The competitiveness of any enterprise depends on the quality of its products. Its high level can only be ensured if there is a well-coordinated organization of enterprise services and using modern tools of the quality management system. Technical control is one of the main components of quality management. Its main task is to prevent the release of products that do not comply with technical and regulatory documentation. This process largely depends on the organization of examinations.
The concept of technical control
Product quality control serves to evaluate the qualitative and quantitative indicators of the goods or services produced. Technical control is a check that covers all stages of the product life cycle, from the receipt of raw materials (input) to the enterprise and ending with the shipment of finished products. In this regard, production is also distinguished, which covers all technological operations and consists of the following types:
- input (raw materials andaccessories);
- operational;
- technological discipline;
- acceptance (quality, completeness, marking);
- technological equipment;
- production conditions and other factors affecting the quality of finished products.
Technical control is a check for compliance with established requirements. A similar procedure is carried out in 3 stages:
- Measuring, collecting other information about the controlled object.
- Processing the received data, comparing them with standard values.
- Develop corrective actions to eliminate nonconformities.
The overall goal of these works is to detect marriage - correctable or final. Its criteria is the presence of defects - deviations from the normative and technical documentation (NTD). Their occurrence requires an analysis of the causes and conditions, as well as a solution to the issue of stopping production and a way to correct the marriage.
The most common causes of defects are violation of design and technological requirements, errors made in the design process, failure to perform control operations, wear and tear of equipment. Therefore, improving quality is closely related to improving the culture of production, qualifications and personal responsibility of employees.
The technical control system includes:
- objects and methods of control;
- performers;
- technical documentation.
Samples are also used during the control operation. These are the units of the object being valued, orits parts, the characteristics of which are taken as the basis of quality workmanship.
Types of control
Technical control is a concept that has many classification features. The grouping of control types is as follows:
| Feature group | Classification | Types of control | Features |
| Technical | Degree of automation | Manual | Using a hand-held measuring tool |
| Mechanized | Use of mechanized controls | ||
| Automated | Control in semi-automatic systems, where part of the operations is performed with the participation of a person | ||
| Automatic | Control in automatic lines without human intervention | ||
| By management method | Active | Directly during the operation | |
| Passive |
After the operation is completed, the fact of compliance/non-compliance with the requirements is stated |
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| By influence on the object | Destructive | The integrity of the object is violated. It is no longer usable | |
| Non-destructive | Control is carried out without changesuitability for further use | ||
| By applicable controls | Measuring | With the use of measuring instruments | |
| Acceptable | The fact that the parameter falls into the range of maximum permissible values without its exact measurement (control by templates, gauges) | ||
| Registration | Registering parameter values | ||
| Organoleptic | Control by sense organs without numerical expression (expert assessment). Used in perfumery and food industry | ||
| Visual | Performed by the organs of vision | ||
| Organizational and technological | By product lifecycle stage | Production | Held at production stage |
| Operational | Under operation | ||
| By production stage | Input | Checking the supplier's products, (main and auxiliary materials, purchased components semi-finished products) | |
| Operational | Performed during or after the completion of the operation | ||
| Acceptance | Is carried out at the last stage. Represents a due diligence | ||
| Inspection | Carried out to check the work of the control service in order to increase the reliability of the results | ||
| Reliability related | By task type | Current | Constantly in progress |
| Prophylactic |
To avoid the appearance of failures or marriage |
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| By execution frequency | Single entry | As the title | |
| Double | |||
| Multiple | |||
| By scope | Solid | Check each item. It is used in cases where there are increased quality requirements, there is no way to ensure the stability of the technology parameters, in a single production | |
| Custom | Based on statistical methods | ||
| Continuous | Controlled parameters are measured on the conveyor | ||
| Periodic | Checking is carried out at certain intervals | ||
| Flying | Estimation of parameters at random times |
Types of technical quality control are regulated by design and technological documentation (KTD), methods, standards approved by the enterprise and other scientific and technical documentation. Their choice depends on the serial production.
There isalso the concept of technological and technical supervision - control, which is carried out by the customer in the process of production work. Most often, this type of verification is carried out in construction.
Methods
Technical control methods include several components:
- measurement technology;
- list of evaluated features;
- controls;
- regulated accuracy.
Product quality control is carried out in the following main ways:
- visual inspection, checking for external defects;
- measuring shape and size;
- conducting hydraulic, pneumatic, mechanical tests for tension, compression, strength and other physical characteristics;
- chemical, metallographic and other types of laboratory analysis;
- radiographic, luminescent, electrophysical, electrothermal, ultrasonic and other special methods;
- by taking samples from test materials;
- carrying out control and acceptance tests of prototypes, batches of products or products of a single production;
- Checking compliance with technological discipline in production.
In recent years, non-destructive control methods (acoustic, X-ray, capillary, magnetic, eddy current and others) have been widely developed in the organization of technical control, which provide a higher economic effect andallow you to expand the possibilities of such an operation.
Statistical evaluation
Technical control system includes the analysis of a large array of measured parameters. They do not have an identical character, their values fluctuate within certain limits, since the errors of the technological process have random fluctuations. When conducting technical control, the following main statistical methods for assessing quality are used:
- bundle;
- causal diagrams;
- Pareto charts;
- bar graphs;
- control cards.
In practice, several methods are usually used simultaneously, which makes it possible to obtain more useful information for analyzing the causes of marriage.
Lamination method
The layering method is one of the simplest. Its principle is to group measurement data (according to the conditions of their receipt, for example, by contractor, equipment, technological operation and other parameters) and process each aggregate separately.
If a difference is found between the stratification parameters, then this allows you to determine the cause (human factor, equipment errors, and others). This method of statistical analysis is used both independently and in combination with other methods.
Case-and-effect diagram
A cause-and-effect diagram is used to identify and systematize the factors influencing the appearance of defects, and is built in the following order:
- choose a problem to find a solution;
- determine the maximum number of factors affecting the controlled parameter;
- identify the most significant factors and conditions;
- determine the causes that affect them;
- analyze the diagram (brainstorming recommended);
- developing an action plan.
If the factors can be quantified, then they are analyzed using Pareto charts. For complex schemes, the method of stratification by individual significant factors is used.
Pareto chart
Pareto charts are used to visualize the relative importance of different causes of defects. Those with the largest percentage are subject to priority elimination.
Such diagrams are also built before and after corrective actions taken to evaluate their effectiveness. They are a graph with columns corresponding to marriage factors. The height of the columns is equal to the relative share in the total number of defects. A cumulative curve is built on their tops.
Histogram
A histogram is also made in the form of a bar graph, but the height of the bar in this case reflects the amount of data falling within this range of values of the controlled parameter. For example, along the abscissa axis, the intervals of variation in the diameter of the shaft neck are plotted, and along the ordinate axis, the number of parts from the batch having such a size. Thus, the histogram shows the distribution of sizes for one of the technological operations or forfinal acceptance.
According to the received columns, an approximating line is drawn. According to this schedule, the reasons for the out-of-tolerance dimensions are analyzed. If the distribution curve has two peaks, then this indicates the union of two factors in the diagram.
Control cards
The basis of the method of control charts is the mathematical theory of probability. When building maps, the following parameters are determined:
- limits for the statistical evaluation of the measured value;
- Sampling frequency and size;
- actions to be taken when the process goes wrong.
Most of the technological processes are described by the Gaussian normal distribution, shown in the figure below.
Objects, goals and objectives
Technical control is one of the components of quality management. Each stage of the product life cycle has its own specifics. The goals, objectives and objects of technical control at each of these stages are:
| Stage | Goals | Tasks | Objects |
| Development | Ensuring compliance with the requirements of the TOR from the customer, as well as the current NTD |
Assessing the level of development quality. Checking the correctness of technical solutions. Assessment of compliance with the requirements of TK, ESKD, GOST, ESTD,ECTPP |
KTD. Prototypes and the technological process for their manufacture |
| Production | Production of products that meet the requirements of documentation, prevention and elimination of defects, process control | Control of quantitative and qualitative parameters |
Raw materials and semi-finished products, purchased components, technological blanks, finished parts, assemblies, products. Technical processes. Equipment and fixtures, metal cutting and measuring tools. KTD |
| Operation | Improve operating conditions and maintenance (MS) | Checking for compliance with NTD during operation, transportation, storage |
Operating release facility. Conditions, modes of operation and maintenance, transportation, storage |
State technical control
State control is a form of checking the compliance of organizations for compliance with technical regulations. It can be carried out both by state organizations and non-state organizations (the right to perform such work is enshrined in licenses). Most often, enterprises of the energy industry and the production of measuring instruments are subjected to such verification.
The main goal of state control is to prevent cases of unfair treatment of consumers frommanufacturers, sellers and suppliers of goods and services. At the same time, the activity of the auditing organization can be expressed in several forms:
- verification of the certificate of conformity, indicating the fulfillment of the requirements of national, international, industry and other standards;
- issuing orders to eliminate violations identified during the inspection;
- suspension or termination of the certificate of conformity;
- bringing a manufacturer or supplier to criminal and administrative liability.
Quality Management
To organize technical control at enterprises, a quality service is being created. It consists of several departments. Its structure may include the following divisions:
- entry control bureau;
- shop technical control bureaus;
- central factory laboratory;
- standards bureau;
- metrological assurance bureau;
- measuring and testing laboratory and other structural units.
The Department of Technical Control and Quality Assurance is headed by the Quality Director. The regulation on this unit is approved by the general director of the organization, and the activities of this structure should be regulated by the enterprise standards adopted in the prescribed manner.
The technical control service works closely with departments such as:
- chief designer (joint development of test methods,requirements for the quality of products and components);
- chief technologist (flow charts with requirements for control operations, joint verification of compliance with technological discipline);
- Chief Mechanic (for ensuring the accuracy of the equipment);
- personnel (recruitment of personnel with the necessary qualifications);
- supply (incoming control);
- financial services (analysis of losses due to marriage and expenses for its prevention);
- production units.
Coordination of the activities of these services, setting the main tasks to achieve quality, as well as making the final decision is made by the chief engineer of the enterprise.
