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Mechanical engineering

EME- 041

Total quality management.LT-10

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Computer science engineering

EOE-072

Quality management.LT-12

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Quality Concept

Evolution of Quality Control

Concept Change

TQM (Modern Concept)

Quality Concept in Design

Review of Design

Evolution of Prototype

Unit 1

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Control on Purchase Product

Procurement of various products

Evaluation of supplies

Capacity Verification

Development of Sources

Procurement Procedure

Manufacturing Quality

Methods and techniques for manufacture

Inspection and control of product

Quality in Sales and Services

Guarantee

Analysis of Claims4


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Generally, when referring to a product, qualitysignifies the degree of its excellence. However,when examined closely, this meaning of quality is

found to be misleading.Limo or a Mercedes or a BMW may be an excellent car

in Europe or America, but its obviously a poor choicefor use in the jungle track of Africa and India.

Similarly, a good walking shoes are not a good option forrunning shoes.

According to IBM Quality equals customer

satisfaction

Thus, there can be no absolute quality rating fora product, without relation to its intended use.

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Quality is the conformance to requirements or

specification.

OR

Quality is fitness for use.

OR

The Quality of a product or service is the fitness ofthat product or service for meeting or exceeding its

intended use as required by the customer.

THE TERM QUALITY IMPLIES DIFFERENT

LEVELS OF EXPECTATIONS FOR

DIFFERENT GROUPS OF CUSTOMERS 6


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Quality CharacteristicsThe quality of a product consists of a number ofelements, each of which has a unique function thatcontributes to making the product fit for itsintended use. The intended quality level of a productor service and the elements are known as

QUALITY CHARACTERISTICS. Following are the building blocks of product quality: Structural Characteristics includes such elements as the length of a

part, the weight of a can, the strength of beam, the viscosity of a fluid

and so on. Sensory characteristics include the taste of good food, the smell of a

sweet fragrance, and the beauty of a model, etc.

Time oriented characteristics include such measures as a warranty,reliability and maintainability.

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Quality Control

Quality control involves operational techniques and

activities aimed both at monitoring and eliminating

causes of unsatisfactory performance at relevant stages

of the quality loop in order to result in economic

effectiveness.

Quality control denotes all those activities which aredirected for maintaining and improving, specifically;

Setting of quality targets

Appraisal of conformanceTaking corrective action where any deviation is noticed

Planning for improvement in quality

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Evolution of Quality Control

Quality of goods and service products has beenmonitored, either directly or indirectly since timeimmemorial. However, using a quantitative baseinvolving statistical principles to control quality is amodern concept.

This quality concept is not new. If we traced back tothe stone age man who examined the point of hisrough hewn stone to see whether it was sharpenough for his purpose.

Our stone age man had one distinct advantage overthe present day quality engineer; since he himselfwas the manufacturer as well as user, he knew

exactly what he wanted and thus made efforts to 9


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attain the quality which would meet his purpose.

This situation changed with social progress.

Egyptians demonstrated a commitment to quality in

the construction of their pyramids.

Greeks set high standards in arts and crafts. The

quality of Greek architecture of the fifth century

B.C. was so envied that it profoundly affected the

subsequent architectural constructions of Rome.

Roman built cities, churches, bridges and roads

inspired by Greeks even today.

Japan although totally destroyed during world war

II. When W. Edwards Damming visited Japan and

lectured on new ideas in 1950, Japanese engineers10


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and top management were convinced of the

importance of statistical quality control as a means

of gaining a competitive edge in the world market.

Subsequently J.M. JURAN, another pioneer in

quality control, visited Japan in 1954 and further

impressed upon them the strategic role that

management plays in the achievement of a qualityprogram. The Japanese were quick to realize the

profound effects that these principles would have on

the future business, and they made a strongcommitment to a massive program of training and

education.

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Changing Quality Concept

In 1974, functional efficiency and aesthetic appeal

are the main factors governing products quality.

After world war II, new technologies and

innovations were made in reference to product

quality. It has been realized that there is more to anyproduct than streamlined appearance and ability to

function well at the time of purchase.

There are attributes such as continued fault freeservice and maintenance costs which are equally

important from the customers point of view.

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The following characteristics constitute quality

satisfaction :

Functional efficiency

Appearance

Ease of installation and operation

Safety

Reliability

Maintainability

Running and Maintenance Cost

The above mentioned quality features do not just occur

in the product. They have to be specially incorporated

in the design and a conscious effort is required during

manufacturing, to achieve them in the actual practice.13


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Total Quality Management (The modern concept)

It has been realized that inspection alone cannot be

build quality into a product unless quality has beendesigned and manufactured into it. Therefore, quality

awareness must begin at the very conception of the

product and continue during the various stages of its

development and manufacture and even during itsusage, to provide feed-back from the users which is

very essential for quality improvement.

Total quality management deals with the productin its totality. It has been recognized that quality is

determined by the combined efforts of various

departments such as Design, Engineering, Purchase,

Production, and Inspection. 14


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The Total quality management (TQM) is a set ofsystematic activities carried out by the entireorganization to effectively and efficiently achieve

company objectives so as to provide products andservices with a level of quality that satisfiescustomers, at the appropriate time and price.

Quality Activities

1. Concept

2. Development

3. Process Planning

4. Material Procurement

5. Production

6. Usage and maintenance15


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Concept1. Market research to study user needs and preferences.

2. Analysis of customer complaints of existing product.

3. Study of competitive product quality.

4. Formulation of qualitative requirements of the newproduct.

Development1. Review of prototype design and value analysis to see

that it meets users requirement at minimum cost.

2. Qualification testing of prototype to assess itsfunctional efficiency, reliability and maintainability.

3. Review of manufacturing drawings for producibility,interchangeability of components and

standardization. 16


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Process Planning1. Process planning and conduct of process capability studies.

2. Design and tooling and process control instrumentation.

3. Formulation of quality standards for complete equipmentand assemblies.

4. Preparation of procurement specification for materials andbought out components.

5. Formulation of inspection procedures.

6. Design/procurement of special test equipments

Material Procurement

1. Capacity verification of vendors.2. Incorporation of quality requirements in purchase orders.

3. Surveillance of quality at vendors works.

4. Quality assurance of incoming material

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Production1. Operation of process control and data feed back for

improvement.

2. Process surveillance and inspection/testing ofproduct.

3. Investigation of defects and causes of out of controlprocess.

4. Analysis of quality data for improvement in theprocess products.

Usage and Maintenance

1. Technical advice for proper operation andmaintenance.

2. Performance feed back on reliability.

3. Failure analysis. 18

TQM l d th i th (F t f


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TQM revolves around three main themes (Features ofTQM):

1. The customer

2. The process3. The people

Every employee should understand the companysvision and mission so that individual efforts will

contribute to the organizational mission. Another core value in the TQM model is management

commitment. It must exist at all levels for the companyto succeed in implementing TQM.

Top management envisions the strategy and createspolicy.

Middle management works on implementation.

At the operational level, appropriate quality

management tools and techniques are used. 19


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Satisfying customer needs and expectations is a

major theme in TQM, in fact it is the driving

force. Without satisfied customers, market share

will not grow, and revenue will not increase.

Management should not second class the customers.

A Key Principle in quality programs is that

customers are both internal and external. The

receiving department of a processed component is

a customer of that processing unit. Feedback from

such internal customers identifies problem areasbefore the product reaches its finished stage, thus

reducing the cost of scrap and rework.

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Gap Analysis


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Gap Analysis

Taking measures to eliminate discrepancies is known asgap analysis.

Customer surveys can help management determinediscrepancies between expectations and satisfaction.

Empowerment

Involving employees in the decision making process so

that they take ownership of their work and of theprocess - is key in TQM.

It is individuals who find better ways to do a job, andthis is high source of pride. With pride comes

motivation. There is a sense of pride in making things better

through the elimination of redundant or non-valueadded tasks.

In TQM, managing is EMPOWERING 21

Th t ll i t d ith th d fi iti


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Three aspects are usually associated with the definitionof quality; they are:

1. Quality concept of design

2. Quality concept of conformance and3. Quality concept of performance

Quality concept of design

Design is the basic function for the creation of productquality. Unless quality is designed into product, itcannot be achieved during manufacturing.

The prime aim of designer is to create a product that

will satisfy a customers need at a price which he iswilling to pay. In a competitive market, the designerhave to keep on striving for higher and higher qualitylevels if their companies are to remain in business.

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Q lit f d i i i fl d b


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Quality of design is influenced by

Appearance


Safety

Reliability

Maintainability

Ease of productionStandardization

Review of design

Evaluation of the prototypePreparation of manufacturing drawing

Formulation of production specification

Design changes during production 23

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Appearance

To the down to earth man, practical minded person,appearance may not be of much importance as long as a

product works, but the designer should keep in mind thenormal reaction of an average customer when stylingthe external shape and finish.

It should remembered that first contact of the product

with the prospective customer is through its shape andfinish, including that ofits packing.

At the same time, overemphasis on the shape and finishis also not desirable, as it increases the cost. The stylingand finish of the product should be compatible with itsfunction.

Generally, sharp lines, corners and abrupt changes

of contour should be avoided in the external shapes.24



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Next to the out-ward appearance, functionalperformance is the only characteristics which a

customer looks for in a product at the time of purchase.Safety

Safety is a requirement of which the user is notnormally aware of, until the lack of it is proved to himby an accident causing damage or injury.

All power-operated machines and equipments shouldhave built-in safety devices and should be designed on

fail-safe principle, i.e. when any failure of theequipment occurs it should automatically be brought tosafe condition.

Attention to the minor details of safety feature during

design can considerably reduce the accident rate. 25

Reliability


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Reliability

Any device or equipment should not only functionwhen it is sold, but it should continue to function

satisfactorily during its intended life. This ability ofcontinued functioning is called reliability.

Unfortunately, reliability cannot be readily checked ormeasured at the time of purchase, yet nothing is more

frustrating to the user than an equipment or appliancewhich is unreliable.

The lesser the number of integral components the lesserwill be the chances of any one of them failing and themore reliable will be the equipment.

The designer has therefore to keep the number ofcomponents to a minimum, and use only components

with proved reliability. 26

Maintenance


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Maintenance

The equipment should be so designed that when afailure does take place it can easily be repaired and put

back into service.Ease of production

However, excellent a design may be, it may not bepossible to exploit it, if cannot be easily manufacturedat a reasonable cost.

Any design basically consists of a number ofcomponents which are grouped in sub-assemblies and

assemblies to form the complete equipment. While the detailed design of individual components is

being prepared, a thought should be given to the processby which the component will be manufactured during

bulk production. 27

Standardization


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Standardization

This is a discipline, whose potentialities have beenrealized only lately.

A substantial improvement in quality and economy canbe achieved if this aspect is given due considerationduring design.

Review of design

Before the primary design has progressed further, itshould be subjected to a critical review by all those whoare connected with the product, such as qualityengineers, production engineers and sales personnel.

The design engineer could explain the salient featuresof the design with the help of mockup model. Duringthis review, each functional representative should beallowed to comment on the design from his point orview.

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The quality engineer for instance could highlight the


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The quality engineer for instance, could highlight thequality problems which were faced in the similarprevious product during manufacture.

Similarly, the production man may be able to visualizethe manufacturing problems, such as non-availability ofa machine or processing equipment with the standard ofaccuracy desired in the design.

In the same way, the sales manager may be able to give

the customer reaction on the features provided in thedesign.

Such a review may make some changes in the designdesirable. These changes or modifications can be

incorporated at the early stages when the design is onthe drawing-board. At a later stage, major changes indesign are very difficult and may upset the entire timeschedule.

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E al ation of the protot pe


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Evaluation of the prototype

Evaluation of the final product is being done to check,

weather the output meets the customers requirement or

not and if not then appropriates steps is being taken toremove flaws and make the product up to mark.

The evaluation of the prototype should be carried out

according to a well-planed evaluation programme,which should clearly lay down aspect to be studied and

specific points on which information is required.

It is advisable that evaluation programme becoordinated by an agency different from the designer, so

that objective of evaluation can be maintained.

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Preparation of manufacturing drawing


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Preparation of manufacturing drawing

This is one of the most tedious and difficult phasesof design, yet quality literally depends upon the

correctness and completeness of the manufacturingdrawings and specifications, because the productionagencies manufacture the product according tothese documents.

If there is any inaccuracy in the drawings, it willobviously be reflected in the product, since themanufacturers take guidance from the drawings and

not from the approved prototype. Therefore, it is obvious that the drawing truly reflect

the final design as it has emerged after evaluationstudies.

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Specification is an important quality document forthe product because it is here that quality of the

product as a whole is defined in precise technicalterms.

The specification forms the basis for all trade

enquires for achieved in the bulk production.Design changes during production

Even when the design has been released forproduction, it cannot be considered to be absolutelyfinal, requiring no further changes.

Certain problems may be faced during productionwhich may call for changes in design.

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However before these changes are approved their


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However, before these changes are approved, theirimplication and effect on quality parameters should bethoroughly gone into by the design and qualityengineering departments.

Once it is decided to incorporate the design changes,necessary amendments should be carried out in all theaffected drawings and specifications.

Generally, whenever any drawing is amended, the

amended copies of the drawing are issued to theconcerned sections, who are asked to return the oldcopies to the design office.

A number of quality problems arises where there is no

proper system of the updating of drawings. The production operator may continue to carry out

machining operations as per the old drawings whichhave since been amended and the discrepancy may be

revealed only in assembly or in final inspection. 33

Product development cycle


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Product development cycle

The product development cycle starts with theassessment of the customers needs and ends when the

design is finally released for bulk production. The mainsteps in the development cycle are listed below:

1. Market survey and analysis ofcustomers needs

2. Formulation of design specification

3. Preliminary design of the product

4. Design review

5. Preparation of the manufacturing drawings and

product specifications6. Manufacture and evaluation of the prototype

7. Pilot production run and adjustment of the design

8. Release of design for bulk production 34

Quality concept of conformance


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Quality concept of conformance

Quality of conformance implies that the

manufactured product must meet the standards

selected in the design phase.

Quality concept of performance

Quality of performance is concerned with how well

the product functions or service performs when put

to use.

It measures the degree to which the product or

service satisfies the customer.

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Control on purchased products


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Control on purchased products

Purchasing department obtains the raw materials and

components for the product from vendors.

If there is any defect in the incoming quality of the

product then an undesirable variability will occur in

the outgoing product.

Vendor quality control is under the jurisdiction of

purchase department.

Quality and cost are the two main aspects for the

selection of vendor.

Vendor selection is also a very important part and is

considered in the product design phase.36


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Another important aspect in vendor quality control involvesdeveloping a long term relationship with a few high-qualityvendors.

This practice have been extensively followed in Japan and hasseveral advantages for both parties.

i.e.

1. Company does not have to go through the vendor selectionprocess again and again. This will save both time and money.

2. Good relations enables the company to depend on the vendorwhen demand for the companys product is uncertain. In

peak demand period company will get adequate raw materialfrom the vendor at short notice also.

3. From vendor point of view, mutual trust is extremelydesirable. In case of an occasional poor shipment, the vendorknows that his contract will not be terminated right away.

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Quality advice on the product to be purchased


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Quality advice on the product to be purchased

Procurement of traditional items

Traditional items are the raw materials which the

company uses for a long continuous time. If a company

needs to obtain, traditional items the company first sends

the requirement to the quality control department to get

the item quality checked and optimized so that the bestproduct reaches to the final customer because day by day

the technology is advancing itself.

Basic need of the quality department is to be more

efficient and accurate, innovations and proper latest upgradation must be done to reach the actual goal.

Time to time review is to be done so that the department

can update itself with latest technology.38

Procurement of new products


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Procurement of new products

Let us require a particular new product just launched inthe market. We come to know about the product from

advertisement, friends or internet. In that information the specification of the new product

is given in details. Before purchasing the productfollowing formalities is to be done:

Testing and procurement of the newly launched product. Comparison with the existing products in all respects.

Procurement of product as perpurchasers design

No manufacture can effort to manufacture every single

item which goes into making of his product. So, it isoften more economical to get some of the componentsas per their own design manufactured by auxiliarycompanies or subordinates.

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When auxiliary companies do the production the


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When auxiliary companies do the production, thespecification of the components is prepared by thequality control department in consultation with the

companys design engineers.Also the manufacturing facilities available with the

auxiliary industries is kept in view while finalizingthe product specifications.

Evaluation of suppliers After the product specification finalization and the

quality to be procured, next step is to locate the likelysources of supply.

Every company has its purchase department who doesthe job of maintaining the tracker or data of thesuppliers of the range of products which are interest to

the company. 40

Selection of viable sources of supply requires proper


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Selection of viable sources of supply requires properevaluation of suppliers with respect to their ability tomaintain the quality of the product at the desired

level, as well as their production capacity. Some of the data required for this evaluation may be

already available with the quality controlorganization if the firm being considered hadalready supplied the store in the past.

On account of increasing complexity of the productsand stringent specification requirements, the

selection can no longer be made on the basis oflowest quotation alone. Low price is meaningless, ifthe supplier is unable to achieve the desired qualityor maintain specified delivery schedule.

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Evaluation of the firm being considered for the first

time requires their capacity verification to be

carried out by the quality engineers of the

purchasing organization.

Final consideration, for the placement of order

should be limited to only those firms who have the

proved capacity to supply the product of required

quality and quantity.

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Capacity verification


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p y

Capacity verification mainly deals with the market analysis ofvendors production resources and his ability for their properutilization.

The necessary data is brushed up by the quality engineers ofthe company before he visits the vendors work.

Before the quality engineer of the purchasing organizationvisit the vendors works, he may be asked to furnish thenecessary data. A form is used by the organization to knownecessary information from the firm.

Preliminary study of the data furnished by the vendor mayitself indicate that the firm is not capable of executing the

order and thus rule out further consideration of the firm.

However, if the firm looks promising, the detailed study of thefirms capacity may be done by the quality engineers.

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Few questions are being placed before the investigators,


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q g p g ,some aspects are as:

1. Does the company able to fulfill the quality of productneeded by the company. Hence, sufficient amount of

place, manpower, machines etc. are needed.2. The machines should be capable to working

throughout and produce sufficient count of product.

3. The firm must have a trained, quality staff who knowshow to do capacity verification also a working qualitycontrol programme.

4. Does the company use considerable number ofcomponents purchased from trade or manufactured by

subcontractors ? If so how does the company exercisequality control on the purchased product ?

5. The sources of raw material needed by the companyhence, the question arises what are the sources of raw

materials required by the company. 44

6. Does the company have complete testing facilities for


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6. Does the company have complete testing facilities forthe product in question ? If not, what alternativearrangements can be made if pre shipment inspectionis to be carried out.

7. Has the firm execute an order of a product similar tothe one being considered. If so details of this ordermust be obtained.

8. What is the financial position and capital in themarket.

9. What are the general details and information of thecompany which reflect the ability of the firm tosuccessfully execute the order in question.

10.And, finally, we know that the attitude of the companytowards their product and staff. Hence it is also

important to have a appreciable attitude. 45

Development of Sources of production


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p p Till now, it was assumed that the product required was

already being manufactured by a number of vendorsand it was a question of choosing the most suitable

supplier amongst them. This, by no means is the normal situation at least in the

developing countries like India.

Quite often the sources of production have to bedeveloped. In this case also capacity verification ofpotential supplier who show interest in the product iscarried out.

However main thing to be looked for in such case is,

whether the firm has the minimum essential plantequipment and skilled manpower?

Once these basic resources are available, manufacturingcapacity can be built up with help of technical guidance

from the purchasing organization. 46

Procurement procedure


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p

After the order is placed with the vendor company, itshould not be assumed that the purchaser has nothing

further to do with the vendor until the store startsarriving.

When the manufacturing process starts, the vendor mayrequire lot of clarification about the drawings and the

specification. It happens that the engineer may requestfor few small variation in the design to facilitate bulkproduction in his plant.

Also, he may permit the workers for use of alternativematerial due to non availability of specified material.

To clarify all these points, quality control organizationof purchasing company would have to study their effect

on the quality of the end product. 47

Manufacturing quality


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Manufacturing quality

Planning for quality

The quality of a product is initially created during

design in the form of design particulars.

However, this creation is only on paper, in the form

of manufacturing drawings and specifications.

Quality is actually built into the product during its

manufacture. The manufacture of a product requires

a host of activities involving different departments

and sections of the manufacturing organization,

having the common aim of achieving the required

quality and quantity targets.48

Planning for manufacture includes the following


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Planning for manufacture, includes the following

activities, all of which contribute towards the

achievement of quality targets.

1. Selection of processes, machines and tools

2. Process planning

3. Design and procurement of jigs, tools and

measuring instruments

4. Planning of process quality controls

5. Planning the quality control in incoming materials6. Planning of the quality appraisal of the final

product

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Process capability


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p y

Process capability represents the performance of aprocess.

With such a multiplicity of processes available for a job,the selection of an appropriate process is not an easymatter.

Choosing a process with over-capacity is as bad aschoosing one with under capability, because an overcapable process will generally be more expensive andwill needlessly increase the production cost.

On the other hand, a process with less than requiredcapability will not meet the quality requirement and

may lead to excessive rejection and rework, whichagain will attract additional cost.

Therefore, from the economic considerations, we mustselect a process whose capability matches the quality

requirement of the job. 50

Process selection


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Once the process capabilities of available process are

known, the process selection is then just a question of

matching the process capability with the tolerancespecified for the job.

As a result of the process capability analysis of

available processes, it may be revealed that more thanone process is capable of meeting the quality

requirements of the product. In such cases further

selection will depend upon other factors such as

economics of production and availability of the

machines or processes.

Sometimes, it may happen that none of the available

machines may be able to meet the required tolerances.51

In that case, a decision is required to be taken at the


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, qappropriate level, whether to install a new machinecapable of the meeting the quality requirements, orutilize the existing machine, even though some of theproducts manufactured on that machine are not likely tomeet the quality standards and will have to be scrapped.

In latter case, 100% sorting inspection will be required

to separate the defective parts, so that the quality of theoutgoing stores can be maintained at an acceptablelevel.

Although it is not an entirely satisfactory quality

situation, as some of the defective products may stillslip through inspection and result in customercomplaints, it may have to be accepted, particularly ifthe proposed new machine is too expensive or the batch

size is relatively small. 52

Process control


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All processes are subject to various influences such asmechanical, electrical and environmental changes, which tendto deviate the process from its initial setting.

The process control aims to regulate the process to counteractthese changes, so that the process quality remains withinacceptable limits.

The modern high speed processes are simply not economical,unless they remain under control. A process going out ofcontrol may result in the production of a large number ofdefective pieces before it is detected, which may result inconsiderable loss, besides upsetting the production schedule.

Therefore, it is imperative that effective control systems bedevised, which are able to detect the deviation in the processat the earliest possible moment, so that corrective measurescan be applied before an appreciable quantity of defective

work is produced. 53

The effectiveness of a process control system dependsh d d i h hi h h i


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p y pupon the accuracy and speed with which the variouselements of control functions are carried out. Anindication of the effectiveness of a control system is

provided by its reaction time.i.e. the time interval between the occurrence of adeviation and the application of corrective action.

The reaction time of a process control system can be

reduced by employing efficient detection and analysistechniques and by keeping the feed back loop as shortas possible.

Short loop can be achieved by installing the inspection

or other process monitoring systems at the productionpoint itself. It has not only the advantage of shortreaction time, but also of generating quality awarenessin the production operators, who see for themselves, the

results of process changes. 54

Process control Techniques


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1. Self check

This is the simplest of control technique and has been in usesince the dawn of civilization. As any job or the operation is

complete, the operator himself carries out the check ofimportant quality parameters.

The check may be visual, or with the aid of simple gauges orinstruments.

A mason checking the face of a wall with a plumb-line or acarpenter checking the joinery pieces with a carpenters ruleare examples of this control technique.

Even with the advancement of technology these simplecontrol techniques have not lost their utility. This can still be

effectively employed in relatively simple and low productionrate processes.

Its main advantage is simplicity and short reaction time.Further no additional staff is required for inspection jobs.

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2. Spot check

This is another of the simpler techniques, where

rather than checking every piece, a few pieces are

checked occasionally to ensure that the product

conforms to the specified quality.

The spot check may be carried out by shop

supervisor.

This control technique is generally used for non-

precision processes giving relatively low variability

such as press work and die-casting.

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3. Stage inspector


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Stage or in-process inspection involves inspection ofthe product after every operation.

This ensures that the defective product is revealed atthe earliest stage, thereby avoiding extra expenditureon the further processing of defective components.

Stage inspection points are located on the shop flooritself, where the semi finished components aretendered to the inspection staff after every importantstage of processing.

During stage inspection, the relevant features of theproduct are inspected as per drawing specification and

only acceptable pieces are released for furtherprocessing.

Those jobs which are not found acceptable, arereturned for rectification if they are rectifiable

otherwise they are scrapped. 57

Stage inspection is used for critical items or for thoseh th i h t i bilit i l ti l


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processes where the inherent variability is relativelyhigh.

However, this method of process control is rather

expensive and time consuming and is definitely notsuitable for the process with a production rate.

Statistical process control technique

Statistical method of process control have beendeveloped only in last few decades to meet the needs ofcomplex mass production processes.

The statistical process control technique are based onthe principle that all processes have their inherent

variability. If the pattern of this process variability canbe established, the trend of the pattern can be used topredict the process quality and apply the necessarycorrection to keep the process under control.

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The two main advantages of statistical process


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g p

control methods are:

1. They provide the information about the likelihood

of a defective job before it is actually produced.

2. It does not require physical inspection of each and

every piece to maintain a high quality level.

The above characteristics make statistical process

controls ideal for high-volume production

processes. Some of the widely used process control

techniques are listed below: Frequency distribution

Control charts

Pre-control 59

Planning process control network


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g p

The final product will comprise of a number of

components and assemblies, some of which may be

purchased items and others may be processed in the

same plant where the final product is assembled.

To ensure the satisfactory quality of the end product,

quality control should cover the various stages ofmanufacture of all components and assemblies

which are processed in the plant. In addition, it

should also cover the quality assurance of allincoming materials and components.

This will require a network of control stations

located at strategic points in the plant.60

Detailed instructions covering the integrated qualityt l t k h t b i d t th th


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control network have to be issued to ensure the smoothworking and success of the quality control programmer.These instructions should include:

1. Quality characteristics to be controlled.2. Delegation of responsibility for the control situation.

3. Procedure for the drawing of samples test pieces andmethods of checking/testing of the quality parameters.

4. Procedure for the analysis of inspection data, includingcriteria for taking decisions regarding, acceptance ofprocess/product quality.

5. Procedure for transmission of information about theprocess quality to the production point andresponsibility for carrying out process adjustment.

6. Procedure for the feed-back of information to theprocess planning and quality planning departments.

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Final inspection


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As the last step in the quality inspection ofmanufactured products, final or pre delivery inspection

is very important in ensuring that all the products are atthe required quality levels with no defects beforedelivery to the clients.

Products are not released, and processes are not

approved until all inspection and test activities havebeen satisfactorily completed and the appropriatedocumentation is available and authorized.

Final inspection consists of a verification process of

satisfactory results of all inspections and tests in the QCprocess, including in line and end of line inspections, toensure that the finished products conform to specifiedrequirements.

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Inspection planning


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Master inspection characteristics fall into twocategories:

1. Quantitative: These are inspection characteristics withunits of measurement used to capture numeric valuesto determine if the product meets certain tolerancelimits.

2. Qualitative: whether passes the quality test.Inspection and testing IQC (incoming material

control)

All incoming material, including purchased materialand suppliers products, must go through IQCprocedure before transferred to warehouse.

IQC inspection should base on IQC standards and

sampling plan. 63

Quality audit


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Quality audit is the process of systematic examination

of a quality system carried out by an internal or external

quality auditor or an audit team. It is an important part of organizations quality

management system and is a key element in the ISO

quality system standard, ISO 9001. Quality audit are typically performed at predefined time

intervals and ensure that the institution has clearly

defined internal system monitoring procedures linked to

effective action.

This can help determine if the organization complies

with the defined quality system processes and can

involve procedural or results based assessment criteria.64

Internal quality audit1 Internal quality audit includes auditing whether the quality system


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1. Internal quality audit includes auditing whether the quality systemis functioning in gear and whether the quality procedures andfunctions comply with quality policy and quality system.

2. Qc department director arranges yearly internal quality auditplans. Audit is carried out as Internal Quality Audit ControlProcedure.

3. Internal quality auditors are selected from each department by QCdepartment director. They should accept internal quality audittraining and have no direct relationship/responsibility with theaudit department.

4. The audit time, audit department and audit programs are carriedout according to the yearly internal audit plan.

5. Auditors should record audit data and have the responsible

department rectify the deviation.6. Corrective actions should indicate corrective content, finish dateand person in charge and QC department is responsible formaking sure that the corrective actions have been implemented.

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Guarantee


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A guarantee is defined as a promise or assurance, especiallyone in writing, that something is of specified quality, content,

benefit, etc. or that it will perform satisfactorily for a given

length of time.Field service data

Guarantee should be based on field service and extensive testdata.

Let us consider a CFL tube with normal life range of 5000 hrsor more. It is not an intelligent move to offer guarantee of5000 hrs, even though the average life of the CFL is 6000 hrs.

When a product is guaranteed for a certain period, thecustomer expects it to function perfectly during its guaranteedlife. If the product fails earlier, he feels that it is substandard,apart from which, any failure within the guarantee period is adirect loss to the company, since free repair or replacement

has to be provided. 66

Identification of parts to be covered


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Let us suppose we have purchased a product say a

television. The thing to be observed is the company

never gives the guarantee on the separate parts rather onthe whole television. But few parts are conditional.

The company doesnt keep that internal part under that

guarantee. This is so because few parts are installed inthe product which is not manufactured by that company

rather by other company so that part doesnt comes

under the guarantee.

We can also consider the example of a Sony walkman

MP3 player. We can get the guarantee of 1 year on the

music player but no guarantee on the earphones.

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Terms of guarantee A guarantee card should include the following information


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A guarantee card should include the following information.

1. Period of validity: The coverage period of the guarantee should be such that the

customer gets more than the value of the product and thecompany gets no loss what so ever.

2. Liability of the manufacturer: Whenever any product fails under the guarantee period its the

liability of the company that the company either gives the

replacement of the product or the repairing of the damaged part.3. Procedure of submitting guarantee claims: This should include the responsibility for the dispatch of a

defective article if it is to be sent to the company or theiraccredited service station.

4. Condition which makes the guarantee invalid: The most important condition is manhandling. After that accident

also caused the guarantee turn invalid. If the product seal isbroken by any means or it was made allowed to handle by anyunauthorized agency it causes invalid guarantee.

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Analysis of claims


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Firstly the complaint reaches to the sales department

in the showroom then it is handover to the repairing

department so that the exact reason of the failure of

the product can be known and if the reason found

comes under the guarantee norms, then the product

is repaired otherwise the product is returned back tothe customer.

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