Quality control and appraisal techniques

QUALITY CONTROL AND APPRAISAL TECHNIQUES
Objectives:
(i) Define the term control
(ii) Highlight the dimensions quality
(iii) Describe the costs of quality
(iv) Define the concept of total quality management (TQM)
Introduction
Quality can have the following meanings:
• the characteristics of a product or service that bear on its ability to satisfy stated or implied needs, and
• a product or service free of deficiencies
• it could also be defined as conformance to customer expectations Dimensions of quality
(i) Performance: Primary product characteristics, such as the brightness of the picture
(ii) Features: Secondary characteristics, added features, such as remote control
(iii) Conformance: Meeting specifications or industry standards, workmanship
(iv) Reliability: Consistency of performance over time, average time of the unit to fail
(v) Durability: Useful life, includes repair
(vi) Service: Resolution of problems and complaints, ease of repair
(vii) Response: Human – to – human interface, such as the courtesy of the dealer
(viii) Aesthetics: Sensory characteristics, such as exterior finish
(ix) Reputation: Past performance and other intangibles, such as being ranked first
Quality Planning
The following are the important steps for quality planning:
1. Establishing quality goals.
2. Identifying customers.
3. Discovering customer needs.
4. Developing product features.
5. Developing process features.
6. Establishing process controls and transferring to operations.
Quality Costs
Quality costs are defined as those costs associated with the non- achievement of product/service quality as defined by the requirements established by the organization and its contracts with customers and society. Quality cost is a cost for poor product of service. Quality cost comprise of:
(i) C o s t of prevention
(ii) C o s t of appraisal
(iii)C o s t of internal failures
(iv)C o s t of external failures.
i. Prevention Cost: costs incurred to prevent quality failures e.g. Marketing / Customer / User,
Product / Service / Design Development, Purchasing, Operations (Manufacturing or Service),
Quality Administration.
ii. Appraisal Cost: cost incurred in determining whether quality has been met e.g. Purchasing
Appraisal Costs, Operations Appraisal Costs, External Appraisal Costs, Review of Test and
Inspection Data, Miscellaneous Quality Evaluations.
iii. Internal Failure Cost: costs incurred due internally due to quality failure e.g. Product or Service Design Failure Costs (Internal), Purchasing Failure Costs, Operations (Product or Service) Failure Costs
iv. External Failure Cost: costs incurred externally due to quality failure e.g. Complaint
Investigations of Customer or User Service, Returned Goods, Retrofit and Recall Costs, Warranty Claims, Liability Costs, Penalties, Customer or User Goodwill, Lost Sales Analysis Techniques Of Quality Cost
The purpose of quality cost analysis is to determine the cost of maintaining a certain level of quality. Such activity is necessary to provide feedback to management on the performance of quality assurance and to assist management in identifying opportunities. These techniques include index numbers, trend analysis and pareto analysis
Index Numbers :
Index Numbers are often used in a variety of applications to measure prices, costs (or) other numerical quantities and to aid managers in understanding how conditions in one period compare with those in other periods.
Trend Analysis:
Good visual aids are important communication tools. Graphs are particularly useful in presenting comparative results to management. Trend Analysis is one where Time-to-Time comparisons can be made which illustrates deviation in quality over time
Pareto Analysis:
Joseph Juran observed that most of the quality problems are generally created by only a few causes. For example, 80% of all internal failures are due to one (or) two manufacturing problems.
Identifying these “vital few” and ignoring the “trivial many” will make the corrective action give a high return for a low money input
Quality Systems
ISO 9000 provides a standard quality standard between suppliers and a customer that helps to reduce the complexity of managing a number of different quality standards when a customer has many suppliers. ISO 9000 is a series of standards for quality management and assurance and has five major subsections as follows:
ISO 9000 provides guidelines for the use of the following four standards in the series.
ISO 9001 applies when the supplier is responsible for the development, design, production, installation, and servicing ofthe product.
ISO 9002 applies when the supplier is responsible for production and installation.
ISO 9003 applies to final inspection and testing of products.
ISO 9004 provides guidelines for managers of organisations to help them to develop their quality systems. It gives suggestions to help organisations meet the requirements of the previous four standards.
Total Quality Management (TQM)
Total Quality Management (TQM) is a philosophy and approach which aims to ensure that high quality, as defined by the customer, is a primary concern throughout the organisation and all parts of the organisation work towards this goal. TQM does not prescribe a number of steps that must be followed in order to achieve high quality but rather should be considered a framework within which organisations can work. The TQM process will be dependent on factors such as customer needs, employee skills and the current state of quality management within the organisation.
Emphasis of TQM
1. The customer defines quality and thus, their needs must be met.
2. Quality is the responsibility of all employees in all parts of the organisation
3. Identify and minimise all costs of quality
4. A continuous improvement culture must be developed to instil a culture which recognises the importance of quality to performance
5. A use of systems and procedures for improvement
1. The customer defines quality: This implies a need to discover customer needs and then focus quality improvement on meeting them. So the customer should be the focus of decision making, but operations managers should still assess what is feasible for the organisation todo.
2. Quality is the responsibility of all employees in all parts of the organization: All staff, whether directly involved in production/ customer contact, or not can set in motion a chain of events which customers will eventually see as poor quality products or services. Staff are required not only to avoid mistakes, but think positively about improving how they perform their jobs. Service Levels Agreements (SLA) provide a formal definition of service between internal areas ofthe organisation
3. Identify and minimise all costs of quality: Quality gurus argue that the cost of poor quality and thus the benefits of improvement in quality should be identified, so quality costs can be classified:
4. A continuous improvement culture must be developed: TQM espouses the process of continuous improvement (CI).
5. A use of systems and procedures for improvement: A key aspect of TQM is developing the procedures which support improvement. ISO 9000 provides a quality standard between suppliers and a customer developed by the International Organisation for Standardisation. Having a predefined quality standard reduces the complexity of managing a number of different quality standards when a customer has many suppliers. The standard is general enough to apply to almost any good or service, but it is the specific organisation or facility that is registered or certified to the standard. Other programmes which attempt to provide national and international standards for quality
are the European Quality Award (EQA) and the Deming Prize.
TQM techniques 2 techniques associated with TQM and used to improve quality in operations are Statistical
Process Control (SPC) and SixSigma.
Statistical Process Control (SPC):
Statistical Process Control (SPC) is a sampling technique which checks the quality of an item which is engaged in a process. SPC should be seen as a quality check for process rather than product design. Quality should be built in to the product during the design stage. SPC works by identifying the nature of variations in a process, which are classified as being caused by„chance‟ causes or„assignable‟causes.
-Chance Causes of Variation:All processes will have some inherent variability due to factors such as ambient temperature, wear of
moving parts or slight variations in the composition of the material that is being processed. The technique of SPC involves calculating the limits of these chance-cause variations for a stable system, so any problems with the process can be identified quickly.
-Assignable Causes of Variation: If an „out-of-control‟ process is discovered, then it is assumed to have been caused by an assignable cause of variation. T his is a variation in the process which is not due to random variation but can be attributed to some change in the process, which needs to be investigated and rectified.
The limits of the chance-cause variations are called control limits and are shown on a control chart, which also shows sample data of the measured characteristic over time. There are control limits above and below the target value for the measurement, termed the upper control limit (UCL) and lower control limit (LCL) respectively.
Six Sigma
SixSigmaisaqualityimprovementinitiativetoachievequalitylevelswhicharewithin6sigma control limits, corresponding to a rate of 3.4 defective parts per million (PPM).Thus 6 sigma can be defined as the process of comparing process outputs against customer requirements.
However 6-sigma has developed from this examination of process variation to become a companywide initiative to reduce cost through process efficiency and increase revenues through process effectiveness. 6 sigma has an emphasis on training – level of expertise is denoted
by black belt green belt etc. Six Sigma contains plans for both increasing effectiveness and efficiency leading to so increased revenues and thusim proving company performance.
– Improving Effectiveness: The level of effectiveness of the organisation is reflected in the level of customer satisfaction. This means that efforts to improve effectiveness will focus on identifying and meeting internal and external customer requirements.
– Improving Efficiency: The aim of every process improvement approach using Six Sigma isto achieve measurable costsavings through a focus on decreasing process variation.
The DMAIC Methodology
6 sigma incorporates a structured approach to improvement called DMAIC. This is a five step methodology of define, measure, analyse, improve and control and is used to both improve process performance and to improve process or product design.It is a cyclical
approach like the PDCA cycle.
– Define – Identify a potential area of improvement and define the project scope.
– Measure – Decide what characteristics of the process require improvement.
– Analyse – Use the data collected in the measure phase to document current performance.
– Improve – Eliminate the root causes of non-random variation to achieve improvements in predictability, dispersion and centering.
– Control – Verify and embed the change through the use of techniques such as control charts
Review questions
1. Define the term quality
2. Outline at least five dimensions of quality
3. Describe the concept of total quality management
4. Enumerate the steps involved in implementing total quality management
5. Explain the steps of the DMAIC methodology
References
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Hayes, R.H. and Wheelwright, S.C. (1984) Restoring our Competitive Edge,John Wiley & Sons Ltd.
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Slack, N. and Lewis, M. (2011) Operations Strategy, 3 rd edn, Pearson Education Limited, Harlow.
Vonderembse, M.A. and White,G.P.(2004)Core Concept s f Operations Management, JohnWiley and SonsLtd., Chichester.