages anddisadvantages.

– Significant value must be retained in a part for manual separation to beeconomically feasible.

– Different design techniques should be employed depending on whether onewants to facilitate manual separation or mechanical separation.

• These fundamental lessons should be kept in mind whengenerating design alternatives.




Process Selection Guidelines




Metric for Selecting Separation Technique

• How do you know which process to design for?

• The following flowchart provides a relatively simple metric fordesign decision support.

Hig h material remo val rate (MRR )?(ap prox. 10 lb s /min for plastics)

Manu al Sep arat ionTechn iqu es ap p lied

Rep eat fo r compo n en ts of assemb ly

Mid -v alu e b ut imp ro vab le MRR?(ap prox. 5 lbs/min fo r p las tics )

Mechanical Sep arationTechn iqu es ap p lied

No

Yes

No

Yes

can did ate desig n

Material Removal Rate = Material [kg] / time [min]From: Coulter, S. L., Bras, B. A., Winslow, G. and Yester, S., 1996, “Designing for Material Separation: Lessons from the AutomotiveRecycling,” 1996 ASME Design for Manufacturing Symposium, ASME Design Engineering Technical Conferences and Computers in

Engineering Conference, Irvine, California, August 18-22, ASME, Paper no. 96-DETC/DFM-1270.




Detached Weight for Cost Neutral Recyling (g/min)

• The amount of material (in grams) that has to be detached perminute if recycling is to be cost neutral for manual disassembly:

– Precious metals:

» gold 0.05

» palladium 0.14

» sliver 5.1

– Metals:

» copper 300

» aluminium 700

» iron 50,000

– Plastics:

» PEE 250» PC, PM 350

» ABS 800

» PS 1000

» PVC 4000

– Glass 6000

Based on West-European hourly rates and

material prices in Sept. 1995

(Philips Center for Manufacturing Technology)

Estimated total industrial labor rate: US$0.6/min




End-of-Life Destination Flowchart(from TNO Industry Delft, The Netherlands)

• General guidelines to determine end-of-life destinations

YES NO

r e s t f r a c t i o n s

Is productdisas sembly part of the policy?

Is the product (or partsof it) fit for mechanicalprocessing?

Which parts can beincinerated, dumped or treated as chemical waste?

Will the material cyclesbe closed?

Which parts can berecycled or reused?

Which parts will besuitable for high andlow quali ty recycling?

r e s t

f r a c t i o n s

YES

NO

Reuse High qualityrecycling

Low qualityrecycling

Incineration Landfill Chemicalwaste




Material Selection Guidelines




Recycling Two or More Materials(from GE Plastics)

Rule of Thumb:You want to take the

shortest path for

material recyclingNOTE: I deall y, you just want

to have ONE mater ial!




Material Compatibility

• Compatibility matrices (or tables) listwhether two materials are compatible,that is, they can be processed together.

• Most tables are for plastics, but somealso exist for metal alloys. Most use a

(rough) scale of 1-4 or 1-3.• Typically, the information regarding

compatibility (and especially detailedinformation) is buried in chemicalhandbooks.

Additive

M a t r i x m a t e r i a l

compatible

compatible with limitations

compatible only in small amounts

not compatible

Important plastics

The table shown here is translatedfrom VDI 2243.

I n case of doubt, see your mater ial expert.

Question:

Are regular and galvanized steel compatible?




Glass and Ceramics Compatibility

+ = good, 0 = moderate, - = poor/nil

The table shown here is from“Ecodesign: A PromisingApproach to SustainableProduction and Consumption”,UNEP/IE, United Nations.

bottle glass window glass drinkingglass

drinking glass(crystal)

TV (screen) TV (cone) TV (neck) LC D (screen) ceramics

bottle glass + - - - - - - - -

window glass + + + - - - - - -

drinking glass + 0 + - - - - - -

drinkingglass(crystal)

- - + - 0 0 - -

TV (screen) 0 0 - - + 0 - - -

TV (cone) - - - 0 - + + - -

TV (neck) - - - 0 - - + - -

LCD (screen) 0 0 - - 0 - - + -

ceramics - - - - - - - - -/0




Compatibility of Metals

• In general, metal parts are easily recycled, but the following

rules and guidelines apply: – Unplated metals are more recyclable than plated ones.

– Low alloy metals are more recyclable than high alloy ones.

– Most cast irons are easily recycled.

– Aluminum alloys, steel, and magnesium alloys are readily separated and recycled

from automotive shredder output. – Contamination of iron or steel with copper, tin, zinc, lead, or aluminum reduces

recyclability.

– Contamination of aluminum with iron, steel, chromium, zinc, lead, copper ormagnesium reduces recyclability.

– Contamination of zinc with iron, steel, lead, tin, or cadmium reduces recyclability.

Metal

(processe d by way

of s melting

process)

Knock-out

elements

(decreases value

of the f raction to

zero)

Penalty e lements

(seriously

decrease value o f

the fraction)

Copper (Cu) Hg, Be, PCB

(polychlorobezene)

As, Sb, Ni, Bi, Al

Aluminum (Al) Cu, Fe, polymers Si

Iron (Fe) Cu Sn, Zn

The table shown here is from“Ecodesign: A PromisingApproach to SustainableProduction and Consumption”,UNEP/IE, United Nations.




A Well Known Laminate Example

Look around and you will see a lot of room for improvement.

From:

“Green Products by Design –

Choices for a Cleaner

Environment”, Office of

Technology Assessment, US

Congress, Oct. 1992.




Material Selection

• “At the onset of a new program, the Design Office, PlatformEngineering, Purchasing and Supply, and the component suppliershould discuss recycling issues associated with a concept anddetermine the „best fit‟ materials and processes for specificapplications.”

• “Suppliers should be encouraged to demonstrate recyclability andto take materials back for recycling at the end of the vehicle‟suseful life to be recycled in automotive and other applications.”

• “The use of materials which have been recycled, including fromold vehicles, is desirable where it is economically viable.”

(from Chrysler Vehicle Recycling Design Guidelines)




Diversity of Plastics

• There is an incredible variety of plastics in modern vehicles.

• However, the top 7 used plastics are (in N-America)

– Urethane; 1990 - 454 mill. lbs, 1995 - ± 493 mill. lbs.

– Polypropylene (PP); 1990 - 437 mill. lbs, 1995 - ± 522 mill. lbs.

– Acrylonitrile/Butadiene/Styrene (ABS); 1990 - 281 mill, 1995 - ± 289 mill. lbs.

– Polyvinylchloride (PVC); 1990 - 264 mill. lbs, 1995 - ± 288 mill. lbs.

– Nylon; 1990 - 208 mill. lbs, 1995 - ± 246 mill. lbs.

– Polyethylene (PE); 1990 - 191 mill. lbs, 1995 - ± 248 mill. lbs.

– Polyester composite (SMC); 1990 - 173 mill. lbs, 1995 - ± 261 mill. lbs.

• Thus, if you have to choose a plastic, try picking one which iswidely used.

• Minimizing material diversity is beneficial for acquisition,storage, manufacturing, recycling, etc.




Main Material Concerns

• Meet environment, health, and occupational safety requirementsfor regulated or restricted substances or processes of concern.

– Do not, or limit, the use of materials which pose human or environmental risk.

• Mark materials according to standards.

• Generate minimal home and pre-consumer scrap duringmanufacturing.

• Make components of different recyclable materials easilyseparable, or use materials which can be recycled as a mixture.

• Standardize material types.

• Reduce painting.




Cathode Ray Tubes - Problem

• Cathode ray tubes (CRTs) pose a major difficulty forrecycling.

• The phosphor-based coating used to provide the necessaryluminescence contains heavy metals and other toxins, while

the glass itself is loaded with lead and barium.

• Recycling a specific design of CRT with known constituentsis relatively straightforward, but finding a process that willhandle very large quantities of CRTs of varying age andspecification is not so easy.




Marking of Plastics

• SAE J1344 – April 1993 contains the standards on markingof plastic parts.

• Based on standard symbols as published by ISO 1043.

• Allows for expansion and inclusion of new symbols for newmaterial. (complete appropriate forms).

• See SAE J1344 for examples and specifics.

•European legislation wil l requir e the marking of all plastic parts with a weight greater than 100 grams.




Positions and Life of Markings

• No position of marking is prescribed, but: – Field service people should be informed regarding the material.

– If practicable, marking should be located where it may be observed while it isin use. May consider multiple markings.

– Marking on the outside is preferred for field service people.

• Also, markings should last: – Markings applied with inks, dyes, paints should not bleed, run, smudge, or

stain materials in contact with the marking.

– Markings should be designed to remain legible during the entire life of thepart.

– Markings which are molded into the part are preferred since they are

permanent and do not require additional manufacturing operations. BUT,molded parts should not create a stress concentration.




Material Selection – Summarizing

General:

• Avoid regulated and/or restricted materials

– These often MUST be recycled, whatever the monetary cost of removal is.

• Use recyclable materials

– Both technically as well as economically

• Use recycled materials, where possible – This increases recycled content

• Standardize material types

– May involve corporate decision

• Reduce number of material types

– Can be done at engineering level

• Use compatible materials, if different materials are needed.

– Single material is preferred, however.

• Eliminate incompatible laminated/non-separable materials.

– These are a major hassle.




Material Selection (cont.)

Manual Separation:

• Avoid painting parts with incompatible paint

– Especially plastics can be contaminated by paint.

• Eliminate incompatible laminated/non-separable materials

Mechanical Separation:

• Reduce number of materials as much as possible

– Probably two materials can be economically recovered

• Choose materials with different properties (e.g., magnetic vs

non-magnetic; heavy vs light), thus enabling easy separation.

• Allow for density separation

– Maintain at least 0.03 specific gravity difference between polymers

– Isolate polymers with largest mass by density

• Eliminate incompatible laminated/non-separable materials




Component Design Guidelines




Component Design

• Apply Design for Manufacturing and Assembly (DFMA)and Serviceability Guidelines as appropriate in componentdesign.

– Facilitate ease of assembly removal and material separation.

– (There is a close correspondence between DFA, DFD, and Design for

Service)

• Route wiring to facilitate removal.

Pins are easy to tap outDifficult toremove

Pressedalignment

pins

Pressed boltsand studs

Complete holesPay attenti on to detail and

reduce the amount of

frustration and special

equipment.

Label dangerous operations.




Minimize Part and Material Count

• To facilitate separation and collection:

– Minimize the number of components within anassembly.

– Minimize material types within an assembly.

– Build in planes of easy separation where this doesnot affect part function.

» Look under a hood for good and bad examples.

– (By the way, think also about modular i ty)

Question: What other (non-DFR) reasons exist for minimizing part and mater ial count?




Classical Component Integration Example

• Springs and their support systems are always classicalexamples of component integration.

• Note the reduction in part and material count.

a) b)

a) Traditional design of springs in a doorlock:different materials, e.g., steel, aluminum

b) Injection molded spring sys tem made from POM(single material product)




Laminates and Paints

• Avoid laminates which require separation prior to reuse.

– Even though unique separation techniques exists, it increases the cost of therecyclable material.

– When laminates are used, design them from compatible materials and adhesives.

Examples :

– Dashboard cover:

» Old design: PVC top foil, PUR foam core, steel support plate

» New design: PP top foil, PP foam core, support layer of PP

– Bumper:

» Old design: PC skin, PUR foam core, steel support

» New design: Integral foam of PC, PP, support frame of PC, PP

• Avoid painting parts wherever possible.




Problems with Paints

• In general, paints contaminate plastics to be recycled. – Compatible paints exists, but the majority is non-compatible.

– One percent (!) of contamination can be enough to ruin a plastic batch forrecycling.

• Many painting processes are subject to regulations. – For example, in case a city-wide smog alarm goes off, certain paintingprocesses (or other processes with volatile compounds) need to be stopped.

• Stripping paint is also a very nasty process.

– Environmentally benign stripping processes exists, but the paint chips still

have to be disposed off.




Component Design - Summarizing

General:

• Integrate parts

– Reduce disassembly time

• Minimize scrap during production

Mechanical separation:

• Avoid using incompatible materials

– E.g., stiffen sections rather than adding foam for noise-vibration-heat areas

Manual:

• Use Design for Manufacturability/Assembly and

Serviceability guidelines• Reduce number of steps to remove a recyclable part

• Reduce chance of contamination

• Route wiring to facilitate removal

– Separate at bulkheads/interface areas




Fasteners –

Guidelines




What about fasteners ?

• In VDI 2243, an example is given on the remanufacture of a four cylinderinternal combustion engine.

• About 32.5% of all activities in the disassembly process consist of theloosening of screws. These activities consume 54% of the entiredisassembly process time.

• According to VDI 2243, this is a typical example.

• The separation of staple, glue, press joints or joints made by deformationnot only require more specialized equipment, but also embody a higher

risk of damaging the component, if it is to be reused.

• Additional problems occur when contaminations such as oil, dirt andcorrosion are present.




Assembly and Disassembly

• Adhere to Design for Assembly guidelines – Good designs take ease of assembly as well as service and recycling into

account.

• Facilitate disassembly (Design for Disassembly)

– Select fasteners which facilitate disassembly by any method includingdestruction (by shredding) after a vehicle‟s useful life.




Reduce and Commonize Fasteners

• Reduce the number and types of fasteners used.

• Select fasteners that do not require post-dismantling materialseparation for recycling.

– When practical, use fasteners of the same (or compatible) material as theattaching part.

– If this is not possible for plastic fasteners, use ferrous fasteners or inserts to allowfor magnetic separation after shredding.

• Commonize fasteners

– Try to design with minimum screw head types and sizes. (remember theVolkswagen Bug‟s 13 mm wrench standardization)

• DO NOT JEOPARDIZE STRUCTURAL INTEGRITY OR FUNCTION !!




Select Proper Coatings

• Corroded fasteners cause severe problems for fast removal of parts

• Select coatings which minimize corrosion.

– This may drive up the cost.

– Phospate & oil coatings have low corrosion resistance

– Better (but more costly) coatings may be warranted for recyclability (andservicability).

• Cadmium coatings should not be used because of potential

health and environmental hazard.




Snap fits

• Use snap fits wherever possible to reduce the use of additional fasteners.

• Molded clips should be removable without breaking off.

IMPORTANT:

• Do not jeopardize product integrity.

• Also, consider long term effects (hardening of plastic,fatigue failure, frustration of broken snaps).




Adhesives

• Joining or bonding materials of the same type withcompatible adhesives enhances recycling.

• But, non-compatible adhesives may cause contaminants toenter the material waste stream.

• Therefore, adhesive selection and the effect on partrecyclability should be discussed with Materials Engineeringas part of the development process at the onset of a program.




VDI 2243’s Fastener Selection Table

• This table gives an overview of a German rating of fasteners.

• It will give you an idea of how different fasteners compare against each other.

• Caution: By no means is thi s a defini te table!

characteristics

of connection

principle

of connection

Static St rength

Fatigue

Strength

Joining

Expenditure

Guidance

Expenditure

Detaching

Expenditure

Destructive

Detaching

Expenditure

Product

Recycling

Material

Recycling

C a r r y i n g

C a p a c i t y

J o i n i n g

B e h a v i o u r

D e t a c h i n g

B e h a v i o u r

R e

c y c l a b i l i t y

good average bad

plastic/metal

adhesive

bonding weldingmagnetic

connection

Velcro

fastener

bolt/

nut

plastic

bolt/

nut

spring

connection

snap

joint

bent-lever

connection

1/4-turn

fastener press-turn

fastener

press-press

fastener band with

lock

Material Connection Frict ional Connection Positive Connection




Fastener Selection – Summarizing

Clear distinction between manual vs mechanical separation guidelines

Manual Separation: • Reduce number of fasteners

• Commonize fastener types

• Use fasteners made of compatible materials

• Consider snap-fits (two-way, if necessary)• Consider destructive fastener removal

– Possible inclusion of break points in material




Fastener Selection: Mechanical Separation

IMPORTANT: Fasteners wil l not be unfastened! – Disassembly time is irrelevant!

Material properties are (again) key issue

In order of preference, use

1) Molded-in fasteners (same material)

2) Separate fasteners of same or compatible material

3) Ferrous metal fasteners (easy to remove due to magneticproperties)

4) Non-ferrous metal fasteners (can be removed using, e.g.,Eddy-current)




Trade-offs

• Design for Recycling can negatively affect performance andcost issues.

– For example, required material substitution is not always possible or will costmore.

• However, in most cases, the trade-offs can be resolved andoften converted in win-win situations.

• Often cited and studied and questioned are the trade-offsbetween design for disassembly and design for assembly.

• Take a look at the DFA guidelines and compare them not justwith DFD, but also with DFR in general.

– Remember, a shredder does not care much about geometry and fasteners…




Product Design for Assembly Guidelines

Product Design for Assembly

1) Overall Component count should be minimized.

2) Minimum use of fasteners.

3) Design the product with a base for locating other components.

4) Do not require the base to be repositioned during assembly.

5) Design components to mate through straight-line assembly, all from thesame direction.

6) Maximize component accessibility.

7) Make the assembly sequence efficient.

- Assembly with the fewest steps.

- Avoids risks of damaging components.

- Avoids awkward and unstable component, equipment, and personnelpositions.

- Avoid creating many disconnected subassemblies to be joined later.




Component Design for Assembly Guidelines

Component Design for Assembly

8) Avoid component characteristics that complicate retrieval

(Tangling, nesting, and flexibility)

9) Design components for a specific type of retrieval, handling, and

insertion.

10) Design components for end-to-end symmetry when possible.

11) Design components for symmetry about their axes of insertion.

12) Design components that are not symmetric about their axes of insertion to be clearly asymmetric.

13) Make use of chamfers, leads, and compliance to facilitate insertion.




DFR – Special Issues




Limiting Factors

• Identify the limiting factors and address these first!

• Look at a combination of the following component aspects: – Weight – If recyclability and recycled content are defined by weight, it makes

sense to look at the heaviest components first. Improving a 10 pound component‟srecyclability rating from 4 to 3 has a larger impact on the overall systemrecyclability than improving a 1 pound component.

– Distance from target ratings – Components with recyclability ratings of 4 and

lower should be improved. Pay special attention to components with arecyclability rating of 4 because they can often relatively easily be changed toobtain a (good) rating of 3. The same applies for material separation ratings, i.e.,first focus on those components with a separability rating of 4.

– Risk – Those components with a high risk are also prime candidates forimprovement.

– Violation of Design for Recycling guidelines – A component which clearly violatessome of the Design for Recycling guidelines may also be a limiting factor and aprime candidate for improvement. Pay special attention to WHY one or moreguidelines have been violated; it may have been done intentionally to, say,increase functionality or manufacturability.

• Often, upon careful inspection, the material or combination of materials is the limiting factor in most parts.




Risk Assessments

• Some basic simple risk assessments with respect to achieving

targets can be doneRisk Low Medium HighRecyclabilit y % Recyclability

identified and

meets initial

t argets. Planned

changes will not

degrade it .

% Recyclability

does not meet

initial target s, but

plan ned changes

provide

improvements.

1) % Recyclability

does n ot meet

initial target s

and/or p lanned

changes do not

provide

improvement s.2) % Recyclability

meets initial

t argets, but

plan ned changes

degrade it below

target level.

Recycled Co ntent Recycled co nt ent

identified and

meets initial

t argets. Plannedchanges will not

degrade it .

Recycled cont ent

does not meet


plan ned changes provide

improvements.

1) % Recycled

content does not

meet initial targets

and/or p lannedchanges do not

provide

improvement s.

2) % Recycled

content meets


plan ned changes

degrade it below

target level.




Management Issue: Recyclability Target Setting

• Goal of designer: Improve vehicle recyclability – 85% (by weight) required recyclability in 15 years

• Current recyclability (first revision) 75%

• Four (yearly) revisions of vehicle expected

• Data available on: – expected production for each year

– estimated reliability of vehicles

• Aim: Aid designer in setting appropriate targets for the

recyclability of each revision of the vehicle




Target Setting: Parameters

• Production Uncertainty: Normal, = 5,000

• Recyclability: Triangular, ± 3%

• Reliability, Weibull distribution

• Monte Carlo simulation used to explore effects of a given set

of targets

Iteration Mean EstimatedProduction

Mean EstimatedRecyclability

EstimatedReliability

1 100,000 75% =7, =11

2 95,000 TBD =7, =113 95,000 TBD =7, =11

4 90,000 TBD =7, =11

5 90,000 TBD =7, =11




Target Setting: Constant Improvement

Iteration 1 2 3 4 5Recyclability Target 75% 78% 81% 84% 87%

Recyclability of Vehicles Retired in a Given Year

Certainties Centered on Medians

0.700

0.750

0.800

0.850

0.900

90%

5%

Trend Chart




Target Setting: Achieving 85% Recyclability

Iteration 1 2 3 4 5Recyclability Target 75% 80% 84% 87% 89%

Recyclability of Vehicles Retired in a Given Year

Certainties Centered on Medians

0.700

0.750

0.800

0.850

0.900

90%

5%

Trend Chart




Inclusion of Uncertainty

• How will changes in technology and legislation affect thetarget definition and prioritization of limiting factors?

legislative limit

product’smeanenvironmentalimpact

Environmental Impact

Initial Product

Range of Expected Regulatory Limits atIteration 5 (one-sided distribution)

Iteration 2

Iteration 3

Iteration 4Iteration 5

Reduction of mean environmental i mpact and variance over several iterati ons

Y

Xcompliance high

legislative mean




Computer-Based Tools




Computer-Aided Design for the Life Cycle System Architecture

ProductModeling

Synthesis & SelectionCAD

Ev aluation Modules

ProblemFormulation

AssemblyModeling

Manufacturing

Recycling

Disassembly

Robustness

Imp rovement

Models

Parametric Assemb lyModel

Geo metry Life-CycleInformatio n

Database of P roductRepresentations

Service

Compa risonModels

Graph ics

Parametrics

Geo metry

Features

Materials D B

Facilities D B

Features,Components, &

Mati ng RelationshipsDB Process DB

Designer

Design System

ProcessModeling

Process Synthesis &Selection

Ev aluation Modules

Simulatio n

Imp rovemen tModels

Compa risonModels




Automotive Center Console

• Given are the geometric(solid) and assemblymodels of a center consoledesign generated using amodern CAD package.

Rightbase

Leftbase

Endcap

BinFront bracket

Bezel Ashtray Latch Armrest

Hinge

Coverplate

Assembly ModelCenter Console

Base Armrest Ashtray &

Lighter

Cupholder

Bin

Leftbase

Rightbase

Bezel

Endcap

Solid Model




Virtual Disassembly

• Disassembly in a Virtual

Reality environmentfacilitates design forrecycling as well as designfor serviceability.

– Other assessments are also beingadded (e.g., demanufacture

process cost assessments)

• The key is to use theexisting product modelsand add functionality inexisting and (for a

designer) familiarsoftware systems.

NSF grants:

– Virtual Design Studio for Servicing and Demanufacture (Rosen, Bras, Mistree, Goel, Baker) – DMI9420405

– CAD for De- and Remanufacturing (Bras and Rosen) – DMI9414715

– Enhancing Reusability by Design (Bras) – DMI9410005

– Integrated Product and De- and Remanufacture Process Design (Bras) – DMI9624787




Kodak Funsaver Virtual Disassmbly

Hand int erface

Camera

components

• Virtual disassemblyallows tracking of basic disassembly pathbased on user/designerexperience.

• This path can be fine-tuned using othertools.



Georgia Institute of Technology

IGRIP Robotic Disassembly Simulation

Disassemblycycle times arecalculated.

Disassembly paths are

simulated and tested.

Different robots can be simulated and programmed

Detailed information about the kinematic and dynamic behavior of the robot can be obtained

Documents

DFR Improve