Since the start of operation, machines and equipment are subject to wear and tear, which increases with the increase in the life of the facilities and leads to the loss of part of their usefulness, and, as a result, a certain part of the cost.

In other words, depreciation is the loss of value (depreciation) of property during operation under the influence of various factors of obsolescence and natural-temporal impact.

The causes of wear and tear can relate either to the object itself, or to the immediate environment of this object (the emergence of more advanced and competitive analogues, the emergence of new technologies or changes in the technological chain in which the object is included), or in areas that are not directly related to the object, then are external to it.

Physical, functional and external deterioration are usually considered as the main factors of impairment (obsolescence).

Physical deterioration - deterioration of the initial technical and economic properties, due to the natural wear of a particular object during operation and under the influence of various natural factors. In other words, this is the wear of the materials from which the object was created, the loss of its original qualities, the gradual destruction of structures, etc.

Functional wear - depreciation of an object as a result of non-compliance of its parameters and (or) characteristics with the optimal technical and economic level. The cause of functional obsolescence can be both a lack of optimal utility and an unused excess of it.

Examples of functional obsolescence include overcapacity, design overcapacity or undercapacity, high ancillary production costs, and so on.

External (economic) wear - depreciation of property due to the influence of external factors, namely: a change in optimal use, legislative innovations, a change in the balance of supply and demand, deterioration in the quality of raw materials, the qualifications of the workforce, etc.

External wear and tear is almost always considered unrecoverable, since the magnitude of the potential cost of eliminating the external elements that caused this obsolescence always, with rare exceptions, exceeds the value added to the property.

Since any object can be subjected to different types of wear at the same time, the cumulative wear is taken into account in the assessment.

The calculation of cumulative depreciation implies a certain procedure for assessing depreciation. It usually takes the following form: present value minus physical depreciation, functional depreciation, and external depreciation. This is the generally accepted sequence of subtracting these various depreciation elements from the present value. The sequencing logic is derived from the normal life cycle of an asset. When an asset is new, the valuation is equal to the price at which it is actually sold.

The presence of a buyer's desire and a seller's desire implies the assumption that the purchase of this asset is economically justified (i.e., there is a business need of some kind). As soon as the assets leave the manufacturing plant, they begin to depreciate. Usually the first element of depreciation is physical depreciation, as the asset will be put into operation and used for its intended purpose. As the asset continues to operate, there are two elements of deterioration - correctable and irreparable depreciation. Correctable wear manifests itself in the form of normal repairs, while irreparable wear manifests itself in such forms as metal fatigue. Physical wear and tear is the only element of depreciation that lasts until some event in the market or in the environment causes functional or external wear.

Typically a manufacturer improves a product incrementally over time, and when the manufacturer announces a "new and improved" version of the machine, there is a new kind of obsolescence of an existing asset. Usually a new version is the result of some technological improvement causing some functional obsolescence. With significant changes in technology, functional obsolescence becomes significant. At this point, the asset is in use, undergoes physical wear and tear, and some functional wear is now added to it. As time passes, external factors such as reduced profitability in industry, increased competition, imports of foreign goods, shifts in market needs or laws, etc. lead to outward obsolescence. This is usually the last element of depreciation affecting the asset.

This is the normal depreciation sequence when using the cost approach. The sequence may change under certain circumstances. It is important that when using the cost approach, the valuer seeks to distinguish between different types of depreciation and ensure that there are no duplicate impairments.

Cumulative depreciation the object of appraisal is defined as the sum of value losses under the influence of all obsolescence (wear and tear) factors. The shelf life factor, taking into account impairment from cumulative depreciation, is determined by the formula:

TO G = K f * TO fun * TO V (5.15)

Where: TO f - coefficient physical wear and tear;

TO fun - coefficient of functional wear;

TO V - coefficient of external (economic) depreciation.

Physical deterioration

Physical wear is a natural process of deterioration of equipment characteristics during its operation under the influence of many factors, such as: friction, corrosion, aging of materials, vibration, fluctuations in temperature and humidity, quality of service, etc.

The growth of physical wear leads to an increase in the probability of emergency equipment failures and to a decrease in the quality characteristics of products manufactured using this equipment, which leads to a decrease in the residual service life of the entire product or some of its components and parts.

There are the following types of physical wear:

1) mechanical wear, the result of which is a decrease in accuracy (deviation from parallelism and cylindricity);

abrasive wear - the appearance of scratches and scuffs on mating surfaces;

collapse, causing a deviation from flatness;

fatigue wear leading to the appearance of cracks, fracture of parts;

jamming, which manifests itself in the adhesion of mating surfaces;

corrosive wear, which manifests itself in the oxidation of the wear surface. Due to the cause that caused wear and tear, physical wear and tear is of the first kind and the second kind.

Physical deterioration of the first kind called wear and tear accumulated as a result of normal operation.

Physical deterioration of the second kind called wear and tear resulting from natural disasters, accidents, violations of operating standards, etc. According to the flow time, continuous and emergency wear are distinguished. continuous wear is called a gradual decrease in the technical and economic indicators of an object with its correct, but long-term operation. One of the types of continuous wear is the mechanical wear of components and parts, which mainly affects the moving parts of machines and mechanisms.

emergency wear is called rapid wear in time, reaching such proportions that further operation of the object becomes impossible, for example, cable breakdown. By the nature of the flow, emergency wear is really instantaneous, but in fact it is the result of continuous hidden wear.

Emergency wear due to external causes is associated with personnel errors, sudden surges in supply voltages, and a discrepancy between the required and available consumables. For example, in internal combustion engines designed for low-octane fuel, when using high-octane gasoline, valves quickly burn out, that is, emergency wear occurs.

Hidden wear called wear, which does not directly affect the technical parameters of the equipment, but increases the likelihood of emergency wear.

According to the degree and nature of distribution, global and local types of wear are distinguished.

global wear and tear called depreciation, extending to the entire object as a whole.

Local wear wear is called wear, affecting various components and parts of an object to varying degrees.

According to the technical feasibility and economic feasibility of restoring lost consumer properties, physical wear can be removable and irremovable.

Removable wear- wear, the elimination of which is physically possible and economically justified, i.e. depreciation, allowing repair and restoration of the object from a technical point of view and justified from an economic point of view.

irreparable wear and tear, those. depreciation that cannot be eliminated due to the design features of the object or is inexpedient to eliminate for economic reasons, since the cost of elimination (repair of equipment or replacement of parts or assemblies) exceeds the increase in the value of the corresponding object.

According to the form of manifestation, physical wear can be technical and constructive. technical wear and tear is called the decrease in the actual values ​​of the technical and economic parameters of the object in comparison with the normative, passport data. Constructive called wear, which refers to the deterioration of the protective properties of external coatings.

Another manifestation of wear and tear is the increase in manufacturing costs in terms of materials, energy, and maintenance and repair costs, which are significantly higher than the average cost for similar new equipment. Sometimes, with an increase in physical wear and tear, there is no increase in costs and costs remain below the average level. This situation may indicate the presence of a delayed repair and an increase in hidden wear.

The amount of physical wear of an object during operation depends on many factors:

the degree of loading of the object, the duration of work, the intensity of use;

the quality of the object - the perfection of the design, the quality of the materials, etc.;

features technological process, the degree of protection of the object from the external environment;

operating conditions - the presence of dust and abrasive contaminants, high humidity, etc.;

quality of care;

service personnel qualifications.

As a result of physical wear and tear, the productivity of machinery and equipment decreases. This is primarily due to the increase in downtime caused by repairs and maintenance, which reduces the useful fund of working hours. In addition, the wear of the machine from a certain point in time begins to affect a number of technical parameters, which also reduces output. For example, for metal-cutting equipment, the accuracy of processing decreases, as a result, more frequent checks and adjustments are required, and the yield of defective products increases. According to statistics, productivity drops to 25% in 10 years of operation. Vehicles have reduced engine power and, accordingly, load capacity and speed.

The amount of physical wear depends on the service life and resource. The service life is measured by the calendar duration of the operation of machines and equipment before the limit state, and the resource is measured by the operating time. For different types of equipment, standard service life has been established. However, the actual service life of machinery and equipment varies greatly, as noted above, due to the influence of many factors: the intensity and mode of operation, the presence of peak loads, the quality and frequency of maintenance and repairs, the state of the environment, etc.

Equipment with wear of up to 5% can conditionally be classified as new, because in this state, it still has no visible defects and technical parameters are practically not changed. Over time, technical parameters begin to noticeably deteriorate, visible defects accumulate.

During the transition to the stage of wear limit, the product is not able to perform a number of functions and can completely fail at any time. In the regulatory and technical documentation for each type of machinery and equipment, the limit state criterion is indicated. A characteristic feature of this stage is the economic inexpediency of repairing the product in the event of its failure. This stage is absent for a number of products that are operated according to their resource, for example, a nuclear reactor is dismantled without bringing it to the limit state, an aircraft and a diesel locomotive are decommissioned, etc.

The working condition of any, even a very old machine, can be restored, so such machines can be operated much longer than their economic life, replacing failing parts and assemblies with new ones.

At some point in time, the machine breaks down and can no longer perform its functions, its value drops sharply to a certain level - the cost of liquidation.

In valuation practice, it is customary to separate direct and indirect methods for determining the amount of physical wear and tear.

Direct methods for determining physical wear and tear are based on examining the objects of assessment, testing in various operating modes, measuring parameters and characteristics, assessing the actual wear of the most important components, identifying and evaluating external and internal defects and loss of commercial value. With the direct determination of wear, various tests of its technical parameters are carried out, while both all significant parameters of the product’s functioning, and only the main ones, can be measured. For example, when testing machine tools, parameters such as the minimum and maximum spindle speed, maximum power, power consumption, vibration force of various nodes at various degrees of loading, electrical resistance of power cables are measured, and all parameters of the test product manufactured on this machine are measured.

In valuation practice, direct methods for determining physical wear and tear are used extremely rarely.

Indirect methods for determining physical wear and tear are based on the inspection of objects and the study of their operating conditions, data on repairs and financial investments to maintain them in working order. The following indirect methods for determining the physical wear and tear of machinery and equipment can be distinguished:

effective age method (lifetime method);

expert analysis of physical condition;

profit loss method;

performance loss method.

Effective age method (lifetime method)

This is the most common method for determining physical wear along with the method of expert analysis of the physical condition.

As mentioned above, the actual service life of machinery and equipment may differ from the normative due to various factors: the intensity of work and mode of operation, the quality and frequency of maintenance and repair, the state of the environment, etc.

When using the effective age method, the following terms and definitions apply:

Service life (economic life T n ) - the period of time from the date of installation to the date of removal of the object from operation (or the full operating time).

Chronological (actual) age T - the number of years that have passed since the creation of the object (or operating time).

Remaining life T O - the estimated number of years until the object is taken out of service (or the estimated remaining operating time).

Effective Age T uh - the difference between the service life and the remaining service life (or the value of the operating time of the object over the past years).

The service life normalized by industry standards for various groups of equipment and mechanisms indicates the allowable operating time of the equipment without a noticeable change in the quality of the machines performing their functions. Sometimes, to determine the service life, the “Uniform norms of depreciation deductions for the complete restoration of fixed assets of the national economy of the USSR”, approved by the Decree of the Council of Ministers of the USSR of 10/22/1990, are used. No. 1072. At the same time, it is assumed that the operating conditions will correspond to those recommended by the equipment manufacturers, and repair and maintenance work will be carried out on time and with high quality. It should be noted that when assessing the market value of machinery and equipment, the service life of the equipment is usually only a guideline for the appraiser.

The service life of machinery and equipment is only advisory for property appraisers, since it reflects their capabilities for average operating conditions. In each specific case of determining the remaining service life of the equipment, physical wear and tear that actually exists at the time of the assessment should be taken into account.

The coefficient of physical wear and tear for objects with different actual ages is determined in different ways.

1) For relatively new equipment under normal operating conditions, the coefficient of physical wear is determined by the formula:

Where: T - chronological age; T n - life time.

It should be taken into account that a manufactured and temporarily unused machine, even being in a warehouse under conditions of careful conservation, has a partial deterioration in technical characteristics, and, consequently, a loss in value. In this case, the cost of equipment at the start of operation may differ significantly from the cost of new equipment, and this should be taken into account when estimating the cost.

So, for example, re-exported VAZ cars supplied to the domestic market of Ukraine due to low demand abroad have a loss of market value from 10 to 30%. And these cars, just like the newly made ones, have a zero service life. The loss of market value occurs due to the fact that during the time interval from the moment of manufacture to the moment of sale, the re-export vehicle has undergone physical wear and tear (due to the following reasons: fatigue processes in materials, oxidation and adsorption of lubricants, corrosion, loss of elasticity of rubber and plastic seals and hoses, aging of paint and varnish coatings and electrical insulating materials, etc.), and functional.

3) For older, more complex equipment, as well as equipment that has worked for more than its economic life and still continues to work, the coefficient of physical wear and tear is determined as follows:

Where: T uh - effective age;

T O - remaining service life.

4) The service life of the equipment is significantly increased due to repairs, in which obsolete and worn-out mechanisms are replaced with new ones and the interfaces in the friction units are restored. This is especially significant during major repairs of equipment, when the main components of the equipment are replaced and the main properties of the most important parts of the machines are restored.

If the object was subjected to major repairs, the coefficient of its physical deterioration is determined as follows:

(
5.18)

The effective age of an object in this case is the weighted average chronological age of its parts. The effective age can also be determined by weighting the investment in the object (repair costs in monetary terms).

Example. The challenge is to determine the effective age of equipment assessed in 2001. We know the original cost and date of purchase. It is known that the equipment was purchased new in 1991, and current repairs were carried out in 1994 and 1996. A major overhaul was carried out in 1999 with the replacement of some units.

The first step is to develop an appropriate basis for comparison, which in this case is the accumulated cost. It is determined by applying the appropriate cost index (assumed to be 10% per year for this example) to the original cost for each year:

If we consider the actual age (or chronological age) as the number of years since the beginning of operation, then the effective age reflects the condition of the asset. If the chronological age is -10 years, then the current age will be less, because the equipment is in better condition as a result of the upgrade compared to the non-upgraded equipment.

The effective age can be determined by weighting the investment in an asset or group of assets. The initial cost is 41900 UAH. and the accumulated value of 80979 UAH. are misleading because they include the excess capital investment made during the 1999 renovation, as these values ​​include twice the assets that were replaced during the 1999 renovation. For example, if a pump was replaced in 1999, both costs count it twice as part of the original investment in 1991 and again in 1999. To adjust the costs, you must remove the excess investment. To do this, we again convert the cost of renewal in 1999 to the cost of 1991 by discounting as follows:

(rounded 8100 UAH)

The cost and accumulated value are then reduced by the excess investment at the acquisition date (in this example, 1991). The summary is shown below:

The next step is to take into account the age of the investment.

This is done by multiplying the accumulated acquisition cost by the appropriate number of years:

The last step is to determine the effective age. This is done by dividing the weighted investment by the accumulated value.

The result, 6.66 years, is an acceptable estimate of the effective age of the equipment we are evaluating.

The problem solved in the example has been simplified to illustrate the methods and concepts used. We used cost information as a peer-to-peer comparison. There are other relevant bases. For example, the evaluator may consider estimating the effective age based on performance.

To calculate the effective age, you can use some simplified methods that do not give as accurate results as the method described in the example. One technique is to use accumulated cost information to determine a composite cost index and use the cost index in the interpolation. If we did this in the example, then the composite cost index, obtained by dividing the accumulated cost by the cost, would be 1.82. Interpolation of this cost index according to the assumed cost index (10%) indicates that the effective age of the equipment is 6.3 years, corresponding to approximately 1995.

Sometimes a technique is used to weight cost by age (that is, cost minus excess investment multiplied by age in years). If this technique is used for the previous example, then the effective age will be 5.5 years.

The reasons for the differences in results obtained using these simplified methods reflect the simplifying assumptions underlying the weighting plan. The methodology used in the example is the most accurate because the age of the investment is actually measured on a peer-to-peer basis. Establishing a composite cost index and interpolating it is not as accurate a method due to the interpolation process as well as variations in the cost index. The third technique (original cost x age) is the least accurate, since using age as a basis implies a proportional relationship, and therefore gives equal weight to all costs.

Expert analysis of physical condition

This method involves the involvement of experts to assess the actual state of machinery and equipment, based on their appearance, operating conditions and other factors. As experts, you can use the employees of the chief mechanic service or the repair service of the enterprise. Also, the evaluator can use the already available data from periodic inspections of the condition of the equipment.

In the general case, you can use the rating scale for determining physical wear and tear, compiled on the basis of research by specialists - experts (Table 5.4) 1

Table 5.4

Estimated scale of physical wear and tear

A significant share of the costs of the enterprise - the costs associated with the use of machinery, equipment, production facilities. Their use has salient feature: Unlike material resources, they are not consumed in one production cycle. Capital resources last for years and wear out.

Depreciation of equipment is the loss of its value and performance. Wear and tear can occur due to many reasons: aging of equipment, loss of its competitiveness, etc. Today, the fight against wear and the extension of the service life of equipment is a very urgent task.

Depreciation in the economic sense means the loss of value of the equipment during its operation. In this case, two types of wear are distinguished: physical and moral. Physical wear occurs due to equipment aging and loss of its performance, and moral wear due to loss of competitiveness.

Physical depreciation is the loss of fixed assets of their original consumer value, as a result of which they become unusable and require replacement with new funds. This is normal wear and tear. It is the result of past periods of operation, environmental influences and downtime. As a result of physical wear, the technical characteristics of the object worsen, the probability of breakdowns and accidents increases, the residual service life of the object as a whole or some of its components and parts decreases. This leads to an increase in waste, the risk of serious accidents, the inability of machines and equipment to meet the requirements for proper functioning. Production costs (materials, energy), maintenance and repair costs also increase.

The physical type of wear is divided into subspecies:

• 1. For the reason that caused the wear, wear of the first and second kind is distinguished. Depreciation of the first kind accumulates as a result of operation. Depreciation of the second kind occurs due to accidents, natural disasters, violations of operating standards, etc.
• 2. According to the flow time, wear is divided into continuous and emergency. Continuous is a gradual decrease in the technical and economic indicators of objects. Emergency - wear, rapidly flowing over time.
• 3. According to the degree and nature of the distribution, wear can be global and local. Global - wear, uniformly spreading over the entire object. Local - wear, affecting individual parts and components of the object.
• 4. According to the depth of flow, partial and complete wear are distinguished. Partial - depreciation, allowing repair and restoration of the object. Full involves the replacement of this object with another.
• 5. If it is possible to restore the lost consumer properties, wear can be removable and irreparable.
• 6. According to the form of manifestation, technical and structural wear are distinguished. Structural wear is manifested in the deterioration of the protective properties of external coatings and the increase in fatigue of the main parts and components of equipment, which increase the likelihood of accidents. Technical wear and tear is wear and tear, expressed in a decrease in the actual values ​​of technical and economic parameters compared to standard or passport values.

To assess the degree of physical wear and tear, the following assessment methods are used:

• - an expert method based on a survey of the actual technical condition object;
• - a method for analyzing the service life, based on a comparison of the actual and standard service life of the equipment.

Methods for calculating physical wear:

1. Effective life is based on the assumption of the reliability of determining the remaining life of the object (Toast). Calculated according to the formula:

Teff \u003d Tn - Toast

where Tn is the standard life span.

Physical depreciation Phi is determined by the following formula:

Phi \u003d Teff / Tn

2. Expert analysis. The following table is used to evaluate wear

Table 1

3. Profit loss method (economic-statistical method).

Physical depreciation Phi is calculated by the formula:

Phi \u003d (Mon-Fri) / Po

where To - profit from the new object, Fri - profit from the object in the current state.

The values ​​for Mon and Fri must be defined for a period (eg month, quarter).

4. Loss of productivity method (economic-statistical method)

Phi = ((Qo - Qt)/Qo)n

where Qo is the performance of the new object (passport characteristic), Qt is the performance of the object at the time of evaluation, n is the Chilton braking coefficient. For objects of the machine-building industry, it averages 0.6-0.7.

5. The method of the stage of the repair cycle.

This method is based on the assumption that the decrease in consumer properties of machinery and equipment during operation linearly depends on the operating time. At the same time, it is assumed that the repair carried out returns part of the consumer properties.

At the end of the repair cycle, that is, before the first overhaul, the value of the consumer properties of the PSr is calculated by the formula:

PSr \u003d PS - Kr * PS

where PS is the consumer properties of the new object, Kp is the relative decrease in consumer properties to the end of the repair cycle.

Accounting for the increase in consumer properties due to major repairs is carried out according to the formula:

PSr \u003d PS -Kr * PS + PS

where PS is an increase in consumer properties due to a major overhaul.

The calculation of physical wear (Phi) is as follows:

Phi \u003d (Pso -PSt) / Pso,

PSt \u003d PS - t * dPS,

t = M*D*Ksm*Kvi*Ts,

dPS \u003d (PSo - Kr * PS + PS) / Tr

where Pso is the value of consumer properties at the beginning of the repair cycle,

t - operating time after overhaul,

M is the number of months worked after the overhaul,

D is the number of working days in a month,

Kcm - shift coefficient,

Kwi - coefficient of intra-shift use,

Ts is the duration of the shift.

6. Method of element-by-element calculation.

When calculating wear using the element-by-element calculation method, it is necessary to represent the object in the form of several basic elements. Depreciation is determined for each element separately and is taken into account taking into account the share in the cost of the entire object. The wear calculation scheme is described by the formula:

Fip = fi*(ci/c)*(Ti/T)

where fi is the actual physical wear of the i-th element, ci is the cost of the i-th element, c is the cost of the object as a whole, Ti is the standard service life of the i-th element, T is the standard service life of the object as a whole.

The decrease in the value of capital goods may be associated not only with the loss of their consumer qualities. In such cases, we speak of obsolescence.

Obsolescence is understood as a decrease in the cost of equipment and other fixed assets until the end of their service life due to a decrease in the cost of their reproduction, as new types of fixed assets begin to be produced cheaper, have higher productivity and are technically more advanced. Therefore, the use of obsolete machines and equipment becomes economically unprofitable as a result of their low productivity and high cost.

The time of obsolescence and its degree are determined by the influence of many factors. First of all, these are the features and scale of production. Machinery and equipment, the use of which becomes unprofitable in some conditions of production, can be successfully used in others. In this case, we can talk about partial obsolescence of equipment. Losses from obsolescence can be eliminated by upgrading and refurbishing equipment, as well as using it to perform work where it remains cost-effective.

Losses from complete obsolescence are eliminated only by replacing obsolete machines and equipment with new, more advanced and cost-effective ones. Sometimes the improvement of existing equipment and machinery is more effective than its replacement. Therefore, a more rational way to reduce obsolescence is the modernization of machinery and equipment.

There are two forms of obsolescence.

Obsolescence of the first kind is due to the growth of the efficiency of production of capital goods. It is caused by the appearance of similar, but cheaper means of labor.

The amount of obsolescence of the first form (Im1) as a percentage of the total initial cost of the object (Zp) is determined by the formula:

Im1 \u003d (Zp - Sv) * 100 / Zp

where Sv is the replacement cost of the object.

Obsolescence of the second kind - depreciation of fixed assets due to the creation of new, more productive and improved equipment.

Obsolescence of the second form (Im2) is determined by the formula:

Im2 \u003d Zp - Zp / (Pr * Tn) - Zp1 / (Pr * Tn1) * To * Pr1

where Zp, Zp1 - the initial cost of the old and new equipment, respectively, Pr, Pr1 - the annual productivity of the old and new equipment, respectively, expressed in the number of products manufactured per year, Tn, Tn1 - the standard service life of the old and new equipment, respectively, in years, That is the remaining life of the old equipment in years.

Obsolescence of the second kind is associated with the emergence of new means of labor that perform similar functions, but are more advanced and productive. As a result, the value of old capital goods decreases.

Both forms of obsolescence are the result of technological progress. From the point of view of the national economy, this is justified, and even necessary, because as a result, obsolete equipment is replaced by more advanced ones, which means that the overall production efficiency increases. At the same time, for a particular enterprise, this positive phenomenon also has negative features: it turns into an increase in costs.

The gradual wear and tear of the means of labor leads to the need to accumulate funds to compensate for the wear and tear of fixed assets and their reproduction. This is done through depreciation.

Depreciation - compensation in cash for the cost of depreciation of fixed assets. It is a way of gradually transferring the value of funds to manufactured products. Deductions intended to reimburse the cost of the depreciated part of fixed assets are called depreciation. Depreciation deductions are accumulated, forming a depreciation fund.

The depreciation rate is the annual percentage of transferring the value of fixed assets to products.

There are two main methods of depreciation calculation: uniform (linear) and accelerated (non-linear).

Under the straight-line method, depreciation is calculated monthly based on its monthly rate. The latter is calculated by dividing the annual depreciation rate by 12.

The advantage of this method is its ease of use. However, it does not take into account the uneven depreciation of fixed assets in certain periods, and does not adequately contribute to the innovation process at the enterprise. In this regard, the method of accelerated depreciation of equipment deserves attention. There are several methods for calculating accelerated depreciation.

One of the most common is the method based on reducing the depreciation period and increasing its annual rates. In this case, depreciation charges in the first years of operation of fixed assets sometimes reach 40%. As a result of applying this method, enterprises quickly upgrade equipment and expand production based on the latest technology. A variation of this method of accelerated depreciation is an increase in the amount of depreciation deductions at individual enterprises in the first years and, accordingly, their decrease in subsequent years of using fixed assets.

Another variation of the accelerated depreciation method is the declining balance method.

The annual depreciation rate in this case will be twice as much as the depreciation rate under the straight-line method. At the same time, the declining balance method does not provide full compensation for the initial cost of labor instruments by the time the standard service life is calculated. To eliminate this shortcoming, entrepreneurs are allowed to switch to a uniform depreciation method from the second half of the service life.

fixed asset accounting depreciation

The concept of depreciation in valuation activities is used in 2 senses:

1. As a technical term that determines the degree of material and physical deterioration of the object of assessment, i.e. partial or complete loss of their original consumer properties;

2. As economic depreciation or obsolescence, which characterizes the loss over time of the initial and replacement value of the appraised object due to a decrease in its usefulness for various technical and economic reasons, both in the object itself, or in the conditions of its life, and outside the object and the specified conditions .

The degree of wear is expressed in shares or percentages in relation to the original or replacement cost of the object. There are physical, functional and economic (external) depreciation generated by the corresponding types of depreciation.

The degree of cumulative wear or the generalized degree of wear can be determined by the dependence:

S=1-(1-V)(1-E)(1-F)

S is the degree of cumulative depreciation or impairment;

F, V, E – percentage of physical, functional and economic impairment, respectively.

Physical deterioration.

As a technical concept different kinds:

1. For reasons causing wear:

ü wear of the first kind, accumulated as a result of normal operation, storage;

ü wear of the second kind, resulting from natural disasters, accidents, violations of operating standards, etc.

2. According to the flow time:

ü continuous wear;

ü emergency wear.

3. According to the degree and nature of distribution:

ü global;

ü local.

4. According to the depth of wear:

ü partial;

ü full.

5. If possible, restore lost consumer properties:

ü removable;

ü irremovable.

Irreparable wear and tear refers to deficiencies that are practically (technically) impossible or not economically feasible to correct at the valuation date.

Removable wear is determined by the cost of its elimination.

The degree of real physical wear and tear is determined by various methods:

1. Straight.

2. Indirect.

Direct methods include accurate methods for determining wear based on the study of relevant objects, their testing, assessment of wear by objective control methods, etc.

The degree of real physical deterioration of a complex object is defined as the average degree of wear of the most important components and assemblies, weighted by their share in the total initial or replacement cost.

functional wear.

Appears in:

1) loss of value caused by the appearance of either cheaper (for the entire set of costs, both investment and operational) objects of the same class, or more economical and productive analogues of other classes;

2) non-compliance of the characteristics of the object with modern general regional standards or safety requirements, environmental restrictions, market requirements, etc.;

3) change in the technological cycle, in which the object is traditionally included (technological wear and tear).

Economic (external) wear.

It is determined by the decrease in the utility of the object as a result of external factors.

Changes in market, economic, financial conditions, etc.

Full replacement cost is the cost of analogue.

Analog- this is an object that performs the same functions as the object being evaluated, has similar characteristics and parameters, has the same principle of operation and design, belongs to the same class, type, subspecies according to the classifier and has the lowest cost among all analogues.

7.Physical wear. Removable and irreparable wear. Direct and indirect methods for determining physical wear. The return-life method. Method of direct monetary measurement of depreciation.

Physical wear, as a technical concept, has various types:

1. For reasons causing wear: 1) wear of the 1st kind, accumulated as a result of operating (storage) standards; 2) depreciation of the 2nd kind, arising from natural disasters, violations of the rules for the operation of accidents, etc.

2. According to the flow time: continuous or emergency.

3. According to the degree and nature of distribution: global, local.

4. According to the depth of wear: partial, full.

5. If possible, restore the lost consumer properties: disposable, irremovable.

Irreparable wear and tear refers to deficiencies that are practically (technically) impossible or not economically feasible to correct at the valuation date. Removable wear is determined by the degree of its elimination. The degree of real physical deterioration is determined by various methods: direct, indirect.

Direct methods include accurate methods for determining wear based on the study of relevant objects, from tests, wear assessment by methods of operational control, etc. The degree of real physical deterioration of a complex object is defined as the average degree of wear of the most important components and assemblies, weighted as their share in the total initial or replacement cost.

Indirect methods include assessment of the general technical condition of the object as a whole, its actual service life, the amount of work performed (productivity), etc.

In valuation activities, indirect methods are mainly used, one of them is an enlarged assessment of the technical condition by a machine-like expert method.

a) Condition assessment new - 5% wear. b)Very good condition - 6-15%.

c) Good - wear 16-35%. d) Satisfactory - wear 36-60%.

e) Conditionally suitable - wear 61-80%. f) Unsatisfactory - wear 81-90%.

g) Unusable - wear 90-100%.

The appraisal also takes into account the distribution of the repair impact and the CCF coefficient.

The most common indirect method is the "age-life" or effective age method. To determine wear using the age-life method: Fn= =

Fn is the degree of irremovable physical wear;

NL - the duration of the economic life of the object or service life;

RL is the remaining useful life;

EA - effective age. The determination of the effective age is based on an analysis of the state of the object, the number of years during which it has been in operation, as well as the remaining useful life at the time of assessment (determined either by an expert or by special calculation methods).

Determine the degree of physical wear of the machine under the following conditions.

Service life 15 years.

Time since production 5 years.

(15-5)/15=2/3=0,6

According to expert assessment, the remaining service life is 5 years.

Effective age 10 years. Wear 0.667.

The definition of EA is based on an analysis of the condition of the item, the number of years it has been in operation, and the remaining useful life at the time of valuation.

It is determined either by expert means or by special calculation methods.

Direct wear measurement method: F=

AC- impairment for any type of depreciation; CN is the total replacement cost.

Irreparable physical wear and tear.

It can be determined for the object of assessment as a whole and by the component-by-component decomposition method.

The "Age, service life" method is used as the main method.

Technical resource - a resource for which the design and testing of an object is carried out.

Assigned resource - a resource that is valid at the time of the assessment, upon reaching which the object is either decommissioned or the resource is extended.

From the safety conditions, the assigned resource is initially assigned less than the technical one, and then, as operating experience and special tests are accumulated, it is extended. The maximum value of the technical and assigned resources is taken as the economic service life.

For objects that retain consumer properties at a given level, the depreciating factor is the reduction in potential income for the remaining service life. This dependence on operating time is linear.

For these objects, the effective age in terms of operating time is strictly equal to the passport one.

The degree of wear is calculated for each parameter separately.

From the condition of ensuring safety, the calculated value of the degree of wear is taken as the maximum value of all parameters.

The remaining calendar life for each operating time parameter is determined by:

RLki=max(NLk-Ak-Tm;NLk*(NLk-Ak-Tm)*Ri/NLi)

NLk - service life according to the calendar.

Ak - calendar time since release.

Tm - the time required to register real estate transactions and formalize the transfer of ownership.

For registration of the aircraft we will take 0.5 years.

Ri - intensity of operating time for the i-th parameter for the calendar year (number of flights per year).

NLi - service life according to the i-th operating time parameter.

In addition to the operating time and the calendar, fatal wear is affected by:

1. Overhaul.

2. Income and expense per hour of flight or one flight, which together determine the beginning of the last stage of the life of the glider (when major repairs are not feasible).

Removable physical wear.

Removable is considered wear, which can be eliminated and the repair is economically feasible.

There are assigned resources before the first overhaul and technical resources.

Impairment for deferred major repairs:

ADcri=Cr*(1-OMRi/MRi)*(1/(1+i)OMRi/Ri)

OMRi - residual overhaul life for the i-th parameter.

i - discount factor.

MRi - overhaul life.

Ri - annual operating time for the i-th parameter.

Cr - cost of overhaul.

Similar information.

Lecture 2. Types of wear. Lubricants. Ways to deal with wear

Technological processes carried out in chemical industry, differ in a variety of parameters. The operating conditions of the equipment are mainly determined by the temperature, pressure and physico-chemical properties of the medium.

Under reliability equipment understand full compliance with its technological purpose within the specified operating parameters.

Durability– the duration of maintaining the minimum allowable reliability under the operating conditions of the equipment and the accepted maintenance system (maintenance and repair).

1.1. Main types of wear

The decrease in reliability and decrease in the durability of equipment are due to the deterioration of its condition as a result of physical or obsolescence.

Under wear and tear one should understand the change in the shape, dimensions, integrity and physical and mechanical properties of parts and assemblies, which is established visually or by measurements.

Obsolescence equipment is determined by the degree of lag of its technical and design purpose from the level of advanced technology (low productivity, product quality, efficiency, etc.).

1.1.1. Mechanical wear

Mechanical wear can be expressed in breakage, surface wear and a decrease in the mechanical properties of the part.

• Breaking

Complete failure of the part or the appearance of cracks on it is the result of exceeding the permissible loads. Sometimes the cause of the breakdown lies in non-compliance with the manufacturing technology of the equipment (poor-quality casting, welding, etc.).

• Surface wear

Under any operating and maintenance conditions, surface wear of parts in contact with other parts or media is inevitable. The nature and amount of wear depends on various factors:

physical and mechanical properties of rubbing parts and media;

specific loads;

relative speeds of movement, etc.

• Wear due to friction forces

Wear is a gradual destruction of the surface of the material, which may be accompanied by the separation of particles from the surface, the transfer of particles of one body to the surface of the conjugated body, a change in the geometric shape of the rubbing surfaces and the properties of the surface layers of the material.

• Abrasion

Abrasion is the relative movement of parts pressed against each other. Rubbing surfaces with any processing have a roughness, i.e. recesses and tubercles. With mutual movement, the tubercles are smoothed out. As a result of the gradual running-in of rubbing surfaces, the work of friction will decrease and wear will stop. Therefore, it is very important to observe the established break-in regime for new equipment.

Another cause of abrasion may be the molecular contact of the surfaces in separate areas, in which they merge by welding. With the relative movement of the surfaces, the welding points are destroyed: many particles come off the friction surfaces.

During friction, the surfaces of the parts heat up. As a result, amorphous layers of run-in surfaces in certain conditions soften, are transferred to certain distances and, once in the depressions, harden.

• Bullying

Scoring is the formation of rather deep grooves on the surface, which serves as a prerequisite for further intense abrasion. It has been established that the most frequent cases of scuffing are in rubbing pairs made of the same metal.

• Abrasive abrasion

In addition to solid particles formed during abrasion, a lot of small particles in the form of dust, sand, scale, soot fall on the rubbing surfaces. They are brought in with the lubricant or formed under certain operating conditions. The effect of these particles is small if their dimensions are less than the thickness of the lubricant layer.

• Collapse deformation and fatigue spalling

With a low quality of processing of rubbing surfaces, the actual contact area is much less than the theoretical one: the parts are in contact only with protruding ridges. When the limiting pressure is reached, the deformation of the crushing of the sections protruding beyond the average contact surface occurs.

A frequent change in the direction and magnitude of the load on the friction surfaces leads to metal fatigue, as a result of which individual particles peel off from the surfaces (fatigue chipping).

1.1.2. Erosive wear

Many media that parts come into contact with contain solid particles (salts, sand, coke in oil streams; catalyst, absorbent, etc.) that cause abrasion or wear. Similar wear is observed with strong and prolonged impacts on the surface of liquid and steam jets. The destruction of the surface of the part, which occurs under the action of friction and impact from the working environment, is called erosive wear .

1.1.3. fatigue wear

There are frequent cases when a part subjected to variable loads breaks at stresses much lower than the tensile strength of the part material. The complete or partial destruction of a part under the action of stresses, the value of which is less than the tensile strength, is called fatigue wear .

1.1.4. Corrosive wear

Corrosion is understood as the destruction of the metal surface, which is a consequence of the occurrence of chemical or electrochemical processes. Corrosion can be continuous, local, intergranular and selective.

At solid corrosion, the surface of the part wears out relatively evenly. According to the degree of uniformity of corrosion destruction of the surface layer, continuous uniform (see Fig. 2.1, a) and continuous uneven (see Fig. 2.1, b) are distinguished.

At local Corrosion destruction does not spread over the entire surface of contact with the medium, but covers only certain areas of the surface and is localized on them. In this case, craters and depressions are formed, the development of which can lead to the appearance of through holes. Varieties of local corrosion are: corrosion individual spots (see Fig. 2.1, c), ulcerative (see Fig. 2.1, d), point (see Fig. 2.1, e).

Intergranular (or intercrystalline) corrosion - the destruction of metals along the grain boundary (Fig. 2.1, e). This type of corrosion is typical for parts made of chromium-nickel steels, copper-aluminum, magnesium-aluminum and other alloys.

Deeply penetrating intergranular corrosion is called transcrystalline (Fig. 2.1, g).

Selective(structural-selective) corrosion consists in the destruction of one or several structural components of the metal at the same time (Fig. 2.1, h).

Rice. 2.1. The nature and forms of the spread of corrosive wear:
a - continuous uniform; b - continuous uneven; c - local;
g - ulcerative; d - point; f – intergranular; g - transcrystalline;
h - structural-selective

According to the mechanism of action, chemical and electrochemical corrosion are distinguished.

Chemical corrosion - corrosion of metal by chemically active substances (acids, alkalis, salt solutions, etc.).

Widespread electrochemical corrosion occurring in aqueous solutions of electrolytes, in an environment of moist gases and alkalis under the action of an electric current. In this case, metal ions pass into the electrolyte solution.

Underground (soil ) corrosion is the result of the action of soil on the metal. In most cases, it occurs during aeration and is local in nature. Soil corrosion is biocorrosion (microbiological corrosion) caused by microorganisms. Most often, it appears in earthen soil, in ditches, in sea or river silt.

External surfaces of equipment, pipelines, metal structures are subject to atmospheric corrosion occurring in the presence of an excess amount of oxygen under the alternating action of moisture and dry air on the metal.

In chemical equipment, the so-called contact corrosion. It occurs at the site of contact between two different or identical metals in different states.

1.1.5. Thermal wear

A significant part of the equipment of chemical and petrochemical plants operates at high temperatures. Under these conditions, being in a stressed state, the steel structure undergoes creep and relaxation over time.

Phenomenon creep consists of slow plastic deformation of a structural element under a constant load. If the stresses are small, then the growth of deformation over time may stop. At high stresses, deformations can increase until the product fails.

Under relaxation is understood as a spontaneous decrease in stress in a part, with a constant value of its deformation, under the influence of high temperature. Relaxation can lead to equipment depressurization and accidents.

Violation of the stability of the structure at high temperatures is due to graphitization, spheroidization and intergranular corrosion.

Process graphitization is the destruction of carbide with the formation of free graphite, resulting in a decrease in the impact strength of the metal. Grafitization susceptible gray cast iron, carbon and molybdenum steels at temperatures above 500 °C.

Spheroidization does not significantly affect the strength of steels. It lies in the fact that lamellar perlite takes on a round granular shape over time.

1.2. Ways to control and measure wear

Qualitative and quantitative methods are used to assess corrosion damage.

Qualitative Method consists in visual inspection of the sample and its examination under a microscope in order to check the state of the surface, detect corrosion products on these surfaces or in the medium, establish a change in color and physico-chemical properties of the medium.

quantitative method consists in determining the corrosion rate and the actual mechanical characteristics of the metal.

An indicator of the magnitude of corrosion is the depth of damage to the metal at individual points, determined with the help of special instruments. The nature of corrosion and its rate are determined by systematic inspections and measurements made periodically during the entire service life of the equipment. However, such periodic examinations require a fairly frequent shutdown of the devices, their preparation and opening, which reduces the productive time.

Therefore, preference is given to the method of continuous monitoring using probes. The principle of operation of the probe is based on the control of changes in the electrical resistance of samples made of the same material as the equipment under study. A sample of certain sizes and shapes is placed inside the apparatus in those areas where the study of the nature of metal corrosion or the aggressive properties of the medium is of greatest interest. The readings of all probes are placed on one shield.

It is more difficult to control the corrosion damage of non-metallic materials. The mechanism of destruction of polymeric materials differs from the corrosion of metals and is not well understood. The difficulty lies in the fact that the polymer swells in the medium and quickly dissolves. These processes propagate deep into the polymer material due to diffusion.

The simplest and most common method for determining the amount of wear is micrometerage , i.e., measuring the actual dimensions of parts using a variety of tools (calipers, micrometers, gauges, templates, etc.).

For a more accurate determination of the total amount of wear, a method is used that consists in determining the mass loss of the sample as a result of wear. This method requires thorough cleaning and rinsing of the parts and a highly sensitive balance.

In some cases, when it is required to control the wear of equipment during its operation (on the go), they use integral method , which provides for determining the amount of steel or cast iron that has passed into lubricating oil as a result of wear of friction surfaces. To do this, take a sample of oil for chemical analysis.

In addition to normal wear, in practice there are frequent cases of so-called catastrophic wear, which occurs very quickly, and sometimes instantly (breakdown). The possibility of catastrophic wear should be established as soon as possible to prevent accidents. To do this, use all possible ways visual inspection and tactile testing.

During an external examination, they check the correct relative position of parts and components of the machine, the density and strength of the joints, fastening to the foundation, etc. The temperature of the rubbing parts and the vibration of the machine or its individual components are determined by touch. Increased temperature and unacceptable vibration may be the result of increased wear.

Breakage of moving parts is easy to establish by knocking or noise by ear or with the help of a special hearing aid.

Wear is a random process, because it depends on a large number factors. Therefore, the analytical description of wear is performed on the average values ​​of wear indicators.

Wear rate- the absolute wear of the part in time, expressed in linear, mass or volume units, and is measured in microns / h, g / h, mm 3 / h, respectively.

Wear rate is the ratio of absolute wear to the sliding distance (µm/km, m/m).

The intensity of linear wear is determined by the equation

I h = h/L,

Where h is the height of the worn layer;
L is the length of the friction path.

The intensity of mass wear is determined by the equation

I m = M/FL

Where M- mass of worn metal;
F is the nominal surface of the friction area.

Relationship between I h And I m is determined by the formula

I h = I mρ,

where ρ is the density of the metal.

As the temperature rises, the hardness of the material decreases, and the equation is used to describe the wear rate as a function of temperature:

I = A exp( BT),

Where A, B- permanent.

To describe the dependence of wear rate on pressure P usually a power equation is used

I = CPn,

Where C, n- permanent.

The surface finish determines the actual contact surface of the rubbing parts. The cleanliness of processing determines mainly the wear during the break-in period. On fig. 2.2 shows the change in surface roughness over time for different initial finishes. Time τ 1 characterizes the running-in period, i.e., when a noticeable change in roughness is observed. At τ >τ 1, a period of steady wear is observed.

The optimum roughness depends on the properties of the materials, the shape of the parts, the working conditions of the friction pairs and the presence of lubricant.

The nature of the wear of parts over time is shown in Fig. 2.3. The initial value of the gap in the connection is determined by the design of the connection. The wear curve can be divided into the following sections:

I is the running-in period, characterized by increased wear due to the rapid destruction of microroughnesses;

II - the period of normal wear, characterized by a constant wear rate;

III - the period of emergency wear, characterized by an increase in the wear rate.

The gap δ 2 corresponding to the transition from the period of normal wear to emergency wear is the maximum allowable. The numerical values ​​of δ 2 are given in specifications for car repairs.

It follows from the wear curve that the wear rate (the tangent of the slope of the tangent to the wear curve) decreases during the running-in period, remains constant during normal operation, and increases during emergency wear. In general, the wear equation will have the form

The simplest linear dependence has the form

Where A, B- coefficients.

RELIABILITY AND REPAIRABILITY OF EQUIPMENT

Any device after manufacture or repair must work for a certain time. The need and frequency of repairs are determined by its reliability.

Reliability- the property of the product to perform its functions, maintaining performance within the specified limits for the required period of time.

performance- the state of the object, in which it is able to perform the specified functions, while maintaining the values ​​​​of the specified parameters within the limits established by the regulatory and technical documentation.

Inoperability- the state of the object, in which the value of at least one of the specified parameters does not meet the requirements of regulatory and technical documentation.

Reliability- the property of an object to continuously maintain operability for a certain period of time.

Refusal- an event consisting in a violation of the object's operability.

limit state- this is the state of the object, in which its further operation must be terminated due to an unrecoverable violation of safety requirements.

Operating time- the duration or scope of the object's work.

Technical resource– operating time of an object from the beginning of operation or its resumption after a major overhaul until the limit state occurs.

Durability- the property of the object to remain operational until the limit state occurs with the established system of maintenance and repair.

maintainability- the property of the object, which consists in adaptability to the prevention and detection of the causes of its failures and the elimination of their consequences by carrying out repairs.

Object under repair- this is an object whose serviceability and operability in the event of a failure or damage is subject to restoration.

Non-repairable object- this is an object, the serviceability and operability of which in the event of a failure or damage cannot be restored.

The above definitions show that the reliability of equipment depends on the quality of maintenance and repairs. Reliability issues should be of the greatest importance in the development of new equipment. In the chemical industry big role in improving reliability is assigned to repair services.

The failure of parts most often occurs not due to insufficient strength, but due to wear of the working surfaces.

secondary resource, i.e., the resource acquired after the first overhaul is not always equal to the primary resource of the new machine. In the car, fatigue or aging accumulates, as it were, not eliminated during a major overhaul. However, the main reason for the low secondary resource is the lower quality of repair work compared to the quality of work carried out during the manufacture of the machine at a specialized machine-building plant.

Quantitative indicators reliability are expressed in the form of any absolute or relative values. Reliability cannot be accurately measured or predicted; it can only be estimated approximately by specially organized tests or collection of operational data.

Reliability is also failure rate λ is the number of equipment failures per unit of time, related to the number of equipment of the same type in operation.

In accordance with the physical picture of wear, a component failure rate curve is constructed (Fig. 2.4). Section I characterizes the change in the failure rate during the running-in period, section II - the failure rate during the normal operation period, section III - the change in the failure rate during the period of increased wear.

Rice. 2.4. Part sudden failure rate curve λ

Possible failure modes:

1. Failures in the early period of operation of the machine. Burn-in failures are the result of imperfection in the manufacturing technology of parts or poor-quality assembly and control.

2. Sudden failures - take place with a sudden load concentration that exceeds the calculated one. They occur randomly, and it is impossible to predict their occurrence, but it is possible to determine the probability of random failures.

3. Failures caused by wear parts are the result of machine aging. Timely inspections, lubrication, repair and replacement of worn parts serve as a means of preventing them.

maintainability It is characterized by the adaptability of the machine to the detection of damage, maintainability and maintainability.

Adaptability to determine damage, to diagnose the technical condition without disassembling the machine depends on the design, the presence of safety, signaling, measuring devices and nodes open for viewing.

Maintainability is evaluated by the ease of access to units and individual parts for inspection and repair and depends on the availability of hatches and covers that can be opened.

Maintainability is determined by the ability of the machine to replace parts and the ability of parts to recover.

Quantitatively, maintainability is characterized by the proportion of the time of correct operation of the device:

Where T b – duration of no-failure operation;
T p is the duration of downtime for repairs;
T o is the time spent on maintenance.

The main requirements for the maintainability of equipment can be divided into two groups.

The 1st group includes requirements that ensure the maintainability of equipment during inspection and repair on site:

a) free access to units and parts subject to inspection, adjustment or replacement;

b) quick replacement of wearing parts;

c) adjusting the interaction of units and parts, broken in the process of work;

d) checking the quality of the lubricant, its replacement or replenishment at the place of operation of the equipment;

e) rapid determination of the causes of accidents and equipment failures and their elimination.

The 2nd group includes requirements that ensure maintainability during repairs at the RMC of enterprises:

a) ease of disassembly and assembly of units, as well as complexes;

b) the use of simple means of mechanization in the operations of disassembly and assembly;

c) the maximum possibility of restoring the nominal dimensions of wearing elements;

d) ease of checking the condition of parts and assemblies after bench tests;

e) the possibility of checking the interaction of all parts of the equipment after repair.

During the operation of any production equipment, there are processes associated with a gradual decrease in its performance and a change in the properties of parts and assemblies. Accumulating, they can lead to a complete stop and serious damage. To avoid negative economic consequences, enterprises organize the process of depreciation management and timely renewal of fixed assets.

Definition of wear

Wear or aging is a gradual decrease in the performance of products, assemblies or equipment as a result of a change in their shape, size or physical and chemical properties. These changes occur gradually and accumulate over the course of operation. There are many factors that determine the rate of aging. Negative impact:

• friction;
• static, impulse or periodic mechanical loads;
• temperature regime, especially extreme.

The following factors slow down aging:

• Constructive decisions;
• the use of modern and high-quality lubricants;
• compliance with operating conditions;
• timely maintenance, scheduled preventive maintenance.

Due to the decrease in performance, the consumer cost of products also decreases.

Types of wear

The rate and degree of wear is determined by friction conditions, loads, material properties and design features of products.

Depending on the nature of external influences on the materials of the product, the following main types of wear are distinguished:

• abrasive appearance - damage to the surface by small particles of other materials;
• cavitation, caused by the explosive collapse of gas bubbles in a liquid medium;
• adhesive look;
• oxidative appearance caused by chemical reactions;
• thermal view;
• fatigue appearance caused by changes in the structure of the material.

Some types of aging are divided into subspecies, such as abrasive.

Abrasive

It consists in the destruction of the surface layer of the material during contact with harder particles of other materials. Typical for mechanisms operating in dusty conditions:

• mining equipment;
• transport, road-building mechanisms;
• Agreecultural machines. Agreecultural equipment;
• construction and production of building materials.

It can be counteracted by applying special hardened coatings for rubbing pairs, as well as changing the lubricant in a timely manner.

gas abrasive

This subspecies of abrasive wear differs from it in that solid abrasive particles move in a gas stream. The surface material crumbles, cuts off, deforms. Found in equipment such as:

• pneumatic pipelines;
• blades of fans and pumps for pumping contaminated gases;
• nodes of blast-furnace installations;
• components of solid propellant turbojet engines.

Often, gas-abrasive action is combined with the presence of high temperatures and plasma flows.

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waterjet

The impact is similar to the previous one, but the role of the abrasive carrier is performed not by the gaseous medium, but by the liquid flow.

These are affected by:

• hydrotransport systems;
• HPP turbine units;
• cleaning equipment components;
• mining equipment used for washing ore.

Sometimes hydroabrasive processes are exacerbated by the impact of an aggressive liquid medium.

cavitation

Pressure drops in the liquid flow around the structure lead to the appearance of gas bubbles in the zone of relative rarefaction and their subsequent explosive collapse with the formation of a shock wave. This shock wave is the main active factor in the cavitation destruction of surfaces. Such destruction occurs in propellers large and small vessels, in hydro turbine and process equipment. The situation can be complicated by the impact of an aggressive liquid medium and the presence of an abrasive suspension in it.

adhesive

With prolonged friction, accompanied by plastic deformations of the participants in the rubbing pair, there is a periodic convergence of surface areas at a distance that allows the forces of interatomic interaction to manifest themselves. It begins the interpenetration of the atoms of the substance of one part into the crystal structures of another. The repeated occurrence of adhesive bonds and their interruption lead to the separation of surface zones from the part. Loaded rubbing pairs are subject to adhesive aging: bearings, shafts, axles, sliding liners.

Thermal

The thermal form of aging consists in the destruction of the surface layer of the material or in the change in the properties of its deep layers under the influence of constant or periodic heating of structural elements to the plasticity temperature. Damage is expressed in crushing, melting and changing the shape of the part. Typical for highly loaded units of heavy equipment, rolls of rolling mills, hot stamping machines. It can also occur in other mechanisms if the design conditions for lubrication or cooling are violated.

fatigue

Associated with the phenomenon of metal fatigue under variable or static mechanical loads. Shear-type stresses lead to the development of cracks in the materials of parts, causing a decrease in strength. Cracks in the near-surface layer grow, merge and intersect with each other. This leads to erosion of small scaly fragments. Over time, this wear can lead to the destruction of the part. Found in nodes transport systems, rails, wheel sets, mining machines, building structures, etc.

Fretting

Fretting is a phenomenon of micro-destruction of parts that are in close contact under conditions of low-amplitude vibration - from hundredths of a micron. Such loads are typical for rivets, threaded connections, dowels, slots and pins connecting the parts of mechanisms. As fretting aging increases and metal particles peel off, the latter act as an abrasive, aggravating the process.

There are other less common specific types of aging.

Wear types

The classification of types of wear in terms of the physical phenomena that cause it in the microcosm is supplemented by a systematization of macroscopic consequences for the economy and its subjects.

In accounting and financial analytics, the concept of depreciation, which reflects the physical side of phenomena, is closely related to economic concept equipment depreciation. Depreciation means both reducing the cost of equipment as it ages, and attributing part of this reduction to the cost of manufactured products. This is done in order to accumulate funds on special depreciation accounts for the purchase of new equipment or its partial improvement.

Depending on the causes and consequences, physical, functional and economic are distinguished.

Physical deterioration

This implies the direct loss of design properties and characteristics of a piece of equipment in the course of its use. This loss can be either total or partial. In the event of partial wear and tear, the equipment undergoes a refurbishment that returns the properties and characteristics of the unit to its original (or other, predetermined) level. In case of complete wear and tear, the equipment is subject to write-off and dismantling.

In addition to the degree, physical wear is also divided into types:

• First. Equipment wears out during planned use in compliance with all the rules and regulations established by the manufacturer.
• Second. The change in properties is due to improper operation or force majeure factors.
• Emergency. A hidden property change causes a sudden crash.

The listed varieties are applicable not only to the equipment as a whole, but also to its individual parts and assemblies.

This type is a reflection of the process of obsolescence of fixed assets. This process consists in the appearance on the market of the same type, but more productive, economical and safe equipment. The machine or installation is physically still quite serviceable and can produce products, but the use of new technologies or more advanced models that appear on the market makes the use of obsolete ones economically unprofitable. Functional wear can be:

• Partial. The machine is unprofitable for a complete production cycle, but is quite suitable for performing some limited set of operations.
• Complete. Any use results in damages. Unit to be decommissioned and dismantled

Functional wear is also subdivided according to the factors that caused it:

• Moral. Availability of technologically identical but more advanced models.
• Technological. Development of fundamentally new technologies for the production of the same type of product. Leads to the need to restructure the entire technological chain with a complete or partial renewal of the composition of fixed assets.

In the case of the emergence of a new technology, as a rule, the composition of the equipment is reduced, and the labor intensity decreases.

In addition to physical, temporal and natural factors, the safety of equipment characteristics is indirectly influenced by economic factors:

• Falling demand for manufactured goods.
• inflation processes. Prices for raw materials, components and labor resources grow, at the same time, a proportional increase in prices for the company's products does not occur.
• Competitor price pressure.
• Rising cost of credit services used for operating activities or for the renewal of fixed assets.
• Non-inflationary price fluctuations in the commodity markets.
• Legislative restrictions on the use of equipment that does not meet environmental standards.

Both real estate and production groups of fixed assets are subject to economic aging and loss of consumer qualities. Each enterprise maintains registers of fixed assets, which take into account their depreciation and the course of depreciation accumulations.

The main causes and ways to determine wear

In order to determine the degree and causes of depreciation, a commission on fixed assets is created and operates at each enterprise. Equipment wear is determined by one of the following methods:

• Observation. Includes visual inspection and complexes of measurements and tests.
• According to the service life. It is defined as the ratio of the actual period of use to the normative one. The value of this ratio is taken as the amount of wear in percentage terms.
• an enlarged assessment of the state of the object is made using special metrics and scales.
• Direct measurement in money. The cost of acquiring a new similar unit of fixed assets and the cost of refurbishment is compared.
• return on further use. The decrease in income is estimated, taking into account all the costs of restoring properties, compared with theoretical income.

Which of the methods to apply in each specific case is decided by the fixed assets commission, guided by normative documents and availability of source information.

Accounting methods

Depreciation deductions designed to compensate for the aging processes of equipment can also be determined using several methods:

• linear, or proportional calculation;
• reducing balance method;
• by the total period of production use;
• in accordance with the volume of output.

The choice of methodology is carried out during the creation or deep reorganization of the enterprise and is fixed in its accounting policy.

Operation of equipment in accordance with the rules and regulations, timely and sufficient deductions to depreciation funds allow enterprises to maintain technological and economic efficiency at a competitive level and delight their customers quality goods reasonably priced.