Responsible for the purchase of quality materials, semi-finished products and components, he must keep a master set of all drawings, change sheets and other materials that may be required for existing orders. In addition, the chief controller should have such a kit so that he can organize control upon receipt of the material. In addition, it is desirable that the chief controller has an exact copy of the orders.
When a large amount of defective material is discovered during the final inspection, the chief inspector should immediately discuss the matter with the inspector in charge of the current inspection, look at all records and establish how the defective parts could have passed through assembly and then to the final inspection. Since most of the marriage is separated during the current control, this fact shows the shortcomings of the quality control system. The study of the reasons for the rejection of products during the final control should be carried out by the chief inspector together with the head of production. A report on the results of the study of the reasons for the marriage (see form 39) must be submitted to the director-
Depending on the moment of carrying out, technical control is divided into input (preliminary), current (intermediate) and final (acceptance). Input control is a check of materials, blanks, parts before they enter production. For example, such control is carried out during the preparation of casing pipes for lowering them into the well (they check threaded connections, internal diameters and straightness, measure the length of each pipe). Current control is carried out after the completion of some part of the production process (production operation or group of operations). For example, checking the curvature of a vertical wellbore. The final control is the control of the finished product after the completion of all production operations for its manufacture. For example, checking an oil well being put into operation.
GOST 40.9001-88 establishes a model for quality assurance in design and (or) development, production, installation and maintenance GOST 40.9002-88 - a model for quality assurance in production and installation, GOST 40.9003-88 - a model for quality assurance during final inspection and testing.
The final control is carried out upon acceptance of finished, fully completed production cycle of parts, assemblies or products.
Shop (section) Type of production Selective, final control, %
At this time, a series of new international standards for quality systems appeared - ISO 9000 standards, which had a significant impact on the management and quality assurance of ISO 9000 General leadership Quality and Quality Assurance Standards ISO 9001 Quality System. Model for quality assurance in design and development, production, installation and maintenance ISO 9002 Quality system. Model for quality assurance in manufacturing and installation ISO 9003 Quality system. Model for quality assurance in final inspection and testing ISO 9004 General quality management and elements of a quality system. Guidelines, as well as terminological standard ISO 8402.
Determine the appropriate locations for the equivalents of acceptance control, in-process control, and final control at your job. Decide if these should be checks on the gateway type or if monitoring will suffice, 10
ISO 10011-1. Guidelines for the verification of quality systems. Part 1. ISO 10011-2 verification. Qualification Criteria for Expert Auditors for ISO 10011-3 Quality Systems. Management of the ISO 9000-1 verification program. Quality Assurance Standards . Guidelines for the selection and use of ISO 9001 Model for design, development, production, installation and maintenance ISO 9002 Model for production, installation and maintenance ISO 9003 Model for final inspection and testing ISO 9004-1. Elements of the quality system. ISO 8402 Guidelines - Quality Management and Quality Assurance. Vocabulary ISO 9000-3. Guidelines for the application of the ISO 9001 standard in the development, delivery and maintenance of ISO 9004-2 software. Quality Systems. Guidelines for ISO 9004-3 services. Quality Systems. Guidelines for recycled materials
Let us give a brief description of the individual types of quality control. Incoming control is subjected to incoming construction Construction Materials, details and designs. They must comply with state standards, specifications, working drawings and passports. Entrance control is carried out on bases of a complete set and in the construction organizations. Operational quality control is carried out on the basis of special instructions that allow you to directly construction site subject completed production operations or construction processes to control. Operational control allows you to identify defects in a timely manner and take measures to eliminate them. Operational control is followed by acceptance final control with an assessment of the quality of construction and installation work performed by the team. Operational quality control is the most effective, because it includes self-control of performers and helps to increase the responsibility of workers, links and teams for the quality of work performed. In addition, it ensures the identification and timely elimination of defects and their causes. Acceptance control is carried out upon acceptance of finished construction products. Acceptance of completed construction facilities for operation, as a rule, is carried out in two preliminary stages, which is carried out working commission, and the final one, performed by the state acceptance committee. Intermediate control is carried out upon acceptance of completed individual types of work, such as digging a trench, laying foundations, waterproofing, reinforcement laid in concrete, embedded parts, etc. These designs and types of work must be checked and accepted before they are hidden by subsequent work -and. On the hidden work an act is drawn up. The list of structures subject to intermediate verification is established by the project and flow charts for the performance of work.
Direct nationalization in all economic areas includes measures leading to the end of all foreign investment. They are usually motivated by political considerations. These measures are aimed at establishing final state control over the economy in the country and include the seizure of all privately owned means of production.
The exported matches were transported without excise duty, but had to be supplied with the seal of the excise inspectorate and its certificates of the quantity of the exported goods, and the excise duty was finally levied only after the excise inspectorate was provided with a customs certificate of the actual export of matches abroad within six months. Production, movement, sale and purchase of phosphorus were regulated by special rules of control by excise supervision.
In the example under consideration, and here we are talking about a machine-building enterprise with a single type of production, the marginal production costs, included in the calculation of the managerial result from the sale of products, are the value obtained as the final calculation of the marginal costs for completed orders. Thus, data are taken here on the actually used basic materials and components (in serial production - standard values, when purchasing on the side - standard prices), as well as the actual hours worked for development work, machining, assembly and technical control, the assessment of which is carried out on the basis of the planned rates of standard costs (defined in the same way as in the example in Fig. 46, the value of 12.80 DM / standard-hour was determined). Which product groups contributed to the total coverage of 1.3 million francs is shown on sheet 2 (Fig. 526).
The Audit Chamber consists of the Board of Auditors (Auditors) and the General Secretariat. The Board of Auditors has the right to check the annual final report on state revenues and expenditures, request documents and information necessary for the audit, decide on the prosecution of violators of financial discipline, etc. Audits are carried out by the General Secretariat and its member bureaus. The Audit Chamber exercises control after the production of expenses or receipt of income to the budget on the basis of accounting and reporting materials. Main directions control activities are checks of the actual availability of state funds and other movable and immovable property of the state, the establishment of the legality of financial transactions, control over compliance with financial procedures established by law. All accounts of public finances, annually reviewed and approved by Parliament, are subject to the control of the Auditing Chamber. The audit report prepared by the Chamber is submitted to Parliament by the government. In Parliament, the audit report is considered in audit commissions set up in both houses.
It is important to understand that the mere fact that deviations exist does not mean that purchasing or production managers are personally responsible for them. Deviations (regardless of their level of detail) only indicate the problem area, but without further analysis they are not the final proof of the personal responsibility of one or another leader for the imbalance that has arisen. Detailed identification of deviations can only help to determine the official who is best able to respond to a changing situation and begin to correct the situation. Note that the use of the budget to control and persecute managers is unlikely to find support among the employees of the enterprise, and therefore is unlikely to be a sufficiently effective method of cost management.
Production departments are responsible for meeting the production plan, hence there may be a tendency to use material that fully or partially does not meet the requirements for it, which can be costly to the enterprise. Suppose that a batch of parts in the third stage of production did not fully meet the technical requirements, but entered for further processing. At the final check in the quality control department, it turned out that this batch of parts could not be received and the assembly, or the customer rejected the entire batch accepted by the control department. All the labor, materials, time were wasted. As a result, the company suffers a loss and disrupts the execution of the order.
However, in some cases the production of parts can be so high and the product so cheap that it is economically advantageous to have a relatively higher scrap rate in order to provide more good product. This will reduce production time, but the inspection time will increase, since a longer final inspection will be required to separate the defective products from the Good. In this case, the chief inspector must (take into account the cost of the finished product, the cost of production, etc., determine the frequency of inspections (and the permissible percentage of rejects, and also establish a list of all product parameters that require verification. He must give the inspector the right to stop production on any operation where there is too much scrap.
Economic managers, economic and technical services, as well as public organizations of production associations and enterprises use methods of analysis in order to draw up a scientifically based plan or obligation, to eliminate bottlenecks in production, to identify and mobilize internal reserves, to objectively assess the results of labor, summing up the competition , substantiation of economic incentives, to control the implementation of state plans, the safety of socialist property, the observance of state and economic discipline. For example, when evaluating economic activity and approving the size of incentive funds, special commissions carefully analyze performance indicators, identify the results of the influence of external factors that do not depend on the activities of the production team, facts of violation of economic discipline, non-fulfillment of business contracts, etc. Only according to the results of the analysis taking into account all the positive and negative reasons affecting the reporting indicators, a final assessment of the work is given.
characteristic feature assembly production is the almost complete absence of final product defects, however, the costs associated with correcting defects in these workshops are relatively high. This feature poses special challenges for technical control, which is particularly difficult in assembly shops.
CONTROL COSTS - Control costs to a business to avoid producing defective products fall into two main categories. The first is prevention costs or preventive costs, i.e. costs of pre-production activities aimed at the preparation of quality instructions and production descriptions, vocational training, production process planning and the collection of data on product quality. The second category is estimated costs. This is the cost of eliminating defects after the product has left the production chain, but has not yet reached the consumer. These include final product inspection, in-process inspection, laboratory testing.
Quality control of manufactured products, compliance with its standards and specifications, registration in in due course documentation for accepted and rejected products, as well as control over the withdrawal from production of finally rejected products
Stationary control points should be created where the most dangerous and critical sections of the road are located. This is usually done after the development stage - acceptance testing of prototypes after the stage of technological preparation - qualification tests, as well as acceptance tests, input and final types of control, inspection control of the production process.
In 1924, Walter Shewhart used statistical methods for quality control purposes and laid the foundation for statistical sampling and quality control processes. The problem of interchangeability of parts, put forward by Whitney, found a final solution. The requirements for manufacturing technology, due to the established tolerances and specifications, could be analyzed in terms of costs and benefits. The works of Shewhart revealed the need to represent production as a system. Over time, it has become apparent that factors such as product design, materials, equipment, worker skills, employee attitudes, workforce turnover and working conditions interact with customer requirements for product quality and price, as well as with financial matters. One of those who drew attention to this was W. Edwards Deming (1950). He believed that management should help improve working conditions and work processes and improve the quality of manufactured products.
The scheme of work of the quality control department in production is simple if the product meets the specified parameters, requirements and technical conditions, i.e., the documents for delivery, it is recognized as fit and goes into sale, if it does not comply, it is recognized as a final or correctable marriage. With the complication of products and the expansion of its range, there was a continuous improvement in the control methods used by the quality control department from the simplest manual measurements to complex instruments, from checking each product, detail - to
In the course of the implementation of the “Product Control” process, in terms of managing the final control of products, the following goal is implemented, ensuring the achievement of the planned level of product quality - supplying the consumer with products that comply with regulatory documentation and contract requirements.
2. Scope of distribution
This instruction (IP) applies to all departments of the organization.
GOST R ISO 9000-2001 Quality management systems. Basic provisions and dictionary IP 6.2-02 - 2002 Staff training
IP 4.2-08-2002 Managing the development of technological documentation and making changes
IP 8.3-01-2002 Management of nonconforming products
STP 8.2-01-2002 Acceptance control of product quality
4. Terms and notation
Terminology in accordance with GOST R ISO 9000.
Accepted designations:
IP - instructions for the process;
QCD - department of technical control;
STP - enterprise standard;
TO - Technical department;
FC - quality form;
TsKI - shop of control tests.
5. Input, output, special criteria for the effectiveness of the process
Entrance - the finished product presented by the quality control department.
Yield - documented results of the final control of the finished product. A special performance criterion is the quality of the final control. Note: the corresponding quantitative indicator and its level, which characterizes the degree of fulfillment of the criterion, is determined when developing quality goals.
6. Responsibility
Responsibility for organizing and conducting the final control rests with the head of the QCD.
Responsibility for steps - in accordance with the scheme given in this IP.
7. Description of the management process
Control process - in accordance with the process below (Scheme 2).
8. Registration documentation
Quality certificates for finished products in the form of FK 8.2-03-2002 are stored in the Quality Control Department for at least five years. Application for final control finished products compiled in the form of FK 8.2-07-2002
|
A responsibility |
Process Diagram |
Procedure |
|
Production division Head of Quality Control Department |
Development of documentation for control Preparation for control Presentation of OTC products Carrying out control Registration of control results Control status identification Release permission Process performance evaluation |
In accordance with IP 4.2-08 A) Provision of workplaces with documentation for, control, including, if necessary, standards, acceptance criteria B) Staff training (if necessary) in accordance with IP 6.2-02 A) In the manner prescribed by STP 8.2-01 B) Application in the form of FK 8.2-07 A) In accordance with the documentation for control B) In accordance with STP 8.2-01 A) In the application form FK 8.2-07 B) In the registration logs of the test results of the TsKI Decision on compliance of product test results with the requirements of the contract Actions with non-conforming products in accordance with IP 8.3-01 Statement in FC 8.2-07 of the signature and personal stamp of the OTC controller Confirmed by the signature of the head (or other employee) of the QCD certificate group and the stamp of the QCD in the product quality certificate issued in accordance with FC 8.2-03 In the report on QCD quality in a year |
2.5. Quality policy of CJSC VMZ Krasny Oktyabr
We strive for leadership
On the market of large sections of rolled products, forgings and products for weapons and military equipment, components of nuclear power plants and a stable position on the market of rolled sections and sheets of special steels in the Russian Federation and the CIS.
Ways to Achieve:
1) Satisfying the requirements and expectations of consumers, and customer representatives in terms of product quality, delivery discipline and cost of metal products of CJSC VMZ Krasny Oktyabr.
2) Constant work to reduce the cost of production by identifying and eliminating risks, costs and losses at all stages of its life cycle.
3) Increasing the effectiveness of measures to ensure product quality at the stages of its life cycle and preventing deviations from specified requirements.
4) Optimization of the use of the organization's available resources
5) Constant work on expanding the range of products intended by the consumer.
6) Interaction only with suppliers that best meet the requirements and expectations of CJSC VMZ Krasny Oktyabr, and the formation of long-term partnerships with them.
7) Creation of working conditions conducive to the retention of existing personnel and the influx of new, highly qualified specialists.
8) modernization of existing production, introduction of new modern technologies.
9) Constant improvement of the effectiveness of the QMS and its compliance with the requirements of ISO 9001 and GOST RV 15.002.
The top management of the organization undertakes to comply with the provisions of this Policy and continuously improve the performance of the organization.
Conclusion
As a result undergraduate practice at CJSC VMZ Krasny Oktyabr, the knowledge gained during the training process was consolidated in production conditions. During the internship, the material necessary for writing a report and a graduation project was collected.
Within the framework of the goals and objectives of the undergraduate practice, the history of the creation and development of the enterprise, production and organizational structure organizations; objectives and policy in the field of quality; enterprise quality management system and activities aimed at improving the quality of products; sequence of interaction of QMS processes.
Bibliography
1. GOST R ISO 9000-2001. Quality management systems. Key points
2. GOST R ISO 9004-2009. Quality management systems. Recommendations for improving performance
3. IP 8.2-01-2002. Product control during production. Quality Management System
4. IP 8.2-02-2002. Final product control. Quality Management System
5. Volgograd Metallurgical Plant "Red October". [Electronic resource]. – 2012 – Access mode: http://www.vmzko.ru/
6. Red October Volgograd Metallurgical Plant, product catalog 2012. - 31s.
7. Industrial enterprises of Russia CJSC "Volgograd Metallurgical Plant "Red October". [Electronic resource]. - 2012. - Access mode: http://ibprom.ru/krasnyy-oktyabr
8. Formation and development of quality management. [Electronic resource].–2012. – Access mode: http://bntu.org/qm/2/163-21.html
The Supplier shall ensure that incoming products are not used or processed (except in the special case described below) before they have been inspected or verified for compliance with specified requirements. Checking for compliance with established requirements should be carried out in accordance with the quality program and (or) methods.
When determining the scope and nature of incoming inspections, account should be taken of quality control measures carried out directly at the subcontractor and recorded evidence of quality assurance of deliveries.
If the supplied product is sold before inspection due to the urgency of production, it must be identified and registered so that it can be immediately returned and replaced in case of non-conformity.
Inspection and testing during production
The supplier must:
1. control and test products in accordance with the quality program and (or) methods;
2. store the product until the appropriate controls and tests have been completed or the necessary reports have been received and verified, unless the product is released under well-defined return procedures. The return of products does not exclude the performance of inspection and testing activities.
Final control and testing
The supplier shall carry out all types of final control and testing in accordance with the quality program and (or) methods in order to obtain evidence of the conformity of the finished product with the established requirements.
The quality program and (or) methods of final control and testing should provide for all types of control and testing, including those established during product acceptance or during production.
Products are shipped when all activities defined in the quality program and/or procedures have been completed with satisfactory results and the relevant data and documentation are available and approved.
Control and test protocols
The Supplier shall develop and maintain records stating that the product has been subjected to controls and/or tests and the results of those controls and/or tests. If the product has not passed the control and (or) testing, apply the procedures for managing products that do not meet the established requirements.
The record must indicate the division or executive supervising and responsible for the release of products.
Quality analysis methods
Applied methods of quality analysis
For quality management (identification and analysis of problems), the following methods are usually used: checklists, brainstorming, process diagram, Pareto diagram, cause-and-effect diagram, time series, control chart, histogram, scatter plot. Most of these methods are statistical. According to ISO 9001:94, 9002:94, 9003:94 (clause 4.20) “The supplier shall determine the needs for statistical methods used in the development, control and verification of process feasibility and product characteristics.” Thus, for a project or enterprise, a set of methods must be defined that will be applied.
All activities throughout the product life cycle require the use of statistical methods. Statistical methods can be divided into three types: methods used to identify problems, methods used to analyze problems, methods used both to identify and analyze problems. The success of the application of a statistical method depends on its simplicity, i.e. from the ability of a person without a special statistical education to apply it. Also, the ratio of labor costs for the application of the method and the benefits that it brings should always be taken into account.
The following is a brief description of quality analysis methods. All these methods are used within the framework of statistical process control, which combines statistical principles and process control. Statistical process control is at the intersection of statistics and process control. It catalysed the quality revolution in Japan and led to the concept of total quality management. Now it is one of the quality assurance tools. A description of the principles of statistical process control is given after a description of individual methods for identifying and analyzing problems.
Control sheet
A checklist is a convenient document form for collecting and analyzing information. It is used to determine the frequency of occurrence of an event. It is also called a checklist. Checklists are used at all stages of the project. They provide data for analysis by more sophisticated statistical methods. Before using them, you need to make sure that all employees who are to fill out checklists have the same understanding of the terms used in them. It is better if there is a checklist for each employee and for each day of work studied. Also, one summary control sheet can be kept by the controller, foreman or foreman.
On fig. 3.1 is an example of a controller's checklist.
| Employee | Number of marriages from 1 to 5 June | Total | ||||
| during the week | ||||||
| Ivanov | I I I I | I I I I | I I I I I | I I I | I I I I | |
| Petrov | I I | I I I I I I | I I I I I | I I I | I I I I I | |
| Sidorov | I I I I | I I I I I | I I I I | I I I I | I I I | |
| Yashin | I I I I I I | I I I | I I I I | I I I I I | I I | |
| Total |
Rice. 3.1 Controller's checklist
This method is used to develop a group of ideas on some issue. As a rule, this is a question “why?”, “How?” or “what?”. For example, “why are there few customers visiting the store?”, or “how to attract more customers to the store?” etc. The question should be formulated and equally understood by all participants in the brainstorming session.
Basic rules for brainstorming:
1. All ideas expressed should be written down, no matter how stupid or unrealistic they seem. How more ideas, all the better. It is better if the notes are kept on a board or flipchart so that everyone can see the ideas already expressed.
2. It is forbidden to criticize or evaluate the ideas expressed, even with negative grimaces. Brainstorming is about generating, not evaluating, ideas. The leader must strictly enforce this rule.
4. You can develop the ideas already expressed.
5. It is better if the idea is written down verbatim, as expressed by the author.
Ideas can be expressed in two ways:
1. Ordered in turn, when the leader sequentially addresses everyone. At the same time, only one idea is expressed at a time. If there are no ideas, then the person skips his turn.
2. Disorderly when ideas are expressed as they arise.
Process Diagram
There are 4 types of process diagrams. These are: drop-down diagram, detailed diagram, flow diagram and application diagram. They describe different aspects of the process. The most commonly used drop-down scheme, which will be discussed below. A detail diagram is a more detailed drop-down diagram that includes all the steps in a process. It requires a lot of time to build and is used only if this effort is justified. A flow diagram is a diagram of the movement of something in the process under consideration. For example, for the optimal placement of employee rooms on a floor, a diagram of the movement of employees when performing their functions on the floor during the working day can be built. After that, the rooms are distributed in such a way as to make this movement minimal. The application schema is a table in which the rows correspond to the actions performed within the process, and the columns correspond to the performers of these actions. At the same time, different icons can be placed at the intersection of rows and columns to distinguish between who performs this action, who checks the correctness, etc.
A drop-down diagram is a step-by-step schematic diagram used to define the main steps of a process or describe the process under study. It shows the sequence of activities in a process and provides a common understanding and terminology for the team members analyzing the process. With a process map in place, the team can identify potential or existing failures and develop measures to prevent them. The drop-down diagram can also be used to describe a new (changed) process that is about to be implemented to improve quality.
To build a drop-down diagram:
1. Determine the main stages of the process under study. There should be no more than 6-7 of them (otherwise the analysis is difficult).
2. Write them out in a sequential diagram in one row at the top of a sheet of paper or board.
3. Then, under each stage, list the main actions included in this stage (again, no more than 6-7).
On fig. 3.2 is an example of a drop-down process diagram.
| Stage 1 Plan to create a report | Þ | Stage 2 Organization of work on writing a report | Þ | Stage 3 Writing a report | Þ | Stage 4 Publication of the report |
| ß | ß | ß | ß | |||
| 1. Determining the objectives of the report 2. Determining what should be expressed in the report 3. Determining who is involved in writing the report and their responsibilities | 1. Determining the content and main topics of the report 2. Determining the order in which sections of the report are discussed 3. Collecting necessary information | 1. Writing sections of the report 2. Editing the report, pairing different sections 3. Stylistic text editing 4. Adding graphs and charts 5. Grammar editing | 1. Development of the report design, the necessary change in the structure 2. Typing and printing of text, inserting the latest versions of graphs and diagrams 3. Proofreading 4. Reproduction and mailing |
Rice. 3.2 Drop-down diagram of the department report generation process
Pareto chart
It is used when it is required to assess the relative importance of identified problems. The Pareto chart is a graph where the problems are located along the horizontal axis, and their relative importance, assessed by any single parameter for all of them (for example, by the cost of damage, or frequency of occurrence) is located along the vertical axis. Issues are listed in descending order of importance. Data for constructing a Pareto chart can be taken, for example, from control sheets. The Pareto chart is named after the Pareto principle, according to which 80% of the damage is caused by 20% of the problems. Pareto charts allow analysts to decide which problems should be solved and which will not bring much effect, as well as to develop a sequence of problem solving.
On fig. 3.3 is an example of a Pareto chart.
Problems
Rice. 3.3 Pareto chart
Topic 4. General Functions 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. Control is one of effective means achievement of the intended goals and the most important function of management contributes to the correct use of objectively existing, as well as man-made prerequisites and conditions for the release of products High Quality. From the degree of perfection quality control, its technical equipment and organization largely depends on the efficiency of production as a whole.
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.
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;
in 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 conformity of the product necessary requirements);
· registration of results of control and tests (documents on results of control and tests are provided to the interested organizations and persons).
Tests of finished products are a special type of control. 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.
When managing control, measuring and test equipment the organization must:
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;
· Adjust hardware and software with the help of specially trained personnel only.
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 tools for assessing the quality of products and preventing defects at various stages of the product life cycle and levels of quality management. An effective control system allows, in most cases, to carry out a timely and targeted impact on the level of product quality, to prevent all kinds 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.
In market conditions of management, the role of quality control services for products of enterprises 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 the following:
development of optimal control plans based on the results of long-term observation, analysis and generalization of information on 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 the 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 the typical composition of the structural units of the technical control department (QCD) of a large enterprise.
Quality control operations are an integral part of the technological process of manufacturing 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 in 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 the work to identify internal defects is almost everywhere accompanied by an increase in claims for manufactured 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 throughput of control services and insufficient number of personnel, leading to disruption in the rhythm of production and sales of products, failure to perform certain work on quality control, 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 wages of employees of the quality control services of enterprises' products;
shortcomings in the bonus systems for personnel of control services, leading to disinterest in the full and timely detection of defects;
non-compliance of the qualifications of inspectors with the category of examinations performed, 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 that 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 prerequisites to eliminate duplication and parallelism in the work of other services of the enterprise, reduce the volume of information processed by them, release many qualified specialists engaged in rechecking products accepted by the technical control service of the enterprise, significantly reduce the number of disagreements that occur when evaluating product quality by various subjects of control, reduce the cost of technical control and increase 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 framework of 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, contributing to the growth of productivity and capital-labor ratio of labor of QCD controllers, increasing the objectivity of inspections and facilitating the work of personnel of control services;
objective accounting and a comprehensive differentiated assessment of the quality of work of various categories of personnel of the control service, determining the reliability of 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 to quality self-control, equipping workplaces with the necessary instrumentation, tools, equipment and documentation, special training for workers, selective control 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 the quality of products 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 indicators of the enterprise, evaluation of the effectiveness of the control service.
At small enterprises, due to a number of objective reasons, the creation of several new divisions as part of the technical control service is not always possible. In such 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 links.
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; input quality control of raw materials, semi-finished products, components and other products obtained through cooperation and used in own production;
monitoring compliance with technological discipline by direct executors 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 flow sheet 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;
definition organizational forms 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 the 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. Typically, 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 data is divided 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 stratify according to 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.
The use of different methods of delamination depends on the 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 make it easier to understand the meaning of the 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. In this case, the changing total is taken as the total for the year preceding this month(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 constructing 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 by significance, those reasons are established that in this moment subject to correction..
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 the frequency of occurrence for certain period 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.
If
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 upper limit tolerance. Check if there is a systematic error in the measuring instruments. If not, then continue to produce products, 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 materials were of 2 different grades, or the machine setting was changed in the process of work, or products processed on 2 different machines were combined into 1 batch. In this case, the examination should be carried out in layers;
g) both the width and the distribution center 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. We will 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 a defective product is 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(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 day, 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.
Related questions
1. What do you understand by quality planning?
2. What are the objectives and subject of quality planning?
3. What are the specifics of quality planning?
4. What are the directions of planning to improve the quality of products at the enterprise?
5. What is the new strategy in quality management and how does it affect the planned activities of the enterprise?
6. What is the peculiarity of planned work in the divisions of the enterprise?
7. What international and national quality management bodies do you know?
8. What is the composition of the quality management services at the enterprise?
9. What do the terms "motive" and "staff motivation" mean?
10. What parameters that determine the actions of the performer can the manager control?
11. What methods of reward do you know?
12. What is the content of theories X, Y, Z?
13. What is the essence of A. Maslow's motivational model?
14. What types of rewards are used in management?
15. What are the features of the motivation of people in Russia?
16. What types of quality awards do you know?
17. What is the essence of quality control processes?
18. List the stages of the control process.
19. On what basis are the types of control distinguished?
20. What is a test? What types of tests do you know?
21. What are the criteria for the decision to control?
22. What is the product quality control system?
23. What is the structure of the QCD and what tasks are assigned to it?
24. Determine the main elements of the marriage prevention system in the enterprise.
25. What is technical control and what are its tasks?
26. What types of technical control do you know?
27. What is the purpose and what is the scope of statistical methods of quality control?
28. What statistical quality control methods do you know and what is their meaning?
29. What is the FSA and what is its content?
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The criterion for the control of manufactured products is the compliance of products with the requirements of design documentation and technical documentation.
A responsibility
The head of the quality service is responsible for organizing product quality control.
Responsibility for the implementation of activities under this procedure lies with the heads of departments.
The head of the occupational health and safety department is responsible for organizing the medical examination of the controllers' vision.
Procedure for carrying out activities
Control of the "first part"
The control of the "first part" is carried out in the press shop, in the plastics processing shop, in the assembly shops in the following cases:
At the beginning of the shift;
When installing again or after repairing a die or mold;
When changing the batch of material;
When changing a worker;
When starting the assembly line.
The “first part” is presented to the inspector for control by the workers. In the assembly shop, the “first part” is the assembly unit. The controller controls the manufactured "first part" in accordance with the requirements of the TD. The acceptance results are recorded with the entry “good” in the column “Control of the first part” of the journal “Registration of control (test) results” (Appendix A) and in the accompanying documentation in accordance with PSK 7530 (Identification and traceability of products).
For negative results:
The controller isolates the "first part" in accordance with CPM 8300 (Control of nonconforming products);
The adjuster adjusts the equipment until a good part is received. If he
cannot resolve the discrepancy on his own, he informs the production foreman for a decision.
The "first part" is stored at the workplace and presented with the manufactured batch for control.
When changing the tooling, the control of the “last part” is carried out, which is stored with the tooling until the next start in production.
Flying production control
Volatile control is carried out by QCD representatives at least once a
week, as well as additionally due to production needs. The business need may be:
Excess losses from the marriage of the controlled part;
Notification of the consumer about the rejection of products.
During its implementation, it is controlled:
Compliance with the requirements of CD, TD, PSK, RI;
The state of marriage zones;
Identification of material and products;
conditions and terms of storage of products in warehouses and production sites;
Compliance with the FIFO method, etc.
The task for "flying control" is drawn up by the QCD (BTK) in the form (Appendix B). In case of detection of conditions that can lead to a deterioration in product quality, the head of the BTK shop issues a "Warning of non-compliance" (Appendix B) in 2 copies. One copy is sent to the head of the department, a copy to the head of the QCD. On the basis of the "Warning of non-compliance", the head of the QCD has the right to stop the acceptance of products by notifying the head of the quality service. The head of the division has the right to stop production at any stage, as well as shipment with immediate notification of the production director.
Interoperational control
Interoperational control is carried out by Quality Control Department based on the requirements of technological processes at least once a week. The results are drawn up in accordance with Appendix B. Actions with nonconforming products identified as a result of the control are carried out in accordance with PSK 8300. Accompanying documentation is drawn up in accordance with PSK 7530.
Control of the operation by the performer
The worker in the process of work must comply with the requirements of RI and TD. If the operation being performed complies with the requirements of the TD, the worker draws up an accompanying label and (or) a route sheet in accordance with PSK 7530. If non-conforming products are detected, the worker is obliged to inform the production foreman and identify it in accordance with PSK 7530.
Final product control
Presentation of products for control is carried out in batches during the shift, but no later than 30 minutes before the end of the shift. The presentation is made at the control posts of the QCD and sites for the final acceptance of products in accordance with the approved layout of the workshop. The contours of the site are marked with white or yellow lines and the tabular "Finished products".
Products for control are presented with accompanying documentation drawn up in accordance with PSK 7530. In assembly shops with a conveyor system, it is allowed to carry out final control during a shift, piece by piece, in accordance with the requirements of RI and TD.
When accepting products, the inspector is prohibited from using the measuring tool of the worker.
The organization of the workplaces of QCD controllers, equipping it with the necessary measuring instruments, testing equipment and documentation is carried out by the head of the workshop - the manufacturer of the products presented for control.
QCD inspectors are prohibited from accepting products:
In the absence of cleanliness and order in the workplace of the production worker;
Manufactured using faulty and non-certified measuring instruments;
Without presenting the "first part" (in the workshops in accordance with clause 4.3.1.1).
The results of product acceptance are recorded in the journal (Appendix A) and in the accompanying documentation in accordance with PSK 7530. The quality of products in the assembly shops is confirmed by the stamp of the quality control department in the places provided for by the TD for the products. QCD inspectors in the workshops that carry out packaging are prohibited from pre-stamping packing lists (passports). If an NP is detected, further actions are taken in accordance with PSK 8300.
Products that are not accepted by the QCD at the first presentation are sorted (or disposed of) by the manufacturer's workshop and presented again within three days. Re-submission is carried out by the production foreman with the provision of an act on the analysis and elimination of defects (Appendix D). The presentation of products according to the "Permission Card" is repeated, while the act is not issued. The number of the act or the “Permission Card” is entered by the QCD controller in the column
"Controller" of the magazine (Appendix A) marked "repeatedly".
The percentage of change from the 1st presentation is calculated weekly by the heads of the BTK in one of two options (according to the number of batches or products presented) according to the formula:
K is the number of rejected batches (products); S - the number of initially presented batches (products). The quality engineer of the OAKP weekly (monthly) analyzes the “Product delivery from the 1st presentation” by the shops on the basis of a certificate provided by the heads of the BTC.
Abbreviations
CI- qualification tests
PSI- acceptance tests
PI- periodic tests
TI- type tests
CDP- chief technologist department
WGC- chief designer department
Ogmeter- department of chief metrologist
PEO- planning and Economic Department
KU- commercial management
PZ- customer representation
LCI- laboratory of control tests