, ,

ope~tions can be improved on a continuous basis through the complete involvement of employees andthe management.

, ,I

In thecqseof service operations. the process of continuous improvement aims at reducing the numberof people involved in providing the service, without affecting the quality and rate of service. Themanagement of a.service-providing firm reduces the number of employees until the point where theprovision of the service becomes slow or stagnant. The management then explores the ways ofimproving the service process.

ThoughJIT is a powerfultool for 'reducingthe firm's inventoryand improvingproductivity,the implementationof JIT pftnciples is difficult as it has to overcome the following barriers: workers' resistance to change,difficulty in accomplishing zero lead-time, zero safety stock and zero idle time. The implementation ofJIT ptanufacturing principles requires great support and commitment from the top management andextensiveemployee training.

Summary: The conceptpf JIT~~~tems;/is b~~ed Pl1 the idea90f~()ntinu()~9.improvement of a firm's, production systems anduthe~li~i~,~tiO~,~f w~~teJrom a/l al'ea~;'Ofthe~rirl.ln. a JIT system, thecomponentsof a product'4nderg9irtga manufacturingoperatjonarriVe justatthetime when they have tobe fed into the productioncprocessby a worker atthe work center.

The JIT.system e~Phtl,~~~Stwo important and,?"utuallYsupporting compon~rt~:\p~oPle's involvement,and total quality cq\Q~r9~:~~~Cl1aracteristicsofq.:Jrr;;~ysteminclude consiS~~l':lt,prq~vctionrate, small lot

. -.- \:- '::':!~"",~"),,,i,'I::," "_ :-,:', -"",::'.:: ,'_ -'''->;.<"'":1<,'«--' ',:<-::;1ii

sizes, closer supplieri~~~ihi9h product qUality,ql,Jickand economic ~et~~~.'fle'Srle facilities, multi-skilled workforce. effecyy~ maintenance~nd continuous improvement in yJg~Jll~t~ods,

'> y' ",::;, .•.."........'." ·.·,;:,(,,:y(.,:riJIT systems can t>e effectjveIYt9Roth'1l~nufactu~l1gand servjc~'fi'm~.)f@. reducing lot sizesand set~p times, th~ ...•. can ensllr~,.,getteri~sp~qtion,and,~reRducepr~,y~ .., services of higherquality.Human cO~l"Si8~rati~r:t ~pdt~~!b~eerremPI9,Y.~~~ and ~aq~~~m ".. and proper rewardsystems are some<,~f.]m"lfr9anl4atl<:>naJ!!!f;equ~!rnen~sfor·frn~e01ef:tmg~.~t?'~~.Yd,~rtem.The Just-In-Time II system pra' ", yBose, Corppration is an advanced system Where an employee of the

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C.2. What are the advantages of JIT?

0.3. What are the characteristics of JIT?

1. EveretteAdam, Production and Operation Management Concept Model and Behaviour.

2. Richard B. Chase, Production and Operations Management.

___ l

UNIT - XIIIQUAliTY CONTROL

Statistical Quality Control (SQC) is an effective method of monitoring a process through the use ofcontrol charts. By collectiflg readily available data from sampl~~,/yariation~inthe process that mayaffect the quality Of the~9.~, product or' service can be detected'a9gcorr~~~ ,b:fore any waste isproduced. This met~od ha~a:distinct advantage overmore traditional quality m~thodssuch as inspection,as resource is used for prevention rather than detection. This has clear implication for businesses, asvaluable resources are prevented from being usedto.manufacture defective products or to provide poor

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services.

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Statistical Quality d~ntrol~s pioneered by Walter A. Shewharf i~ the early 19~Os.W Edwards Deminglater applied SPC ~ethod~iinthe United States during WOrfd'''lt\'ar II, thereby successfully improvingquality in the manClf~ctur:of munitions and other strategialilyimportant pr()ducts. Deming was alsoinstrumental in intr(jducingSPC methods to Japanese industry after the war'had ended.

Shewhart createdt~~;IJ~~i~fOr th~control chart'andI~hec~n=~~f;Ofast~f~iOf .statistical control bycarefully designed :~xp~rim~rlts. While Dr. Shewhart d~w front\~~ure.mathel'fiaticaJstatistical theories,he understood that~~t~fr~IT)PhYSi~1 PfRcesses neverpr6duce~;:~l1CJrmaldistribution curve" (a Gaussiandistribution, also ~~m?~Jyreferred to as a abe" curvT").~t:)i~i~~vered that observed variation inmanufacturing data'·\didi·n.ot.'. alwa·.. YS.'.be..h.•...a.ve the sam.e,.w.. aya. s.'.a·'at.a'.it.". nature <..f..or. example, Brownian" ' ' <1"",:""",'0";:',,,.;,,::::,,--:,,,,,,,,,:.,,,<,--,,-:,,,,,:"'" ""',, ",", ", ':> - :,':,>",:,,;',:,;,':> ,'.>',

motion of particles) ..Dr.Sf;1eWhart cOhcJuded that while every pro~ss.displaysvariation, some procf3ssesdisplay. controlled variation that is natural to the process (common causes of variation), while othersdisplay uncontrolled variation that is not present in the process causal system at all times (specialcauses of variation).

The follOWing section relates to manufacturing rather than to the service industry, although the p'Anciples,of SQC can be successfully applied to either.

In mass7manufacturing, the quality of the finished article was traditionally achieved .through 100% inspectionof the product; accepting or rejecting each article based on how well it met its design specificatic:ms. Incontrast, Statistical QualityControl uses statistical tools to observe the performance of the productionprocess in order to predict significant deviations that may later result in rejected product.

~"Two kinds of variations occur in all manufacturing processes: both these process variations'caus'e

'isubseql:!ent variations In the final product. The first are known as natural or common causes of variationand may be variations in temperature, specifications of raw materials or electrical current etc. Thesevariations are small, and are generally near to the average value. The pattern of variation will be similarto those found in nature, and the distribution forms the bell-shaped normal distribution curve. Thesecond kind is known as special causes, and happens less frequently than the first

I '

For example, a breakfast cereal packaging line may be designed to fill each cereal box with 500 gramsof product, but some boxes will have slightly more than 500 grams, and some will have slightly less, in'acco~dance with a distribution of net weights. If the production process, its inputs, or its environmentchanges ~for example, the machines doing the manufacture begin to wear) this distribution can change.For example, as its cams and pulleys wear out, the cereal filling machine may start putting more cerealinto each box than specified. If this change is allowed to continue unchecked, more and more productwill be produced that fall outside the tolerances of the manufacturer or consumer, resulting in waste.While in this case, t",e waste is in the form of "free" product for the consumer, typically waste consistsof rework or scrap. """" I

. :. .<;..',\.<;dili,/« .. .. ....; < .<By observing at theng~tt~rne wt,,~~~~p,~R~g in th~ process~ratJed.l9 ac:h~~~~~.m~;,guafitv engineer orany member of thet~aID.,~esp<>nsible for the prod~ction line can troublesP~2lJhEl\ root cause of the

v~~ation that has cr~hti~;;~Rthe process and cOrr~; the problem. " .'. ;itJ.0~r;.~:;j,SQC indicates WhEl~.;.iI1<:~~ionshould be taken in!a: proCeSS, but it also>~~~when NO actionshOuld be taken. AJ1.e;X;.i~Bleis a person W~()wQ~19flike to maintain a cons<>,?t';~()~yweight and takesweight measurements Vle~kly. A person who does 'not understand SPC c~~C~Ptsjmight start dietingellery time his or heoyei~~tincreased, 0Featmore~very time his or her wei~mt9~c:reased. This type ofaction could behannfld'~~~POSSibIY g~gerate e"{el1more vt;lriation in bOdY'il~jt;J.~t~<"~PCwould accountfor normal weight variati()rlc;.ind better;i~9icate whE;lnthe personis in factgaig!f)Q9J'.i}osing weight.

QUALITYAssu~I!J ,d'" '\1, .., ~~~"~

Quality asslJranceipclug~~,;\qU;.ilitYlq~~,,£?rand als,o'refers to e~Ph~§isonq~~JjtY,ilq the design of theproducts, processes~n<;t"j~bs>al'lc;lil1;:p~~o~nel sE;llectiqnand tr~.ininQ. BLlt ()f';~lIth.~.§e it is mainly usedin quality control. S91.W~:~illb~,';'f: g';quali~y,co':'trol indelf1il. " ·t~

':: J:'::::""':';:' '~i~'-~'~~~~';",:,:,",~';'~~'Y " '~:: , '>', .,'~r,;~ORGANIZATION FORQUAI...

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Quality'c?ntrol is astaff'function'concemed withthepreventidn of~defects.if1mianufacturing so that,items may be made properly at the first time only and not to be rejected later. In order to achieve thisend, s~veral activities are to be peJiormed. There must be inspection and control of incoming rawmaterials to insure that they meet specifications, there must be planning and control of manufacturingprocesses to insure that suitable methods are being used and that machines and equipment are

I performing satisfactqrily, there must be in-process inspection to insure that items being fabricated meetspecification, there ~st be final inspection and testing for product peJiormance. .r .In order to carry on 1,1hesefunctions, a separate department is created which is called Quality controldepartment. The per$on who heads the department is known as Manager of Qualit~ontrol or Managerof Quality Assurance.' It should however be noted that quality control is not the responsibility of personnelof the quality department but everybody in the organization should be responsible to ensure the quality ofthe end product.

I

a) Assistance in the evaluation of customer requirements to arrive at a clear understandingof the product quality objectives. '

b) Review design. documentation to see the design standards and practice and foridentification of potential quality problems.

c) Validate the accuracy and completeness of design proof tests and qualification tests.

d) Check the documents to ens~e that all drawings and specifications in use are currentand correct. !'

e) Provide information on previous quality problems encountertd for consideration in newprOd esi n " I.~~' . . .

2. Control

a)

b) requirements.

c) purchase orders and

d) not of an acceptable

e) Conduct follow-up to assure that corrective action is accomplished in a timely manner.I

Action supporting the product after delivery: I ' .a) Assure that product service specifications are clear and correct.

c) Assure that repair and modification are performed in accord~Q'pe with company'quality.""1 ••••

requirement. '.•r'

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d) Analyze complaint data of customer satisfaction and initiate appropriate corrective action.

ACCEPTANCE SAMPLING

<Ii~e(I) ~r:ethe supplied goods to be accepted or rejected? (it) if accepted, what kind of risk do we incurin'terms of bad quality? (Hi) should the batch, which has been manufactured in the plant, be shippedouts,ide.to the customer or not? Here we are talking about mass scale procurement of raw material andof mass scale shipment of finished goods.

We have to go for sampling because it is not possible to check all items. The cost of 100% inspectionis very high in most cases and many of the acceptance tests require destructive testing of the item, and,therefore a sampling procedure is must in such cases. The acceptance sampling procedure eitheraccepts or rejects the incoming lot in total. Such an outright rejection of the lot by the customer oftenresults in remarkable quality improvement on the supplier side. This is an important motivational factoroperating in acceptance sampling.

One must however note that in certain types of products 100% inspection is unavoidable. For instance,nuclear plant equipment.

Inspection is of ~9:ris one wperein eac."inspection f does"rcharacteristics -Jhper~ent inspectiqn

t percent inspectionwever, cent percent

tic. Only importantay be verified. Cent

It involves .(Inspection

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It is time c

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~ alternative to 1" Y,~eS\~~i~~i~I,.i~Sthe lot is decided b ' tSiof?t~~5Pi~~~,sample ~nforms to allbt is acceptedotheiKis rejectec!. Since the acceptanceis based on the inference drawn from the sample, the technique is known as acceptance sampling.

ighly repetitive anddefective ones.

Sampling inspection however is subjected to sampling errors as there is always a chance that thesample may not be representative of the population from which it is drawn. This at times may causeacceptance of a lot of bad quality or rejection of a lot of good quality.

Sampling errors in acceptance sampling are minimized by selecting a sample which is representative ofthe lot (Le;'by choosing the sample at random so that every portion of the lot will have equal representationin the simple) such a sampling is known as random sampling. If the s)lmple is true representative of thelot then .only a few good lots will be rejected and only a few bad 10(5 will be accepted. Sampling planutilizing .appropriate sample size (n) allowable number of defectives called acceptance number usuallytakes care of quality ;,.ssurance function adequately.

Acce~ta9ce sampling .RIC\nis a set of rules which prescribe the procedure to be adopted in preparing

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the lot, selecting the sample (5), conducting inspection of the sample (s) and fixing criteria fora~.N~:!or rejection of the lot. . ti;~.':!,

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'{i ,~;i·,Variable Basis: In this, inspection of samples is conducted on measurement (variables)basisim(Le. on the ba~ of actual measurements). Examples of variables are: Weight of a ~Cket(in!!i.kgs), length of a component (in mm/cm/meters), life test of a part (in hours), tensile st~ngth of.a rod (kgs/cm2) etc. . I:' .,'Attribute Basis : In this, inspection of samples is carried out on 'go' andtno go' basis (Le... ,determining whether or not the product in the sample conforms to the specifications). Examplesof attributes are cracks (e.g, pressure gauge is either cracked or not cracked), colbur (e.g.furniture has a desired colour or it has not), appearance (e.g. surface finish of the coveris, eithersatisfactory or it"inon. . . tio' 'Jedor c;f). preseheed'f'burTsetc.

...., . "'" .... .... .... .,,/£;~~~~;.... ...,. ...,?':Minor defect: A de ec I 0 er than critical and major defee, at oe rfbt materially reduce theusability of the product for its intended purpose is called minor defect. e.g. scralches on the paintof the outer casing of a gear box; lack of smoothness on th, edges of CRCA sheet (if the sheetsin 'subsequent operation are trimmed), poor surface finist{ in rough turned blanks, etc. '

may be either aeet the standardatisfy say threed due to one ors. bad surface,d a casting that

Inspection is to ve .single characteristiagainst a particulacharacteristics it ismore faults like blofaulty microstructurhas anyone or mar

Defects can broadl

Critical deJto use e.g.

ardous orunsafeetc.

Major defeof the item ifastener etc.

e or appei~rance,ssing thread ofa

The placement of defect in a particular classification varies from item to item, depending UPQ~f~rposefor which the item is designed. For example, scratch on the paint of gear box housing is a minor'defectwhile rcratch on the paint of a kitchen cabinet or dining table is a major defect. Theref6re',"whileinspecting, 'an inspecto'r must have clear understanding of the required char,flcteristics,Pel'mittedvariations, type of defects and classification of defects. .

Defect classification referred to above is utilized in acceptance sampling as under;

i) A separate sampling plan is chosen for each class of defects.

;!~!:;~.~ sampling plan for critical defects is generally tight whereas for minor defects it is comparativelylE' loose.

S..,mmary : Often 100% inspection is impracticable or uneconomical. Inspector's fatigue or repetitiveoperations ~n be serious obstacle to good 100% inspection since some defective pieces may escapewit~ the good pieces. On the contrary, the quality of the product accepted may be better with modernstatistical'acceptance sampling procedures than would be the case if the same product were subjectedtq 100% inspections.

19cePtan~decision to accept or to reject a lot is based on the inspection of a single sample, it is calledsll1gle sampling; if the decision rule requires inspection of a second sample (when the acceptance orrejection of the lot on the basis of inspection of the first sample is non conclusive), it is called doublesampling; and if the decisigD rule in which there is possibility of taking more than two samples before thefinal decision on acceptance or rejection of the lot is reached, it is called multiple sampling.

CONCEPT OF TQM

rteanin~ : TOM is nO~l{~~r()ugh the involve mem~thods in the fact tQrganization. The trqcapartments. Ensuriilyquality related PI'dpt take into consideruPon'the: services reric>tproperly evaluateMo~eover, delays inConsumers. This haremove these discreThe entire ,organizatii?to two 'categories-eanq intern.al customqepartm~nt should trusect to give shape to~mployees. Some of

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process, skill sets, systems

I Rarticipation of shop floor employees through initiatives like quality circles

)- I Improvement in interdepartmental coordination and functioning through initiatives like QITs (QualityImprovement Teams)

')0 Proper maintenance of machinery and other capital equipment through initiatives like Totalj=)roductivityManagement

SIX SIGMA AT MOTOROLA~y,L', ", " .. ' ••

'~otorola realized the importance of quality, when a Japanese firm took over Motorola's tele.visiontnanufacluring plant and was able to produce TV sets with 1120th of the defects, which were thereallrin9 Motorola management. This is when the company realized that its quality programs were not up

To ensure that emplhad spent more thapercent of the trainprinciples to desigbenchmarking progcompetitors.

Motorola initially trieemployees were notwere of no help eitdifficult because of tthe "Motorola Univspending around $1initiatives have giveand by mass custo .these six sigma qupagers, cell phones,operates.

Summary: Quality is one of the key issues, whicb define an organization'.s competitive position in themarket. Till the mid-seventies quality was only defined by perioc:1-fCmaintenance, but companies tOdayare using quality advantage as a competitive weapon against the competitors. To gain competitiveadvantage in the market through quality, organizations have adopted the total quality ma,n~ementapproach. The TQM philosophy states that maintaining' and improving quality is not just the preroga~iveof quality control department but each and every employee of an organization is equally responsible. A .clever and well-executed advertising may attract customers initi'ally, but if the prodUct supplied does not,

. • Imatch customer's quality expectations then in all probability the customer will shift to a comp-etitor's-product. . . ' " IiQuality is conformance to requirements. A well designed and properly produced product witho~! .~~·~f'ierror may not be perceived as a quality product by the customers if it does not satisfy their requiremems·"lri .

to the mark and decided to take quality seriously to improve its competitive position in the market. BobGalvin, the then CEO of Motorola, became.an icon as he was able to improve the performance ofMotorola with his quality initiatives. As a result the company carved out a place for itself in the market asworldwide leader in quality. At the forefront of this change was the "Six Sigma" concept, which isastatistical measure of variation from expected results. Six sigma, as a quality initiative, aims at redUcingthe number of defects to 3.4 per million. In order to achieve this level of perfection, Motorola employeesrecord and analyze each and every defect that is found in any function of the production process.Another quality initiative was to reduce the 'cycle time" or the time taken to complete an operation.

Motorola's management conducts top-level meetings to review quality programs and the analysis andinferences are communicated throughout the organizations so that all levels in the organizations areaware of the quality programs. Non-executive employees participate in quality initiative\thrltlugh Motorola'sParticipative Management Program (PMP) PMPs are composed of employees working in the samearea or those who are involved in achieving the same objectives. These'teams",meet regularly toevaluate quality programs, identify problems or initiate new quality programs. In order ,to motivateemployees to performt.a~(~aving~l~chi~yedd~e to theimpr()vemenf;ih;the.qt:i~lityiS shared amongstthe employees. .' c. '. " • I,,,,,, ,'. . '.:

~1t?~!~~:~:~;e~~i~~:~~~~~~~~~h:et;~,,!b~!:C1t;:;::b~:~~jeated to qualitYissue~,,;whiCh range fron'J\;b' 'ty improvement'facturing sys~~rTlt()achieve the qualitY'~ . Motorola uses

aluate and cort\pare it§.products againstttts of other top";;'::1 e'" 'I'

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ttomup, but they realized their mien the shop.floor~~~tisticalahdot~~rtechniquesl ··.~ntrainedbosses.:'~~s,~?e~()od .thT co~ ementation' was1~~5~();1;' '~t~~bChPr?ble' any established

usa~a§Ofi:;i ecui~es" e. company was> tn~ttrajnin9,Y;aP<:J.~oca . These q'ualityy tij'~rochi~,;!J6tsWithsiz unit to 1,00,000

!;,-:'':'-,>:,'\ ~f:~i':;:~can fill the "'dfderWlthin g it. Because of".-,;_~"~,~.",, . ',,',,':'," t, ' ,- .',0' '. "'~\:':'''';::: ':.:'r"_'"",, ,'}::,:~:':',/ I'e .....!e~mpany cancl~imleadersf!)"in the':~igtl,technology field of

«>rnmuhications and has become a~eyplay~rirtother areas where it , .

LI'r>: ,,), ','i,trh~r~aLeeight differeht.quality dimensions that a company can leverage to gain competitive advantage.i!!~Jheyare performance, features, reliability. conformance. durability, serviceability, aesthetics and perceived

'lqualit}/.,Random samples. statistical control charts and acceptance plans are some of the tools that are.;,!~seqJor,quality control.

'1

,:Col1trol~.harts are used tofind out if the quality of the product is within acceptable limits. The p chart is,~sedtQ control the percentage of defectives in the sample. X and R charts are used to control sample

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i.roeans~nd sample ranges. Average outgoing quality (AOO) curves and operating characteristics (OC)·curve~ explain the workings of acceptance plans.

For a service organization. the quality can be judged only through the feedback from the customers.