Quality –An IntroductionChandran Udumbasseri, Technical consultant

Introduction The concept of quality is linked with excellence. It is an absolute entity and either very difficult to achieve or the province of a select few.Viewed from the point of customer it is the goal of each and every business. It is the conformance to requirements. It is the product designed and works properly or it is fitness for use. There are multiple elements of fitness for use. Each of these elements is a quality characteristic, which is the fundamental building block out of which quality is constructed.a). Structural: like length, frequency, and viscosity.b). Sensory: like taste and beauty.c). Time-oriented: reliability and maintainability.d). Commercial: like warranty.e). Ethical: like courtesy and honesty.

Control and quality controlControl refers to the process employed in order to meet standards. The process consists of observing our performance, comparing this performance with some standard and then taking action if the observed performance is significantly different from the standard.

Control process involves a sequence of steps as follows:a. Choosing the control subject: i.e., choosing what we intend to regulate.b. Choosing a unit of measure.c. Setting a standard or goal for the control subject.d. Choosing a sensing device, that can measure the control subject in terms of

the unit of measure.e. Measuring actual performance.f. Interpreting the difference between actual and standard.g. Taking action on the difference.

So quality control is the process through which we measure actual quality performance, compare it with standard, and act on the difference.

This control applies to a variety of control subjects: materials, processes, products, tests, plans, decisions, etc.

Much activity is devoted to preventing quality problems from happening.

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a. Quality improvement: this is to find ways to do better than the standard.b. Quality planning: Launch new products, processes etc., in ways, which will

result in minimal need for subsequently quality improvement.

Quality task: The quality function.

The operation in any industry can be depicted as given in figure.

ServiceMaintenance Use RetailWholesale

The spiral shows that many activities must be performed to attain fitness for use.Some of these are performed within the manufacturing or service companies. Others are performed elsewhere like venders, merchants, regulators, etc. This

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collection of activities is called quality function. Some look upon the spiral or the quality function as a system i.e., a network of activities or subsystems.

The system concept

When companies grew in size the functions were departmentalized or each department became a quality function. So interdepartmental co-ordination became the most important criteria for achieving the quality objectives. So large companies introduced the system concept. Under this, managers collectively agree on quality policies as well as specific quantitative quality goals or objectives to be met. The managers plan for meeting these objectives.

Because all this co-ordination is of an interdepartmental nature, it requires the participation and agreement of the respective departmental managers. This require a great deal of analytical study it became a practice to use quality specialists to collect and analyze the pertinent data, draft proposals, and otherwise assist the managers to attain co-ordination.

Designing for quality

Modern design process involves the following steps:a. Design review to provide early warning of potential trouble.b. Design related data collection and analysis.c. Replacement of empirical ways with formalized and quantified approaches.

For modern products, attainment of fitness for use involves a balance among competing parameters and costs. The aggregation of these parameters and costs, from the inception of the design to the end of the operational life, is called the cost effectiveness. The figure given below gives the elements of cost effectiveness.

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-Readiness -Reliability -Power -Maintainability -Safety -Range -Serviceability -Survivability -Accuracy -Flexibility -Speed

-Concept studies -Number of information -Development -Production -Service -Repair -Training

For a product typical phases are design concept, feasibility, and experimental, pre-production, production release.

Elements of a typical reliability program

The failures in performance were initially thought of manufacturing or inspection problem. But later it was understood that design is the major problem creator. Fitness for use problems is broken down as given:Design problem ------ 40%Manufacturing -------- 30%Field condition ----------30%

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Product cost effectiveness (Worth, value)

Total costs (Life value)

Effectiveness

Availability Dependability Capability

The reliability is defined as the probability of a product performing without failure a specified function under given condition for a specified period of time. This definition implies the following requirement.

a. Quantification of reliability in terms of a probability.b. A statement defining successful product performance.c. A statement defining the environment in which the equipment must operate.d. A statement of the required operating time between failures.

So the reliability program included design, production and environmental factors. A reliability program typically includes the following activities:

a. Setting overall reliability goals.b. Appointment of the reliability goal.c. Stress analysis.d. Identification of critical parts.e. Failure mode and effect analysis.f. Reliability prediction.g. Design review.h. Selection of supplies.i. Control of reliability during manufacturing.j. Reliability testing.k. Failure reporting and corrective action system.

The significant aspect of reliability is quantification. Like weight, strength, etc, Reliability can be submitted to specification and verification. The tasks in reliability program require actions from many functions. So it necessitates written definitions of tasks with time bound formal planning. Early warning of new product problems may be tabulated as follows:

Phases of new product progression Forms of early warning of new product problems

Concept and feasibility study Concept reviewPrototype design Design review, reliability prediction, failure mode

and effect analysis.Prototype construction Prototype test, environmental test, overstressingPre-production pilot production lotsEarly full-scale production In-house testing, consumer panelsFull-scale production Employees as test panels, prompt feedbackAll phases Failure analysis, data collection and analysis.

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Reliability apportionment, prediction and analysisThe process of reliability quantification involves three phases:

a. Apportionment or budgeting: this is to allocate reliability objectives.b. Prediction: failure rate is calculated based on prior performance data and

probability theory.c. Analysis” Identify strong and weak portions of the design to serve as a base

for improvements, trade offs, etc.

Reliability prediction is a continuous process starting with productions based on a design analysis and historical failure rate information. The evaluation ends with reliability measurement based on data from customer use of product.

Selection of tolerancesThe selection of tolerances is based on the following:

a. Fitness for use and hence the salability of the productb. Costs of manufacture and quality costs.

By scientific study the design should establish the proper balance between the value of precision and the cost of precision.Tools for establishing tolerance include the following:

a. Regression studies: The processes variables are studied and data collected. By using regression equation data are computed with computer aid to establish critical component tolerance on a basis, which is within the confidence limits.

b. Tolerances for interchanging dimensions: Numerous designs involve interacting dimensions. All these interacting elements and their dimensions have their own tolerances.

Involvement of large elements makes tolerance wider and cause nonconformities. In most companies, specifications contain an extensive array of unduly tight tolerances i.e. tolerances not really needed to achieve fitness for use. Most of the time shop-floor face problem due to such tight tolerance and then the shop go with a loose tolerance. This makes unrealistic tolerance loosely enforced. Recently this is overcome by accepting realistic tolerances rigidly enforced.

Design reviewDesign reviews are based on the following concepts:

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a. Design reviews are made through customer demand or through top management policy declaration.

b. Design reviews cover parameters like reliability, maintainability, safety, weight, packaging, etc.

c. It is made as per customer requirement, internal goals, or experience with previous products.

The main problem with design review is from the design department itself because designers feel what they made is final and a review and modification or any external suggestion is not a requirement.

Failure mode/Failure effect and fault tree analysisTwo techniques provide a methodical way to examine a design for possible ways in which failures can occur. In the failure mode and effect analysis (FMEA) a product is examined for all possible ways in which failure may occur. For each potential failure an estimate is made of its effect on the total system. In addition a review is made of the action being taken to minimize the probability of failure. In FMEA method a ranking procedure is applied. The probability of occurrence of a failure mode is given one ranking. The failure is classified component wise and the severity is ranked from very low to very high. A scale of 1 to 5 can be used. A risk priority number can also be calculated. Generally, failure mode and effect analysis on one item is helpful to designers on other items in the system.In fault tree analysis the starting point is the list of hazards or undesired events for which the designer must provide some solution. If we take safety, such list can be prepared from records of actual accidents or near misses. Each hazard on the list then becomes a failure mode requiring analysis. The analysis leads to direct causes and then to the origin of these causes. Branching out of origins and causes gave the name ‘tree’ to this analysis. The approach is the reverse of failure mode and failure effect analysis.

Evaluating designs by testsThe tests used to evaluate a design are given below:Performance-----Determine ability of a product to meet basic performance requirements.Environmental---Evaluate ability of product to withstand defined environmental levels.Stress-------------Determine levels of stress the product can withstandReliability--------Determine product reliability and compare to requirements.Maintainability---Determine time required to repair and compare with requirements.

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Life----------------Determine wear out time of the product.Pilot run-----------Determine if fabrication and assembly processes are capable of meeting design requirements

Accelerated testing is a common form of securing reliability test data at reducing testing cost. In such test the product subjected to perform at abnormally high levels of stress and the results are extrapolated to the expected lifetime.

Corrective action systemA corrective action system is a company wide coordinated effort that has several objectives:

a. Collect all information on product failures and discrepancies.b. Detect and assure resolution of problems affecting reliability.c. Keep management aware of the status of problems affecting product.d. Disseminate failure and other reference data for use in preventing similar

problems in product modification and in failure products.

Statistical quality control

Statistical quality control is needed to bring about the following improvements to the finished goods.

1. It offers advance caution to check defects and the defects are detected in the earlier stages.

2. Statistical quality control minimizes scrap arousal and reworking possibilities are reduced.

3. The inspection requirements are reduced considerably since control techniques help to prevent defects at early stages.

Definition: SQC is defined as the technique based on theory of probability and applied on quality problems to estimate variation from quality standards in a continues running processes and maintain adherence to those standards.

Characteristics:1. Directly measurable: dimensions, rpm, density etc.2. Non-measurable aspects: cracks, breakages, fatigue etc.3. Countable defects

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SQC techniques1. Sampling schemes2. Control charts

Sampling schemesIn this type of testing a specific quantity of items are taken for inspection instead of 100% of the products.. Samples are taken randomly. Both the 100% inspection and sampling inspection are compared below:

100% inspection Sampling inspectionMore time consuming Time spent is limitedChances of sampling error is nil

There is sampling error

The inspection create fatigue, negligence and boredom so less effective

Results have reasonable accuracy

In case of destructive testing the test is not possible

The test can be conducted as number of samples is limited

Good sampling plan1. Cost of sampling should be as low as possible.2. Both the producer and customer should not be affected by unreasonable

rejection or acceptance due to sampling inspection.3. The sampling plan should be flexible in terms of lot size, sample size, etc.

Acceptance samplingDue to sample inspection sometimes, good items may be rejected or bad items may be accepted. This is because the samples collected are not representative samples. So there is a certain amount of risk involved in accepting or rejecting based on sampling inspection.

Terms used in acceptance sampling plans1. Lot size: The number of items included in a lot for inspection.2. Sampling size: The number of items chosen in random from a lot for

inspection.3. Acceptance number: maximum number of defective items in the lot for

acceptance.

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4. Lot quality: percent defectives actually present in the lot offered for inspection.

5. The minimum number of defectives in the sample lot for rejection.

Sampling plan

Single sampling: Select a random sample of ‘n’ items from the lot and inspect all ‘n’ items. If the defects are below ‘c’ number, which is acceptance number, then pass the lot. If the defects exceed the value ‘c’ number then reject the lot.

Double sampling: After the first sampling and completing the test make another sampling. If the second samples pass the criteria then accept the lot otherwise reject the lot.

Average outgoing qualityWhen a sample plan rejects a lot the lot is subjected to 100% inspection. The defects are replaced and the lot is made 100% good items. If the lot is accepted by sampling method then there is the risk of passing defects. The average number of defects in a lot is called average outgoing quality (AOQ);

AOQ = Average number of defectsx100No. of items in lot

The maximum quantity that can be passed on the average is known, as AOQ limit sampling error and this will get reduced with increase in the number size of samples.

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Operating characteristic curve (OC curve)Take % defects on x-axis and probability of acceptance of lot on the y-axis. This plot is called OC curve. It indicates acceptance sampling and its quality. As quality of lot decreases its probability of acceptance gets reduced.

Control chartControl chart is defined as chronological (hour by hour, day by day) graphical comparison of actual product quality characteristics with limits reflecting the ability of produce as shown by the past experience on product characteristics.

Control quality during manufacturing of a product can be achieved by control chart. It has three horizontal lines:

1. Standard level of quality2. Upper line indicating upper quality level3. Lower line indicating lower quality level.

A random sample is taken and tested and the results are plotted graphically. The graph will show capacity of the process to produce desired quality. Any deviation will mean the process is influenced by external causes.

UCL

SQL

LCL

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How to read a control chart?1. Out of control limits ---- points outside control limits.2. Run: points appear continuously on one side of the control line and number

of points is called length of the run.a. Seven point length of run is abnormalb. Even six point length of run is considered abnormal in following

cases:b.1. At least 10 out of 11 points appear on one side of the central lineb.2. At least 12 out of 14 points occur on one side of the central control line.b.3. At least 16 out of 20 points occur on one side of the central control line.

Seven point length – on one side

Ten point length – on one side

3. Trend: When the points make a continuous upward or down ward curve this is called trend.

Upward trend down ward trend

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3. Approach to the control limits: Considering points which appear the 3-sigma control limits, if 2out of 3 points occur outside of the 2 – sigma lines, this case is considered to be abnormal.

3-sigma line

2-sigma line

2-sigma line 3-sigma line

5. Approach to central line: If most of the points lie within the central 1.5 sigma lines this is an appropriate way of sub-grouping. Approach to the central line does not mean a controlled state, but it means mixing of data with a different population in subgroups, which make the width of control limits too wide. In this situation it is necessary to change the way of sub-grouping.

3-sigma line

1.5-sigma line

6. Periodicity: when the curve repeatedly shows an up – and – down trend for the same interval, this is abnormal.

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Advantage of control charts1. A chart provides a useful record for supervision2. A chart is much more clearly and more easily understood than lot of figures

and sketches.3. Management finds charts very useful

The objective of control chart

1. It is used to determine whether a process is in statistical control2. It guides the production people whether the process capability is in line with

the specification.3. Any trend in the process can be easily understood and corrective action can

be taken.

Quality improvement

Operator controllable defectsIn the shop floor the operator controls the production. His vigilance towards the defect and its rectification then and there is one of the most effective quality control functions. But all human beings make errors. Some school of quality management put forward the concept called zero defects. The assumption of this concept was that operator errors are the main source of quality troubles and all operators can be remedied by proper motivation. But actually this is not having any base. What the facts show is that:

1. The bulk of defects are management controllable and not operator controllable.

2. There are multiple sub-species of operator controllable error; the matter is not as simplistic as motivation alone.

The operator controllable errors can be due to the following:a. Inadvertent errors.b. Errors due to lack of technical skills.c. Willful errors.

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Each of these errors has outward symptoms. These symptoms can be analyzed by the following methods.

a. Pareto analysis: The total errors committed by each operator during a specified duration are calculated and their percentage and cumulative percentages were calculated. Errors due to lack of skill or technical capability can be evaluated by this method.

b. Matrix of operators versus defect types.c. Matrix of operators versus time.

Inadvertent errors (errors due to not paying attention)Failure to pay attention is an important source of human error. Inadvertent errors exhibit several distinguishing features. They are typically:

a. Unintentional: the operator does not want to make errors.b. Unwitting: At the time of making an error the operator has no

knowledge of having made an error.c. Unpredictable: No one knows beforehand when the worker will make

an error, or what type of error will be made.

Inadvertent errors show randomness. Remedy for this type of error involves two major approaches:

a. Reducing the extent of dependence on human attention: This is called fool proofing.

b. Making it easier for human beings to remain attentive: This approach employs psychological tools (e.g. job rotation, rest periods) as well as technological tools.

If the lack of attention is deliberate then motivation can improve the operator approach. But inattention that is involuntary is the result of limitations in the human organism and hence is presumably not responsive to motivation.

Technique errorsThey are:

a. Unintentional: The worker wants to do good work, not bad work.b. Selective: The errors are confined to some type due to lack of technique.c. Consistent: Workers having technique can avoid error situations.d. Witting and unwitting: Worker may not know the outcome of his work. He

lacks the technical background to plan his work and make available his ability as and when required.

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e. Unavoidable by the unaided worker: The worker knows only one-way of doing. He lacks knowledge to do in another way.

The technique error is consistent and selective to certain type of defects. To find out the cause of this error it is necessary to study the work methods used both by successful and unsuccessful workers. Find the difference in their work and what lacks the unsuccessful worker. Train the unsuccessful worker the methods adapted by successful worker. The possible options are the following:

a. Train the inferior performers.b. Change the process so that the process itself embodies the special methods.c. Foolproof the operation

The error can be monitored and corrected. The sequence is;a. Collect data on a particular type defect to signify worker-to-worker

differences.b. Analyze data on a time-to-time basis to reveal consistency.c. Identify the consistently the best and consistently worst performances.d. Ask the workers and study the work methods used by the best and worst

performers to identify their differences in technique.e. Study these differences further to discover the beneficial knack, which

produces superior results.f. Bring any one up to the level of the best through appropriate remedial

actions.

Will full errorsWill full errors are those, which workers know they are making and which they intend to keep on making.

a. Writing: At the time the error is made, the worker knows that an error has been made.

b. Intentional: The error is the result of a deliberate intention by the worker to commit an error.

c. Consistent: The worker who cause willful errors usually do so on continuing basis.

Willful errors do not exhibit randomness. It shows a pattern of consistency and is not restricted to one type of defect.Many willful errors are operator initiated. Workers may have real or fancied grievances and get their revenge by neglect of quality.

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Remedy for willful errors takes several forms.a. Improve communication: The decision taken by managers should be well

understood by operators. The table given below shows how the managers and workers can reach different conclusions from identical factual situations.Mangers view Operators view Shop interpretationNon-conforming materials were approved after discussion with the customer

Rejected materials were accepted by managers

Management does not regard quality of product

Old machine needs repair, since new machine is ordered it is not necessary to repair old one

Defects are produced by machine which needs repair, but management is not interested to repair the machine

Management is not having intention to spend money to get quality

Operator suggestion for improving quality was investigated and found to be uneconomic

Operator suggestion for improving quality has not been answered

Management is not interested in improving quality

b. Establishing accountability: Carelessness can cause damage and it may continue if not inspected and real cause established. If person who caused the damage is identified it is natural that he will not repeat it for fear of penalty.

c. Foolproof the operation: Fool proofing may be feasible with some type of defects.

d. Remove the offender: This option is often open to managers.e. Motivate the worker

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Theories of motivationThe studies by behavioral scientists have provided some useful theories to help us understand how human behavior responds to various stimuli.

Human needs Forms of quality motivationPhysiological needs Opportunity to increase earnings

by bonus for good workSafety needs: protected employment

Job security; quality makes sales, sales make jobs

Social needs: need to belong to a group and be accepted

Employee as member of a team

Ego needs: need for self respect and respect for others

Pride for workmanship to achieve a good score. Recognition through awards

Self fulfillment needs: the urge for creativity for self expression

Opportunity to propose creative ideas, to participate in creative planning

Job dissatisfaction and satisfaction: jab dissatisfaction is the result of specific dislikes – the pay is low, the working conditions are poor, the boss is unpleasant. It is possible to eliminate these dislikes – raise the pay, change the working conditions, reform the boss. The job satisfaction depends on what the worker does. The satisfaction comes from such things as job challenges, opportunities for creativity, identification with groups, responsibility for planning, etc.

Theory X and theory YTwo theories bring to the controversy about whether workers have lost their pride in their work. Is the change in the worker or in the work?Under theory X, the modern worker has become lazy, uncooperative, etc. So they should be motivated by skillful use of incentives and penalties.Under theory Y there has been no change in human nature. What has changed is the way in which the work is organized. Hence the solution is to create new job conditions, which permit the normal humans derive to assert themselves.But there is no conclusive evidence to support any of these theories.

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Shop operation under theory X and theory Y

Theory X Theory YPiece work rate as incentive Less emphasis on piece work

rates; greater use of supervisory leadership

Emphasis on disciplinary measure like wage penalty, etc

Emphasis on why and how to improve poor quality performance

Depend on inspection personnel Depend on production personnelPetrol inspection to see setups are correct

Depend on operators for correctness of setup

Petrol inspectors are authorized to stop production if defects are found

Operators stop the machine when the inspectors finding of defects

Formal inspection approval for piece work payment

Limited use of formal inspection approval

Debates on shop floor on authority to shut down machines

Debate on shop floor on interpretation of specification and measurement

Relation ship between operators and inspectors hostile

Relation between operators and inspectors are good

Upper management criticism for high scrap losses at inspectors

Upper management criticism for high scrap losses at production

Operators reluctant to do quality jobs

Operators take initiative to do quality jobs

Improvement proposals from operators were not negotiated

Operators were consulted to introduce improvement

Job design and planningA worker can produce a good product if he has self-control. If this self-control is not feasible, then worker responsibility should be based on ‘best effort’ or meeting process control criteria rather than product criteria.TrainingTraining on quality includes technological information on specifications, standards, facilities, processes, tools, materials, and products. It includes the

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information needed to make clear the worker’s responsibility for taking actions and making decisions.Training should be provided with respect to ‘knack’. Knack becomes the answer to the worker’s logical question: ‘what should I do different from what I am doing now?’

SupervisionWorker’s behavior is strongly influenced by the supervisory and managerial conduct. This conduct is reflected in giving adequate priority to quality. Worker ideas should be given priority and good quality work should always be appreciated.

Communication to employeesManuals of procedures should be available to the worker.Journals, bulletins and posters are general communicating medium to the work force.Meetings with workers to discuss on scrap and quality should be conducted.Specific aids, like knack, for good performance should be communicated to the work force.Quality incentivesMost of the quality incentives are non financial in nature. They take such forms as:

1. Recognition through publicity awards of prizes, etc.2. Delegation of special responsibility.3. Presentation of certificate of qualification.4. Providing opportunities for participation in work projects, planning,

etc.

The chief measure of quality is the percent of work that is done right the first time.

Motivation campaignsSome companies go for motivation campaign to get quick change in the behavior toward quality. There may be some external factors such as customer’s pressure for adapting such quick actions. Such campaigns are like packages:

1. A motivation package to employees to reduce their own errors.2. A prevention package to employees to assist in management

controllable errors.

Purposes and prerequisitesBefore launching campaign the purpose should be well understood.

a. Make aware to employees that quality performance is important; e.g., quality makes sales, sales make jobs.

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b. Convince the worker that there is something in their daily work to contribute to quality.

c. Show the worker what to do to contribute on the regular job.d. Establish the best way of doing the job as reference.e. Interact with employees for ideas for quality improvement.f. Measure performance and progress and decide for rewards.

The management should reduce management controllable errors before going for such campaigns. There should be substantial evidence for employee controllable errors. A mutual confidence should be developed between management and employees. The top management should take personal interest in quality improvement and preference should be given for quality. The supervisors should be willing to hear suggestions and ideas of employees for quality improvement.

Organization and planningA committee should be appointed to plan and guide the campaign. Budgets and schedules are established. Diagnostic support is provided to carry out the detailed work of setting goals.

The motivational packageMotivation packages are designed based on what kind of worker behavior is expected. Such behavior applies primarily to operator controllable defects and include principally:

a. Reduction of willful errors.b. Retaining to improve technique and acquire the knack of superior

performers.c. Technological changes like fool proofing.

Prevention package

The purpose of this package is to secure worker behavior with respect to management controllable errors. Management controllable errors are the result of management failure to meet the criteria for operator self control. So a potentially useful role of the worker is to help identify with precision the nature of these failures to meet the criteria for self-control.The introduction of error cause removal forms helped many companies to solve many problems. This form is given to workers and if any problem is found in the operation then the operator give ideas and suggestions in writing so that the problem can be solved at early stage instead of waiting for investigation.

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Worker study teamsIn this approach workers are encouraged to take training courses in problem solving. Teams of workers are organized to engage in discussion and solution of departmental problems. In Japan such groups are called QC circles. This group comprises about 10 workers and work leader of a single department. The purpose is to conduct studies to improve the effectiveness of work in their department. The studies may involve productivity, cost, safety, etc. Training is given to participants based on three major elements.

1. Training on statistical tools (data collection and analysis using statistical methods, pareto analysis, ishikawa diagrams, etc.)

2. Study of successful projects worked out by other QC circles.3. Proving the effectiveness of the training by completion of an actual project,

using help from other circles. This aspect of training includes preparation of the final report and recommendations for action.

In Japan this movement gave stunning success. The effect on product quality has been significant. Western countries did not adapt this movement. The main problem lies on cultural background.

a. Managers and engineers are reluctant to delegate to the work force.b. The work force does not consider that it has a responsibility to help

the managers to improve the company’s performance.

Quality improvement- Management controllable defects

Sporadic and chronic quality problemsA sporadic problem is a sudden adverse change in the status quo, requiring remedy through restoring the status quo.A chronic problem is a long-standing adverse situation, requiring remedy through changing the status quo.The distinction between the two:

1. Both have different methods for solving. Chronic problems require break through method.

2. Sporadic problems are dramatic and require immediate attention. Chronic one in not dramatic because it has been there for long time and often difficult to solve.

Break through sequenceThe break through sequence for solving chronic quality problems is this:

a. Convince the need for a break through. It may be a change in quality level

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b. Identify most important areas having quality problems.c. Organize for the missing knowledge so that a break through is possible.d. Collect and analyze the facts so that an action is possiblee. Determine the effect of change and find ways to overcome resistance.f. Introduce the change.g. Implement control parameters to hold the new level.

Break through in attitudeChronic problems need investigation also time and resources.

1. Collect data on percent defects, rework cost, expenditure due to delayed delivery, etc.

2. Collect enough data to establish loss of sales income caused by defects.If a improved program is possible check the percent return on investment, time required to pay back the investments through savings.

Identify the vital few projects (Pareto principle)The Pareto study helps to identify the vital few situations that contribute to problems. The priority of improvement projects to solve the problems and its impact on over all departments can be studied using Pareto method.

Organize for break through in knowledgeIt may be necessary to acquire additional knowledge to solve chronic problems. The investigation of a chronic problem can be aided by organizing a steering arm and a diagnostic arm. A steering is a person from various departments who give direction and advice on the improvement program. The steering arm provides:

a. Definition and agreement on the specific aims of the improvement program. Suppose the problem is excessive quality cost. Then steering committee decides the number of products to be included in the study and to what extend the cost has to be reduced.

b. Create causes of the problems. A break through is inter-departmental and all these departments generate theories on causes.

c. Conduct the experiment and collect the data.d. Find out ways to overcome the ‘resistance to change’ and introduce new

approach.e. Implement the solution to the problem.

A diagnostic arm is person or persons who determine causes of the problems. Diagnostic arm provides:

a. The time required for the investigationb. The diagnostic skills

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c. Objectivity of analysis

In US professional specialist carry out diagnosis and in Japan supervisors or non-supervisors conduct the diagnostics.

Conduct the problem analysisThe solution to problem involves two journeys – diagnostic and remedial.Diagnostic journey consists of:

a. Study of symptoms of defects and develop theories of the causes.b. Analyze and experiment to establish the true causes.

The definitions of the terms are given:A problem is a potential risk from existence of defects.A project is a problem selected for solution through diagnosis and remedy.A symptom is an observable phenomenon arising from and accompanying a defect.A theory is an unproved assertion as to reasons for the existence of defects and symptoms.A cause is a proved reason for the existence of defect.A diagnosis is the process of studying symptoms, taking and analyzing data, conducting experiment to test theories and establish relationships between causes and effects.A remedy is a change that can successfully eliminate or neutralize a cause of defects.

Diagnostic journey creates confusion because no body takes initiative to solve chronic problems. Some of the confusions are listed below:

1. Confuse symptom with cause. In scrap data sheet there is a column to enter the cause of defects. The managers confuse this cause as symptom and think no further diagnosis is required.

2. Confuse theory with cause. To explain the causes of defects many theories are put forward. Some people take these theories as causes. When theories are put to experiment and a remedial method is developed then only that particular theory becomes the basis of cause.

In diagnostic journey first analysis is to determine whether the defects are operator controllable or management controllable. When it comes to management controllable then it is necessary to find causes over design, manufacturing, etc.

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Test of theoriesTheories can be tested in three ways:

1. Using past data,2. Using current production3. Conducting test and experiments

Using past dataSometimes past results are available regarding a specific cause. This type fo analysis involves relating product quality data to some theory of causation – process, tools, operators, etc. The relationship may be examined using various statistical tools such as ranking, correlation and matrices.

Using current productionPast data cannot give many of the information required for some type of cause. In such case the current production is subjected to process capability study, dissection of process and product, cutting new windows in the process and experiment.Process capability is studied to know whether process can hold tolerances.

Conducting test and experimentsFour types of diagnostic experiments are in use:

Type of experiment Purpose of approachEvaluating suspected dominant variables

Divide a lot into several parts and evaluate changes in values of a variable

Exploratory experiments to determine dominant variables

Plan statistical experiment to follow a number of variable characteristics to yield quantifying data and to under stand interaction of these variables

Production expt Make small changes in selected variables and evaluate the effect to find optimum combination of variables

Simulation Use computer to study the variability of several dependent variables

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Diagnosis of non-dissectible characteristics

A characteristic is dissectible if it is measurable during the process of manufacture.A characteristic is non-dissectible if it cannot be measured during such progression.For non-dissectible characteristic:1. Convert non-dissectible to dissectible characteristic:

1.1. Measure some related properties. For tensile strength check hardness 1.2. Create new instrument1.3. Use of parallel pilot plant; laboratory check on pilot plant of the same

process gives early information about the process before going for manufacture.

2. Correlate process variables with product results: Take data from current production for those variables whish are believed to influence the product characteristic under study. Then by statistical means correlate cause and effect relationship.

3. Experiment using trial lots: Trial lot are specially designed to process so as to derive conclusions on a wider range of applications.

RemedyOnce the diagnosis has established the cause –and-effect relationships the next step is recommending remedy.

1. Remedy through change in technology: Many remedies involve changes in processes, instruments, methods, etc. The diagnosis for cause often points to this and clarifies the economics as well. As the cost of remedy raises the need for return on investment calculations becomes acute. When the process variability exceeds tolerable range then improvement would involve a form of research.

2. Remedy through change in standards: One of the possible remedies for chronic defects is to change the standards. One of the directions of diagnosis should be to look validity of the standards. A review of standards can be carried in following cases:

2.1.A lack of correlation between defects from field complaints and that found by factory inspectors.

2.2.The personnel who set the standards have no knowledge of the needs of fitness for use.

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2.3.Nonconforming components are regularly repaired or discarded but never been subjected trial of fitness for use.

2.4.Case in which the user specifying to his detriment.

Remedy by enduring the defects: Sometime this is economical solution in certain cases. Even when the defects make the product unfit for use they may be endured if they occur rarely. In such case the cost of finding a defect through sorting goes up as the percent defective declines.

Deal with resistance to changeThe change has two facets:

1. Technological change: the effect on the machine, products, procedures, etc.2. Social change: the effect on the people involved.

Recommendations:1. Establish the need for change in terms that are important to the people

involved.2. Use participation to get ideas on both types of changes.2.1. Understand the goals and problems of people for whom the change is

intended.2.2. Participate those who are going to get affected by change.2.3. If the change is work system then allow the workers to create as much

of the change as possible.2.4. Consider change catalyst to help in the planning and implementation

of the change.2.5. Treat all people with dignity.2.6. Introduce change gradually in small quantities.2.7. Produce rewarding results early.2.8. Guard against surprises by keeping everyone informed.

3. Gain agreement on the change:3.1. Try persuasion to secure change.3.2. Change the environment so that it is easy for the individuals to change

his point of view.3.3. Remedy the causes of resistance.3.4. Create a social climate that favors the new habits.3.5. Explain the dos and don’ts that a person must under the change

condition.3.6. Eliminate technical jargon in explaining the change.

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3.7. Put yourself in the other person’s place.

Institute changeConvince the necessary departments to take action to institute the changes. Gain the approval from management and install the solution in a way that will make it effective.The presentation to management should explain the size of the current problem, the proposed solution together with a summery of alternatives solutions, the cost of the remedy and the expected benefits.Installing the proposed solution requires adequate training.

1. Present a clear definition of the new procedure and provide sufficient training.

2. Seek out opinion leaders in a group and also work with the groups as a whole in gaining acceptance.

3. Choose the right time for implementing the change.

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