broad considerations for sustainable engineering - richard wysk, north carolina state university

Some broad considerations for i bl i isustainable engineering

Richard A. Wysk

Dopaco Distinguished Professor

Industrial and Systems Engineering

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North Carolina State University 

AgendaAgenda• Sustainability   ‐‐ a brief overview• Sustainability from an engineering perspective• Sustainability from an engineering perspective

– This could be the world’s most difficult engineering problemg g p

• What’s new in the manufacturing world?– Direct manufacturing (DM) and hybridDirect manufacturing (DM) and hybrid manufacturing (HM)

• New directions in DM, HM and sustainabilityy• Observations and conclusions

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Why Engineer for Sustainability?Why Engineer for Sustainability?

• Should be considered as part of a concurrent pengineering team effort.

• 80% of the environmental damage of a product is bl h d f f h destablished after 20% of the design activity is 

complete.• Business case analysis• Business case analysis

– Customers demand products with less environmental impact,

• Governmental agencies are developing and enforcing tighter regulations.

Pay me now or pay me laterPay me now or pay me later

A Vision of Sustainable Engineering Systems 

Environmental ObjectivesEnvironmental Objectives

• Protect the biosphere• Protect the biosphere– Minimize the release of pollutants that endanger the earth.

• Sustainable use of resources– Use raw materials at a level where they can be sustained.

• Reduction and disposal of waste– Minimize waste wherever possible. When waste cannot be avoided, recycling will be adopted.

Environmental ObjectivesEnvironmental Objectives

• Wise use of energy• Wise use of energy– Use environmentally safe energy and invest in energy conservationenergy conservation.

• Risk reduction– Minimize health risk to employees and the– Minimize health risk to employees and the community.

• Marketing of safe products and servicesMarketing of safe products and services– Sell products that minimize environmental impact and are safe for consumers to use.

Life Cycle AssessmentLife Cycle Assessment

• Common methodologyCommon methodology– Society of Toxicology and Chemistry (SETAC) has developed a 4‐step process for completing a Lifedeveloped a 4 step process for completing a Life Cycle Assessment (LCA).

• Cradle to grave assessment.

• Dependent on large amounts of data.

• Steps: Goal Definition, Environmental Impact Inventory, Impact Assessment, Interpretation.

What Is Life‐Cycle Assessment (LCA)? LCA i l ti l f k d t i id tif dLCA is a analytical framework used to examine, identify, and evaluate the energy, resource, and environmental implicationsof a process, product, or system across its life span from cradle to grave.cradle to grave.

RawMaterial Acquisition and Processing

Linear View of Products

Raw Material Acquisition and Processing

Manufacturingg

Use

Disposal

Source: EPA (2006) – LCA: Principles and Practice Courtesy of Ranji Ranjithan

Inventory AnalysisScope InventoryInventory

Product Life Stages

Raw Material Acquisition and ProcessingPrimary Materials

AirborneEmissions

ManufacturingSecondary M i l

Waterborne E i i

Use

Recycling

Reuse

Materials Emissions

End of Life ManagementEnergy  Other 

Releases

Use a SCOR Model to determine how this works in a PLAN,SOURCE, MAKE, DELIVER, and RETURN environmentCourtesy of Ranji Ranjithan

Techniques to Reduce Environmental Impactq pDesign to minimize material usage

• Material usage– Packaging and distribution

• Programs to accept back packaging (computers)

– Production system( )• Ex.: plastic body panels (Chrysler) that require no paint

– Product• Minimize “high impact” materialsMinimize  high impact  materials

• Increase use of materials that can be processed together

• Can different polymers be remelted together (e.g. compatibility)? 

Techniques to Reduce Environmental ImpactTechniques to Reduce Environmental Impact          Design for Disassembly

• Guidelines similar to DFA.• Some key differences:• Some key differences:

– Snap‐fit design (integral fasteners) must work during removal as well as insertion should a partduring removal as well as insertion should a part be needed for remanufacturing.

– For recycling only “tearing apart” is of interest.– Must consider ergonomics and time. Disassembly time may be very different than assembly time.

Techniques to Reduce Environmental ImpactTechniques to Reduce Environmental Impact          Design to Recycling

• Primarily material choice.• Typical materials recycled in US

Recycling Rate (%)

1993 2006

– High density polyethylene (HDPE) 10.6   26 – Polyethylene terephthalate (PET) 18.0   24– Low‐density polyethylene (LDPE) 1.9    1– Polypropylene (PP) 1.5    9– Polyvinyl chloride (PVC) 0.8     1

Techniques to Reduce Environmental ImpactTechniques to Reduce Environmental Impact          Design to Recycling

• Other recycling:Gl ( l h t d d t lt)– Glass (can lower heat needed to melt)

– Metal chips

( k ld’ !)– Paper (ask McDonald’s!)

• New technologies– Chips or identifiers to automatically recycle (auto industry)

Styrofoam – A problem?!?Styrofoam  A problem?!?

Short‐term answersShort term answers

• Compacting reduces volumeCompacting reduces volume

• Doesn’t really eliminate the problemproblem

Techniques to Reduce Environmental Impact            N T h l iNew Technologies

Polystyrene FoamPolystyrene Foam Recycling System Employing Limonene SonySony

Techniques to Reduce Environmental ImpactTechniques to Reduce Environmental Impact          Design to minimize hazardous materials

• Functionally equivalent materials can have a large impact on the environment.a large impact on the environment.– Ex.: switch from using polystyrene to less‐impacting plastics such as high density polyethylene (recycled at much higher rate)

• No impact on design performance.

Ch i l t id• Chemicals to avoid• Material impact comparisons

– Must also consider cost differences.

Techniques to Reduce Environmental Impact            Design for energy efficiency

• Reduce energy consumption of product– Specify best‐in‐class energy efficient components (air 

conditioners, refrigerators)– Have subsystems power down when not in use (copiers)– Permit users to turn off systems in part or whole– Permit users to turn off systems in part or whole– Solar‐powered electronics (calculators)– Vibration harvesting– Insulate heated systemsy– Make parts whose movement is powered as light as possible 

(autos, planes)• New materials and processes give many new opportunities• Must be qualified and accepted; designers must understand how to• Must be qualified and accepted; designers must understand how to design with them (“design rules”); may limit suppliers

• Buy to fly (Can be 200:1)• 100 pounds can mean 2% in MPG

Supportability Considers Total System “ f h ”“Cost of Ownership”

Mike Battaglia; https://c3.nasa.gov/dashlink/static/media/other/Design4Supportability.pdf

Okay, so this has been going on for a d d h ’decade or more.  What’s next?

• Changes in reclamation• More efficient methods

• Changes in manufacturing• New paradigms 

• Changes in designChanges in design• Unconventional geometries

• Changes in materials• Composites (higher strength to weight ratio)• Composites (higher strength to weight ratio)• Up to 2% gas reduction per 100 pounds

• Materials usage efficiency• 200:1 buy to fly ratio

Something very newSomething very new

A New Prosthetic ArmA New Prosthetic Arm

• Titanium for efficiency/medical compatibility

• Mesh structure• Weighs about 4 poundspounds

• Can change the life of a limb amputeep

Impossible to build without additive h dmethods

Functional using mechanical switchingFunctional using mechanical switching

Medical/Dental/V i A li iVeterinary Applications

March 24 2006 (Chicago) -- The number ofMarch 24, 2006 (Chicago) The number of total knee replacements performed in the U.S. will leap by 673% -- reaching 3.48

illi b th 2030 di tmillion -- by the year 2030, according to a new study presented at the 73rd annual meeting of the American Academy of Orthopaedic Surgery in Chicago.

Hip replacements will increase by 174% toHip replacements will increase by 174% to 572,000 by 2030, according to the new findings, which are based on historical

d t f 1990 t 2003 dprocedure rates from 1990 to 2003, and on population projections from the U.S. Census Bureau.

Direct ManufacturingDirect Manufacturing

• Producing a product directlyProducing a product directly from a descriptive model.– In the mechanical part domain– In the mechanical part domain, taking a CAD model and directly manufacturing a partg p

Additive Manufacturing• Direct Manufacturing (DM)

– Direct from CAD model without toolingDirect from CAD model without tooling

• No process engineering

– Short lead time

I d d t fid lit– Increased product fidelity

– Ready to use end products

• Additive processes Painted SLA Consumer Goods PartAdditive processes– Traditional Rapid prototyping (RP) process

• 3D printer, SLA, FDM, SLS, SLM, EBM…

– No geometry limitation

– Push button manner operation

– Restricted in material, accuracy, and surface finish, y,

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Electron Beam Melting (EBM)Electron Beam Melting (EBM)

• Electron BeamMelting (EBM) is a type of rapidElectron Beam Melting (EBM) is a type of rapid prototyping for metal parts. The technology manufactures parts by melting metal powder layer per layer with an electron beam in a high vacuum. Unlike some metal sintering techniques, the parts are fully solid, void‐free, and extremely strong. Electron Beam Melting is also referred to as Electron Beam Machining.

• High speed electrons .5‐.8 times the speed of light b b d d th f f th k t i lare bombarded on the surface of the work material 

generating enough heat to melt the surface of the part and cause the material to locally vaporize. EBM does require a vacuum, meaning that the workpiece is limited in size to the vacuum used.workpiece is limited in size to the vacuum used. The surface finish on the part is much better than that of other manufacturing processes. EBM can be used on metals, non‐metals, ceramics, and composites.

Current directions in ManufacturingCurrent directions in Manufacturing – Additive Manufacturing

Selective Laser

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Electron Beam Melting (EBM)

Selective Laser Melting Processes (SLM)

Some other EBM partsSome other EBM parts

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EBM and Selective Laser Melting (SLM)EBM and Selective Laser Melting (SLM) 

• Produces parts to about casting quality directly from a CAD model

• Does not have the geometric limitations of castinglimitations of casting– Draft, parting line, etc.

• Materials properties are• Materials properties are getting close to cast quality

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State of the Art for AMState of the Art for AM

• Push bottom process – no process engineeringPush bottom process  no process engineering component

• Functional metals are now being produced• Functional metals are now being produced

• Net‐shape or near net‐shape parts can be d dproduced

• Geometrically few limits, except for precision

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Recent directions in Rapid 

CNC RP Method: A model is machined on a 3 Axis mill with an

Manufacturing ‐‐ SubtractiveCNC‐RP Method:  A model is machined on a 3‐Axis mill with an indexer and tailstock using layer‐based toolpaths from numerous orientations about an axis of rotation.  

Round stock, fixed b t h k

Small diameter flat‐end mill tool

between chucks

4th‐axis indexer

TailstockTailstock

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CNC‐RP MethodologyCNC RP MethodologySTEPS TO CREATE A PART ( MT. Bike Suspension Component)

(Side View) (Side View) (Side View)

1. First orientation of part section is machined1. First orientation of part section is machined3. Third orientation is machined3. Third orientation is machinedRotate StockRotate StockRotate Stock

3 d o e a o s ac ed3 d o e a o s ac ed

2. Second orientation is machined2. Second orientation is machined2. Second orientation is machined 4. Fourth orientation is machined4. Fourth orientation is machined4. Fourth orientation is machined

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CNC‐RP MethodologySTEPS TO CREATE A PART ( MT. Bike Suspension Component)

5. Left support section is machined5. Left support section is machined 7. Temporary supports are removed7. Temporary supports are removed

6. Right support section is machined6. Right support section is machined8. Part is severed from stock at supports8. Part is severed from stock at supports

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CNC RP MethodologyCNC RP Methodology• Creation of complex parts using a series of thin layers 

( li ) f 3 i t l th t d t(slices) of 3‐axis toolpaths generated at numerous orientations rotated about an axis of the part

• Toolpath planning based on “layering” methods used by other RP systems

• “Slice” represents visible cross‐sectional area to be machined about (subtractive) rather than actual crossmachined about (subtractive) rather than actual cross section to be deposited (additive)

• Slice thickness is the depth of cut for the 2½‐D toolpathsT l d i fl t d ill tt ith l fl t d• Tool used is a flat end mill cutter with equal flute and shank diameter (or shank diameter < flute diameter)

• Stock material will be cylindrical, therefore toolpath z‐zero 

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location will be same for all orientations

Methodology (cont )

Flat end mill cutter

Methodology (cont.)

“Staircase” effect

bl fRegion not visible from current orientation

Set of visible slices from current orientation

Toolpath planning using this approach is done with ease in current CAM

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Toolpath planning using this approach is done with ease in current CAM software (MasterCAM rough surface pocketing)

Fixture Planning• Approach uses “sacrificial supports” to retain the prototype within the 

stock material

• Round stock clamped between opposing chucks

• As prototype is rotated b/w toolpaths sacrificial supports are incrementally created

• Supports cut away to remove finished part

• Current approach assumes model surfaces exist along axis of rotation– Only one fixture support cylinder used on each end

– No change to visibility calculations

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Some other CNC‐RP partsSome other CNC RP parts

(e)

(f)

(a)

(d)

(g) (h)

(b)

(c)

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(c)

A broad comparisonA broad comparison

Characteristic EBM Casting Machining CNC‐RP

Geometry Very good Fair Good Goody y g

Tolerance/SF Fair Fair Very Good Good

Energy Fair(Part specific) Very Good Very Good Good

Set up cost Very good Fair Fair (Part specific) Very good

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Is it possible to get the best of both additive and b i f i ?subtractive manufacturing?

A hybrid EBM and CNC‐RP system

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It would be nice to ..It would be nice to ..

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Zeus • Zeus, a Siberian Husky with a missing front paw

• First patient with front limb amputation

• Different design needed for the attachment 

Combining Additive and Subtractive ProcessingCombining Additive and Subtractive ProcessingCAD model Part with CNC RM fixtures RP process. EX: 

EBMSTL model for EBM with all sacrificial supports

Part for CNC RP with supports

Part from RP process 

Identify functional surfaces

CNC‐ RM Process

Final part from AIMS 

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EBMMethodologyEBM Methodology

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And ..And ..

So where is our future headed?So where is our future headed?

• Design rules will change significantlyDesign rules will change significantly– We will not be limited to the use of solid mechanical components for high performancemechanical components for high performance products

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Our future …Our future …

• Manufacturing cost and energy needs to beManufacturing cost and energy needs to be viewed/justified using operational costs as well as production costwell as production cost– Possibility of eliminating more than 50% of the product weightproduct weight

For instanceFor instance

Magnus René CEO of ArcamMagnus René, CEO of Arcam.

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Non‐dense mesh partsNon dense mesh parts

Hi h h t• Higher shear parts can be obtained with less 

t i lmaterial• Better strength/weight 

ti b ttratios can be gotten• Directional mechanical 

ti bproperties can be obtained

IssuesIssues

Conclusions

• We are entering a new paradigm for engineeringP d i i P i i d i i i– Product engineering, Process engineering, production engineering are changing

– We need to address these engineering functions in an integrated manner

• We have the ability to alter the use performance characteristics of all future mechanical productsp– Strength to weight ratio

– Buy to use ratio

Sustainability product responsibilities– Sustainability product responsibilities

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