Topic 5 Instruments and techniques of quality management

Topic 5. Instruments and techniques of quality management Plan 1. Instruments of quality control: structure, purpose, sphere of implementation 2. Statistical methods of quality management. 3. QFD method and spheres of its using in a quality management system. Key words: instruments of quality control, «brain storming» , elementary methods, types of diagrams, statistical methods of quality management, statistical analysis, QFD method, basic, desirable, proper quality.

1. Instruments of quality control: structure, purpose, sphere of implementation. The most of quality control methods (quality management) are used for numerical data analysis for meeting the TQM’s requirement “decisionmaking process must be based only on facts”. In order to know how well an organization is performing, data on performance measures are necessary. TQM requires that an organization continually collect and analyze data in order to improve decision making accuracy, achieve consensus and allow prediction, based on past history.

The facts don’t always have a numeric expression, that’s why the decision-making process requires knowledge of behavior, operational analysis, statistics and optimization theory. Japanese Union of Scientists and Engineers (JUSE) has developed a set of 7 quality control instruments, which can facilitate quality managing through the analysis of various factors.

7 instruments of quality control: • • • affinity diagram; diagram (figure) of bonds; the “tree” diagram ("decision tree"); matrix diagram ("table of quality"); vector diagram; diagram of program implementation process; • matrix of priorities.

Collecting outgoing data for quality control instrument is usually done during the "brainstorming". The group of "brainstorming" must include anyone, who understands how to solve a particular problem.

To organize the "brainstorming" a team leader should: ь clearly formulate the topic, which is proposed for discussion; ь prepare for the "brainstorming": collect all the necessary participants in the group, articulate questions, listen to the ideas without interrupting the speakers; ь choose leaders, who are well oriented in the discussed topic, familiarize them with the peculiarities of the problem and give them time to think over about its solution;

To organize the "brainstorming" a team leader should: ь organize "brainstorming", giving each participant an opportunity to present his or her solution, while making notes of all the ideas in the most conspicuous place without imposing their views. Total time of discussion is 30 -45 min; ь perform processing of discussion results, basing on received proposals; formulate ways and means for problem solution, considering the cost, the implementation time and possible outcomes of success.

Affinity diagram It is an instrument that reveals the process breach by combining related oral data. This quality control instrument is based on the principle of various data affinity and first of all demonstrates the association. The best quantity of group members is 6 -8. Diagram of affinity creation stages: • to identify the subject or topic that will be the basis for data collection; • to gather data (data can be collected in consistently, every message of every group member can be registered on a separate card); • to group the related data according to different directions. The analysis is completed, when the data are grouped according to the amount of leading directions.

Diagram of bonds It is an instrument, which reveals the logical relationship between the main idea, problem and various data. It is objective is to match the main causes of process infringements, detected with a help of affinity diagrams to the problems requiring solution. This diagram is mostly logical instrument and is more creative. It can be used in the following cases: • when the topic is so complex that links between different ideas can not be found with the help of regular discussion; • when the temporal sequence, whereby steps are implemented, is crucial; • when there is a chance that the problem, raised in the question is only a symptom of more fundamental problem.

The “tree” diagram It is an instrument that provides a systematic solution for the existing problem or satisfaction of consumer’s needs at different levels. The procedure of “tree” diagram creation is similar to the outlined procedure of the diagram of affinity creation. But it is important that the object (the problem), which should be investigated, is precisely defined and recognized.

The “tree” diagram

Matrix diagram It is an instrument that reveals the importance of various bonds and is the principal among 7 quality control and quality building instruments. This diagram serves for organizing large data amounts in such a way, that the logical connections between the different elements can be graphically illustrated. The purpose of the matrix diagram is to show links and correlations between tasks, functions underlying their relative importance. Therefore, in the final case matrix diagram shows the compliance of certain factors and events to the variety of reasons for their occurrence.

Matrix diagram

Vector diagram It is an instrument that allows to plan the best time for all the necessary activities with the aim of quick and successful goal achievement. The use of this instrument is possible only after identifying of all the problems, which should be resolved, and necessary measures, deadlines and stages their solution (after the construction of first 4 diagrams).

This instrument is widely used to: • assure that the planned execution time is optimal; • implement monitoring of planned activities, develop projects and plan production.

Diagram of program implementation process It is an instrument for evaluation of the terms and appropriateness of program implementation according to the vector diagram with the aim of their adjustment during execution. This diagram reflects the sequence of actions and decisions, which are necessary to achieve the result. It is widely used to solve complex problems in the field of development and production, getting large orders, etc.

It is the most effective: ь when developing a new program to achieve the desired result, providing the opportunity for preplanning and tracking action sequences by the analyzing the problems that may arise during the performance; ь when "catastrophes" in planning process are possible. Describing the sequence of actions in details, this instrument helps to avoid the "planning disaster". As a result of these actions’ careful analysis, undesirable result that allows making appropriate adjustments is predicted.

Matrix of priorities (matrix data analysis) It is an instrument for processing large amounts of numerical data, obtained in the construction of matrix diagrams for priority data identifying. Whereas the matrix of priorities application requires statistical knowledge, this instrument is used in practice much less. In particular, in cases when there is a need to presente numeric data of matrix diagrams in illustrative form.

2. Statistical methods of quality management Increased competition on the national and international levels stipulates the necessity of statistical methods use. Statistical methods of quality control were found essential for cost-effective quality management, as well as a means of efficiency of manufacturing and trading processes, product quality improving.

To solve the problems, related with the product quality, 7 traditional methods are widely used: v v v v control sheets; control cards; scatterplots; histograms; Pareto charts; cause and effect diagrams; time series.

For quality control it is necessary to collect and process certain data describing even the same parameters of the product, but can not be repeatedly obtained under the same conditions. Systematization, processing and researching of data amount with the help of using a variety of methods for identifying certain patterns, according to which they are subjected, are called statistical processing; data and methods which are used in this process are called statistics. Typically, to process and analyze data several statistical methods are used.

Statistical methods are divided in 2 groups: • to analyze and collect numerical data; • to analyze and collect non-numerical data.

The essence of the elementary methods To control quality it is necessary to collect and process certain data that characterize not only the same product parameter and can’t be repeatedly obtained under the same conditions. That’s why, while operating with the quality control there are operations with a lot of data, which characterize products parameters, process conditions, and so on. These data always differ during repeated measurements, that is data scattering is always observed. Analyzing it the solution of the problem can be found.

THE PROCEDURE FOR EXISTING PROCESS: Шidentify the start and finish of the process; Шexplore the whole process from the beginning till end; Шdefine the process steps (activities, decision making, input, output); Шdesign a process scheme; Шconsider the diagram with experts associated with the process; Шmake the improvements in the process scheme, based on this analysis; Шcheck process scheme in comparison with the actual process; Шdate reference map and future use (is an actual process protocol).

PROCEDURE FOR THE DEVELOPMENT OF A NEW PROCESS: Шidentify the beginning and the end of the process; Шclearly imagine the process steps that should be developed (activities, decision making, input, output); Шdefine the process steps (activities, decision making, input, output); Шconstruct process scheme to present process; Шanalyze this scheme with experts, associated with the process; Шmake improvements in the process scheme, based on this analysis; Шdate reference map and future use (is an actual process’s protocol).

Control sheet (control table) It allows to determine the frequency of certain events. This is an instrument of primary data registration. It can be used in the control of quantitative and qualitative characteristics.

Control sheet (control table)

Cause and effect diagram (Ishikawa diagram, "fish skeleton" diagram) It is a mean of understanding and identifying dependencies between the result and its potential causes. Many potential causes are reflected in main categories and sub categories like the fish skeleton. The Japanese define the process as the interaction of 4 M: material, equipment (machine), human resources (man) and methods, which can be expressed graphically.

Cause and effect diagram (Ishikawa diagram, "fish skeleton" diagram)

THE BUILDING PROCEDURE: ь description of the chosen problem (its features, place of origin, time detection, places of spreading); ь formation of the reasons’ list: • by "brain storming"; • by studying all the stages of the process; ь diagram construction, defining the result in the box on the right and positioning causes category on the left; ь diagram deployment, noting all the reason levels in ascending order; ь selection and identification of a small number (3 -5) of higher level causes that have the greatest impact on the result. To identify the main problems’ causes it is necessary to find the repetitive causes

Histogram It is one of column diagram options, that displays the frequency dependence of getting quality parameters into some interval values. Histogram is used to present the data in form of pictures and helps with the input control (allows to visualize the data difference).

Pareto chart It is used to analyze the causes of defects. The process of finding ways for problems’ solution with this method starts with the classification of the individual factors (financial, through equipment, staff, suppliers, etc. ), data’s collecting and analyzing separately into groups. While using a Pareto chart to control the key factors, ABC analysis is widely used.

Shewhart control cards It reflects the change nature of certain index in time. This is time period with statistically defined upper and lower limits, coated on both sides of the midline of the process line (upper and lower control limits). Characteristic output over the control limits implies a violation of the process stability and requires the analysis of the causes.

Scatter diagram It is used when it’s necessary to analyze, what happens to one variable while another one is changing and to establish the relationship between them. This may help to set the mathematical model of depending variables.

3. QFD method and spheres of its using in a quality management system It is original Japanese methodology, the aim of which is to guarantee the quality from the first stage of the process. The most significant contribution to its development was made by Y. Akao, S. Mizun, Y. Furukawa. In 1983 QFD was introduced in the USA and a few years later in Europe, where it is not widely used now.

Basic quality is an amount of product properties that the consumer considers to be mandatory. Desirable quality is an amount of product properties that is presented for the consumer as the unexpected value that is an additional bonus. Proper quality is an amount of product properties that are its technical and functional characteristics.

Basic elements of QFD: • first key element – clarifying the consumer requirements in the form of preferences in abstract form; • second key element – transformation of customer requirements into the product overall characteristics’ • third key element – defining link between specific properties and the degree of customer satisfaction; • fourth key element – choice of quality parameter that would ensure the consumer expectations and the competitiveness; • fifth key element – establishment of specific quality parameter ranking.

Stages of "consumer voice" tracking in QFD: v planning (consumer needs and wishes are transformed into product characteristics); v project development; v process projecting (quality parameters are transformed into concrete manufacturing operations); v realization projecting (instructions are developed and instruments of quality control are chosen).