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Recycling Guidelines. Design for Recycling Guidelines. Most recycling guidelines are divided into three categories: Component design Material selection Fastener selection

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design for 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 which processes 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
Fundamental Lessons Learned
  • As part of ongoing efforts in improving vehicle recyclability, a number of fundamental lessons have been learned from the disassembly of vehicles and studies by the Vehicle Recycling Partnership:
    • 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 and disadvantages.
    • Significant value must be retained in a part for manual separation to be economically feasible.
    • Different design techniques should be employed depending on whether one wants to facilitate manual separation or mechanical separation.
  • These fundamental lessons should be kept in mind when generating design alternatives.
metric for selecting separation technique
Metric for Selecting Separation Technique
  • How do you know which process to design for?
  • The following flowchart provides a relatively simple metric for design decision support.

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 Automotive Recycling,” 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
Detached Weight for Cost Neutral Recyling (g/min)
  • The amount of material (in grams) that has to be detached per minute 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
End-of-Life Destination Flowchart (from TNO Industry Delft, The Netherlands)
  • General guidelines to determine end-of-life destinations
recycling two or more materials from ge plastics
Recycling Two or More Materials(from GE Plastics)

Rule of Thumb:

You want to take the shortest path for material recycling

NOTE: Ideally, you just want to have ONE material!

material compatibility
Material Compatibility
  • Compatibility matrices (or tables) list whether two materials are compatible, that is, they can be processed together.
  • Most tables are for plastics, but some also exist for metal alloys. Most use a (rough) scale of 1-4 or 1-3.
  • Typically, the information regarding compatibility (and especially detailed information) is buried in chemical handbooks.

In case of doubt, see your material expert.

Question:

Are regular and galvanized steel compatible?

The table shown here is translated from VDI 2243.

glass and ceramics compatibility
Glass and Ceramics Compatibility

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

The table shown here is from “Ecodesign: A Promising Approach to Sustainable Production and Consumption”, UNEP/IE, United Nations.

compatibility of metals
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 or magnesium reduces recyclability.
    • Contamination of zinc with iron, steel, lead, tin, or cadmium reduces recyclability.

The table shown here is from “Ecodesign: A Promising Approach to Sustainable Production and Consumption”, UNEP/IE, United Nations.

a well known laminate example
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
Material Selection
  • “At the onset of a new program, the Design Office, Platform Engineering, Purchasing and Supply, and the component supplier should discuss recycling issues associated with a concept and determine the ‘best fit’ materials and processes for specific applications.”
  • “Suppliers should be encouraged to demonstrate recyclability and to take materials back for recycling at the end of the vehicle’s useful life to be recycled in automotive and other applications.”
  • “The use of materials which have been recycled, including from old vehicles, is desirable where it is economically viable.”

(from Chrysler Vehicle Recycling Design Guidelines)

diversity of plastics
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 is widely used.
  • Minimizing material diversity is beneficial for acquisition, storage, manufacturing, recycling, etc.
main material concerns
Main Material Concerns
  • Meet environment, health, and occupational safety requirements for 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 during manufacturing.
  • Make components of different recyclable materials easily separable, or use materials which can be recycled as a mixture.
  • Standardize material types.
  • Reduce painting.
cathode ray tubes problem
Cathode Ray Tubes - Problem
  • Cathode ray tubes (CRTs) pose a major difficulty for recycling.
  • The phosphor-based coating used to provide the necessary luminescence contains heavy metals and other toxins, while the glass itself is loaded with lead and barium.
  • Recycling a specific design of CRT with known constituents is relatively straightforward, but finding a process that will handle very large quantities of CRTs of varying age and specification is not so easy.
marking of plastics
Marking of Plastics
  • SAE J1344 – April 1993 contains the standards on marking of plastic parts.
  • Based on standard symbols as published by ISO 1043.
  • Allows for expansion and inclusion of new symbols for new material. (complete appropriate forms).
  • See SAE J1344 for examples and specifics.
  • European legislation will require the marking of all plastic parts with a weight greater than 100 grams.
positions and life of markings
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 is in 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 the part.
    • 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
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
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
Component Design
  • Apply Design for Manufacturing and Assembly (DFMA) and Serviceability Guidelines as appropriate in component design.
    • 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.

Pay attention to detail and reduce the amount of frustration and special equipment.

Label dangerous operations.

minimize part and material count
Minimize Part and Material Count
  • To facilitate separation and collection:
    • Minimize the number of components within an assembly.
    • Minimize material types within an assembly.
    • Build in planes of easy separation where this does not affect part function.
      • Look under a hood for good and bad examples.
    • (By the way, think also about modularity)

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

classical component integration example
Classical Component Integration Example
  • Springs and their support systems are always classical examples of component integration.
  • Note the reduction in part and material count.
laminates and paints
Laminates and Paints
  • Avoid laminates which require separation prior to reuse.
    • Even though unique separation techniques exists, it increases the cost of the recyclable 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
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 for recycling.
  • Many painting processes are subject to regulations.
    • For example, in case a city-wide smog alarm goes off, certain painting processes (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
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
what about fasteners
What about fasteners ?
  • In VDI 2243, an example is given on the remanufacture of a four cylinder internal combustion engine.
  • About 32.5% of all activities in the disassembly process consist of the loosening of screws. These activities consume 54% of the entire disassembly process time.
  • According to VDI 2243, this is a typical example.
  • The separation of staple, glue, press joints or joints made by deformation not 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 and corrosion are present.
assembly and disassembly
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 including destruction (by shredding) after a vehicle’s useful life.
reduce and commonize fasteners
Reduce and Commonize Fasteners
  • Reduce the number and types of fasteners used.
  • Select fasteners that do not require post-dismantling material separation for recycling.
    • When practical, use fasteners of the same (or compatible) material as the attaching part.
    • If this is not possible for plastic fasteners, use ferrous fasteners or inserts to allow for magnetic separation after shredding.
  • Commonize fasteners
    • Try to design with minimum screw head types and sizes. (remember the Volkswagen Bug’s 13 mm wrench standardization)
  • DO NOT JEOPARDIZE STRUCTURAL INTEGRITY OR FUNCTION !!
select proper coatings
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 (and servicability).
  • Cadmium coatings should not be used because of potential health and environmental hazard.
snap fits
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
Adhesives
  • Joining or bonding materials of the same type with compatible adhesives enhances recycling.
  • But, non-compatible adhesives may cause contaminants to enter the material waste stream.
  • Therefore, adhesive selection and the effect on part recyclability should be discussed with Materials Engineering as part of the development process at the onset of a program.
vdi 2243 s fastener selection table
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 this a definite table!
fastener selection summarizing
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
Fastener Selection: Mechanical Separation

IMPORTANT: Fasteners will 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 magnetic properties)

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

trade offs
Trade-offs
  • Design for Recycling can negatively affect performance and cost issues.
    • For example, required material substitution is not always possible or will cost more.
  • However, in most cases, the trade-offs can be resolved and often converted in win-win situations.
  • Often cited and studied and questioned are the trade-offs between design for disassembly and design for assembly.
  • Take a look at the DFA guidelines and compare them not just with 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 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 the same 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 personnel positions.

- Avoid creating many disconnected subassemblies to be joined later.

component design for assembly guidelines
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.

limiting factors
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’s recyclability rating from 4 to 3 has a larger impact on the overall system recyclability 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 a recyclability rating of 4 because they can often relatively easily be changed to obtain 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 for improvement.
    • Violation of Design for Recycling guidelines – A component which clearly violates some of the Design for Recycling guidelines may also be a limiting factor and a prime candidate for improvement. Pay special attention to WHY one or more guidelines 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
Risk Assessments
  • Some basic simple risk assessments with respect to achieving targets can be done
management issue recyclability target setting
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
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
inclusion of uncertainty
Inclusion of Uncertainty
  • How will changes in technology and legislation affect the target definition and prioritization of limiting factors?
automotive center console

Center Console

Cupholder

Base

Armrest

Ashtray &

Lighter

Bin

Bezel

Leftbase

Rightbase

Endcap

Automotive Center Console
  • Given are the geometric (solid) and assembly models of a center console design generated using a modern CAD package.

Assembly Model

Solid Model

virtual disassembly
Virtual Disassembly
  • Disassembly in a Virtual Reality environment facilitates design for recycling as well as design for serviceability.
    • Other assessments are also being added (e.g., demanufacture process cost assessments)
  • The key is to use the existing product models and add functionality in existing and (for a designer) familiar software 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
Kodak Funsaver Virtual Disassmbly
  • Virtual disassembly allows tracking of basic disassembly path based on user/designer experience.
  • This path can be fine-tuned using other tools.