Manufacturing defect. “What are defects and how to deal with them

Alexander Khrulev

When conducting expert research, there are various malfunctions components and assemblies of the car Vehicle(АМТС), defined as a condition in which a unit / unit does not meet the requirements of regulatory and technical documentation.

The causes of malfunctions can be different and are usually associated with various disruptions in the production, operation or maintenance of the vehicle, as well as in connection with the natural aging processes. For an expert investigating malfunctions and the reasons for their occurrence, it is necessary not only to carry out the research correctly in order to establish the true cause of the malfunction, but also to describe it correctly. Why it is necessary to use the correct terminology when describing the properties of the research object.

1. A little about the terminology of GOST.

The terminology regulated by the relevant regulatory documents should also be used in expert research. This principle allows an expert to show that he has the relevant specialized knowledge in a given area, since one of the signs of this knowledge is the possession of the correct terminology. On the contrary, if an expert (expert) uses erroneous terminology, this may be a sign of the unreliability of the research results, and the dissatisfied party has the opportunity to challenge such an expert opinion on formal grounds (expert incompetence).

Terms defining product properties, including products (products) of the automotive industry, including quality indicators and product deficiencies, are established by state standards (GOST), and the use of such terms is mandatory for use in all types of documentation, textbooks, teaching aids, technical and reference literature. Otherwise, the use of these terms is recommended. This means that the expert opinions must also use the correct terminology established by the standards.

Thus, state standards establish the terms used in science and technology and define the basic concepts in the field of reliability and product quality management. The product itself is viewed as a materialized result of the labor process, which has useful properties, obtained in a certain place for a certain period of time and intended for use by consumers in order to meet their needs, both social and personal. At the same time, products have many different properties that can manifest themselves during their creation and operation, i.e. in the development, production (manufacture), testing, storage, transportation, maintenance, repairs and use (the term "operation" is applied to such products, which in the process of use consumes its resource).

Product quality is a technical and economic concept that covers only those properties of products that are associated with the ability of products to meet certain social or personal needs in accordance with its purpose. The quality of a product depends on the quality of its constituent products and materials. If the product consists of mechanical engineering products, then the properties that determine the quality of products include the properties of individual products, as well as such properties of a set of products as homogeneity, interchangeability, etc.

Product quality indicator quantifies the suitability of products to meet specific needs. The nomenclature of quality indicators depends on the purpose of the product. For multipurpose products, this nomenclature can be numerous. The product quality indicator can be expressed in various units, for example, kilometers per hour, hours for failure, points, etc., and can also be dimensionless.

When considering the indicator of product quality, a distinction should be made between:

- the name of the indicator (for example, the failure rate);
- the numerical value of the indicator, which may vary depending on various conditions (for example, 500 hours).

Permissible deviation of the indicator product quality is determined by comparing the actual and permissible values of this indicator. A deviation is considered acceptable if the actual value of the product quality indicator does not go beyond the limits established by the regulatory documentation. The fact that the actual value of the indicator goes beyond the established limits means that the product in question (its unit) has a defect.

The permissible deviation can be characterized, for example, by the depth and area of dents (shells, chips, scratches) on the surface of the product, as well as by their number, if their values do not exceed the limit. In this case, the nominal values, from which in this case the permissible deviations are counted, are equated to zero. They act in a similar way when a requirement is written in the technical documentation, for example: "the gap should not be more than 0.5 mm", which means that the nominal value of the gap is zero.

State standards also define the term "product tag"- a qualitative or quantitative characteristic of any properties or states of a product, as well as a "product parameter" - a product attribute that quantitatively characterizes any of its properties or condition.

2. So what is a "defect"?

According to GOST, a defect is each individual non-conformity of a product with established requirements... Thus, if the considered unit of the finished product has a defect, then this means that at least one of the indicators of its quality or parameters has gone beyond the permissible value, or one of the requirements of the regulatory documentation for the characteristics of the product is not met (not met).

Examples of defects can be part size out of tolerance, improper assembly or adjustment (adjustment) of the unit (unit), scratches on the protective coating of the product, unacceptably high content of harmful impurities in the product, the presence of burrs on the threads, etc.

A defect in itself may not lead to a complete inoperability of the product., however, worsens its consumer properties and reduces to one degree or another its quality, quality indicators and parameters. In the subsequent operation of defective products (i.e. products with a defect), defects lead to failures (malfunction).

3. What is the correct use of the term "defect"?

In practice, experts performing expert studies often confuse the term "defect" with terms such as "malfunction", "damage", "failure". As a result, the conclusions use terminology that does not meet the accepted standards.

According to GOST, the term "defect" is used for finished products of industrial production - during quality control during their manufacture and repair. At the same time, the term "defect" does not apply to the subsequent use (operation) of the product.

On the contrary, the term "malfunction" used in the use (operation), storage and transportation of products. So, for example, the phrase "nature of the malfunction" means a specific unacceptable change in the product, which was in good working order before it was damaged (was in good condition). Unlike the term "defect", the term "malfunction" does not apply to all products, including not all products, for example, unacceptable deviations of the quality indicators of materials, fuel, chemical products, etc., are not called malfunctions.

Obviously, the term "defect" is associated with the term "malfunction", but is not synonymous with it. A malfunction is a specific condition of a product caused by a specific event - damage, which is a violation of the working condition of the product. Damage- this is an event in which a violation of the serviceable state of the product occurs due to the influence of external influences exceeding the levels established by the normative and technical documentation for the product.

Thus, unlike a manufacturing defect, damage arises in service, as well as during storage and transportation of finished products. At the same time, being in a faulty condition, the product may have one or more defects in production.

In the event of a malfunction, the investigated unit (unit) may remain workable, when it can perform the specified functions, while maintaining the values of the specified output parameters within the limits established by the regulatory and technical documentation, or become unworkable when the value of at least one output parameter does not meet the established requirements.

The term "defect" should also be distinguished from the term "refusal"... Failure is an event in operation, consisting in a malfunction of the product, which was operable before the failure occurred. Failure may result from the presence of one or more defects in the product, but the appearance of defects does not always mean that a failure has occurred, that is, the product has become inoperative.

Thus, phrases such as "an operational defect" or "a defect is of an operational nature", which are often found in expert opinions, are probably an example of not quite correct terminology - for example, according to GOST 15467-79, there are no defects in operation, and a defect can only have constructive or production in nature. Perhaps it would be more correct to indicate in such cases the "operational damage" or the "operational nature of the malfunction", i. E. on an unacceptable change in the product that occurred in operation.

However, the specified features or even errors in the use of certain terms are not as unambiguous as it might seem at first glance.

4. According to GOST or not according to GOST?

When analyzing GOST, which establish the terminology for describing the reliability of products, it is easy to notice certain inconsistencies. So, in GOST 15467-79 there is both an internal contradiction and a contradiction with the technical literature in the field of vehicle operation and repair. GOST 15467-79 states that "being in a faulty condition, the product has one or more defects." But if a defect occurs during production (repair), and a malfunction occurs during operation, storage ..., then in a malfunctioning state, the product has a malfunction (malfunctions), but not defects.

Traditionally, the term "defect" was used in domestic technical specifications for control and sorting during repairs. In educational literature, repair manuals, they usually write that during the incoming inspection of the repair fund (defect detection), the presence or absence of defects that have arisen in operation is checked. From this comes the very term "fault detection".

The GOST also says that flaw detection is quality control of repaired products. But this is also not entirely true. Fault detection is the control of the repair fund, i.e. objects received for repair. And the repaired products pass in accordance with GOST acceptance control. In this case, we are not talking about defects that arose during the repair process, but about defects (malfunctions, damage) that arose during operation. Although such defects could be interpreted in two ways - including as defects in parts for subsequent assembly during repair (secondary production).

It is noteworthy that GOST R53480-2009 generally gives a different definition to the term "defect", without even referring to GOST 15467-79. This GOST indicates in relation to a malfunction that they can be "constructive" (not "constructive", as in GOST 15467-79), and "production", while the term "operational failure" is not established, i.e. malfunction as a result of violation of operating rules or as a result of natural aging processes does not occur.

According to GOST R53480-2009 "malfunction is a state of a product characterized by the inability to perform the required function ...", "failure - loss of a product to perform the required function", i.e. event, and "inoperative state - the state of the product, in which it is unable to perform the required function ...". Those. in the event of a malfunction, according to GOST R53480-2009, a failure occurs, and the product becomes inoperative. What in general directly contradicts GOST 15467-79.

Further, according to GOST 27.002-89, in the presence of damage, the serviceable state of the object is violated, and the serviceable state is preserved. But if a malfunction occurs in accordance with GOST R53480-2009, an inoperative state of the product occurs. In GOST R53480-2009, in the definition of the term "damage", the term "malfunction" is not used at all.

Thus, definitions in GOST R53480-2009 do not correspond in form and content to definitions in GOST 27.002-89 and GOST 15467-79... At the same time, GOST R53480-2009 does not say that it replaces GOST 27.002-89, and in online stores GOST 27.0023-89 is listed as valid, like GOST 15467-79. As a result, there are no reliable terms for operation at all to describe faults that would not cause contradictions with one of the current GOST.

All the specified inconsistencies and contradictions in GOST are one of the reasons for the contradictions in the terminology used in practice. So, the term "defect" in the sense of "operational" or directly the term operational defect are used in a number of fundamental regulatory and technical documents. Among NTD, which uses a similar, not entirely permitted terminology, the following:

1. Methodology for assessing the residual value of vehicles, taking into account technical condition P-03112194-0376-98,
2. Methodological guide of the Ministry of Justice of the Russian Federation "Research of motor vehicles in order to determine the cost of refurbishment and assessment (methodological guide for forensic experts)",
3. Guiding document RD 37.009.026-92 "Regulations on maintenance and repair vehicles owned by citizens ",
4. Rules for the provision of services (performance of work) on maintenance and repair of motor vehicles,
5. Rules of operation car tires AE 001-04.

Obviously, if in the normative and technical documentation one or another term is used that is not established by GOST, then for experts who use NTD in their practice, it will not be a gross mistake to use the same terminology. It should be noted that although the GOST does not indicate such concepts as "operational defect" and "operational malfunction", it does not contain direct prohibitions on such terms. If we take into account that according to GOST 15467-79 "it is allowed to use industry terms that are not established by this standard, reflecting the specific features of the industry's products", then the use of such terms can still be considered acceptable, at least until the state standards and NTD are brought to normal a state that does not contradict each other in the use of terms and common sense.

On the other hand, in some industries, for example, in aviation, there is a stricter attitude towards terminology, and there are no terms like "operational defect". Taking into account this positive experience, as well as in order to eliminate the contradictions of GOST when describing the reliability of AMTS, further terminology is given only in accordance with GOST 15467-79.

5. What defects are there - according to the sources of their occurrence?

As you know, for the production of products, both the production itself and the design documentation (drawings), according to which this product (product) is manufactured, is necessary. In accordance with this, depending on the source of the occurrence of defects, a distinction is made between design and manufacturing defects(fig. 1).

So, non-compliance of products with the requirements of the technical specifications or the established rules for the development (modernization) of products refers to structural defects... Design defects are caused by suboptimal choice of the product structure, errors in the choice of design forms and sizes of parts, errors in the choice of materials for parts and the selection of component parts, setting erroneous requirements for the quality of manufacturing of assemblies and parts, incomplete or poor-quality performance of all calculations necessary to determine the requirements for design units of the product, taking into account the existing loads and confirmation of the reliability of the product. Such defects arise as a result of mistakes made by designers (designers) during the design process, as well as errors of research engineers when performing research work, testing and fine-tuning of prototypes of products, on the basis of which technical design documentation for the production of products is developed. Since the design documentation is the basis for the technological processes of the production of products, design defects are the most difficult both in terms of their identification and their elimination during the further release of products.

In expert practice, in general, structural defects of AMTS are a rather rare phenomenon, not only because of the large amount of development work before introducing products into mass production, but also due to the great complexity of this type of defects for study, as well as the higher qualifications and experience required for such studies. an expert. In addition, in the vast majority of cases structural defects are latent defects products that cannot be detected during the final inspection in the production process (see below). And, finally, the manifestation of a structural defect in operation in many cases is difficult to separate from a malfunction resulting from errors during maintenance or violation of the rules of operation.

An example of a design defect jamming of the oil pump pressure relief valve of the engine of a 2009 model year. The valve design is a spring-loaded plunger installed with a small clearance in a cylindrical body (fig. 2). The oil discharge hole is made with a large diameter on the side, and the plunger has a small relative length (ratio of length to diameter). When the engine is running, the plunger moves, and at the moment the side hole opens, forces arise that twist the plunger. As a result, over time, diagonal wear forms on the surface of the cylindrical bore (similar to operational wear), which manifests itself as a step that prevents the plunger from moving to open the valve. At a certain point, a seizure of the plunger can lead to a significant increase in pressure in the lubrication system and the extrusion of the oil filter O-ring (similar to a maintenance error - incorrect installation of the oil filter). In this case, the designers made a mistake - they assigned an excessively large diameter of the side hole and / or an excessively short plunger length.

Non-compliance of products with the requirements of regulatory documents for manufacturing refers to manufacturing defects... Such defects are formed in the process of manufacturing parts, assembling and debugging structural units (assemblies and assemblies). This type can be attributed to defects caused by non-compliance of the materials used with the requirements of technological documentation, violation of production technology, unskilled personnel actions. As production involves various stages, manufacturing defects may be due to defects in material and / or his chemical heat treatment(discrepancy between hardness, structure, coating thickness, etc.), defects in machining(inconsistency of roughness and dimensions with the assigned tolerances) and defects in product assembly... By the nature of the manifestation, manufacturing defects can be generally divided into inconsistencies in material properties, inconsistencies in geometric shape and roughness, and mechanical defects.

As practice shows, manufacturing defects are no less difficult for expert research than constructive ones.

An example of a latent manufacturing defect a breakdown of the exhaust valve of a 2008 Ford Mondeo engine with a mileage of 18,000 km due to turning on crankshaft the driving sprocket of the timing chain due to rough processing of the mating surfaces of the parts and insufficient tightening of the sprocket bolt. With a small circular displacement of the sprocket, a drop in power occurred, and a knock appeared from the piston touching the exhaust valve plates, as a result of which excessively deep smooth grooves were formed on the piston bottom (Fig. 3) from contact with the plates (the damage looks like a violation of the operating rules - exceeding the permissible speed , however, then the notches would be smaller and stepped). Further, after a run with this malfunction about 1000 km, fatigue failure of one of the exhaust valves occurred, which led to the destruction of the piston and engine failure. When examining the engine, the manufacturing defect was confirmed not only by traces of typical valve fatigue failure (Fig. 4), but also by characteristic annular traces and twisting chips on the mating parts (Fig. 5).

The term "defect" is used not only for quality control of a product during its manufacture, but also for its repair, for example, during defect detection (drawing up lists of defects) and quality control of repaired products. In this case, we are talking about renovation, how about the type of production, which can be conditionally called secondary production(This term was introduced by Prof. KT Koshkin during the development of industrial repair).

Secondary production can also include periodic Maintenance products performed in operation in accordance with the regulations. During maintenance, dismantling, installation and replacement of elements and assemblies (for example, filters, sealing elements), draining and refueling can be carried out operating fluids, as well as partial disassembly and assembly of the product (for example, when replacing the timing belt on engines), i.e. assembly work similar to those performed during production and repair.

In general, during repair and maintenance, the same manufacturing defects are possible that occur in the main (primary) production. When performing repairs, as in the main production, various parts can be manufactured (additional repair parts, ranging from simple bushings, studs, etc. to complex plain bearings, body repair parts). Repair defects are possible both in repaired parts and in new ones installed instead of worn ones. At the same time, defects in parts of the first type are mainly associated with incompleteness and / or errors in defect detection (for example, undetected cracks and deterioration of the material properties of the part in operation prior to repair), while defects of the second type occur when the quality of the component material is low. supplied from the outside and used in the repair production during the assembly of the product.

In practice, the most common defects in secondary production are associated with poor-quality assembly of the product, although the use of low-quality components is also not uncommon.

An example of a defect in secondary production (repair)- severe wear of the cylinder-piston group of the engine of a BMW 520 2005 release, which occurred over 10,000 km of run after repair. The defect is associated with contamination of the engine with abrasive particles and is caused by poor-quality washing and cleaning of the engine intake manifold from carbon deposits formed in operation prior to repair, i.e. associated with an error in the assembly of the engine. As a result of the ingress of particles from the manifold into the cylinders, the upper piston rings were extremely worn out in a specific way (Fig. 6) - along the upper end surface, which caused a drop in compression and an increase in oil consumption above the permissible level.

Example of a defect in secondary production (service)- installation of a low-quality roller when replacing the timing belt on the engine car ford Mondeo. Due to the non-perpendicularity of the end plane of the roller to its outer cylindrical surface, the belt was displaced (slipped) up to the stop in the cover and its edge quickly deteriorated (destruction of the rubber layer and unweaving of the base cord), as a result of which the belt broke off when the car ran 50 km after service.

In some cases, in practice, it is not possible to clearly divide all defects strictly into design and production. For example, the appearance of cracks or accelerated wear of a part can be associated both with the wrong choice of the design form, material and modes of mechanical and heat treatment, and directly with deviations in the process of manufacturing and heat treatment of the part.

In the expert practice of investigating AMTS malfunctions, the exact determination of the source of the defect - whether it is design or manufacturing errors, is often complicated by the lack of information from the manufacturer, necessary for this. In order to accurately indicate the type of defect, in many cases it is necessary to compare the parameters of the defective part with the technical requirements of the drawing for its manufacture, which is almost impossible to obtain from the manufacturer. As a result, it is impossible to establish whether the defect appeared due to the deviation of the parameters of the part from the requirements of the drawing, or the design documentation contains an error that causes a defect under certain conditions (for example, when the size of the part is made at the border of the tolerance field).

In such cases, the defect can be called constructive and production.

An example of a design and manufacturing defect- turning the main bearings of the crankshaft of the 2008 car engine in the cylinder block bed. At the same time, no characteristic traces of oil starvation were found on other liners, which indicates the normal operation of the lubrication system. The defect was caused by insufficient interference of the liners in the bed and the peculiarities of the base material of the liners (plasticity), however, its manifestation in operation was largely facilitated by the design features of the assembly - the absence of locating locks on the liners and the oil-collecting circular groove in the bed. As a result, with a slight displacement of the liner from its original position, the lubrication hole of the bed closed and the engine failed with damage to the crankshaft and the bed of the cylinder block.

6. More defects - from the nature of their manifestation and influence on the parameters of the product.

During the production process, product control is always carried out, one of the main tasks of which is to identify defects. In accordance with this, defects in their influence on the parameters of products can be different, which makes it possible to distinguish several types of such defects.

State standards establish the following types of defects (Table 1).

Table 1. Types of product defects.

Obvious defect	A defect, for the detection of which, in the regulatory documentation mandatory for this type of control, appropriate rules, methods and means are provided
Hidden defect	A defect for the detection of which the relevant rules, methods and means are not provided for in the regulatory documentation mandatory for this type of control
Critical defect	A defect in the presence of which it is practically impossible or unacceptable to use the product for its intended purpose
Major defect	A defect that significantly affects the use of the product for its intended purpose and (or) its durability; but not critical
Minor defect	A defect that does not materially affect the intended use of the product and its durability
Recoverable defect	Defect, the elimination of which is technically possible and economically feasible
Fatal defect	Defect, the elimination of which is technically impossible or economically inexpedient

Division of defects into explicit and hidden is determined by the prescribed rules, methods and means of product quality control. Moreover, to control rules include his routine (regulations, schedule), to methods- technology (methods, techniques, sequence of operations), volume (number of monitored indicators or parameters) and accuracy, and to means of control- the equipment used (stands, testing machines, equipment of positions and sites on landfills, etc.), measuring and recording equipment, as well as tools and devices.

All defect examples in section 8.5 above describe hidden defects that are not detected by the methods used in the control of finished products. Among all the defects of complex aggregates detected during the operation of AMTS, such defects are most common. At the same time, the term "latent defect" is used everywhere in the acts of inspection of damaged cars, which means a defect that the expert simply did not find during an external, often very cursory, superficial inspection of the car. In this case, the rules and methods of control actually exist, and, in addition, such "defects" should be called damages rather than defects.

When developing regulatory documents, mainly when establishing control methods for manufactured or repaired products, all possible defects can be subdivided into critical, significant and insignificant... This division is based on an assessment of the degree of influence of each considered defect on the indicators of its quality, efficiency and safety of product use, taking into account its purpose, modes and operating conditions. The specified division of defects is made for the subsequent selection of the type of product quality control (selective or continuous).

In all of the above examples, the defects were significant, since they allowed operation, but significantly limited the product life.

For some types of products, certain sets of defects, each of which, when considered separately, is of minor importance, may be equivalent to a significant or even critical defect and should be classified in the appropriate category. Collections of major or major defects with minor defects can similarly be equivalent to a critical defect and should be categorized as critical.

In individual industries, if necessary, a more detailed classification of defects can be made according to the degree of their influence on the efficiency of product use.

In accordance with the above classification of types of defects, sometimes, based on the results of product control, the following units are distinguished (in particular, products):

- critically defective, i.e., having at least one critical defect;
- significantly defective, that is, having one or more significant defects, but not having critical defects;
- slightly defective, that is, having one or more defects of minor significance individually and in aggregate, but not having significant and critical defects.

The absence of an insignificant defect can be controlled selectively in a batch of parts. Control of the absence of a significant defect is usually carried out as a continuous one, with control of all parts in a batch, and in order not to miss a critical defect, product control must be not only continuous, but in some cases also repeated.

Recoverable and Fatal Defects are determined in relation to the specific conditions of production and repair under consideration, taking into account the necessary costs and other factors. One and the same defect can be classified as removable or irreparable, depending on the design features of the unit and on whether it was discovered at an early or early stage. final stages technological process of production (repair). At the same time, fatal defects can become removable due to the improvement of production technology (repair) of products and a reduction in the cost of eliminating the defect.

The examples of hidden defects given above in section 8.5 show that some of them were practically impossible to detect by any available methods (including disassembling the unit) for a long time before the appearance of external signs. Therefore, for this stage, we can talk about the inability to eliminate defects, which, nevertheless, is of a certain conditional nature (a defect cannot be eliminated because it cannot be detected). Further, after the detection of external signs of malfunction (knocking, loss of power, etc.), but before serious damage and / or breakdowns of parts (malfunction of the unit), the defects were removable - by replacing worn out or damaged parts and repairing or replacing associated with them details. However, after the destruction of parts (failure, loss of performance of the unit), the defects again became irreparable, since due to the damage received, the unit could no longer be repaired.

The practice of expert studies of motor vehicles shows that in some cases irreparable defect of an individual unit is mistakenly interpreted in relation to the entire AMTS as a whole... Obviously, if the unit has an unrecoverable defect, this means that only this unit needs to be replaced, which, however, does not require replacing the entire AMTS to eliminate the defect.

7. How to establish a defect?

There is a big difference in the methods of detecting defects during the control of industrial products and in the event that a defect manifests itself in operation.

During production many obvious defects are easily detected by external examination (visually). However, if the regulatory documentation provides for checking the absence of any defect with a tool, device or disassembly of the controlled product, then such a defect also belongs to the category of obvious ones, despite the impossibility of its visual detection. Latent defects, on the contrary, as a rule, are revealed after the product arrives at the consumer and its operation, or with additional previously unforeseen checks, in connection with the discovery of other (obvious) defects.

The main methods used in the control of products in order to identify defects:

Measuring method- a method for determining the values of product quality indicators, carried out on the basis of technical measuring instruments. The method is based on information obtained using technical means of measurement and control. Using the measuring method, the values of such quality indicators as size, hardness, pressure, speed, etc. are determined and the obtained values are compared with the established regulatory and technical documentation. The measuring method is the main one in the control of products during the production process, but it is also widely used in expert practice to establish the cause of the malfunction of components and assemblies as an addition to other methods.

Registration method- a method for determining indicators of product quality, carried out on the basis of observing and counting the number of certain events, items or costs. The method is based on information obtained by registering and counting the number of certain events, for example, product failures during testing, counting the number of defective products in a batch, etc. The method is mainly used in manufacturing.

Calculation method- a method for determining the values of product quality indicators, carried out on the basis of the use of theoretical and (or) empirical dependences of product quality indicators on its parameters. It serves to determine the values of the mass of the product, indicators of its productivity, power, strength, etc. individual quality indicators (parameters) of products. This method is also called indirect measurement method(or by an indirect measurement method). There are methods for calculating the error of indirect measurement (calculation) by errors of direct measurements, while the accuracy of indirect measurements cannot be higher than the accuracy of direct measurements, the results of which are used in the calculation.

Organoleptic method- a method for determining the values of product quality indicators, carried out on the basis of an analysis of the perception of the sense organs. It is based on information from the human sense organs about the receipt of the corresponding sensations by them. The values of quality indicators are found by analyzing the received sensations on the basis of available experience. Therefore, the accuracy and reliability of such values depends on the qualifications, skills and abilities of those who determine them. The organoleptic method does not exclude the possibility of using technical means (magnifier, microscope, microphone, auditory tube, etc.) that increase the sensitivity and resolution of the sensory organs, and is widely used to determine the quality indicators of products, the use of which is caused or associated with emotional impact on consumers.

The organoleptic method is the main one in expert studies of many defects and malfunctions of AMTS, and often the only one for many experts performing such studies. The results obtained by this method depend on the physiological characteristics of the organism of a particular expert (for example, visual acuity, color perception ability, etc.), as well as his experience in identifying faults. Practice shows that in the case of complex malfunctions of units such as an engine or a gearbox, the organoleptic method, as a rule, is not enough to accurately determine the cause of the malfunction, which requires its joint use with other methods, including measuring and / or calculation.

Sociological method- a method for determining the values of product quality indicators, carried out on the basis of collecting and analyzing the opinions of its actual or potential consumers. It involves the collection of opinions of actual or potential consumers of products is carried out orally, by polling or by distributing questionnaires, through conferences, meetings, exhibitions, tastings, etc.

Expert method(method of expert assessments) - a method for determining the values of product quality indicators, carried out on the basis of a decision made by experts. Unlike the sociological method, it does not involve a survey of consumers, but of experts in this field.

In expert studies of AMTS defects and malfunctions, sociological and expert methods also find application - for example, the sociological method (consumer survey) makes it possible to establish the circumstances preceding the manifestation of a defect, and the method of expert assessments helps to find the cause of complex malfunctions if the reason is not obvious and has an ambiguous explanation ...

The described methods are obviously universal in nature, i.e. are applicable to any types of malfunctions, including operational ones, caused by various reasons, including violations of the AMTS operating rules.

Thus, when conducting expert studies of malfunctions during the operation of AMTS, the same methods for identifying defects are used that are used for controlling products during the production process, and the more complex the defect, the more methods for its identification can be used in the complex. However, there are peculiarities in identifying defects detected during the operation of AMTS.

8. Hidden defects - what are they "eaten" with?

Latent defects, which make up the majority of all defects detected in the operation of automatic telephone exchange, represent a significant problem not only for consumers and experts, but also for manufacturers.

Identifying and, especially, correcting AMTS defects is particularly difficult. This is associated with great difficulties of a methodological, technological, organizational and economic nature, for example, in connection with a large production program, high automation of production processes and often with a rigid connection of the used expensive technological equipment to the configuration of the manufactured parts. As a result, when a defect is detected, especially a constructive one, its elimination can be so difficult and costly that it will be possible only with the complete removal of products from production.

In practice, the manufacturer often knows about the presence of a structural or manufacturing defect, but it only manifests itself in a part of cars, and since its elimination is associated with great production difficulties, a decision is made not to change anything until the model is changed, and in the new model of the unit, the appropriate adjustments have already been made.

Another side of this problem is the lack of direct communication between the industry and the consumer of the product. The presence of intermediaries (dealers, importers) in some cases makes it difficult for the manufacturer to obtain timely and objective information about the discovery of a defect. The peculiarities and specifics of the work of some dealers suggests that if a malfunction is detected, the consumer will be more likely to blame for its occurrence than the true cause (defect) is established, which will require some work with the manufacturer to carry out warranty repair (replacement) of a defective unit or unit.

When determining the cause of the malfunction, additional difficulties are introduced by the average low qualification of the dealership personnel, which does not always allow correctly assessing the signs, causes and consequences of a malfunction of a number of complex AMTS units. Similar problems arise with the involvement of independent experts - practice shows that not all of them can properly investigate a malfunction, establish and prove the presence of a defect. Therefore, manufacturing defects often become the subject of lengthy litigation between the consumer and the seller of the automatic telephone exchange. As a result, information about a defect, especially one of a single nature, often does not reach the manufacturer, which does not allow the manufacturer to timely take appropriate measures to identify and eliminate defects in the manufactured product. And only in the case of a mass defect, when the same type of claims from consumers become especially numerous, the manufacturer receives the necessary information (although often also not in full).

An example of a single defect- breakage of the upper piston ring when assembling the engine of a 2008 model car at the manufacturer's plant. In connection with the use of modes of reduced loads and speeds in operation, the defect began to appear only with a significant mileage of 50,000 km in the form of an increase in oil consumption. When examining the engine, it was found that the ring was broken at the lock and did not perform its sealing functions from the very beginning of operation, which was confirmed by the absence of running-in traces on the ring and cylinder (Fig. 7). However, this defect turned out to be the subject of a lengthy litigation between the seller (dealer) and the consumer, which, obviously, could be an obstacle for the manufacturer to receive information about the defect in a timely manner and in full.

As example of a mass defect can drive GQ18 car engine Nissan almera. This engine was designed on the basis of a smaller engine displacement by increasing the cylinder bore. In this case, one of the threaded holes for the gearbox mounting bolt on the cylinder block turned out to be close to the surface of the 4th cylinder, which, when tightening the gearbox mounting bolts, led to cylinder deformation and reduced engine durability several times. However, the manufacturer, having received information about this defect, chose to replace or repair the defective engines under the factory warranty, as it was more economically feasible. Subsequently, the engine with this structural defect was discontinued only after the end of the production of this car model.

If the manufacturer received information about a latent defect and, after checking it with appropriate methods, found it in the factory product, then the so-called "recall" of defective products from service... Since the latent nature of such defects often does not allow checking the units at the place of service of the AMTS, upon recall, the defective unit (unit) is replaced on the part of the product where the defect was installed and confirmed.

Considering the problems of identifying hidden defects in the operation of AMTS, it should be noted that expert research on the identification of defects is not only a service provided by an expert (expert organization) to the customer, but in the event of a defect being identified, it helps the manufacturer to eliminate defects and improve the quality of products. Therefore, when performing such works, the most important is their quality - completeness of the study, strict logic of proof, confirmation of similar cases when analyzing sources of information, etc.

9. Who are the experts?

In operation products, the search for defects, as a rule, is significantly complicated not only by their latent nature, but also by the fact that it is always necessary to determine what exactly the malfunctioning state of the research object is connected with - with violation of the rules of operation, maintenance, or with its defect.

When conducting expert research, an expert, as a rule, deals with the operation of AMTS, when the signs of a defect that are detected on a new product could be destroyed as a result of wear or breakdown of a part that occurred during the development of a defect in operation. In addition, as noted above, the overwhelming majority of defects detected in operation are latent. In this case, the establishment of a defect is possible only through a detailed analysis of the entire set of symptoms of malfunction and related information, including the history of operation and maintenance of the unit (unit).

A feature of latent defects is that many of them manifest themselves in the initial phase of AMTS operation - usually with runs of no more than several thousand km (rarely up to 15,000-20,000 km), in the form of wear and tear of parts. However, under appropriate operating conditions (reduced loads, revolutions), the manifestation of defects is possible with longer operation. In many cases, this makes it difficult to establish a defect, and the longer the operation was before the signs of a malfunction appeared, the more difficult it is to establish the defect.

The practice of expert studies of complex aggregates and their defects shows that, in the general case, to identify defects requires not only the highest qualifications and experience of an expert, but also a large amount of research. This is due to the above non-obviousness of defects and ambiguity of the cause of the malfunction. In such a situation, in order to determine a defect, a comprehensive analysis of all possible causes of a malfunction is required using the entire complex of methods for identifying defects and a detailed analysis of the entire history of AMTS.

However, in practice, a simplified approach to such studies is often used, in which a number of errors are made that do not allow to strictly prove that a particular malfunction was caused by a defect, and not, for example, by a violation of operating rules, and vice versa.

Typical inaccuracies and mistakes of experts performing research on malfunctions and defects of complex units are as follows:

1. The history of AMTS operation is not taken into account... In operation, various events are possible (maintenance, repair, sudden changes in ambient temperature, etc.), which can lead to a malfunction. Ignoring the history of automatic telephone exchange in many cases does not allow finding the true cause of the malfunction.
2. Measurement, calculation and expert methods are not applied... The use of only the organoleptic method does not allow to establish the nature of wear or breakage of some parts, as a result of which it is not possible to correctly determine the cause of the malfunctions.
3. Existing operating experience is not taken into account and the causes of malfunctions set out in the relevant technical literature. A number of auto component manufacturers publish special technical manuals for reasons and signs of faults in their products, which detail the experience of production and operation of this type of product. Ignoring such experience in the overwhelming majority of cases does not allow finding the true cause of the malfunction.
4. All causes of a malfunction are not analyzed that give similar or similar characteristics. In this case, often only one cause of a malfunction is indicated a priori, while there may be several reasons, and each of them requires a detailed study and analysis.
5. Metallographic and chemical studies are unreasonably applied... For example, possible reasons and the signs of a specific malfunction indicated in the relevant literature have no connection with the quality of the fuel, however, a fuel study is nevertheless carried out, on the basis of which (if the fuel parameters deviate from the requirements of GOST), an unreasonable conclusion can be made about the operational nature of the malfunction.
6. Proof of the cause of the malfunction is not presented, the reason itself is not precisely formulated. Often, a conclusion is made about a particular cause of a malfunction without rigorous proof. From the point of view of the examination methodology, when investigating faults, it is necessary:

1) first solve "a simple diagnostic task"- to establish the fact of a defect (malfunction),
2) then decide "a difficult diagnostic problem"- to determine the specific cause, the mechanism of its occurrence,
3) and only after that decide "classification problem"- to classify a defect (malfunction) as manufacturing or other on the basis of the identified cause.

However, in practice, many experts skip one of the stages of the study and immediately give a classification. There are cases when the expert opinions missed not only the cause of the malfunction and the mechanism of its occurrence, but even the very fact of the defect. As a result, the conclusion indicates only a certain general nature of the malfunction (operational, production), while a defect is a specific non-conformity of the product, requiring precise indication of what kind of non-conformity it is.

Since the establishment of a defect is the most difficult expert work, the above errors, on the one hand, do not allow us to accurately establish that this malfunction was caused precisely by a defect, and on the other hand, they make it possible to indicate another reason that does not correspond to the existing signs of a defect.

Thus, various inaccuracies and errors made in the investigation of AMTS malfunctions make it difficult to establish a defect or make such a determination impossible.

Literature

1.GOST 15467-79. "Product quality management. Basic concepts, terms and definitions".
2. GOST 15895-77. "Statistical methods of product quality management. Terms and definitions".
3. GOST 27.002-89. "Reliability in technology. Basic concepts. Terms and definitions".
4. GOST R 53480-2009 "Reliability in technology. Terms and definitions".
5. Instructions for organizing the production of forensic examinations in state forensic institutions of the system of the Ministry of Justice of the Russian Federation. Approved by Order No. 347 of the Ministry of Justice of the Russian Federation dated December 20, 2002.
6. Guiding document RD 37.009.026-92 "Regulations on the maintenance and repair of vehicles owned by citizens (cars and trucks, buses, minitractors) "(approved by order of the Department of Automotive Industry of the Ministry of Industry of the Russian Federation of November 1, 1992 N 43).
7. Rules for the provision of services (performance of work) for the maintenance and repair of motor vehicles (approved by the decree of the Government of the Russian Federation of April 11, 2001 N 290).
8. Rules for the operation of automobile tires AE 001-04. Approved by the order of the Ministry of Transport of the Russian Federation of January 21, 2004 N AK-9-r.
9. Methodology for assessing the residual value of vehicles, taking into account the technical condition R-03112194-0376-98. Approved by the Head of the Department road transport Ministry of Transport of the Russian Federation G.P. Nikolaev December 10, 1998
10. Methodological guide of the Ministry of Justice of the Russian Federation "Research of motor vehicles in order to determine the cost of refurbishment and assessment (methodological guide for forensic experts)". Approved by the Scientific and Methodological Council of the RFTsSE. Minutes No. 14 dated 24.10.07
11. Kostochkin V.V. Reliability of aircraft engines and power plants.- M .: Mechanical engineering, 1976.- 248s.
12. Khrulev A.E. "Repair of engines of foreign cars" .- M .: Publishing house "Behind the wheel", 1999.- 480 p.
13. Petrosov V.V. Repair of cars and engines. - M .: Academy, 2005. - 224 p.
14. Technology of auto repair production. Textbook for universities / ed. K. T. Koshkina. - M .: Transport, 1969 .-- 568 p.
15. Khrulev A.E. "Fatigue is different ... or On the permissible speed and their excess." - "Car and Service", №5 / 2010.
16. Khrulev A.E. "On examination, cause-and-effect relationships and experts", part 1.- "Car and service", No. 6/2008.
17. Khrulev A.E. "On examination, cause-and-effect relationships and experts", part 2.- "Car and service", No. 7/2008.
18. Khrulev A.E. "Unobvious and incredible" .- "Car and service", №8 / 2011.
19. Federal Law of May 31, 2001 N 73-FZ "On State Forensic Expert Activity in the Russian Federation".
20. Memo for forensic experts and judges.- www.sudex.ru.

GOST 15467-79

(ST SEV 3519-81)

Group T00

STATE STANDARD OF THE UNION OF SSR

Product quality management

BASIC CONCEPTS

Terms and Definitions

Product-quality control.

Basic concepts. Terms and definitions

Date of introduction 1979-07-01

APPROVED AND PUT INTO EFFECT by the Resolution of the USSR State Committee for Standards of January 26, 1979 N 244

REPLACE GOST 15467-70, GOST 16431-70, GOST 17341-71, GOST 17102-71

REVISED (June 1986) with Amendment No. 1, approved in January 1985 (IUS 4-85)

This standard establishes the terms used in science and technology and definitions of basic concepts in the field of product quality management.

The terms established by this standard are mandatory for use in documentation of all types, textbooks, teaching aids, technical and reference literature. Otherwise, the use of these terms is recommended.

There is one standardized term for each concept.

The use of synonymous terms of the standardized term is prohibited.

The established definitions are allowed, if necessary, to change in the form of presentation, without violating the boundaries of concepts.

It is allowed to use industry terms that are not specified in this standard, reflecting the specific features of the industry's products.

The reference appendix provides explanations and examples for a number of terms.

The standard provides an alphabetical index of the terms it contains.

The standard is fully consistent with ST SEV 3519-81.

38. Defect	Each individual non-conformity of products with established requirements
41. Obvious defect	A defect, for the detection of which, in the regulatory documentation mandatory for this type of control, appropriate rules, methods and means are provided
42. Hidden defect	A defect for the detection of which the relevant rules, methods and means are not provided for in the regulatory documentation mandatory for this type of control
43. Critical defect	A defect in the presence of which it is practically impossible or unacceptable to use the product for its intended purpose
44. Major defect	A defect that significantly affects the use of the product for its intended purpose and (or) its durability, but is not critical
45. Minor defect	A defect that does not materially affect the intended use of the product and its durability
46. Recoverable defect	Defect, the elimination of which is technically possible and economically feasible
47. Fatal defect	Defect, the elimination of which is technically impossible or economically inexpedient

To the term "Defect" (clause 38)

If the considered unit of production has a defect, then this means that at least one of the indicators of its quality or parameters has gone beyond the limit value or one of the requirements of the regulatory documents for the characteristics of the product is not met (not met).

Failure to comply with the requirements of the technical specifications or the established rules for the development (modernization) of products refers to design defects.

Failure to comply with the requirements of regulatory documents for the manufacture or delivery of products refers to manufacturing defects.

Examples of defects can be: part size out of tolerance, improper assembly or adjustment (adjustment) of the device (device), a scratch on the protective coating of the product, an unacceptably high content of harmful impurities in the product, the presence of burrs on the thread, etc.

The term "defect" is associated with the term "malfunction" but is not synonymous with it. A malfunction represents a specific condition of a product. In a defective condition, the product has one or more defects.

The term "defect" is used to control the quality of products at the manufacturing stage, as well as to repair them, for example, during defect detection, drawing up lists of defects and quality control of repaired products.

The term "malfunction" is used in the use, storage and transportation of certain products. So, for example, the phrase "nature of the malfunction" means a specific unacceptable change in the product, which was in good working order before it was damaged (was in good condition).

Unlike the term "defect", the term "malfunction" does not apply to all products, including not all products, for example, unacceptable deviations of the quality indicators of materials, fuel, chemical products, food products, etc. are not called malfunctions.

The term "defect" should also be distinguished from the term "failure".

A failure is an event involving a malfunction of a product that was serviceable prior to the occurrence of the failure. Failure may result from the presence of one or more defects in the product, but the appearance of defects does not always mean that a failure has occurred, i.e. the product has become inoperative.

To the terms "Obvious defect" and "Latent defect" (clauses 41, 42)

The division of defects into explicit and latent is determined by the established rules, methods and means of product quality control.

Control rules include its routine (regulations, schedule), methods - technology (methods, techniques, sequence of operations), volume (number of monitored indicators or parameters) and accuracy.

The means of control include the equipment used (stands, testing machines, equipment of positions and sites on landfills, etc.), measuring and recording equipment, as well as tools and devices.

Many obvious defects are revealed by external examination (visually). However, if the regulatory documentation provides for checking the absence of any defect with a tool, device or disassembly of the controlled product, then such a defect belongs to the category of obvious ones, despite the impossibility of its visual detection.

Latent defects, as a rule, are revealed after the product arrives at the consumer or during additional, previously not foreseen checks, in connection with the discovery of other (obvious) defects.

To the terms "Critical Defect", "Major Defect" and

"Minor defect" (clauses 43, 44, 45)

When developing regulatory documents (mainly when establishing control methods for manufactured or repaired products), all possible defects can be subdivided into critical, significant and insignificant. This division is based on assessing the degree of influence of each considered defect on the efficiency and safety of product use, taking into account its purpose, device, quality indicators, modes and operating conditions.

The specified division of defects is made for the subsequent selection of the type of product quality control (selective or continuous) and for assigning such characteristics of sampling as the risk of the consumer (customer).

In order not to miss a critical defect, product control must be continuous and, in some cases, repeated. Control of the absence of a significant defect is allowed to be carried out selectively only with a sufficiently low value of the consumer's risk. The absence of an insignificant defect can be controlled selectively at a relatively high value of the consumer's risk.

In individual industries, if necessary, a more detailed classification of defects can be made according to the degree of their influence on the efficiency of product use.

In accordance with the given classification of defects, sometimes, based on the results of product control, the following units are distinguished (in particular, products):

critically defective, i.e. having at least one critical defect;

significantly defective, i.e. having one or more significant defects, but not having critical defects;

insignificantly defective, i.e. having one or more defects of minor significance individually and in aggregate, but not having significant and critical defects.

To the terms "Recoverable defect" and "Fatal defect" (clauses 46, 47)

Elimination and non-elimination of a defect is determined in relation to the specific conditions of production and repair under consideration, taking into account the necessary costs and other factors.

One and the same defect can be classified as removable or irreparable, depending on whether it was discovered at the early or at the final stages of the production (repair) technological process.

Fatal defects can also be categorized as removable due to the improvement of production technology (repair) of products and a reduction in the cost of correcting defects.

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Manufacturing defects include:

Uneven stitching and folded hem;

Misalignment of parts;

Offset and skew of the picture;

Fittings displacement, fabric distortion;

Gaps in the lock and centerpiece, uneven covering of the sealing layer;

Indistinct riffle, asymmetrical belts.

The sizes of defects are determined by the greatest length, area and standards.

The grade of products for subtle and noticeable defects is determined by the standards of finished products with these defects.

All products of leather haberdashery and travel items are subdivided into 1st, 2nd and 3rd grades in quality, depending on the raw materials and production defects found on the products. The nomenclature of raw material defects (leather, leather substitutes, fabrics) is set out in the sections for footwear and textile goods.

Manufacturing flaws include: incorrect selection of parts (different colors, different measurements), lining or threads not matching the color of the top, uneven shading of parts, loosely stretched lining, hardened lining from improper adhesion, skewed parts, wrinkles and folds, top stitching, uneven or poorly tightened stitching, loose thread ends at the end of the stitching, slanted or wrinkled fittings, loose locks or buttons, weakness of the anti-corrosion coating or improper application.

In leather goods, contamination, shedding of dye, omissions in the connection of parts, burn-throughs, loops, defects exceeding the tolerance for second-class products, more than three defects are not allowed.

The main weaving defects are: looping (loose lagging thread), crests (indiscriminate tangling of threads), tightening (wavy edge), uneven density and zebra pattern.

Defects in painting include: spreading of paints, asymmetry of individual parts of the pattern, shedding of the paste, fragility of the dye, and embroidery defects - the irregular shape of the pattern, weak thread tightening, knots, cuts, etc.

When sorting tapes, cords and tapes, the number of cuts in one piece is also taken into account. The maximum number of cuts and the minimum length of each cut are specified in the standards.

Defects of incorrect modeling can be: inconsistency with the direction of fashion, inconsistency of the design for the purpose, inconsistency of the recommended materials and finishes for this model.

In case of improper design, such defects may arise as: mismatch of parts in shape and size, incorrect arrangement of parts, incorrect consideration of the properties of recommended materials. Therefore, in the process of modeling and design, all operations must be clear and correct so that the main characteristics of the product properties are not violated during the manufacture of the model.

From the above, the following conclusions can be drawn.

To control the quality of textile haberdashery, a restrictive system (system of tolerances) is used, which allows, taking into account the type, size, quantity and location of the defect, to determine its admissibility. The grade of cotton sewing thread is established by a point system when the defect is evaluated in points. The quality of textile haberdashery is checked by external examination of a certain number of products selected from the received batch. The sample sizes are indicated in GOSTs and TUs for the relevant goods. When determining quality, vices are taken into account appearance(local and common), physical and mechanical indicators (width, weight, density, breaking load, etc.), color strength and other indicators. The list of indicators is determined depending on the type and purpose of the product. Most of the textile haberdashery products are not classified into grades. The exception is cotton sewing threads, as well as curtain-tulle and lace products, divided into varieties.

Leather goods, with the exception of watch belts, are of the 1st and 2nd grade. When determining the grade, defects in the upper material and manufacturing are taken into account. Quality checks are carried out on a random basis. Metal haberdashery products are not subdivided into grades. The quality of products is determined by the results of external examination, measurement, compliance of physical and mechanical indicators with standards. In addition to general requirements, specific requirements are also imposed on products - specified in the standards for individual products. For blades, this is the cutting ability determined by cutting the hair off the canopy at a distance of 10 cm from the clip. For zippers, the ease of movement of the lock and the ability to connect and disconnect the links of the fastener.

The quality of leather goods is directly affected by the property of the source material, i.e. raw materials. The process of modeling and design also plays an important role in the manufacture of a competitive product. Finishing materials should complement and harmonize in the overall composition. All this in a complex will only increase the quality and competitiveness of haberdashery and bring it to a level corresponding to consumer demand.

When developing new types of products, their high quality must remain unchanged.

The signs of good quality common to all products are: correct shape and exact dimensions of the product; strong and correct connection of individual parts to each other; correct functioning of products; correct heat treatment of steel products and hardness that meets the requirements of the standard; thorough surface treatment of products; absence of burrs, pits, scratches and other defects; continuous and durable coating of metal parts.

The correctness of the shape of the products is checked by external examination, and the dimensions - by measuring the selected samples. The correctness and strength of the connection of parts is established both organoleptically and by laboratory means. Heat treatment of steel products is usually checked in a laboratory way.

The quality of the surface finish is established by external inspection of the products.

To check how sharpened the ends of the sewing needles and safety pins are, a prick test is made, easily touching the points with the skin; the sensation of a prick should appear. For products such as hairdressing razors, safety razor blades and hair clippers, the quality of sharpening and threading of the cutting parts is of great importance. For all types of razors, the quality of sharpening and refueling is checked by cutting with a sliding motion along the razor's edge of a 30-40 mm long human hair clamped in the fingers of the hand. The cutting performance of the comb in a hair clipper is tested by cutting off a bundle of human hair inserted between the teeth of the comb.

To check the quality of metal haberdashery products from the lots presented for delivery, samples are taken in an amount from 1 to 20% (according to technical conditions). In products manufactured in one grade, no more than 2-3% of products in a batch that do not meet technical conditions are allowed. A batch of goods with a large against the allowed number of products that do not meet technical conditions is completely rejected.

An assessment of the quality of leather goods is given by their appearance and by physical and mechanical indicators provided for in the regulatory documentation.

When checking the appearance, attention is paid to the artistic and coloristic design, the quality of the raw materials and accessories, and the workmanship.

Natural, artificial and synthetic leathers, films, fabrics, paper, cardboard used in the production of leather goods must be resistant to abrasion and weathering, and in texture and color must correspond to the modern fashion trend.

When joining and processing the edges of parts, the following requirements must be observed:

The stitching of the thread seam should be even, well-tightened, without looping, skipped stitches, punctures and thread breaks;

The weld seam must be uniform along the entire contour, without displacement and burn-through;

The folded edge should be flat, tightly glued, well disassembled in the corners;

Cut edges should be clean, even, without fringes, painted over and not painted over;

The braid should tightly connect the parts, be free from folds and twists.

Shaped units and parts of products should not have folds and violations of the face layer of the material, and parts should not have burrs.

The accessories in the set must have a uniform coating, fastening that ensures reliable closing and opening of products. Arbitrary opening of locks when tilting and shaking products is not allowed.

Handles and shoulder straps are made in two or more folds, with or without a pad, depending on the material and type of product. In addition, they must be firmly attached and easy to use.

Threads, finishing materials (edging, keder, braiding, etc.), coloring of cut edges, handles, gutters, shoulder straps, ribbons, zippers, overlays should be in the color of the main material of the top or be combined with each other.

Leather haberdashery products must be carefully finished, not have traces of glue, ends of uncut threads.

The coloring of the upper materials must be resistant to dry and wet abrasion.

Of the physical and mechanical indicators, the main one is the strength of thread and welded seams.

The strength of fastening of handles and shoulder straps for bags of all types (except for smart and cosmetic), suitcases, briefcases, knapsacks is also normalized.

For travel bags and school bags and school bags, the weight of the products is taken into account.

Sorting products. Depending on the quality of workmanship, the grade of the product is determined. Leather goods, except for watch belts, are divided into two types. Sorting takes into account defects in the material of the top and manufacturing defects (on the outside of the product).

Defects in the upper material include typical defects in leather and fabrics, for example, fragrance, impersonality, scratches, wrinkles for natural leather, closeness, under-braids, stripes along the weft and warp, skewed patterns - for fabrics.

Manufacturing defects include line or weld deviations, uneven flange widths, needle punctures, misaligned parts, and misaligned fittings.

When sorting men's and women's bags in the first grade, no more than two defects are allowed, in the second - no more than three. For the rest of the products in the first grade, up to three defects are allowed, and in the second - up to four defects.

In leather goods, shattering and tearing of the material coating, holes and burn-throughs of the weld seam, skipping stitches, dirt, cracks, chips, ruptures of the top materials and accessories, loosening of rivets, buttons, eyelets, failure of locking accessories are not allowed.

10% of the batch is subject to quality control.

For the assessment of physical and mechanical indicators, 3% of products are selected, but not less than 5 pieces. The test results are valid for the entire batch.

Gloves and belt and watch belts are subject to mandatory certification. For leather goods in contact with the skin (mittens, belts, gloves), artificial leather and polymer materials for school bags, school bags and children's bags, a hygienic certificate is required.

Labeling and packaging of leather goods are regulated by GOST 25871-83.

Most leather goods are marked with cold or hot stamping, sometimes with the use of foil, silk-screen printing or stamping with indelible paint on the lining, tape, or paper label attached to the product. Sports bags can be marked on the inside of the shoulder strap or flap. For watch belts and waist belts, the free part of the throat is branded on the inside or the wristband under the belt (for watch belts).

The marking must contain the trade mark, the name of the manufacturer and its address, the name of the product, the model number, the grade and number of the standard, and the date of manufacture.

In the marking of gloves and mittens, their size is indicated.

Packaging plays an important role in maintaining the quality of products during transportation and storage. Packaging methods are provided for in regulatory documents.

Most products are packed in boxes or thick paper 1 at a time; 2; 10 and 20 pcs. with laying them with thick paper. Belts and belts are stacked in 10 or 20 pieces. in bundles and bundles in boxes.

Smaller suitcases (during transportation) are put into suitcases large sizes with paper lining, and suitcases made of ABS plastic and polystyrene are packed in corrugated cardboard boxes.

Bags, briefcases, folders made of genuine leather are packed in boxes one by one, previously wrapped in paper or placed in a plastic bag.

Gloves are packed in branded bags made of thin thick paper or polyethylene, followed by packing in boxes of 10 pairs.

Storage should be organized so as to prevent damage to products.

Particular attention should be paid during storage to maintain a constant reference temperature and relative humidity in the room.

For storage of leather goods, the relative humidity of the air should be within 60%, and the temperature should be from 10 to 25 ° C.

With high humidity, the skin swells, loses its shine, can become moldy, and the high temperature leads to drying out of the leather.

Leather goods are stored on racks. The number of rows in height should be such as to prevent deformation of the products. For example, the height of stowage of leather bags should not exceed five places, suitcases of a rigid structure should be stacked on the edge in rows of no more than 4 pieces. in height, and suitcases of a semi-rigid design - on the wall of the case no more than 10 pcs. in a row.

From time to time, products that have been stored for a long time should be inspected and transferred.

When storing products made of genuine leather, ensure safety from insect and rodent damage.

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