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Types and methods of technical control of product quality. Product quality control that cannot be neglected What quality control systems exist

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Quality control. Kinds quality control

quality control view

Quality control is one of the main functions in the quality management process. This is also the most voluminous function in terms of applied methods, which is the subject of a large number of works in various fields of knowledge. The value of control lies in the fact that it allows you to detect errors in time, so that you can quickly correct them with minimal losses.

What is control? There are different definitions of control in a number of sources. The 1994 version of the ISO 9000 series states that inspection is the activity of measuring, examining, testing or evaluating one or more characteristics of an object and comparing the results obtained with specified requirements to determine whether conformity has been achieved for each of these characteristics.

Taylor's system gave an excellent mechanism for managing the quality of each specific product (part, assembly unit), but production is a process. And it soon became clear that it was necessary to manage not the quality of individual products, but processes.

The phase of quality control begins in the 1920s as an attempt, if not to resolve, then to weaken the contradiction in the form characteristic of the previous phase of quality development. The starting point is the work performed in the department technical control Western Electric Company, USA. In May 1924, a member of the department, Dr. Shewhart, handed over to the chief a short note that contained a method for constructing charts, now known throughout the world as "Shewhart's control charts."

The statistical methods proposed by Shewhart gave managers a tool to focus their efforts not on how to detect and remove bad products before they were shipped to the customer, but on how to increase the yield of good products in the process.

Around this time, the first sampling tables were developed by Dodge and Roming. Together with Shewhart's control charts, these works began statistical methods quality management, which later, thanks to William Edwards Deming, became very widespread in Japan and had a very significant impact on the economic revolution in that country.

Quality systems have grown in complexity as they have included services using statistical methods. The tasks in the field of quality, solved by designers, designers, technologists and workers, have become more complicated, because they had to understand what variations and variability are, and also know what methods can be used to reduce them. A specialty has appeared - a quality engineer who must analyze the quality and defects of products, build control charts, etc. In general, the emphasis has been shifted from inspection and detection of defects to their prevention by identifying the causes of defects and eliminating them at the design and development stage based on the study of all the constituent parts of the processes, the relationships between them, and the management of these processes.

Motivation of work has become more complex, since it now takes into account how finely tuned the process is, how certain control charts of regulation and control are analyzed. To vocational training training in statistical methods of control, analysis and regulation was added. The relationship "Supplier - consumer" has become more complex. Standard tables of statistical acceptance control began to play an important role in them.

One of the remarkable achievements of quality control practice was the creation of a quality audit service, which, unlike the technical control departments, was not engaged in sorting out products, but, by controlling small samples from batches of products, checked the performance of the quality assurance system in production.

The core concept of quality assurance in this phase was the following postulate: « The main goal remains - the consumer should receive only suitable products, i.e. products that meet standards. The reject is stored as one of important methods quality assurance. But the main effort should be focused on managing production processes, ensuring an increase in the percentage of yield of good products.

The introduction of the concept of quality assurance into practice made it possible to significantly increase production efficiency with a sufficiently high quality of products and services, which created the conditions for the formation of a global market for goods and services. At the same time, there was a growing understanding that every production process has a certain limit to the yield of suitable products, and this limit is determined not by the process itself, but by the system, i.e. the whole set of activities of the enterprise, organization of labor, management, in which this process takes place.

It follows from this that control should be carried out regarding the quality of the functioning of the entire system at all stages of its functioning.

Let's start with input control:

One of the elements of the relationship with the supplier is the organization of input control, which refers to the quality control of the supplier's products (initial materials, components, information) received by the consumer organization and intended for use in the manufacture, repair or operation of products, as well as the provision of services. Its main goal is to exclude the possibility of penetration into the production of raw materials, semi-finished products, components, tools, information with deviations from the quality requirements reflected in contractual obligations. The imperfection of this type of control can bring significant losses to both the manufacturer of the product and its consumer.

Input control is very time-consuming and expensive, while it duplicates the output control of the issuing enterprise. In this regard, it is becoming increasingly important to abandon input control by strengthening output control, which entails the establishment of a special relationship with the supplier. Abroad, the practice of such relations has existed for a long time. For example, in the Japanese company Bridgestone Corporation, the supplied parts and raw materials are controlled mainly to check their quantity and compliance technical documentation. Checking the quality of materials is not carried out, since it is carried out by suppliers before being sent to the consumer. This system is based on mutual trust and cooperation.

In accordance with the terms of the supply agreement, incoming control can be either solid, and selective. For its implementation on industrial enterprises specialized subdivisions are created in the QCD system. Incoming control laboratories function at medium and large enterprises. The main tasks of these departments are:

Carrying out input quality control of material and technical resources entering the organization;

Registration of documents based on the results of control;

Control of technological tests (samples, analyzes) of incoming resources in workshops, laboratories, control and testing stations;

Monitoring compliance by warehouse workers with the rules of storage and issuance of incoming products to production;

Calling representatives of suppliers to jointly draw up an act on defects found during incoming inspection, etc.

Demonstration of the effectiveness of input control is the reduction of cases of low-quality material and technical resources or services entering production.

Input controls include:

Periodic monitoring of the effectiveness of the supplier's quality assurance system (the so-called "second party" audit);

The requirement for the supplier to accompany the shipment of goods with protocols of control procedures;

The requirement for the supplier to carry out one hundred percent control and testing of the supplied material and technical resources or services;

Selective acceptance tests of a batch of goods by the supplier and the consumer at the same time;

The use by the supplier of a formal quality assurance system defined by the consumer (for example, based on ISO 9000 standards).;

Requirements for independent certification of the supplier's products by a third party.

If you are guided by the international standard ISO 9001:2008, then in section 7 "Manufacturing of products" in subsection 7.4 "Purchasing", paragraph 7.4.1 states: "The organization must ensure that the purchased products comply with the established procurement requirements. The scope and nature of control in relation to the supplier and purchased products should be determined by the degree of influence of these products on subsequent production of products or on finished products.

The Organization shall evaluate and select suppliers on the basis of their ability to supply products in accordance with the Organization's requirements.

Criteria for the selection, evaluation and re-evaluation of suppliers should be established. Records should be kept of the results of such evaluation and subsequent actions.”

In paragraph 7.4.2 "Purchasing information" we read: "Purchasing information must contain a description of the products ordered and include, where appropriate:

Requirements for the approval of products, procedures, processes and equipment;

Requirements for personnel qualification;

Requirements for a quality management system.

The organization must ensure that the adequacy established requirements for purchases before they are reported to the supplier.

And finally, paragraph 7.4.3 “Verification (verification) of purchased products reads as follows: “The organization must determine and implement control measures or other activities necessary to ensure that purchased products meet the requirements specified in the purchase information.

In cases where the Organization or its consumer intends to check (verify) the purchased products at the supplier's enterprise, the Organization must establish in the procurement information the intended measures for such verification and the method of product release.

The next stage of control in order to ensure quality is process control.

Control in the production process plays a dual role. On the one hand, this is one of the management functions, and on the other hand, it acts as an integral part of the production process. In this regard, planning involves the development and use of maps and control plans. Verification at each stage should be linked to the appropriate documentation for the finished product. Carrying out technical control in the production process should be clearly planned and regulated. Test and technical control procedures are documented, including a description of the specific equipment required for their implementation.

Section 4 of ISO 9001:2008 in subsection 4.1 point e) states: The organization shall monitor, measure, where possible, and review the processes included in the quality management system.

Next comes the comment. When incorporating external processes that affect product conformity to requirements, the organization shall establish controls for those processes. The control of such processes needs to be identified in the quality management system.

Clause 7 Production, subsection 7.1 Production planning c) states: “When planning production processes, the Organization shall determine, in the applicable form, the appropriate activities for:

Verification (verification),

Approval (validation),

monitoring,

Control and testing in relation to this product;

Product Acceptance Criteria.

To determine the compliance of the actual characteristics and quality indicators of products, processes or services with the requirements established by standards or other regulatory documents, it is necessary to have sufficiently complete and reliable information about the object, which can be obtained using measurements, control, tests. Data obtained as a result of the listed methods at all stages life cycle product or process development, will create an objective basis for acceptance management decisions in the field of quality assurance.

Quality control is a verification of the conformity of a product or process, on which its quality depends, to established requirements:

At the stage of product development, control consists in checking the compliance of the prototype with the terms of reference, technical documentation.

At the manufacturing stage, it covers quality, completeness, packaging, labeling, the state of production processes.

At the stage of operation, quality control consists in checking compliance with the requirements of operational and repair documentation.

Quality control includes three main steps:

Obtaining primary information about the actual state of the control object, controlled features and indicators of its properties;

Obtaining secondary information - information about deviations from the specified parameters by comparing the primary information with the planned criteria, norms and requirements;

Preparation of information for the development of appropriate control actions on the object under control in order to eliminate or prevent such deviations in the future.

A controlled attribute is a quantitative or qualitative characteristic of the properties of an object that is subject to control.

The method of control is a set of rules for the application of certain principles for the implementation of control.

Controls- these are products (devices, fixtures, tools, test benches) and materials (for example, reagents) used in the control.

According to the current species classification, quality control is subdivided according to the following species characteristics:

A) depending on the object of control - control of quantitative and qualitative characteristics and properties of products, technological process (its mode, parameters, characteristics);

B) by position in manufacturing process all types of quality control are divided into:

1. Control in the process of designing a new product;

2. Input quality control of raw materials, materials and semi-finished products supplied to the enterprise;

3. Control of the finished product, which in turn includes interoperational control (control of the product or process during the execution or after the completion of a certain operation) and final control of the finished product, based on the results of which a decision is made about its suitability for delivery or use;

4. Analysis of special processes, combining research and testing, to localize the causes of product properties that do not meet specifications, determine the possibility of improving quality characteristics and make sure that the corrective actions taken have given the necessary full and lasting effect;

By coverage of controlled products allocate continuous control, i.e. control of each unit of production, carried out with the same completeness, and selective - control of samples or samples from a batch or product stream;

By connection with the object of control in time exist:

Volatile control - control at random moments, selected in in due course; its effectiveness is determined by surprise, the rules for ensuring which must be specially developed. This control, as a rule, is carried out directly at the place of manufacture, repair, storage, etc.;

Continuous control - control, in which the flow of information about controlled objects occurs continuously;

Periodic control, in which the receipt of information about the controlled parameters occurs at set intervals.

Where possible, use of the product distinguish between destructive control (in which the object of control is not subject to further use) and non-destructive control (without violating the suitability of the object of control for further use for its intended purpose); in the first case, the product may remain usable, but the method of control does not guarantee this for every item tested;

By degree of use of controls they distinguish measuring, registration, organoleptic, according to the control sample (by comparing the signs of product quality and the control sample), technical inspection. The decision regarding the object of organoleptic control is made only on the basis of the results of the analysis of sensitive perceptions (for example, an assessment of color shades, smell). With this type of control, means can be used that are not measuring, but increase the susceptibility of the senses;

Depending on the level of technical equipment exist:

Manual control, in which non-mechanized controls are used to check the quality of parts, products;

Mechanized control, in which mechanized controls are used;

Automated control, which is carried out with partial direct participation of a person;

Active control, which affects the course of the technological process and processing modes in order to control them.

By organization structure allocate:

Self-control - quality control carried out by the performer himself,

Single-stage control, which is carried out directly by the manufacturer and an employee of the technical control department;

Multi-stage control - control carried out by the contractor, operational control, acceptance control by the QCD employees.

By type of tested parameters and quality features check:

Control of geometrical parameters, i.e. control of linear, angular dimensions, roughness, shape, etc.;

The control physical properties, such as heat, electrical conductivity, melting point and others;

The control mechanical properties: stiffness, hardness, plasticity, elasticity, strength, etc.;

The control chemical properties: chemical analysis the composition of the substance, the determination of corrosion resistance in different environments, and others;

Metallographic studies covering the control of the micro- and macrostructure of blanks, semi-finished products, parts;

Special control, implying control of tightness, the absence of internal defects, for example, using ultrasound;

Control of functional parameters, i.e. operability of devices, systems, devices in various conditions;

Visual control - control appearance object.

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What is product quality control

Quality control(QualityControl) - any planned and systematic activity carried out in production, which is carried out to guarantee confirmation that the goods produced, services and, in general, any processes performed comply with the established requirements and certain standards of consumers.

According to ISO standard 9000:2000, which defines such norms, quality is a set of specific characteristics and properties of a product or service to satisfy certain needs. At the same time, it should be taken into account that the indicated features of product quality control could be measured and controlled. For example, they include weight, dimensions of the product and packaging, cost, packaging, etc. There are 2 main groups of product features: qualitative and quantitative. The first can be, for example, artistic design, and the second - the dimensions and technical aspects.

Goals of product quality control

1) Increasing efficiency in working with clients. When the quality of the product improves, the number of consumers grows, while maintaining the already existing customer base. This is a good strategy where there is no need to consider competitive pricing.

2) Formation of industrial culture. If the quality management system is correctly built and established, then this has a positive effect on the motivation of the employees of the enterprise, and a certain production culture is formed. Accordingly, the number of mistakes made by employees is reduced, which helps to avoid additional costs and improve the process of product quality control.

3) The growth of the competitiveness of the enterprise, the level of investment in it. Here, success is guaranteed to those firms that exceed customer expectations. An established quality management system increases customer loyalty and creates an impeccable image of the company, strengthens its position.

What are the types of product quality control

1) Total control - all products pass through it. In this case, special attention is paid to any defect of the product in the process of its creation.

2) Selective - not all products pass through it, but only part of it. This is a kind of preventive technique that prevents the possibility of a marriage. This process is monitored by a special group at the enterprise, which is called the product quality control department.

3) Incoming control - the procedure through which the associated raw materials go through before they are put into production. All supplier materials are carefully checked and analyzed in order to improve the quality of the final product.

4) Interoperational (current) control extends to the entire production process, when between its certain stages the products are checked for compliance with storage standards, stipulated technical regimes, etc.

5) Output (acceptance) control - it is already the final product, what happened as a result. Everything is checked in accordance with accepted standards and regulations, a thorough inspection for defects is carried out, labeling and packaging quality are also taken into account. And only after complete quality control of the products and verification, permission is given for the supply of goods.

How to compare the quality of your products with the quality of competitors

To find out how your product differs from the offer of competitors, you can conduct a blind test. The tool allows you to understand how to refine the product in order to maintain its position in a competitive market.

How to apply this method, learn from algorithm, which you will find in the article of the electronic magazine "Commercial Director".

Tests as a special type of quality control

Experimental determination (research) of quantitative and qualitative specifics of products, which is carried out in accordance with established standards, is a test of finished products. Various characteristics of the product are taken into account. There are several fundamental types of product quality control tests:

- preliminary - testing of test samples in order to determine the possibility of acceptance tests;

- acceptance - tests to determine readiness for launching into the production process;

- acceptance tests - such tests, as a result of which the readiness of the product for shipment to the client is determined;

– periodic – one-time tests carried out every 3 years in order to check the constancy production technologies;

- typical - quality control tests carried out with serial products, when some additions have been made to its production process or composition.

What does the quality control department do?

OTK is an independent division of the company and reports directly to its director. The main functions of the department are tracking the product that does not meet the standards and certain standards, removing it from production. Also, the quality control department not only monitors and is responsible for product quality control, but also works to increase the sense of responsibility of employees, monitors discipline in the company.

The department sometimes includes: groups, laboratories for technical control of external acceptance, the technical bureau of the QCD, the bureau of the TC in the shops.

Functions of the quality control department:

1. Control over the quality and integrity of the products manufactured by the company, for its compliance with all necessary indicators, standards, technical specifications, execution of the necessary documentation for accepted products and subject to return due to defects, as well as control over the removal from production of completely rejected products in special rejection isolators and their disposal.

2. Presentation of finished products to representatives of the customer, if it is provided for by the contract.

3. Analysis and accounting of defective goods of the enterprise; thinking over and organizing projects for the prevention and elimination of defects in production; finding the guilty in the release of improper products.

4. Collecting customer opinions and obtaining information from them on the quality and reliability of products.

5. Quality control of incoming raw materials, materials, semi-finished products and components from suppliers' factories; identification of low-quality batches, drawing up acts on them and subsequent claims to suppliers.

6. Regulation of the process of acquisition, packaging and conservation of finished products.

7. Preparation and introduction of new standards and specifications.

8. Control over the presence of the company's trademark on finished products.

9. Tracking the state of measuring instruments that are in production and submitting them at the right time for state verification.

10. Control over the quality of manufacturing products and the condition of the tools and production equipment in operation at the enterprise.

11. Preparation and submission to the director for approval of schedules type checks serial products. Carrying out such checks in due time. This takes into account compliance with GOSTs, MRTU, TU.

12. Compliance monitoring necessary conditions and norms for the storage of not only finished products, but also other products, components, raw materials.

13. Organization of product quality control at all stages, providing it to the client at the first request.

14. Preparation and implementation of up-to-date methods of product quality control and quality assessment.

15. Conducting unscheduled product quality tests, as well as individual stages of production, raw materials, components, storage standards, etc.

16. Direct participation in testing of updated products and in all necessary approvals and clearances. Performing all necessary actions to effectively ensure product quality control.

17. Preparation, implementation and control of the process of certification of finished products.

18. Acceptance of components for the enterprise, necessary materials and raw materials necessary for production, quality control of these deliveries, as well as the preparation of all related documentation for this.

19. The introduction of high standards and requirements for the quality of products, the desire to motivate employees to produce a high-quality product, resisting any possibility of defects or defects in production.

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How is quality control organized?

The organization of product quality control is a set of actions to ensure the manufacture of goods that meet all the necessary established standards and requirements.

Technical control is a check of the ratio of the object of control and the established technical requirements.

For the production of high-quality goods, it is necessary to have a powerful technological enterprise that keeps pace with progress. In this regard, the quality management system for work and the products themselves implies the fulfillment of the following conditions:

1) Processing and updating technical documentation, which guarantees the production of good quality goods;

2) Development and mastering of technological processes in such a way that during their implementation the master could easily follow all the instructions and do his work, guided by the available action plan, without spending a lot of time understanding it, studying it, without needing to use additional supporting documents;

3) Preparation and use of accompanying documentation, which should record all data on quality control by specialists and supervisors in accordance with drawings and technological processes (the so-called operational, final product quality control);

4) Carrying out a systematic verification of the accuracy of the used measuring instruments, devices, and if they turn out to be faulty, their immediate removal from production;

5) Maintaining a significant level of culture and order in production, in workshops, in warehouses;

6) Provision of production with all the necessary relevant materials and components provided for by the technical documentation;

7) Rhythmic work of production;

8) Qualification of the personnel of the enterprise involved in production. It must be of the appropriate level.

What are the stages of the product quality control process?

1. Choice of methods - full total control of product quality or selective checks;

2. Choice of the purpose of control;

3. Development of a test plan:

Objects of control;

Norms subject to scrutiny;

Subjects of control;

Control methods;

The scope and means of product quality control (full, selective, manual, automatic);

Time frame of inspections, their duration;

Sequence, methods and tolerances.

4. Fixing the values of the actual and prescribed.

5. Determination of the identity of discrepancies (detection, identification of quantity).

6. Summing up, resolution.

7. Written fixation of the decision.

9. Communication of the decision (oral or written report).

10. Evaluation of the decision, taking measures to eliminate shortcomings.

Quality control of products and raw materials

Andrea Cuomo, production director of the Extra M factory, Moscow

As soon as my colleagues and I arrived at pasta factory"Extra M", it immediately became clear to us - it is necessary to completely change the system for checking and controlling the quality of products and raw materials (flour and water), as well as approaches to cooperation with suppliers. It is obvious. It was not possible to act on the example of work in Italy: almost all Italian producers use their own resources and, for example, use water directly from natural sources. We have completely different conditions in Russia. We decided to do the following.

3 stages of quality control of raw materials:

1) Express test of the quality of purchased raw materials

Usually we unloaded the whole flour, then its samples were tested in the laboratory. Now we take a small part of the flour and first of all carry out an express test, as a result of which we check compliance with the standards in 3 parameters: moisture content, whiteness and the degree of sieving. With satisfactory results of raw material quality analyzes, we already begin to completely unload raw materials and only then we carry out more in-depth and detailed tests, some of which sometimes take quite a long time - sometimes up to five hours (for example, gluten analysis).

If the results of our check do not meet the necessary norms and quality standards, then we return the flour back to the supplier. Only the flour that has adequately passed all the stages of our thorough quality control is supplied to the production.

2) Involving suppliers in quality control of incoming raw materials

Now we work according to the following principle: as soon as the raw materials are brought and unloaded, we immediately take two samples for testing, and not one, as before. After the express test, we keep one for ourselves and immediately send it to the laboratory, and send the second back to the supplier. So we take care of the two-way quality control of products and raw materials, and at the same time save the supplier's time. If, after carrying out more thorough tests, problems with the quality of the flour delivered to the plant are revealed, having learned from us the results of the test of our laboratory, the supplier will be able to independently examine the sample sent by us and draw conclusions.

3) Daily quality checks of raw materials and finished products

Every day we additionally test the flour before sending it to production - it undergoes an examination on special equipment designed specifically for such studies. Then the finished product itself is tested. In addition, the water used for kneading the dough is subjected to an additional check every morning. It is pre-cleaned, undergoing chemical treatment in special installations.

Thanks to a thorough check and careful quality control of flour, we have identified the most reliable partners for ourselves and now we constantly cooperate only with them. In addition, by saving time on inspection, we manage to produce more goods in short time. However, the introduction of an additional stage of checking the quality of the product required some additions to the work of the staff. For example, new reporting documentation had to be introduced, and the operators of the bulk flour storage warehouse had to undergo additional training.

What are the methods of product quality control

1. Histogram. This is the most effective method product quality control - a method of data processing. This method is ideal for ongoing quality control in the production process, studying the possibilities of technological processes, and analyzing the activities of individual performers. A histogram is a graphical method of presenting data grouped by how often it falls within a certain interval.

2. Delamination. This quality control method is used to obtain specific information, is based only on reliable data and helps to identify causal relationships.

3. Control cards. They demonstrate the process on a graph, showing its dynamics over time. Using this method, you can quickly trace the beginning of the drift of parameters for any quality indicator during the technological process. This will help to take preventive measures in a timely manner and prevent defects in finished products.

Control cards are used to control the quality of the product during its production. They record information about the process. There may be several formats for such records, depending on the type of product and the purpose of its production. The result of such cards is the timely detection of the moment when a failure occurs, and control over the quality and production process begins to be lost. Then you can take the necessary measures in time. As experience shows, a small number of types of marriage is a large proportion of their total number. The total frequency of manifestation of types of marriage of the category "other" should not exceed 10%.

This diagram is widely applicable. It is sometimes called the 80/20 curve because 80% of defective products are due to 20% of all possible causes.

4. Pareto diagram - a scheme based on a combination of discrete features, ranked in descending order and having a cumulative frequency. Speaking specifically about production, it should be noted that quality problems are fraught with losses (defective products and the costs associated with their production).

It is imperative to clarify the picture of the distribution of losses. Most of they are due to a number of basic defects caused by a small number of main causes. So, having found out the causes of the appearance of the main especially important defects, it is possible to eradicate almost all losses by concentrating all attention and efforts on eliminating precisely these causes. This is precisely the principle of the Pareto chart, which in our time is used and applied very actively. A simple joint discussion of the main factors, as a rule, is not enough, since the opinions of various people are rather subjective, and, moreover, they are also not entirely correct. The foundation of any event must be reliable information. It is this that allows us to get the Pareto diagram - another serious method of product quality control.

5. Ishikawa's scheme. Japanese professor Kaoru Ishikawa is the author of many books on management and quality control. The famous diagrams, or as they are also called, Ishikawa's schemes (some people know them as circles of quality and graphs of causes and effects) made the name of the scientist known throughout the world.

So, the Ishikawa circuit is a logical construction 4 essential elements quality control and their relationship. Materials, equipment, people, raw materials - of them, in fact, the diagram consists. All these four factors are ranked according to their importance to the goal. As you understand, in the structure, the scientist grouped the very "ingredients" that affect the quality of the product.

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Of course, in fact, the number of constituent elements is much larger, so each of them can be further divided into accompanying, less significant elements. In the diagram, they are drawn with arrows.

To use the Ishikawa diagram, you first need to identify the most key elements that affect quality control, and then isolate the causes and effects.

With the help of such a diagram, you can analyze the quality of the product itself or its individual components, thoroughly analyze all the components and factors, their influence on the quality as a whole and separately. Also, the scheme allows us to calculate the most acceptable and best way to improve the quality of the product.

The Ishikawa Scheme, another practical quality control method, brings together and visually demonstrates all aspects that affect a particular problem. It helps to recognize and resolve a large number of organizational, economic, and production issues.

Means of product quality control

1) means of non-automatic control;

2) machines and automatic quality control systems;

3) means of control of automatic process control systems.

The first group is used to collect information about the quality characteristics of the product. Most often they are used in manual control, they differ in rather low productivity. It is quite difficult to control them.

The second group helps to obtain information about the parameters that comprehensively indicate the quality of the object under control. They may contain scanning devices, indicators and recorders, etc. All of them, for the most part, characterize products according to the “good - defective” principle. Examples of such systems include devices for sorting balls by diameter, machines for accounting and sorting pistons, etc.

The third group of product quality control (APCS) is designed to provide useful information that can be used to actively influence the course of the entire technological process in case of its unexpected violation.

What are the costs of product quality control

In the estimate for quality control, you can enter:

1. Inspections and tests: payment for the work of inspectors and other employees involved in the tests. This is especially true for scheduled inspections. Repeated checks of defective, rejected elements, as well as their testing, sorting, etc., as a rule, do not fit into this estimate.

2. Checks and tests of supplied materials:

Payment for the work of inspectors and test personnel of various levels;

Expenses for various laboratory tests that are performed to evaluate and control the quality of materials;

Costs for the work of inspectors and personnel involved in the testing of materials and conducting their assessment directly at the supplier's production.

3. Materials for testing and inspections:

The cost of consumables that are used in the control and tests;

The cost of materials and samples destroyed during the inspection.

The price of test equipment is usually not fixed in this estimate.

4. Process control: payment for the activities of employees who perform control and testing in production.

5. Acceptance of the customer's product:

Expenses for testing already finished products before delivery;

The cost of testing products at the customer's place before delivery.

6. Verification raw material and spare parts: this takes into account the costs of testing raw materials, spare parts, etc., which are associated with changes in the technical requirements of the project, a significant shelf life, etc.

7. Product audit:

The cost of auditing the quality of technological operations. Such actions can be carried out either during the manufacturing process, or already with final product;

The cost of all reliability checks that are carried out on manufactured products;

Expenses for quality assurance by insurance companies, government organizations, etc.

The results of product quality control - stable quality and customer loyalty

Alexey Martynenko, managing partner of UmalatFrescolatte, Sevsk

Before we start working with any supply farm and conclude a cooperation agreement with it, we come there and find out how milk is produced, check if the cows are sick with mastitis; we evaluate the general sanitary condition of the farm, pay special attention to the availability of cooling equipment. If something does not satisfy us and at least partially does not meet the established standards, we immediately refuse to cooperate. Mozzarella is a very delicate product, which must be made without fail from the purest quality milk, in which the content of any antibiotics is unacceptable. At the same time, it must be cooled immediately after milking, otherwise harmful bacteria will begin to multiply in it.

All the milk that is brought to our enterprise is carefully checked by us in many ways. We reveal the percentage of fat, protein, density, as well as the presence of bacteria. If at least something does not suit us, the entire accepted batch is immediately returned to the suppliers.

The product that has passed all our checks and meets the established standards, we certainly begin to pasteurize. We do this at a temperature of 72 C, the process lasts 20 seconds. This procedure helps to keep only beneficial bacteria in milk, killing all unnecessary microorganisms.

Then we leave the product for 12 hours and only after this exposure we send it to production. The very procedure for creating cheese is quite difficult and consists of many stages. Each of them is closely monitored and recorded by special employees. This allows later, if any shortcomings are found, it is easy to recognize exactly where, at what stage they were made.

Next, the cheese goes through laboratory tests, samples of all batches are checked. If problems or inconsistencies are identified, the entire batch is written off. If the result is positive, we still keep the samples for archiving in case there is any complaint from the buyers. Then we will be able to quickly respond and identify the problem of the party.

While the cheese is being delivered to the distributor, we can still control the temperature along this section of the journey with the help of special temperature sensors. We put them in all containers with cheese. However, its further safety, unfortunately, can no longer be traced. It's annoying if the cheese spoils on the counter of the store due to improper storage conditions. And buyers may consider that this product itself is not of high quality ...

I personally carefully monitor the quality of our products and often leave my contact number phone number and personal signature - Alexey Martynenko. Many consider such a move insane - after all, I publicly advertise my data, my mobile. You can see for yourself. For example, in Azbuka Vkusa stores, butter packages contain this information. I really care about my business and take personal responsibility for the quality of our product. For 2 years of such practice, I received only 2 calls, but even then without any complaints.

Bottom line: after two years of work and experiments, the quality of our products has definitely increased. The Test Purchase program on Channel One has already noted our result 4 times.

Information about the author and company

Andrea Cuomo, director of production at the Extra M factory, Moscow. JSC "Extra M"
Field of activity: production of pasta (a division of the Italian company DeCecco). Number of personnel: 240 (in Moscow). Main brands: DeCecco, Noble, Extra M, Saomi.

Alexey Martynenko, managing partner of the company Managing partner of UmalatFrescolatte, Sevsk. Umalat Frescolatte. Field of activity: production of soft cheeses. Form of organization: CJSC. Location: Sevsk (Bryansk region). Number of employees: 167. Annual turnover: 500 million rubles. (in 2011). Manufactured products: feta cheese, mascarpone, mozzarella, ricotta, feta, chechil; butter(products are produced under the Umalatte umbrella brand and the Umalat, Pretto, Salatta, Unagrande brands). Managing partner experience in the position: since 2003. Participation of the managing partner in the business: co-owner (55%).

Topic 4. General functions of product quality management

4.4. Control, accounting and analysis of quality management processes

4.4.1. Organization of product quality control and defect prevention

Quality control occupies a special place in product quality management. It is control as one of the effective means of achieving the intended goals and the most important function of management that contributes to the correct use of the objectively existing, as well as the prerequisites and conditions created by man for the production of high-quality products. The efficiency of production as a whole largely depends on the degree of perfection of quality control, its technical equipment and organization.

It is in the process of control that the actually achieved results of the system functioning are compared with the planned ones. Modern methods of product quality control, which allow achieving high stability of quality indicators at minimal cost, are becoming increasingly important.

The control- this is the process of determining and evaluating information about deviations of actual values from given values or their coincidence and analysis results. You can control the goals (goal / goal), the progress of the plan (goal / will be), forecasts (will be / will be), the development of the process (will / be).

The subject of control can be not only performing activities, but also the work of a manager. The control information is used in the regulation process. So they say about the expediency of combining planning and control into a single control system (Controlling): planning, control, reporting, management.

Control is carried out by persons directly or indirectly dependent on the process. Verification (revision) is control by persons independent of the process.

The control process must go through the following stages:

1. Definition of the control concept (comprehensive control system "Controlling" or private checks);
2. Determination of the purpose of control (decision on the appropriateness, correctness, regularity, effectiveness of the process
board);
3. Scheduling the test:
a) objects of control (potentials, methods, results, indicators, etc.);
b) verifiable norms (ethical, legal, industrial);
c) subjects of control (internal or external control bodies);
d) control methods;
e) the scope and means of control (full, continuous, selective, manual, automatic, computerized);
f) timing and duration of inspections;
g) the sequence, methods and tolerances of checks.
4. Determination of actual and prescribed values.
5. Establishing the identity of discrepancies (detection, quantification).
6. Making a decision, determining its weight.
7. Documenting the solution.
8. Metaverification (validation verification).
9. Communication of the decision (oral, written report).
10. Evaluation of the solution (analysis of deviations, localization of causes, establishment of responsibility, study of possibilities for correction, measures to eliminate deficiencies).

Types of control are distinguished by the following features:

1. By belonging of the subject of control to the enterprise:
interior;
external;

2. On the basis for the control:
voluntary;
according to law;
according to the statute.

3. According to the object of control:
process control;
decision control;
object control;
control over the results.

4. By regularity:
systemic;
irregular;
special.

Quality control should confirm the fulfillment of specified product requirements, including:

input control (materials should not be used in the process without control; inspection of the incoming product must comply with the quality plan, fixed procedures and can take various forms);

intermediate control (the organization must have special documents that fix the procedure for control and testing within the process, and carry out this control systematically);

final control (designed to identify compliance between the actual end product and that provided by the quality plan; includes the results of all previous checks and reflects the product's compliance with the necessary requirements);

registration of control and test results (documents on control and test results are provided interested organizations and persons).

special kind controls are testing of finished products. Andtest is the determination or study of one or more characteristics of a product under the influence of a combination of physical, chemical, natural or operational factors and conditions. Tests are carried out according to the relevant programs. Depending on the goals, there are the following main types of tests:

Preliminary tests - tests of prototypes to determine the possibility of acceptance tests;
acceptance tests - testing of prototypes to determine the possibility of their production;
acceptance tests - tests of each product to determine the possibility of its delivery to the customer;
periodic tests - tests that are carried out once every 3-5 years to check the stability of the production technology;
Type tests - tests of serial products after making significant changes in the design or technology.

The accuracy of measuring and testing equipment affects the reliability of the quality assessment, so ensuring its quality is especially important.

From normative documents regulating metrological activity, allocate: Law of the Russian Federation on the uniformity of measurements and international standard ISO 10012-1:1992 on the confirmation of the metrological suitability of measuring equipment.

In managing control, measurement and test equipment, the organization shall:

determine what measurements should be made, by what means and with what accuracy;
document the compliance of the equipment with the necessary requirements;
regularly calibrate (check the divisions of the device);
determine the methodology and frequency of calibration;
Document the results of the calibration;
provide conditions for the use of measuring equipment, taking into account the parameters environment;
Eliminate faulty or unusable control and measuring equipment;
Perform equipment adjustments and software using only specially trained personnel.

Passage of control and testing of products must be confirmed visually (for example, using labels, tags, seals, etc.). Those products that do not meet the verification criteria are separated from the rest.

It is also necessary to identify the specialists responsible for carrying out such control and establish their powers.

To make a decision on control and organization of control processes, a number of criteria may be important: its effectiveness, the effect of influencing people, the tasks of control and its boundaries (Fig. 4.5).

Rice. 4.5. The main components of the criterion for the decision to control

Quality control system products is a set of interrelated objects and subjects of control, used types, methods and means of assessing the quality of products and preventing defects in various stages product life cycle and quality management levels. Efficient system control allows in most cases to carry out a timely and targeted impact on the level of product quality, to prevent all sorts of shortcomings and malfunctions, to ensure their prompt identification and elimination with the least expenditure of resources. Positive results of effective quality control can be identified and in most cases quantified at the stages of development, production, circulation, operation (consumption) and restoration (repair) of products.

AT market conditions management, the role of quality control services of enterprises' products in ensuring the prevention of defects in production is significantly increasing, their responsibility for the reliability and objectivity of the results of inspections being carried out, and preventing the supply of low-quality products to consumers is increasing.

The need for priority improvement of the activities of the technical control services of enterprises is determined by their special place in the production process. Thus, close proximity to controlled objects, processes and phenomena (in time and space) creates the most favorable conditions for employees of control services for the following:

development of optimal control plans based on the results of long-term observation, analysis and generalization of information about the quality of the initial components of the finished product, the accuracy of equipment, the quality of tools and equipment, the stability of technological processes, the quality of work of performers and other factors that have a direct impact on product quality;

prevention of marriage and ensuring the active preventive impact of control on the processes of occurrence of deviations from the requirements of approved standards, specifications, parameters of existing technological processes, etc.;

timely carrying out in the required volume of all the foreseen control operations;

purposeful operational change in the conditions of operation of the object of control to eliminate emerging failures and prevent the production and supply of products of inadequate quality to consumers.

It should be emphasized that quality control carried out by the relevant departments of enterprises is primary (preceding in time) in relation to control by other subjects of quality management. This circumstance indicates the need for priority improvement of the activities of technical control services at enterprises. Figure 4.6 shows typical composition structural divisions department of technical control (QCD) of a large enterprise.

Quality control operations are integral component technological process of production of products, as well as their subsequent packaging, transportation, storage and shipment to consumers. Without the employees of the control service of the enterprise (workshop, site) carrying out the necessary verification operations in the process of manufacturing products or upon completion of individual stages of their processing, the latter cannot be considered fully manufactured, therefore they are not subject to shipment to buyers. It is this circumstance that determines the special role of technical control services.

Rice. 4.6. Structural divisions of OTC

Technical control services are currently functioning at almost all industrial enterprises. It is the departments and departments of quality control that have the most essential material and technical prerequisites (testing equipment, instrumentation, equipment, premises, etc.) for conducting a qualified and comprehensive assessment of the quality of products. Nevertheless, the reliability of the results of quality control carried out by the personnel of these services often raises reasonable doubts.

At some enterprises, the exactingness and objectivity of technical control workers when accepting manufactured products remain at a low level. The weakening of work to identify internal defects is almost everywhere accompanied by an increase in claims for products. At many enterprises, there is an excess of the amount of losses from claims and reclamations for low-quality products over the amount of losses from defects in production.

The detection of many defects in products only by consumers of products indicates the unsatisfactory work of the technical control services of enterprises and, in particular, the lack of the necessary interest and responsibility of the personnel of control departments in the full detection of defects in the serviced production areas.

In the structure of product quality control services of many enterprises, there are mainly subdivisions that provide technical and technological aspects of quality control. At the same time, the organizational, economic and information functions of departments and departments of technical control are not sufficiently developed. Many enterprises in the work of these departments have such problems and shortcomings as:

low capacity of control services and insufficient number of personnel, leading to disruption in the rhythm of production and sales of products, failure to perform certain quality control work, the emergence of uncontrolled production sites;

unreliability of control results;
low exactingness and subjectivity in assessing product quality;
weak technical equipment and shortcomings of metrological support;
imperfection of measurement methods, duplication and parallelism in quality assessment work;
relatively low wage employees of quality control services for products of enterprises;
shortcomings in the bonus systems for personnel of control services, leading to disinterest in the full and timely detection of defects;
discrepancy between the qualifications of inspectors and the category of examinations performed, the low educational level of employees of the quality control department of enterprises.

The elimination of the noted shortcomings in the work of technical control services, which impede the achievement of high preventive measures, reliability and objectivity of inspections, can have a versatile positive impact on the processes of formation and evaluation of the quality of products.

Firstly, technical control, aimed at preventing the imbalance of production processes and the occurrence of deviations from the requirements established for the quality of products, contributes to the prevention of defects, its detection at the earliest stages of technological processes and the prompt elimination of defects. minimal cost resources, which undoubtedly leads to an increase in the quality of products, an increase in production efficiency.

Secondly, strict and objective quality control of products by QCD employees prevents the penetration of defects beyond the gates of manufacturers, helps to reduce the volume of low-quality products supplied to consumers, reduces the likelihood of additional unproductive costs inevitably arising from poor control to identify and eliminate various defects in already assembled products, storage, shipment and transportation of low-quality products to consumers, its incoming control by special units and the return of defective products to manufacturers.

Thirdly, the reliable operation of the quality control service creates the necessary prerequisites for eliminating duplication and parallelism in the work of other enterprise services, reducing the volume of information processed by them, releasing many qualified specialists engaged in rechecking products adopted by the enterprise technical control service, and significantly reducing the number of disagreements that have place in assessing the quality of products by various subjects of control, reducing the cost of technical control and increasing its efficiency.

Improving the activities of departments and departments of technical control of enterprises should first of all provide for the creation, development and strengthening within the control services of those units that are able to effectively solve the following tasks:

development and implementation of measures to prevent defects in production, to prevent deviations from the approved technological processes, to prevent malfunctions that lead to a deterioration in the quality of products;

development and implementation of progressive methods and means of technical control that contribute to the growth of productivity and capital-labor ratio QCD controllers, increasing the objectivity of inspections and facilitating the work of personnel of control services;

objective accounting and comprehensive differentiated assessment of labor quality various categories personnel of the control service, determining the reliability of the control results;

preparation of the necessary data for subsequent centralized processing of information on the actual state and changes in the basic conditions and prerequisites for the production of high-quality products (the quality of raw materials, semi-finished products, components, etc. supplied through cooperation, the quality of work of workers, the state of technological discipline in workshops and on sites, etc.), as well as information on the achieved level of product quality;

carrying out work to expand the introduction of self-control of the main production workers (in particular, the formation of a list of technological operations transferred for quality self-control, equipping workplaces with the necessary instrumentation, tools, equipment and documentation, special training for workers, selective control of the activities of performers transferred to work with a personal brand, evaluation of the results of the introduction of self-control in production, etc.);

conducting special studies of the dynamics of product quality during their operation, involving the organization of an effective information relationship between suppliers and consumers on product quality issues;

planning and technical and economic analysis of various aspects of the activities of the product quality control service;

coordination of work of all structural subdivisions of departments and departments of technical control of the enterprise;

periodic definition absolute value and the dynamics of costs for product quality control, the impact of preventive maintenance, reliability and cost-effectiveness of technical control on the quality of products and the main performance indicators of the enterprise, evaluation of the effectiveness of the control service.

On the small businesses due to a number of objective reasons, the creation of several new units as part of the technical control service is not always possible. AT similar cases the functions listed above can be transferred for permanent execution not to newly created units, but to individual specialists of the quality control service that are part of one or another of its structural units.

In existing working conditions a fairly quick and effective increase in the objectivity of product quality control is achieved as a result of changing the incorrect system that has developed at many enterprises for evaluating and stimulating the work of various categories of personnel in control services, creating a genuine interest of these workers in improving the quality of their work, and ensuring the reliability of ongoing inspections.

To significantly improve the results of product quality control, it is also necessary to concentrate the efforts of employees of control services to ensure the priority development of progressive types of technical control that make it possible to prevent defects in production. Figure 4.7 shows the composition of the elements of the marriage prevention system at the enterprise and their relationship. The effectiveness of its activities directly affects the quality indicators of the enterprise, therefore it is of enduring importance.

The development of progressive types of technical control implies the need for priority improvement:

product quality control at the stage of its development;

standard control of design, technological and other documentation for newly mastered and modernized products; incoming quality control of raw materials, materials, semi-finished products, components and other products obtained through cooperation and used in our own production;

monitoring compliance with technological discipline by the direct executors of production operations;

self-control of the main production workers, brigades, sections, shops and other divisions of the enterprise.

Rice. 4.7. The system of marriage prevention at the enterprise

The correct use of the listed types of control contributes to a significant increase in its active impact on the process of forming the quality of products, since it is not a passive fixation of defects in production, but the prevention of its occurrence.

The use of these types of control allows for the timely detection of emerging deviations from established requirements, the prompt identification and elimination of various causes of a decrease in product quality, and the prevention of the possibility of their occurrence in the future.

4.4.2. Methods of quality control, analysis of defects and their causes

Technical control- this is a check of the compliance of the object with the established technical requirements, an integral and integral part of the production process. Subject to control:

raw materials, materials, fuel, semi-finished products, components coming to the enterprise;
manufactured blanks, parts, Assembly units;
finished goods;
equipment, tooling, technological processes for manufacturing products.
The main tasks of technical control are to ensure the release of quality products, in accordance with the standards and technical specifications, to identify and prevent defects, to take measures to further improve the quality of products.

To date, a variety of quality control methods have been developed, which can be divided into two groups:

1. Self-check or self-check- personal check and control by the operator using the methods established by the technological map for the operation, as well as using the provided measuring tools in compliance with the specified check frequency.

2. revision (examination)– verification carried out by the inspector, which must correspond to the content of the process control chart.

The organization of technical control consists in:
design and implementation of the quality control process;
determination of organizational forms of control;
selection and feasibility study of means and methods of control;
ensuring the interaction of all elements of the product quality control system;

· development of methods and systematic analysis of marriage and defects.

Depending on the nature of the defects, the marriage may be correctable or irreparable (final). In the first case, after correction, the products can be used for their intended purpose, in the second case, it is technically impossible or economically unreasonable to make a correction. The perpetrators of the marriage are being identified and measures are being taken to prevent it. Types of technical control are shown in Table 4.3.

When controlling the quality of products, physical, chemical and other methods are used, which can be divided into two groups: destructive and non-destructive.

Destructive methods include the following tests:

tensile and compression tests;
impact tests;
tests under repeated-variable loads;
hardness tests.

Table 4.3

	Classification sign	Types of technical control
	By appointment	Input (products from suppliers); industrial; inspection (control control).
	By stages of the technological process	Operational (in the process of manufacturing); acceptance (finished products).
	By control methods	Technical inspection(visual); measuring; registration; statistical.
	By completeness of coverage by control of the production process	Solid; selective; volatile; continuous; periodic.
	On the mechanization of control operations	Manual; mechanized; semi-automatic; auto.
	Influence on the course of processing	Passive control (with a stop of the processing process and after processing); active control (control during processing and stop the process when the required parameter is reached); active control with automatic adjustment of equipment.
	By measuring dependent and independent tolerances	Measurement of actual deviations; measurement of limit deviations using passable and impassable gauges.
	Depending on the object of control	Product quality control; control of commodity and accompanying documentation; process control; control of technological equipment; control of technological discipline; control of qualification of performers; monitoring compliance with operating requirements.
	Influence on the possibility of subsequent use	Destructive; non-destructive.

Non-destructive methods include:

magnetic (magnetographic methods);
acoustic (ultrasonic flaw detection);
radiation (defectoscopy using x-rays and gamma rays).

4.4.3. Statistical quality control methods

The meaning of statistical methods of quality control lies in a significant reduction in the cost of its implementation compared to organoleptic (visual, auditory, etc.) with continuous control, on the one hand, and in the exclusion of random changes in product quality, on the other.

There are two areas of application of statistical methods in production (Fig. 4.8):

when regulating the course of the technological process in order to keep it within the specified limits (left side of the diagram);

upon acceptance of manufactured products (right side of the diagram).

Rice. 4.8. Areas of application of statistical methods of product quality management

To control technological processes, the problems of statistical analysis of the accuracy and stability of technological processes and their statistical regulation are solved. In this case, tolerances for controlled parameters specified in the technological documentation are taken as a standard, and the task is to strictly keep these parameters within the established limits. The task of searching for new modes of performing operations in order to improve the quality of the final production can also be set.

Before undertaking the application of statistical methods in the production process, it is necessary to clearly understand the purpose of applying these methods and the benefits of production from their application. It is very rare that data is used to judge quality as received. Usually, seven so-called statistical methods or quality control tools are used for data analysis: stratification (stratification) of data; charts; Pareto chart; causal diagram (Ishikawa diagram or "fish skeleton"); control sheet and histogram; scatter diagram; control cards.

1. Stratification (stratification).

When dividing data into groups in accordance with their characteristics, the groups are called layers (strata), and the separation process itself is called stratification (stratification). It is desirable that the differences within the layer be as small as possible, and between the layers as large as possible.

There is always a greater or lesser spread of parameters in the measurement results. If we carry out stratification by the factors that generate this variation, it is easy to identify the main reason for its occurrence, reduce it and achieve an increase in product quality.

Application various ways delamination depends on specific tasks. In production, a method called 4M is often used, taking into account factors depending on: a person (man); machines (machine); material (material); method (method).

That is, delamination can be done like this:

By performers (by gender, work experience, qualifications, etc.);
- by machines and equipment (by new or old, brand, type, etc.);
- by material (by place of production, batch, type, quality of raw materials, etc.);
- according to the method of production (by temperature, technological method, etc.).

In trade, there can be stratification by regions, firms, sellers, types of goods, seasons.

The pure stratification method is used when calculating the cost of a product, when it is required to estimate direct and indirect costs separately for products and batches, when assessing profit from the sale of products separately for customers and products, etc. Stratification is also used in the application of other statistical methods: in the construction of cause-and-effect diagrams, Pareto diagrams, histograms and control charts.

2. Graphical presentation of data widely used in industrial practice for clarity and to facilitate understanding of the meaning of data. There are the following types of charts:

BUT). The graph, which is a broken line (Fig. 4.9), is used, for example, to express changes in any data over time.

Rice. 4.9. An example of a "broken" graph and its approximation

B) Pie and strip plots (Figures 4.10 and 4.11) are used to express the percentage of data under consideration.

Rice. 4.10. Pie Chart Example

The ratio of the components of the cost of production:
1 - the cost of production in general;
2 - indirect costs;
3 - direct costs, etc.

Rice. 4.11. Ribbon Chart Example

Figure 4.11 shows the ratio of the amounts of proceeds from the sale of certain types products (A,B,C), a trend is visible: product B is promising, but A and C are not.

AT). The Z-plot (Fig. 4.12) is used to express the conditions for achieving these values. For example, to evaluate the general trend when registering actual data by month (sales volume, production volume, etc.)

The graph is built as follows:

1) the values of the parameter (for example, sales volume) are plotted by months (for a period of one year) from January to December and are connected by straight line segments (broken line 1 in Fig. 4.12);

2) the cumulative amount for each month is calculated and the corresponding graph is built (broken line 2 in Fig. 4.12);

3) final values are calculated (changing total) and the corresponding graph is built. For the changing total, in this case, the total for the year preceding the given month is taken (broken line 3 in Fig. 4.12).

Rice. 4.12. An example of a Z-shaped plot.

The ordinate axis is revenue by months, the abscissa axis is the months of the year.

By changing the total, you can determine the trend of change over a long period. Instead of a changing total, you can plot the planned values on the graph and check the conditions for achieving them.

G). The bar graph (Fig. 4.13) represents the quantitative dependence, expressed by the height of the bar, of such factors as the cost of the product from its type, the amount of waste as a result of marriage from the process, etc. Varieties of the bar graph are the histogram and the Pareto chart. When plotting a graph along the y-axis, the number of factors influencing the process under study is plotted (in this case, the study of incentives to purchase products). On the abscissa axis - factors, each of which corresponds to the height of the column, depending on the number (frequency) of the manifestation of this factor.

Rice. 4.13. An example of a bar chart.

1 - the number of incentives to buy; 2 - incentives to buy;

3 - quality; 4 - price reduction;

5 – warranty periods; 6 - design;

7 - delivery; 8 - others;

If we sort the incentives to buy by the frequency of their occurrence and build a cumulative sum, we get a Pareto chart.

3. Pareto chart.

A scheme built on the basis of grouping by discrete features, ranked in descending order (for example, by frequency of occurrence) and showing the cumulative (cumulative) frequency, is called a Pareto chart (Fig. 4.10). Pareto is an Italian economist and sociologist who used his chart to analyze Italy's wealth.

Rice. 4.14. An example of a Pareto chart:

1 - errors in the production process; 2 - low-quality raw materials;

3 - low-quality tools; 4 - low-quality templates;

5 - low-quality drawings; 6 - other;

А – relative cumulative (cumulative) frequency, %;

n is the number of defective units of production.

The above diagram is built on the basis of grouping defective products by types of marriage and arranging in descending order the number of units of defective products of each type. The Pareto chart can be used very widely. With its help, you can evaluate the effectiveness of the measures taken to improve the quality of products by building it before and after making changes.

4. Cause and effect diagram (Fig. 4.15).

a) an example of a conditional diagram, where:

1 - factors (reasons); 2 - large "bone";

3 - small "bone"; 4 - middle "bone";

5 - "ridge"; 6 - characteristic (result).

b) an example of a cause-and-effect diagram of factors affecting product quality.

Rice. 4.15 Cause-and-effect diagram examples.

A cause and effect diagram is used when it is required to investigate and depict the possible causes of a particular problem. Its application allows you to identify and group the conditions and factors that affect this problem.

Consider the form cause-and-effect diagram in fig. 4.15 (it is also called the "fish skeleton" or Ishikawa diagram).

Chart order:

1. A problem is chosen for solution - a "ridge".
2. The most significant factors and conditions influencing the problem are identified - the causes of the first order.
3. A set of causes influencing significant factors and conditions (causes of the 2nd, 3rd and subsequent orders) is revealed.
4. The diagram is analyzed: factors and conditions are ranked in order of importance, those reasons that are currently amenable to adjustment are established.
5. A plan for further action is drawn up.

5. Control sheet(cumulative frequency table) is compiled to build histograms distribution, includes the following columns: (Table 4.4).

Table 4.4

Based on the control sheet, a histogram is built (Fig. 4.16), or, with a large number of measurements, probability density curve(Fig. 4.17).

Rice. 4.16. An example of presenting data as a histogram

Rice. 4.17. Types of probability density distribution curves.

The histogram is a bar graph and is used to visualize the distribution of specific parameter values by frequency of occurrence over a certain period of time. By plotting the allowable values of a parameter on a graph, you can determine how often that parameter falls within or out of the allowable range.

When examining the histogram, you can find out whether the batch of products is in a satisfactory condition and technological process. Consider the following questions:

what is the width of the distribution in relation to the width of the tolerance;
what is the center of distribution in relation to the center of the tolerance field;
what is the form of distribution.

a) the form of distribution is symmetrical, then there is a margin for the tolerance field, the distribution center and the center of the tolerance field coincide - the quality of the lot is in a satisfactory condition;

b) the distribution center is shifted to the right, that is, the fear that among the products (in the rest of the lot) there may be defective products that go beyond the upper tolerance limit. Check if there is a systematic error in the measuring instruments. If not, then continue to produce products by adjusting the operation and shifting the dimensions so that the center of distribution and the center of the tolerance field coincide;

c) the center of distribution is located correctly, however, the width of the distribution coincides with the width of the tolerance field. There are fears that when considering the entire batch, defective products will appear. It is necessary to investigate the accuracy of the equipment, processing conditions, etc. or expand the tolerance field;

d) the distribution center is displaced, which indicates the presence of defective products. It is necessary by adjustment to move the distribution center to the center of the tolerance field and either narrow the distribution width or revise the tolerance;

e) the situation is similar to the previous one, the measures of influence are similar;

f) 2 peaks in the distribution, although the samples were taken from the same lot. This is explained either by the fact that the raw material was 2 different varieties, or in the process of work, the machine setting was changed, or products processed on 2 different machines. In this case, the examination should be carried out in layers;

g) both the width and the center of distribution are normal, however, a small part of the products goes beyond the upper tolerance limit and, separating, forms a separate island. Perhaps these products are part of the defective ones, which, due to negligence, were mixed with good ones in the general flow of the technological process. It is necessary to find out the cause and eliminate it.

6. Scatter (scatter) diagram is used to identify the dependence (correlation) of some indicators on others or to determine the degree of correlation between n data pairs for variables x and y:

(x 1 ,y 1), (x 2 ,y 2), ..., (x n , y n).

These data are plotted on a graph (scatterplot), and the correlation coefficient is calculated for them using the formula

covariance;

Standard deviations of random variables x and y;

n– sample size (number of data pairs – Xi and ati);

and - arithmetic mean values Xi and ati respectively.

Consider various variants of scatter diagrams (or correlation fields) in fig. 4.18:

Rice. 4.18. Scatterplot options

When:

a) we can talk about a positive correlation (with increasing x increases y);

b) shows a negative correlation (with increasing x decreases y);

in) with growth x y can both increase and decrease, they speak of the absence of a correlation. But this does not mean that there is no relationship between them, there is no linear relationship between them. An obvious non-linear (exponential) dependence is also presented in the scatter diagram G).

The correlation coefficient always takes values in the interval , i.e. at r>0 - positive correlation, at r=0 - no correlation, at r<0 – отрицательная корреляция.

For the same n data pairs ( x 1 , y 1 ), (x 2 , y 2 ), ..., (x n, y n) you can establish a relationship between x and y. The formula expressing this dependence is called the regression equation (or regression line), and it is represented in general form by the function

at= a +bX.

To determine the regression line (Figure 4.19), it is necessary to statistically evaluate the regression coefficient b and permanent a. For this, the following conditions must be met:

1) the regression line must pass through the points ( x,y) average values x and y.

2) the sum of squared deviations from the regression line of values y must be the smallest over all points.

3) to calculate coefficients a and b formulas are used

Those. the regression equation can approximate real data.

Rice. 4.19. Regression line example

7. Control card.

One way to achieve satisfactory quality and maintain it at this level is the use of control charts. To control the quality of the technological process, it is necessary to be able to control those moments when the manufactured products deviate from the tolerances specified by the technical conditions. Let's consider a simple example. Let's follow the work of the lathe for a certain time and measure the diameter of the part made on it (per shift, hour). Based on the results obtained, we construct a graph and get the simplest control card(Fig. 4.20):

Rice. 4.20. Control Chart Example

At point 6 there was a disorder of the technological process, it is necessary to regulate it. The position of the VCG and NCG is determined analytically or according to special tables and depends on the sample size. With a sufficiently large sample size, the limits of the VKG and NKG are determined by the formulas

NKG \u003d -3,

VKG and NKG serve to prevent the disorder of the process, when the products still meet the technical requirements.

Control charts are used when it is required to establish the nature of faults and evaluate the stability of the process; when it is necessary to establish whether the process needs regulation or should be left as it is.

A control chart can also confirm process improvement.

The control chart is a means of recognizing deviations due to non-random or special causes from the likely changes inherent in the process. Probable changes rarely recur within predicted limits. Deviations due to non-random or special causes signal that some of the factors affecting the process need to be identified, investigated and controlled.

Control charts are based on mathematical statistics. They use operational data to establish limits within which future research will be expected if the process remains ineffective due to non-random or special reasons.

Information about control charts is also contained in the international standards ISO 7870, ISO 8258.

The most widely used control charts mean X and range control charts R, which are used together or separately. Natural fluctuations between control limits should be controlled. You need to make sure you select the correct control chart type for the specific data type. The data must be taken exactly in the order in which it was collected, otherwise it loses its meaning. No changes should be made to the process during the data collection period. The data should reflect how the process goes naturally.

A checklist can indicate potential problems before defective products are released.

It is customary to say that a process is out of control if one or more points are out of control.

There are two main types of control charts: for qualitative (pass - fail) and for quantitative signs. For qualitative features, four types of control charts are possible: the number of defects per unit of production; the number of defects in the sample; the proportion of defective products in the sample; the number of defective items in the sample. At the same time, in the first and third cases, the sample size will be variable, and in the second and fourth cases, it will be constant.

Thus, the purposes of using control charts can be:
identification of an unmanaged process;
control over the controlled process;
evaluation of process capabilities.

The following variable (process variable) or characteristic is usually to be studied:
known important or most important;
presumably unreliable;
on which you need to get information about the capabilities of the process;
operational, relevant in marketing.

In this case, it is not necessary to control all the quantities at the same time. Control cards cost money, so you need to use them wisely: choose stats carefully; Stop Mapping When Goal is Achieved: Continue to map only when processes and technical requirements are holding each other back.

It must be kept in mind that the process may be in a state of statistical regulation and give 100% rejects. Conversely, it can be unmanageable and produce products that meet 100% of the technical requirements.

Control charts allow you to analyze the possibilities of the process. Process capability is the ability to function properly. Typically, process capability refers to the ability to meet technical requirements.

There are the following types of control charts:

1. Control charts for quantitative control (measured values are expressed as quantitative values):

a) the control chart consists of the control chart, which reflects the control over the change in the arithmetic mean, and the control chart R, which serves to control changes in the dispersion of the values of quality indicators. It is used when measuring such indicators as length, mass, diameter, time, tensile strength, roughness, profit, etc.;

b) The control chart consists of a control chart that controls the change in the value of the median, and a control chart R. It is used in the same cases as the previous card. However, it is simpler, and therefore more suitable for filling in the workplace.

2. Control charts for regulation on qualitative grounds:

a) control card p(for the proportion of defective products) or the percentage of rejects, is used to control and regulate the technological process after checking a small batch of products and dividing them into good and defective ones, i.e. identify them by quality. The proportion of defective items is obtained by dividing the number of defective items found by the number of items inspected. It can also be used to determine the intensity of output, the percentage of absenteeism, etc.;

b) control card pn(number of rejects), is used in cases where the controlled parameter is the number of defective products with a constant sample size n. Pretty much the same as the map. p;

c) control card c(number of defects per one product), is used when the number of defects found among constant volumes of products is controlled (cars - one or 5 transport units, sheet steel - one or 10 sheets);

d) control card n(the number of defects per unit area), is used when the area, length, mass, volume, grade are not constant and it is impossible to treat the sample as a constant volume.

When defective products are found, it is advisable to attach different labels to them: for defective products detected by the operator (type A), and for defective products detected by the inspector (type B). For example, in case A - red letters on a white field, in case B - black letters on a white field.

The label indicates the part number, product name, technological process, place of work, year, month and date, the nature of the defect, the number of failures, the cause of the defect, and the measures taken.

Depending on the goals and objectives product quality analysis, as well as the possibilities of obtaining the data necessary for its implementation, analytical methods for its implementation differ significantly. This is also affected by the stage of the product life cycle covered by the activities of the enterprise.

At the stages of design, technological planning, preparation and mastering of production, it is advisable to use functional cost analysis (FCA): this is a method of systematic study of the functions of an individual product or technological, production, economic process, structure, focused on improving the efficiency of resource use by optimizing the ratio between consumer properties object and the costs of its development, production and operation.

Basic Principles FSA applications are:
1. functional approach to the object of study;
2. a systematic approach to the analysis of the object and its functions;
3. study of the functions of the object and their material carriers at all stages of the life cycle of the product;
4. compliance of the quality and usefulness of product functions with their costs;
5. collective creativity.

The functions performed by the product and its components can be grouped according to a number of features. By area of manifestation functions are divided into external andinternal. External - these are the functions performed by the object when it interacts with the external environment. Internal - functions that perform any elements of the object, and their connections within the boundaries of the object.

According to the role in meeting the needs among external functions, there are major and minor. The main function reflects the main goal of creating an object, and the secondary function reflects a secondary one.

By role in the workflow, internal functions can be divided into main and auxiliary. The main function is subordinate to the main one and determines the operability of the object. With the help of auxiliary, the main, secondary and main functions are implemented.

According to the nature of the manifestation, all of the listed functions are divided into nominal, potential and actual. Nominal values are set during the formation, creation of an object and are mandatory. Potential reflect the ability of the object to perform any functions when the conditions of its operation change. Real are the functions actually performed by the object.

All functions of an object can be useful or useless, and the latter can be neutral and harmful.

The purpose of the functional cost analysis is to develop the useful functions of the object with the optimal ratio between their significance for the consumer and the costs of their implementation, i.e. in the choice of the most favorable for the consumer and the manufacturer, if we are talking about the production of products, a solution to the problem of product quality and its cost. Mathematically, the goal of the FSA can be written as follows:

where PS is the use value of the analyzed object, expressed as a set of its use properties (PS=∑nc i);

3 - the costs of achieving the necessary consumer properties.