Quality control, as well as testing, depending on the stage of the product life cycle, can be carried out at the production stage (the so-called production control), as well as at the operation stage (in other words, operational control). In our article, we will consider the concept and types of product quality control, as well as analyze other thematic aspects.
Category concept
Quality control should be understood as checking the conformity of the qualitative or quantitative characteristics of the process, on which the quality of the product, or the product itself, depends on certain technical requirements. The existing types of product quality control in the aggregate are the most important component of the production process. It is worth noting that they are primarily aimed at checking the reliability in the manufacture, consumption or operation of the product.
The essence of quality control
The purpose of applying the currently known methods and types of product quality control at an enterprise is to obtain information regarding the condition of the facility and compare the obtained indicators with pre-established requirements, which are recorded in special drawings, supply contracts, standards, technical specifications and other documents.
Control involves checking products directly at the beginning of the production process and during maintenance. Moreover, in case of deviations from the regulated requirements in terms of quality, it implies the adoption of corrective measures that are aimed at producing a product of adequate quality, as well as full-fledged maintenance during the operation and absolute satisfaction of consumer requirements.
Lack of control
Product control includes certain measures at the place of its creation, development or at the place of its operation, following the results of the implementation of which deviations from the norm of the required level of quality that were allowed can be eliminated by production employees even before the release of the defective product or product that does not correspond to the technical requirements. It is important to keep in mind that insufficient control at the stage of manufacturing a serial product, as a rule, leads to problems of the financial plan. It entails unplanned costs.
What is included in quality control?
Before considering the classification of types of product quality control, it is advisable to understand what this category includes. It is important to indicate the following elements:
- Input control of the quality characteristics of raw materials, main and auxiliary materials, components, semi-finished products, as well as tools that are delivered to the warehouses of the production structure.
- Operational production control, first of all, compliance with a certain technological regime. In addition, in this paragraph we can talk about the interoperational acceptance of products.
- Systematic control, first of all, over the condition of machines, equipment, cutting and measuring tools, various measuring instruments, models of weighing facilities and testing equipment, dies in use and new devices, production conditions and subsequent transportation of products. It is worth noting that these are far from all existing checks.
- Control of prototypes and models.
- Control of the finished product (small units for assembly, subassemblies, parts, assemblies, products, blocks).
Modern definition of quality control
Currently known types of product quality control cover all processes of a product’s life cycle, starting from control of input plan resources, control of production preparation and production of a marketable product, as well as control of product operation and ending with control related to product storage. It is important to note that the control of operation is advisable to attribute to the control of the operation of the equipment. It is necessary to confirm durability, determine reliability, study the nature and nature of random failures.
By the totality of types of product quality control, as we have found, it is necessary to understand the control of qualitative and quantitative characteristics. In the modern definition of a category, there is an addition that these features are represented by attributes and variables. The measurement of the latter is based on continuous-type numeric scales. This, for example, length or weight. Attributes are evaluated either without measuring in details (as an example, we consider the use of a device for testing in accordance with the “fit-not-fit” principle under technical specifications) or in a subjective way (something may or may not have some kind of attribute, for example , the surface is finished good or bad). It must be added that the assessment of the quality of marketable products, if the characteristics are represented by attributes, is called an assessment based on an alternative attribute.
Random roots of the measured value can be determined by the influence of numerous, as a rule, practically insignificant factors in the manufacture of a marketable product. It is worth knowing that it is impossible to predict them. This is a change in temperature, defects in materials, conditions of transportation and storage, deviation of the voltage in the network directly from the nominal value and so on.
GOST classification
Today, types and methods of product quality control are classified in accordance with a number of features. All the divisions considered in the article fully comply with GOST 16504–81. So, if we take the stage of product development and existence as the main parameter, the types of technical quality control of products are the following:
- production control, which is carried out at the production stage;
- operational control, which is implemented at the stage of operation of commercial products.
Coverage
In terms of completeness of coverage of a commercial product, it is customary to distinguish the following types of product quality control at the enterprise:
- Solid, in which all units of marketable products are subject to control.
- Selective, according to which a relatively small number of product units from the entire population is controlled.
- Flying, which is carried out suddenly, in other words, at unplanned moments in advance.
- Continuous procedure. This type of product quality control is carried out in relation to liquid and effervescent materials. It fully ensures the continuous flow of information regarding controlled characteristics.
- Periodic, that is, the receipt of information about controlled features is carried out through the established parameters of time.
Continuous and selective control
Separately, it is advisable to consider such categories as continuous and selective control. The fact is that it is fundamentally important to see the difference. So, continuous (continuous) should be understood as the ultimate version of one hundred percent (comprehensive) control. In other words, in this case, the procedure is implemented for each unit of marketable products. Carrying out this type of technical control of product quality is associated with significant costs. That is why, as a rule, it acts as a proof of the general hypothesis regarding the nature of the change in the random variable that is controlled.
Under the sampling procedure in accordance with GOST 15895–77, it is necessary to consider periodic sampling for analysis or periodically performed a certain number of measurements of the qualitative characteristics of marketable products. It is worth knowing that the sample size or the number of measurements should be determined based on the methods of mathematical statistics.
Production stage
In accordance with the stage of the production process, it is customary to distinguish the following types of product quality control: input, operational, acceptance, output and inspection. Let's consider them in more detail:
- Incoming control of materials, raw materials, components, in other words, control of the supplier’s product, delivered to the customer or consumer and intended for use at the stage of operation, manufacture or repair of marketable products.
- Operational control of quality characteristics during the manufacturing process of the product to evaluate the technological process with adjustment in the future, if necessary.
- Acceptance control (it does not necessarily apply to the finished product) is implemented to make decisions regarding the validity of the goods.
- Output control of the finished product. Often it is called the finish.
- Inspection control should be understood as a procedure that relates to an already controlled product. In this case, the previously discovered marriage is deleted. This type of quality control of catering products or other business sectors is carried out if you need to check the quality of the technical control department. It is worth noting that in some cases inspection control is carried out by representatives of the customer in order to increase the responsibility of the manufacturer’s control structure.
Influence on the object of control
In accordance with the criterion of influence on the object, the following types (methods) of technical control of product quality are distinguished:
- Destructive control procedure, during the implementation of which the suitability of the object in terms of use may be violated.
- Non-destructive testing, according to which the suitability of the object for use is maintained.
Use of controls
And finally, the fifth criterion selected for the classification of quality control according to GOST is the use of controls. In accordance with it, it is customary to distinguish the following varieties of the control procedure:
- measuring control, which is carried out using measuring means;
- registration procedure, which is implemented by registering the values of parameters subject to control, processes or commercial products;
- organoleptic control, in accordance with which primary information is perceived by the senses;
- visual control should be understood as an organoleptic procedure that is carried out by the organs of vision;
- technical inspection should be considered as control, which is implemented, as a rule, by means of the senses, and, if necessary, by special means (their nomenclature is determined by the relevant documentation).
Final part
So, we fully examined the varieties, in other words, the methods of quality control in production. In addition, they touched on those species that in practice go beyond the limits of the production process (we are talking about operational control, the procedure mandatory today). It is worth noting that the classification developed in accordance with GOST is quite extensive. It contains five criteria for the formation of a full and understandable structure of the studied category.
It is worth noting that in the modern world the importance of product quality control is extremely great. This can be explained by the increasing needs of society, the development of new information technologies, increased competition in both the domestic and international markets, as well as other numerous factors.