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The Globalization of Manufacturing in the Digital Communications Era of the21st Century: Innovation, Agility and the Virtual Enterprise

Proceedings of the Tenth International IFIP WG 5.2/5.3 ConferencePROLAMAT 98

IFIP PROLAMAT 98 - September 9-10-11 & 12, 1998 Trento, Italy

# 122

Teaching Environmentally Conscious Design

J. JeswietMechanical Engineering, Queen’s University, Kingston, Canada

AbstractEnvironmental impact is an increasingly important question to the design engineer,hence the need for educators to include this in the engineering curriculum.Integration of environmental issues into manufacturing engineering and designeducation is discussed. Students are shown how, in modern society, the designerplays a central role in determining what the environmental impact is of a part or asystem of parts. Designers influence environmental decisions through orderingmaterials and shapes and through creating designs which predetermine whichprocess will be used to make a part and ultimately what happens to a part. Twocase studies are used to illustrate how designers can reduce environmental impacts.

KeywordsEducation, Life Cycle Engineering

1 INTRODUCTIONSince the warning signal by the Club of Rome [1], "Green Manufacturing" isbecoming increasingly important. Both manufacturing and design engineers areconfronted with the need to design and manufacture in a more environmentallyfriendly manner. Hence the field of Life Cycle Engineering [LCE] is taking onincreased importance. The environmental trilogy reduce, reuse and recycle [thethree r’s of environmental work], has become familiar and creates the challenge ofdesigning and manufacturing in a more environmentally friendly manner. Environment impacts are an increasingly important question to designengineers, and there is a need to include this in the engineering curriculum.Environmental issues were addressed in recently at the Departments of MechanicalEngineering at Delft Technical University [2] and at Queen’s University. Thefollowing briefly describes some of the content. Environmentally consciousmanufacturing and design, has two needs: 1) a philosophy of designing andmanufacturing in an environmentally friendly manner , and 2) a set of tools basedupon solid engineering principles to further enhance the philosophy ofenvironmentally friendly design and manufacture. It should be noted thatmanufacturing will always have an environmental impact and a goal should be tooptimize manufacturing to have the least environmental impact.

2 COURSE ORGANIZATION: lecture topicsThe course content is outlined in the following. Details are available upon

request.




- Objective of including LCE in design.- Driving forces in LCE: or how we got here.- The place of LCA with respect to design.- A brief, abridged history of LCA.- Variations of how LCA is viewed, and how it can be viewed as a control

system.- A general description of LCE.- The LCE of a part: what needs to be considered.- Units & evaluation methods for the designer; calculation examples.- Standards of which the designer should be aware; ISO and SETAC [3].- Results of two case studies.- Concept of reDesign and reManufacturing.- Conclusions and References.Acronyms are standard fare in most technical fields and some are shown here

because they indicate the type of information used in the lectures:LCA : Life cycle analysisECD : Environmental conscious productionDfx : Design for xDFA : Design for assemblyDFD : Design for disassemblyDFM : Design for manufactureDFS : Design for serviceDFR : Design for recycling

It can be seen that design is a prominent feature and that the designer plays animportant role in deciding what the environmental impact of a part will be.

LCA is central to environmental work and time is spent on the history of LCAand the driving forces which have set the agenda for environmental work.Although LCA started in the 1960's with primary interests in packaging, it can beconsidered in terms of a feedback system, as shown later in figure 1.

2.1 Definition of LCA and associated termsBecause interpretations often differ LCA is defined as: «a technique thatconcentrates not upon one sole environmental facet of a product, but upon all itsaffects upon the environment at all steps in manufacturing, including use, disposaland eventual reuse». Although it is called a technique, one can also consider it as aphilosophy . It quantifies inputs and outputs of a product at every stage in terms ofenergy use, raw materials and polluting emissions [3]. LCA looks at the wholepicture instead of focussing upon one negative aspect of a product. Behavior isassessed in terms of emission outputs in response to varying degrees of input. Thiscan be useful in addressing the issue of governmental environmental regulationsaimed at reducing a specific type of emission, be it air pollution, water pollution orsome other environmental effect [5]. When designing and producing a part thereduction of one type of emission may lead to disproportionate increase in anotheremission; LCA is a technique which strives to correct this.

LCA can be used in the following ways:




� to assess/compare total environmental impacts of product /designalternatives;� to improve a product by recording important causes of environmentalimpact;� to develop a new product in an environmentally responsible way.

LCA is now being actively applied in a large variety of industries such as theelectronics, household appliance and automotive industries. These are all highvolume, large economy of scale industries and provide us with a key to where LCAtechniques and research should be applied: to high volume industries. LCA comprises a three-phase series of analysis, after having defined the goaland scope (boundary conditions). There are:

Phase I: inventory analysis, life cycle inventory (LCI); consists of identifyingand quantifying energy and materials used including resultant environmentalreleases/burdens that occur during the entire life cycle; (the italicized terms arethose used by SETAC in their list of components of LCA).Phase II: impact assessment, consists of assessing the environmental impacts ofenergy and materials used, including the final product, plus any environmentalreleases/burdens over the entire life cycle.Phase III. improvement assessment, includes evaluating the opportunities toimprove environmental performance and implementing potential changes.

Some definitions from ISO/TC 207 [4] are included for information:� Life cycle: the consecutive and interlinked stages, and all directly associatedinputs and outputs, of a system from the extraction or exploitation of naturalresources to the final disposal of all materials as irretrievable wastes or dissipatedenergy.� Environmental burden: any change to the environment which, permanently ortemporarily, results in loss of natural resources or deterioration in the naturalquality of air, water or soil.� Environmental impact: the consequences for human health, for the well-beingof flora and fauna or for the future availability of natural resources, attributable tothe input and output streams of a system.� Environmental impact assessment (EIA): a process to determine the magnitudeand significance of environmental impacts within the confines of the goals, scopeand objectives defined in the life cycle assessment.� Recycling: a set of processes for diverting materials, that would otherwise bedisposed of as wastes, into an economic system where they contribute to theproduction of useful material.� Recyclability: property of a substance or a material and parts made thereof thatmakes it possible to be recycled.� Sustainability: development which meets the needs of the present withoutcompromising the abilities of future generations to meet their own needs. Definedin the Brundtland report [6].




2.2 Design in Life Cycle EngineeringLife Cycle Engineering can be approached as a control problem and figure 1 givesa graphical illustration of how that control diagram can be constructed. Thecontrol diagram includes loops and decision points of which a designer must becognizant. For instance, a designer must be aware of a design for service (DFS)loop or decision points such as reuse (I), remanufacture (K), or recycle (N). Thiscontrol system makes the designer central to Life Cycle Engineering. However,control models need to be developed which fit into the different parts of thescheme shown in this figure. Also legislation is needed to make control applicable.




A more detailed view can be obtained by looking more closely at the designer atpoints E, K and Q; smaller blocks can the be created to model the system at thispoint. The designer makes environmental choices in two ways. Materials arechosen thereby narrowing down the choice of methods by which a part ismanufactured. Figure 2 is an illustration of this. In effect the designer "pushesthrough» environmental choices. Environmental decisions are also made bychoosing existing parts, such as tubular products made of a specific material andcross-section, thereby «pulling through» environmental decisions.

The box representing the design loop can also be considered in more detail as

shown in figure 3. Here it can be seen the designer must take many factors intoaccount including new factors that must be added to the decision process such asthe environment and remanufacture. All these processes need to be combined in acontrol or optimization procedure to maximize and aspects of a design, includingthe environment. Indeed, such an optimization process can also have a positivefinancial effect upon balance sheets.




These blocks show the phases needed to accomplish the long term goal ofsustainabiliy and can be viewed in terms of control optimization. The designermust recognize the marketplace is changing rapidly and new technology nowallows us to reduce landfill impact by not designing a new product but changingthe method of delivering a service. The telephone answering service is a goodexample. Instead of purchasing an answering machine, a customer can now do thiselectronically through a telecom [7]. However, although there are many goodintentions for more environmental responsibility, there still is a tendency to dumpused products in, among other things, the third world. Requirements must becomemore stringent with concurrent improvements in legislation.

Environmental Assessment of Interconnecting Devices. To aid the designer inproviding environmentally friendly designs, much more information is needed.For instance, as stated by Feldmann in reference [7], there is a need for theenvironmental assessment of interconnect devices, a comparison of nationalrecycling strategies, and an up to date assessment of the state of the art of recyclingtechnologies. In the case of electronic devices, there will be new printed circuitboard technologies which are brought into the market. Normally only thetechnological features of new substrate materials are considered, however in thereis a glaring lack of data about the ecological effects for circuit boards. Hence theobvious need to collect life cycle data for different interconnecting devicetechnologies in order to compare environmental impacts. New benchmarkstrategies are needed to deal with new materials such as ceramics andthermoplastics.

There is also a need for designers to be aware of how national recyclingstrategies compare. Due to different environmental laws and needs, there are a lotof differences in national recycling strategies. With respect to the globalization ofmarkets, there is a need to compare recycling rates in different companies withsales and the respective influence of ecological laws. It would be useful to havebenchmarking information with respect to many large volume industries such asthe electronics industry to which one can refer.

There is also a need to exchange information on the state of the art of recyclingtechnologies on an example product, for example automobiles. These are detailswhich should eventually be fed into the design loop.

3 UNITS AND METHODS OF EVALUATIONThe designer must be able to evaluate environmental impact, EI , therefore it isdiscussed in detail, hence the following.

Fifteen different methods are identified as methods used to calculate the EI fora product [8]. The total number is unknown but a recent, internal, survey indicatesmany more than fifteen. However in order to keep the discussion informative onlyfifteen different methods of evaluation are discussed. Each method includesdifferent inputs, hence different units appear in the end result. Therefore with allthe variations there is a large diversity in units. Fortunately, many of the units usedin EI calculations are standard, for example kilograms and energy.




In some cases, evaluating EI includes political considerations, which gives anon-technical weighting. This creates a problem for the designer especially forforeign markets and creates a need for an agreed set of international units formanufacturers. Also, in many cases, the equations used are empirical at best, anddo not have a rigorous mathematical derivation.

3.1 Which Method?The question which arises, is which method should be used? Parameters whichcome into play in most parts manufacturing are: material, energy, and fluids. Thesehave an influence on other parameters such as waste and toxicity. Hence theseshould be taken into account in part design.

Supporting the foregoing is a survey of the issues which have contributed toconcern about the environment in past two decades [8]. These indicate whichparameters play an important rôle. Issues which have created concern for theenvironment in OECD countries are:� Oil crisis [1973]; energy shortage and economics.� Chemical plant spills [1970's]; fluids and toxicity.� Tanker oil spills [1970's]; fluids and toxicity.� Paper recycling [1970's issue]; materials waste (volume), fluids and toxicity.� Packaging industry waste [1970's issue]; materials waste (volume).� Acid rain [1970's issue]; toxicity, air quality (air is defined as a fluid).� Nuclear power plant environmental hazards [1970's - 80's]; radiation.� Rain forest depletion [1980's]; material shortage, climate, oxygen supply.� Liquid waste dumping [1970's]; toxicity and fluids.� Solid waste dumping [1980's issue]; material waste volume and toxicity.� Ozone layer and CFC´s [1990's issue]; UV damage, toxicity, food supply.� Compulsory acceptance of used goods [1990's]; material waste volume.It may be noted that terms repeated in the foregoing list are underlined and are

included in the following list: materials, fluids, toxicity and energy. The sameparameters were common factors in the methods of calculation.

It is moot which parameters are important and which method is better, plusthere will be industrial constraints and goals which do not match these parameters.It should be noted that often the person consulted about which method is better hasa vested interest in that method. One method of calculation which is popular withsome European Designers is the eco-indicator [9]; a materials software toolassociated with this method is IDEMAT [9] which has been used with somesuccess, and is used to educate students because of its simplicity. This user friendlymaterials data base gives results in eco-points for material choices when choosingmaterials for a design.

4 SUCCESSFUL EXAMPLES: Detailed Case StudiesStudents and designers, also need examples to show how optimization can alsohave a positive effect upon the environment. These show that considering theenvironmental impact of a part can have a positive effect upon the balance sheet.

There are few detailed examples to which manufacturing engineers can refer forsuccessful examples of designs with the environment in mind.. Large scale successstories are quoted [2], however these studies do not give specific details, oftenbecause of their proprietary nature. Hence more detailed case studies are needed inthe public domain for reference by designers. Two cases, which fit into the schemeshown in figure 2, are cited here.




4.1 Case 1: Designing With Reduced Amounts of MaterialIn this case [10] a traditional material, nodular cast iron, was used. Parts could beoptimized due to advances in casting techniques allowing designs to be revisited.There was a decrease in: 1] the amount of material needed, 2] the energy neededfor production, 3] the waste. This was made possible because thinner nodular castiron parts could be poured with more advanced control techniques, includingadvanced cooling and metal flow techniques. Details of Nodular Cast Iron. Ductile iron (nodular cast iron) is a relatively newoffshoot of the traditional cast iron family. It has very high tensile strengths whichcan be varied with microstructure. Typical stress/elongation [σm/elongation] valueswhich can be attained are: 350 MPa/30%, 800 MPA/3%, 1400 MPa/10%. Themodulus is the same as that of steel and yet it is 10% lighter than steel, it isrelatively inexpensive to produce and its fatigue properties are comparable to thoseof steel.

The Process [some technical metallurgy details]. Nodular cast iron is usuallyproduced with a 25 mm thick wall, and reducing this to a 6 mm to 8 mm requiressophisticated foundry equipment and control. In order to determine if nodular castiron could be poured to thinner sections, a part with dimensions of 290x230x60mm, with thick ribs and thin wall thicknesses, down to 3 mm, was poured.

For nodular cast iron, the critical step in producing the right structure is duringgraphite formation. Standards for achieving the right metal structure, such as ISO1083 and DIN 1693, are of limited use because they define limits according to veryconservative minimum values based upon material cross sections >25 mm with nonodule count requirements, no matrix structure requirements, and no chemicalcomposition requirements. Usual ductile iron standards, ISO and DIN, set requiredgraphite nodule densities of 100 to 400 nodules per mm2 in a 25 mm thick, orgreater, cross section. In 3 mm sections a much higher nodule count is necessary,in the range of 2000 to 3000 nodules per mm2.

Because material strengths for thin nodular cast iron parts were also unknownspecial material tests had to be done.

Material Strength. Usually cast iron test samples are cylindrical but for thiswork rectangular cross-sections were used, similar to steel plate testing, accordingto DIN 50114 [gauge length/width = 50mm/12.5mm]. Also, in order to check iftest sample geometry had an effect upon mechanical properties, samples were cutfrom 15 mm thick nodular cast iron, with a 300 nodules per mm2 density. Flatsamples were cut to 3mm x 12.5mm x 50mm, and cylindrical samples to 6.35 mmdiameters. Results are shown in table 1. It may be seen that there is little effect dueto the cross section. To establish the mechanical properties of cast iron for 3 mmsections with 2000 nodules per mm2 , tensile tests were conducted.

Prototypes. Having determined that cast parts with fine, uniform porosity andacceptable strength could be produced, with acceptable strengths, three practicalprototype parts from the automobile industry were chosen for further study. In theautomotive industry, in particular heavy trucks [with a net weight of 9 tons],30%of the structure is due to castings [1000 kg ductile iron, 1500 kg lamellar castiron and 500 kg aluminum and steel] and for automobiles this is greater than 40%

The parts chosen were: a complex form [a stabilizer bracket for a truck], a smallpart with dimensions smaller than 300x200x200 mm [a gear box support], and apart with critical strength and temperature requirements [an exhaust manifold].Both the bracket and gear box support are usually made of welded steel, and theexhaust




Table 1. The effect of test sample geometry

Melt Cylindrical section Rectangular section

Rm, MPA Strain, % Rm, MPA Strain, %

1234

451486464461

18.517.517.415.8

492486477476

20.317.322.518.8

average 466 17.3 483 19.7

Rm _ tensile strength, MPA

. manifold is usually made with much thicker cross-sections. Both brackets aresubject to fluctuating stresses, hence a fatigue analysis had to be made.

Gearbox support bracket. The gear box support bracket is subject to fluctuatingforces: ±1.5 kN, [R=-1]. An estimate for the number of cycles the part gives 3x106

cycles. Using these criteria the part was subjected to fluctuating stresses. The samepart was made in four different ways: from welded steel, weighing 0.71 kg, madefrom three welded pieces [part 1], plastically deformed HSLA, weighing 1.2 kgand 12 mm thick [part 2], and two different nodular cast iron shapes, with 3mmthicknesses [parts 3 and 4]. The welded steel part [part 1] failed in the test period,as shown in figure 6. It was replaced with a much stronger, over dimensionedHSLA [part 2] which did meet fatigue requirements. A finite element analysis ofpart 3 showed a stress concentration at one of the bracket holes and by redesigningthe part, which should have been done earlier, lower stress concentrations wereachieved [part 4]. It can be seen, in figure 4, that this design more than adequatelymeets fatigue requirements.

Stabilizer Bracket. This part of the truck is made of five welded steel pieces, 6mm thick and weighing 3.54 kg. The manufacturer estimated the number of stresscycles at 8.4x105, fluctuating at ±20kN [R= -1]. The nodular cast iron shape waskept as similar as possible, with mass reductions where possible. Ten steel partswere fatigue tested and fifteen cast iron parts were tested at various stress levels.Figure 4 shows the results. Both parts meet design fatigue requirements, with thesteel part showing a slightly higher strength but also having a greater deviation inthe results.

Exhaust Manifold. An exhaust manifold made of 7 mm thick nodular cast ironand was redesigned with 2.5 mm thick walls. The part was tested for 1500 hours ona 315 kW engine with a typical operating cycle and with a maximum temperatureof It functioned without failure.




Results for Case 1. It was found that: 1) sections as thin as 3 mm could bepoured, without loss of quality; 2) while using thin nodular cast iron sections in atruck body, strengths can be maintained while reducing costs by 50% per part [lessmaterial is used and there will be lower production times with reduced costs]; 3)several hundred kilograms of weight can be saved in making a truck, since 25% ofa truck is cast iron.See table 2.

Average trucks have 1000 kg of cast iron, which may be reduced substantially.Truck weight could be reduced even further with aluminum parts, however costscan easily triple because thicker sections are needed. An energy audit is likely toshow the energy used to produce the aluminum is higher than for nodular castiron.

Table 2. Summary of results for nodular cast iron study.__________________________________________________

Part 1 Part 2 Part 3Former weight, kg 4.72 1.2 3.54New weight, kg 2.46 0.61 2.12Weight savings, % 48 50 40Old thickness, mm 7 12 6New thickness, mm 2.5 3 3Estimated Cost savings per part, % 50 50 40__________________________________________________




4.2 Case 2: Optimizing a Manufacturing ProcessThis case fits into a situation which is between input D and output E in figure 2.For the pilger rolling process shown in figure 5 [11], lubricant flow was reducedfrom 300 l/min to 30 l/min, reducing energy consumption and decreasingenvironmental impact by properly designing lubrication nozzles. Lubrication costswere also decreased and productivity increased due to less down time lubrication

techniques had been used to cool theprocess; lubricant was sprayed onto thedeformation area with crude copper tubenozzles. Research showed that properlyaimed laminar flow produces uniformcooling. Using this information andadvanced fluid flow techniques,efficient cooling patterns were designed.Improvements were possible because:1) more advanced numerical analysisand computational methods are nowavailable [12], and 2) more advancedmachining techniques gave moreprecise nozzles; in short, technologicaladvances allowed improvement. Seetable 3 for results.

Table 4. Summary of Pilger Rolling______________________________Fluid use: Before After 300 [l/min] 30[l/min]Gains due to fluid reduction:· 90 % decrease in fluid use; with a reduction in toxic elements· A dramatic decrease in air pollution with decrease in fluid· Energy saved [%, whole process] 12 %· Production rate increase 15 %______________________________

5 CONCLUSIONThe concept of the designer being a contributor to environmental impact and

how that fits into an LCA control loop has been introduced. Details of howdesigners can be introduced to environmental conscious design have beenpresented. Two case studies illustrate show how the design fits into the Life Cyclecontrol system.

6 REFERENCES1. Limits to Growth, Club of Rome, © 1972 Universe Books, New York2. J. Jeswiet. ECM Report, PT group TU Delft, 1996.3. SETAC, Society of Environmental Toxicology and Chemistry, Pensacola,

Florida..4. ISO/TC 207 WG1. Int’l Standards Organization/ Tech’l Committee 207

Working Group 1, ISO Geneva.5. L. Alting. «Life Cycle Engineering & Design». Annals of CIRP, v44/2/1995;569.




6. «Our Common Future», The Brundtland Report, © 1978 Oxford UniversityPress.

7. Winter annual meeting, CIRP Life Cycle Group meeting, 1998, v 47/2/98.8. M. van Beers. «Life Cycle Analysis». TUDElft report, Jan. 1996.9. J.C. Brezet course notes. «Inleiding milieugerichte produktontwikkeling».

TUDelft, Netherlands, 1995.10 «Designing and Manufacturing Smarter with Traditional Materials». P.C. van

Eldijk and J. Jeswiet. Contructeurs dag Symposium, April 1996, TUDelft.11 «Optimization of a Cooling System: Cooling of Pilgered Seamless Tubes».

W.E. Carscallen, J.Jeswiet, P.H. Oosthuizen. Annals of CIRP vol. 43/1/1994: p223

12 «Stability of Laminar Flow in a Rectangular Duct». Tatsumi , T. &Yoshimura, T. J. of Fluid Mechanics, vol. 212: p 437

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