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QUALITYCONTRO

L

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It is a relative term, used with reference to the end use of the product.

The word Quality have variety of meanings:- Fitness of purpose

Grade

Degree of preference

Degree of excellence Fulfillment of the promise

Quality

Quality ofdesign

Quality ofconformance

Quality ofperformance

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Concerned with the tightness of specification for the manufacture ofthe product.

Factors controlling the quality of design:-

Type of customers in the market Intended life, environmental conditions, reliability, importance of continuity of

services.

Profit considerations

Special requirement of the product such as strength, fatigue resistance, life, etc.

Economic considerations and feasibility.

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Concerned with how well the manufactured product conforms to qualityof design.

Important factors:- Adequate quality and proper maintenance of raw material, machines, tools, measuring

instruments.

Selection of proper process and there should be adequate process control duringmanufacturing.

Operators should be well trained and experienced

Proper care for shipment and storage of finished goods

Properly planned inspection programme.

QUALITY OF PERFORMANCE Concerned how well the manufactured product gives its performance.

It depends upon:- Quality of Design

Quality of Conformance.

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It is a systematic control of various factors that affect the quality ofthe product like material, tools, labor, working conditions, etc.

The entire collection of activitieswhich ensures that the operationwill produce the optimum quality of product at minimum cost.

As the tools, devices or skills through which qualities activities arecarried out.

Itsa name of the departmentwhich devotes itself full time to qualityfunctions.

System, plan or method to solve quality problems.

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Give assurance the only good quality products are sent to thecustomers.

Standardizations of products according to quality specifications.

Try to curtail the effective over all cost by controlling the process and

reducing waste and scraps. To bring hidden costs (idleness) to picture.

To bring the concept ofinterchangeability in the products.

To rehabilitate the rejected products, if possible.

Determine a way-out of manufacturing difficulties.

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It is a graphical representation of the collected information.

Information may be pertain to measured characteristics.

It detects the variation in processing and warns if there is any departurefrom the specified tolerance limits.

In others words, control chart is:- A device which specifies the state of statistical control

A device for attaining statistical control, and

A device to judge whether statistical control is attained or not.

Control charts

Control chart forvariables

X chart, R chart,O Chart

Control chart forattributes

P chart, nPchart, C chartand U chart

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X bar and R or X bar and Sigma charts are used in combination for thecontrol process.

X bar chart shows the centering of the process i.e. it shows the average ofthe samples.

R chart shows the uniformity or consistency of the process i.e. it showsthe variations in the ranges of the samples.

Sigma chart shows the variation in the process. Control charts are used to determine whether a given process can meet

the existing specifications without a fundamental change in productionprocess.

To secure information to be used in establishing or changingproduction process.

To secure information when it is necessary to widen the tolerance. To secure information to be used in establishing or changing

inspection procedure or acceptance procedure or both. To provide the basis for current decisions on acceptance or rejection of

manufactured or purchased part.

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1) Calculate the average X and range R for each sub group:-

X = X1+X2+X3+X4+X5/5

R = Highest Value Smallest Value

2) Calculate the grand average X and average range R .

X = X / N ( X = Average of averages)

R = R/N

3) Calculation of 3 Sigma limits on control chart X chart.

Upper control Limit X = X + 3 XLower control Limit X = X 3 X

where,

X = standard deviation of the averages = / n

n = sample size

= standard deviation of the universe

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Calculate 3 Sigma control limits for R Chart:-

UCL R = D4R or D2

LCL R = D3R or D1

Plot the X and R chart :-

X chart, the central line should be solid horizontal line. The upper and lower limits line should horizontal dotted lines at the computed

values.

In R chart central line will indicate R

control limits will be shown by dotted horizontal lines at computed values

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X-BAR AND R CONTROL CHARTS

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Control chart for the fraction defective is called as P chart.

Fraction Defective : Ratio of the number of defective articles in anyinspection to the total number of articles actually inspected.

Fraction defective is always expressed as a decimal fraction.

P-chart may be applied to quality characteristics.

Central Line for P chart, P = Number of defective articles/Totalnumber of

articles inspected.

Control Limits for P chart are:-

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Record the date for each sub group on number inspected and numbersdefectives.

Compute p ( Fraction defective) for each subgroup.

p= Number of defective in subgroup = np/n

Total number inspected in subgroup Compute p, the average fraction defective.

p = Total number of defectives during a period

Total number inspected during period

Compute trial control limits.Central line = p

Plot each point as obtained, plot trial control limits as soon ascalculated.

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If subgroup size is constant, the chart for actual number of defectives,known as np chart is used.

When subgroup size is constant, np chart preferred over p chart:- Saves one calculation for each subgroup, the division of number of defectives by sub

grouping size to get fraction defective p.

Some people may understand the np chart more readily.

Control limits:- p = np/n

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Applies to the number of defects in a sub-group of constant size.

C = Total number of defects/ Number of sub-groups

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When the subgroup size varies from sample to sample.

The control line of the u chart will however vary.

The larger the number of units in a sample, narrower the limits.

U= C/n= Number of defects in a sample/Number of units in a sample.

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VARIABLE CHARTS ATTRIBUTES CHARTS

1. Examples: X, R , charts P, np, C, u charts

2.Type of data required:- Variables data (Measured values of characteristics)

Attribute data ( Using Go-No-Go gauges)

3. Field of Applications: Control of individualcharacteristics

Control of proportion of defectives or numberof defects or number of defects per unit.

4. Advantages:-a). Provides maximum utilization ofinformation available from data.b). Provides detail information on processaverage and variation for control ofindividual dimensions.

a). Data required are often already availablefrom inspection records.b). Easily understood by all persons. As moreeasier den X bar and R charts.c). It provides over all picture of qualityhistory.

5. Disadvantages:-

a). Not easily understood till training is notprovided.b). Can cause confusion between controllimits and specification limits.c). Cannot be used with go-on-go typegauge inspection.

a). They do not provide detail information for

control of individual characteristics.b). They do no recognize different degrees ofdefectiveness. ( weightage of defects).

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If all the points in a chart lie within UCL and LCL , then the processis said to be in control indicating presence of chance causes only.

If one or more points lie beyond UCL and LCL, then the process is

said to be out of control showing the presence of assignable caused andnecessity of some remedial measures.

If points lie predominantly on one side of the central line then itis not safe to derive any conclusion about the process control.

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In coming materials ( Attributes or variable charts)

For studying tool wear ( Variables charts)

Manufacture components like pistons, shafts, spindles, balls,pins, holes, slots, etc. ( Variable charts)

Final assemblies like automobiles, televisions, etc. ( attributescharts)

Bullets and shells ( attributes charts)

Defects in components made of glass ( attributes chart)

Range and complex products like bomber engine, turbines, etc.( attributes charts).

Punch press works, forming, spot welding, etc. ( attributes charts)

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Its a process of evaluating a portion of the product/material in alot for the purpose of accepting or rejecting the lot as eitherconforming or not conforming to a quality specifications.

2 ways in which inspections is carried out:-

100 % inspection Sampling inspection

100 % inspection all the parts or products are subjected to inspection

Sampling inspection only a sample is drawn from the lot andinspected, if the sample is good enough the lot is accepted otherwise

entire lot is rejected. Sampling inspection is more practical, quick and economical.

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The cost and time required for sampling inspection is quite less.

Problem of inspection fatigue which occurs in 100% inspection iseliminated.

Smaller inspection staff is sufficient.

Less damage to the products as only few items are subjected tohandling during inspection.

The problem of monotony and inspector error are minimized.

The lot is disposed of in shorter time so that scheduling and deliveryare improved.

It exerts more effective pressure on quality improvement. Since, therejection of entire lot on the basis of sample.

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May not always represent the exact picture as only part is inspected.

Likelihood of making wrong decision in 2 ways :- A really good lot may be rejected because of sample drawn may be bad.

A really bad lot may be accepted because sample drawn may be good.

In the first case producer has to suffer the risk, associated risk is calledas producer risk.

In the latter case, consumer runs a risk of accepting bad lots, associatedrisk is called as consumers risk.

Success of sampling scheme depends upon:- Randomness of samples.

Sample size

Quality characteristic to be tested.

Acceptance criteria

Lot size.

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For an attribute sampling plan is a graph of fraction defective in a lotagainst the probability of acceptance.

For a fraction defective p in a submitted lot, the OC curve shows theprobability Pa that such a lot will be accepted by the sampling plan.

There are 3 parameters :- N= Lot size from which the samples are drawn

n= Sample size

C = Acceptance number

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Producers risk

Consumers risk

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Sampling plans may be grouped in 3 categories:- Single sampling plans

Double sampling plans

Multiple sampling plans

In Single sampling plan 3 numbers are specified:-

N = lot size from which the sample is drawn n = sample size

c = acceptance number

Eg. N = 50, n = 5, c = 1 Take a sample of 5 items from a lot of 50, if the sample contains more than 1 defective

reject the lot, otherwise accept the lot.

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Inspect thesample of n

pieces

If the

number of

defectives

Does not

exceed c

Accept the

lot

Exceed c

Reject the

lot

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Double sampling plan:- The decision of acceptance or rejection of lot is based on 2 samples.

A lot may be accepted at once if the first sample is good enough or rejected at once ifthe first sample is bad enough.

If the first sample is neither good nor bad enough, the decision is based on theevidence of the first sample and second sample combined.

Parameters:-

n1=Number of pieces in the first sample

c1= acceptance number of the first sample

n2 = number of pieces in the second sample

n1+ n2=number of pieces in the two samples combined

c2= acceptance number for the 2 samples combined.

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Inspect the n1 pieces

If the no. of defectives

Doesnt

exceed C1

Accept the

lot

C1

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Multiple Sampling Plan:- It is generally used when three or more samples of stated size are permitted and

when the decision on acceptance or rejection must be reached after a stated numberof samples.

Phrase sequential sampling is generally used when a decision is possible after eachitem is inspected and when there is no specified limit on total number of units to be

inspected.COMBINED SAMPLES

Sample Samplesize

Size Acceptance number

Rejectionnumber

First n1 n1 c1 r1

Second n2 n1+n2 c2 r2

Third n3 n1+n2+n3 c3 r3

Fourth n4 n1+ n2+n3+n4 c4 r4

Fifth n5 n1+n2+n3+n4+n5 c5 r5

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Total quality control:- Effective system of integrating quality maintenance and quality improvement efforts of the

various groups in the organization, so as to enable production and services at the mosteconomical levels, which allow full customers satisfaction.

Stress on prevention of defects rather than setting it right by rectification.

Total quality can be achieved only through total Employee Improvement.

Total quality function includes:- Development of product specifications based on needs of users and economical

considerations. Interaction with product design

Reliability and development testing

Process capability studies Quality planning for control of production process

Quality control for incoming material Vendor quality control and vendor development

Interaction with service engineering

Training of staff and customers Quality audit, etc.

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COMPREHENSION

COMMITMENT

COMPETENCE COMMUNICATION

CORRECTION

CONTINUANCE

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Challenges faced by business in todays time:- Increase in product complexity and size of operations

Stiff competition at national and international levels.

Survival of the fittestis the slogan now the company follow to stayin business.

3 main pillars :- Consumer awareness

National and international legislations

To strive for excellence and grow in business responsibility for product quality hasshifted from operator to foreman to inspector to quality control deptt. and later on toQuality Management.

Can survive the fierce competition if it paid attention to plan, achieve,maintain and improve quality constantly to meet new challenges.

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Business

Environmental concern

Nationaland

internation

al eco.

Cost ofmanageme

nt

Technicalinnovations

Staffexpectation

s

Nationaland

internation

alcompetition

Interest ofshareholder

s

Nationaland

internation

al

legislations

Customersatisfaction

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TQM is an integrated organizational approach in delighting customers(both external and internal) by meeting their expectations on acontinuous basis through everyone involved with the organizational working on continuous improvement in all products/processes alongwith proper problem solving methodology.

TO DELIVER HIGHEST VALUE AT LOWEST COST is the mainobjective of TQM

It was first released in Japan.

It is a organization wide quality focused culture. It is a system approach to quality management and a journey to achieve

excellence in all aspects oforganizations activity.

The launching of ISO : 9000 series standards is an attempt to help theindustrial organizations in adopting TQM

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Total - The responsibility for achieving Quality rests with everyone abusiness no matter what their function. It recognises the necessity todevelop processes across the business, that together lead to the reliabledelivery of exact, agreed customer requirements. This will achieve themost competitive cost position and a higher return on investment.

Quality- The prime task of any business is to understand the needs ofthe customer, then deliver the product or service at the agreed time,place and price, on every occasion. This will retain current customers,assist in acquiring new ones and lead to a subsequent increase inmarket share.

Management - Top management lead the drive to achieve quality forcustomers, by communicating the business vision and values to allemployees; ensuring the right business processes are in place;introducing and maintaining a continuous improvement culture.

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As per Prof. Leopald S. Vasin, TQM is the control of alltransformation processes of an organization to best satisfycustomersneeds in the most economical manner.

TQM is a management approach of organization, centered on quality,based on the participation of all its members and aiming at long term

success through customer satisfaction and benefits to the members oforganization and society. (ISO : 8402/IS 13999)

As per Sashkin and Kiser, TQM may be defined as creating anorganizational culture committed to the continuous improvement ofskills, teamwork, processes, product and service quality and customer

satisfaction. As per Atkinson, As a strategic approach to produce the best

product and services possible though constant innovation.

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Objective:- Continuous quality improvement at every stage, at everyplace and at every level.

Approach:- management involvement and leadership, empoweringstaff, team work and action research.

Scale:- every one working in the organization is involved includingsuppliers and customers.

Standard :- Do it Right First Time EveryTime.

Measure:- Customers satisfaction internal and external.

Philosophy:- Prevention of defects not detection and then correction

Tools:- Commitment, participation, motivation, education andtraining, organization development, quality system.

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Customer Satisfaction (Internal and External):- TQM aims atsatisfying the customers requirement which never remain constant butkeep on changing with the change in times, environmentalcircumstances, needs, fashions, standard of living, etc. Suitability (Fitness for use)

Reliability ( It should give efficient and consistent performance) Durability, the life aspect of quality

Safe and foolproof workability - Affordability

Maintainability - value of money spent by customers

Aesthetic look - Good image and customer confidence

Good packaging

Versatility ( Can serve number of purposes)

Variety in products and services

After sales service and support to customer

Customer information and demonstration

Speed of service ( quick response time)

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Do it right first time:- TQM adopts the zero defect policy. Rigorous application of EPDCA approach i.e. Evaluate Plan Do Check Act

Continuous Improvement:- Organization has to cope up with the changing requirements of the customers.

TQM strives for ever better quality, cost reduction to face competition and for thesurvival of the organization.

Employee Involvement:- All employees working in the organization should be involved in TQM operation. Requires every member of the organization to accept quality as his major area of

responsibility.

A positive attitude towards customer and constant enhancement of quality must beingrained in the minds of employees.

Empowering the Staff:- Assist to accomplish optimal business results through team work. Empowerment occurs when employees are adequately trained, with relevant

information and best possible tools and are fairly rewarded for best results. Result of empowerment, creativity, productivity, motivation, commitment and

customer service.

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Bench Marking:- Its the practice of identifying, studying and building upon the best practices in the

industry or the world.

Companies keeps on updating themselves regarding external environment tocompare their process, products and services with best industry practices.

Establish quality targets which enhances the competitive strength.

Feedback Mechanism:- Customer feedback and employee feedback, to create customer oriented quality

culture

Provide an accurate evaluation of operations of the company, internal and external.

Information can be collected through questionnaire surveys, interviews, use of focus

groups and field complaints , suggestion systems etc.

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W.E. Deming, father of TQM, suggested PLAN-DO-CHECK-ACT cyclefor the implementation of the TQM in any organization.

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A. Advantages unique to TQM:-a) It makes the company a leader not the follower.

b) Creates goal directed connection between customer, management and workers.c) Makes company more sensitive to customer needs.

d) Makes company adopts more readily to change.

B. Benefits to Customers:-a) Fewer problems with product or services.

b) Better customer care.c) Greater satisfaction

Unique Advantagesof TQM Customers

Company Staff

Benefits

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C. Benefits to the Company:-a) Better product qualityb) Staff more motivated and quality consciousc) Product improvementd) Reduced quality costs.e) Increased market.

f) Increased competitive position of the firm, improved profitability.g) Good public imageh) Improved human relation and work area morale

D. Benefits to Staff:-a) Empowermentb) Enhancement of job interest and security

c) More training and improvement in skillsd) More recognitione) Reduced employee grievances.