Fuzzy Logic Based Eco-QFD

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Fuzzy logic based Eco-QFD:An enabler of Sustainability

S. VINODH, Assistant Professor, Department of Production Engineering

J. SRIKRISHNA, UG final year, Production Engineering

N. NARENDHIRAN, UG final year, Production Engineering

NIT Trichy



Overview

Introduction - Indian Industrial scenario

Need for Sustainable Technologies

Problems faced in implementation of SustainableTechnologies

Overview of the Case Study

Methodology

Analysis of Case Study Results and Discussions

Industrial implications and Development



Introduction Indian industrial

scenario Focus on small scale industries Every large or medium scale industry associated with large

number of small scale plants

Small scale units, primarily sub-contractors, manufacturers of

sub-assemblies of products manufactured by large scale units Sustainable practices in small plants are often neglected due

to financial considerations

Approach to identify critical processes in manufacture of

products that create undesirable impact on environment Incorporating alternate techniques or changing manufacturing

modes to facilitate sustainable manufacturing.

Incorporating aspects of Value engineering, lean

manufacturing in such units.



Need for Sustainable Technologies

The need for environment friendly manufacturingtechnologies is essential and vital in todays

global state of affairs.

Resource optimization and environmental impact

have become the focus of government agencies.

It is imperative that industries strive to reduce

environmental impact be it in reducing wastes,

chemical effusions. Increasing need for environmental certifications

and demand for eco-label products .



Problems faced in implementation of

Sustainable Technologies

Producers point of view

The question remains on the application of

environmental criteria in product design.

Design modifications for environmental purpose

should not compromise on the traditional design

requirements like function, cost, quality

Constraints associated with the inclusion of environmental criteria have to be tackled and

related costs have to be reduced



Problems faced in implementation of

Sustainable Technologies

Consumers point of view Receptivity of Eco-Designed products has not been

favourable in the markets due to the fact that they aremore focussed on Environmental Impact Analysis

rather than customer requirements. Key issue for a successful Eco-Design product is not

only to meet environmental objectives but also to takeinto account cost effectiveness, market demand, andmulti-functionality requirements

Quality Function Deployment (QFD) is used toincorporate customer needs into product designconcepts, Product Planning, Process Planning toachieve total customer satisfaction



Overview of the Case Study

An industrial case study of a disconnecting switch used in

an electrostatic precipitator The novelty of the study is that it reports an application of

fuzzy logic based QFD for a disconnection switch to achievebalance between customer satisfaction and environmentalacceptability

Eco-Design product development problem has beenformulated as a fuzzy multi objective model.

The introduction of environmental considerations into QFDmodel leads an optimal balance between overall customersatisfaction and environmental acceptability.

Kuo et al (2009) developed an Eco-QFD to provide aframework for designing Eco-products by integrating theLCA into QFD throughout the entire product developmentprocess



Eco-QFD is a useful tool to integrate not only theenvironmental concerns but also quality, cost, andcustomer needs to improve the product design process.

By applying fuzzy theory in the Eco-QFD, the productdevelopment team can overcome the vagueness anduncertainty faced in group decision making processes.

Various technical attributes and environmental concernscan be prioritized such that the product development team

can concentrate their limited resources on critical issues todevelop customer-oriented environmentally friendlyproducts.

The practical approach facilitating the balance betweencustomer satisfaction and environmental acceptability

through customer voice translation incorporated with fuzzymethod gains vital importance. In this context, fuzzy logicbased Eco-QFD proposed by Kuo et al. (2009) has beenselected as the technique for our study.



Methodology Identify customer requirements and technical

attributes in QFD

Customer Requirements(CRs) identified from a widevariety of sources, such as surveys, focus groups,interviews, trade shows, complaints, and expert

opinions are translated into technical andEnvironmental attributes (TAs). When TAs are satisfiedCRs are satisfied.

Expert views are preferred as they are more technical,

objective and easily understandable. Life cycle analysis applied from the raw material,

manufacturing, distribution, use, and disposal stages isemployed to effectively identify the attributes



The next step involves the evaluation of therelationship between the requirements and attributes.

The relationship is determined qualitatively, such asstrong, medium, weak, and no relation withappropriate weights by a cross-functional team (or agroup of experts).

Customer needs and environmental concerns arecomplicated and often imprecise. So fuzzy approaches,such as fuzzy sets, fuzzy arithmetic, and fuzzyDefuzzification methods, can be applied (Vanegas &Labib, 2001; Wang, 1999; Zhou, 1998).

Fuzzy methods can be implemented to determinerelationship between needs and attributes objectively(Fung et al 1998).



Fuzzy sets, fuzzy operations, and fuzzy preference relation

As per Zadeh, a fuzzy set (subset) A in X, is characterised by a membership

function (x) which associates with each point in X a real number in the

interval [0,1] with the value of (x) representing the grade of membership of x in A. The larger f a(x) represents the stronger degree of

membership of x in A.

In classical sets the transition for an element in the universe between

membership and non-membership is abrupt and well defined or crisp.

For an element in a universe that contains fuzzy sets, this transition can begradual

This transition among various degrees of membership can be thought of

as conforming to the fact that the boundaries of the fuzzy sets are vague

and ambiguous. Hence, membership of an element from the universe in

this set is measured using a function that attempts to describe vaguenessand ambiguity. Thus a fuzzy set is one containing elements that have

varying degree of membership in contrast to a crisp set where

membership is assigned a value 1(full) else 0

The height of the fuzzy set means the maximum degree of membership. If

there is at least one element with the height of one, then the fuzzy set is

normalized.



Operations of triangular fuzzy numbers



LINGUISTIC VARIABLES

Vast amount of the information in human communication involves

natural language terms that, by their very nature, are often vague,

imprecise, ambiguous, and fuzzy, and the use of fuzzy sets gains

importance.

Linguistic variables are variables whose values are words or

fundamental terms or phrases of our natural language.

For example, {very low, low, medium, high, very high} can beexpressed. Basic variables can be defined as [0, 1] in order to

evaluate suitable situation of the criteria (attributes), where 1 can

be regarded as the optimal suitable situation, while 0 can be

regarded as the poorest situation. Since words, in general are less

precise than numbers the concept of a linguistic variable serves thepurpose of providing a means of approximate characterization of

phenomena which are too complex or too ill defined to be

amenable to description in conventional quantitative terms



Analysis of Case Study The Disconnecting switch is used in precipitator circuits in

thermal power plants in maintenance application in isolation,

grounding during maintenance of the high voltage circuit of the

electrostatic precipitator.

An electrostatic precipitator (ESP), is a particulate collection

device that removes particles from a flowing gas (such as air)using the force of an induced electrostatic charge. They are

highly efficient filtration devices that minimally impede the flow

of gases through the device, and can easily remove fine

particulate matter such as dust and smoke from the air stream.

The switch is used to disconnect the field from high voltage inoff condition and to earth the field. So the onus is on making the

switch eco sustainable by improving the design and

manufacturing processes.

Analysis involves the following steps.



First step Involves identifying the various technical and environmental requirements for

the design and manufacture of the switch. This suffices all customer needs.

These needs are weighed by experts whose weights are in the form of linguistic

variables. These variables are then defined as triangular fuzzy numbers.



Based on the LCA, the product stages of raw material, manufacturing, distribution,use and disposal processes have been evaluated and analyzed. The experts haveidentified 16 customer requirements by the companys sales network andmarketing surveys .

These 16 customer requirements are further categorized into five levels with cost,function, appearance, delivery and environment. To evaluate the weight for eachCR, a scale of 13579 is used, where 1 means the weakest and 9 means thestrongest relation. Each expert provided a crisp value (linguistic variable isconverted into crisp value) for each CR. Then, the crisp value for each CR given byeach expert is fuzzified. For example, the computation of weight of CR9 is asfollows

This gives us the weight for each CR.

Fig 1summarizes the fuzzy results of determining the weight for each customer

requirement.20 customer requirements were identified by experts. The experts proceeded to

value these CRs on a scale of 1-9 as explained earlier. Table 1 includes both crisp

and fuzzy values .the former have been included to differentiate them from the

latter. The equation at the end of step 1 has been used to find the weights of each

CR. These weights will be used in Tables 2, 3 and 4.



Fig 1: Fuzzy result for weighing importance of each Customer Requirement



Second step Involves the evaluation of the relationship between customer

requirements and technical attributes. The relationship may be

strong, medium or weak, represented by numbers (9, 5, and 1),while the blank shows no relationship.

However, as the dimension of customers requirements increase,the number of potentially related design variables becomes muchlarger. One of the main problems associated with a largerelationship matrix is the difficulty in laying down priorities and

importance using an accurate number. This is due to the fact thatthe value setting process is typically vague or imprecise in practice.Second, the data available for product design is often limited,inaccurate, or vague at best particularly when developing anentirely new product

So let S is the relationship matrix with the order of n r between CRs

and Technical Attributes (TAs) assuming that there are r TAs (here18) based upon life cycle analysis.



18 technical attributes that affect the products performance has been shown in Table 2.The relative importance of each TA with respect to each CR was valued. As in the

previous case, three experts valued this inter-relationship. Only the final weight (after

considering all three values) has been presented for a particular CR vs. TA relation. The

calculations were done using the equations at the end of step 2. These results will be

carried over to Tables 3 and 4.



Step 3 Involves evaluating the importance of each technical attribute (TA).

This is done by calculating the rank of each TA

Fig 2, depicts the important attributes which control the design and manufacture of the

switch, the ones that can be improved so as to make it as eco sustainable as possible. Ranks

give us the relative importance of the TAs

The evaluation of each TA has been carried out in Table 3. The calculations were done using

the equations involved in step 3. The summarization presents the total impact of each TA.

Relative importance of each TA has been calculated from which the rank of each TA was

determined as shown in Table 3. The ranking results will be used in Table 4.



Fig:2 Eco-QFD relationship and rank of attributes



Fig 3: Ranking difference with exclusion and inclusion

of environmental factors



Results and Discussions From Fig 2 we infer that certain attributes could be improved for overall

improvement of the switch, which enable it to be economically andenvironmentally sustainable. Although the method only covers the part of

identifying and prioritizing the attributes, it is however an important step inimplementing changes in design and manufacture. This is followed by theassessment of each attribute in order of their ranks for effectiveimprovements. In the study, changes were made in materials constituting theswitch and in the manufacturing stages with improved overall sustainability of the switch. For example, from Table 3, changes were made in the manufactureof sheet steel components which reduced material wastage and recycling

scrap. This method is best suited for products consisting of 10-20 components. From Fig 3 it could be inferred that certain attributes have a lesser rank with

EC. These attributes have a considerable impact on the environment and haveto be targeted for improvement. Such an improvement helps to minimiseresource utilisation, resource wastage, increase resource recycling andminimise environmental impact as a whole. Although these methods havebeen adopted in certain industries in the country there remains still a large

portion of small and medium scale industries where impact minimisation isstill low priority. These industries still use a major portion of the resources andmethods have to be adopted to reduce environmental impact as a whole.



The following changes were made in,

Sheet steel: Computerised, optimised CNC Machinery. Production of subcomponents as a downstream process of main component production.

Produced scrap in shapes, sizes suitable for rerolling mills.

Copper components: Copper forgings have replaced copper forgings. Forgingsproduce less scrap and recycling is trimmed down.

Punching holes instead of drilling holes. Punching produces buttons whichcan be sub components or recycled. Drilling produces boring scrap whichescapes to environment and pollutes.

The relative importance of each TA without considering environmentconsiderations was calculated and the rankings have been presented inTable 4. Then rankings with and without the inclusion of environmentalfactors was compared and studied.



Industrial ImpactThe conduct of the case study enables the introduction of environmentalawareness to customer requirements, assessment of environmental performanceas a design objective and evaluation of the potential of product for re-use and

recycling. The organisation has reaped the following benefits.

Better adherence to statutory regulations: The key attributes were identified andonus was on improving them with better material selection and better equipments

Productivity has been improved to an extent of 5%.

Reduced cost of product at better quality by means of implementation of ISO14000 standard.

Cheaper downstream processes of effluent treatment:

Reduced scrap production is achieved using value stream mapping. The scrappercentage got reduced from 27% to 22%.

Workspace utilisation has been improved by means of ensuring proper flow of operations.

Improvement in international customer base has been achieved with enforced

standards and adherence to regulations. The industry gains licence to producesophisticated machinery for a number of industries by conforming toenvironmental certifications like ISO14000 Environmental Management Systemsand ROHS compliance.

Better customer satisfaction.



Conclusions and Future Development This paper applies Eco-QFD to provide a framework for designing eco-

friendly products by integrating the LCA into QFD throughout the entireproduct development process. The Eco-QFD framework is a useful tool tointegrate not only the environmental concerns but also quality, cost, andcustomer needs to improve the product design process thus making theproduct economically worthwhile. By applying fuzzy theory in Eco-QFD,the product development team can overcome the vagueness anduncertainty faced in group decision-making processes. On conduct of thecase study, the framework enabled the product development team to

prioritize technical attributes and environmental concerns so that theteam can focus on utilising their limited resources on vital issues todevelop customer-oriented eco-friendly products. This is very important inthe contemporary industrial scenario for the development of sustainableproducts.

The inferences derived from the conduct of the study are applicable tosimilar manufacturing organisations. The case study could be carried out

using several tools/techniques of sustainable engineering for differentmanufacturing organizations across varied sectors in different countries.The methodology can be programmed and software tools could becreated that help in achieving results in very quick time. Creation of suchsoftware tools will pave the way for easy, effective and quick processes



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Fuzzy Logic Based Eco-QFD

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