A belt drive for CNC machines is a mechanism that converts the rotational movement of a shaft into movement along a translational axis. The main tool for this transfer is toothed belt. Due to its presence, the processing of the workpiece along a given axis is ensured, in order to obtain a higher indicator of accuracy and productivity. Belt driven transmission is one of the most common, due to its purpose.
purpose
Most simple design transmission of this type represented by pulleys, with a belt stretched over them. It fits only part of the pulley, forming a wrap angle. It depends on its indicator how good the clutch will be. The higher the index, the higher the quality of the clutch.
With the help of a pulley-roller, the wrapping angle can be increased. If it is too small, then the machine will be able to fulfill its purpose only partially.
Thanks to the belt drive, rotational movements can be converted into translational ones. The device is able to perform a similar conversion in reverse. The unit provides transmission by friction. The design of the equipment involves the presence of three links:
- leader;
- slave;
- intermediate.
The last element is represented by a rigid belt, which makes it possible to form a flexible connection. Between the links, a friction force is formed, which forms and transmits power.
The gear for the CNC is responsible for the speed of work and the productivity that the machine will have.
This type of transmission is used on units, the configuration of which requires the location of the shafts at a large distance. To connect them, a toothed belt is used. For good work transmission, it must be well tensioned.
High-quality tension can be obtained in several ways:
- by moving the pulley of the device;
- using tension rollers;
- supplementing the swinging plate with a working motor.
Fixation is carried out using special plates. This type of transmission is used when the movable part does not have a large mass. Tension rollers are responsible for the girth of the pulley.
Kinds
Exists a large number of types of belt drives. They differ in a number of ways. Classification is made according to characteristics. The main features that divide transmission into different types, are:
- external qualities of the cross section of the belt;
- number and types of pulleys;
- the location of the shafts and the belt in relation to each other;
- the presence of additional videos;
- the number of shafts that the belt covers.
The appearance of the cross section can be: flat belt, V-belt, poly-V-belt, round belt, toothed belt. Wedge and poly-wedge type products are the most common. Used with low power drives.
The arrangement of the shafts in relation to each other can be parallel and intersecting. Parallel spans the pulleys either in one direction or in opposite directions. With an intersecting arrangement, the angle is different.
The number and types of pulleys suggest the presence of shafts: single pulley type, double pulley type, stepped pulley type. The number of shafts that the belt covers is two or more. Auxiliary rollers are divided into: tension, guides, or may be absent.
For the manufacture of flat belts, leather, cotton yarn, rubberized fabric are used. The connection is carried out in several ways: by stitching using small straps, with glue or metal clips. If the belt is loosely tensioned, intermittent slippage is possible. The quality of the product is affected not only by the angle of coverage, but also by its dimensions.
For the manufacture of wedge-shaped options, a rubberized fabric is used. The profile of this type of belt has a trapezoid shape. In one row, several products are stretched. When used, the slippage rate is minimal. Their difference is smooth operation. Together with wedge-shaped options, metal-cutting machines equipped with a numerical program management.
An analogue can be a ball screw pair capable of providing a screw transmission.
Advantages and disadvantages
Having provided optimal tension, wrap angle and coefficient of friction, you can create a load sufficient for the CNC machine to work well. The use of a belt drive has both positive sides, as well as negative ones.
Advantages:
- silent and smooth operation;
- no need for high-precision processing;
- resistance to overload and vibration;
- no need for lubrication;
- affordable cost of the mechanism;
- availability of conditions for manual use;
- ease of installation on the machine;
- in the event of a belt break, the drive does not break;
- power is transmitted over a long distance;
- there is the possibility of interaction with a frequency of large rotation;
- the presence of protection systems that reduce the likelihood of breakdowns in the event of a malfunction.
Flaws:
- pulleys are large-sized elements;
- slippage entails a decrease in the transmitted load;
- small power indicator;
- periodic replacement of the belt is necessary;
- risk of malfunction if parts are contaminated or used in an environment with high rate humidity.
The number of advantages outweighs the level of disadvantages. It is possible to reduce the influence of the negative aspects of the equipment by observing the rules for its operation. At periodic maintenance the chance of device failure is reduced.
Usage
CNC units equipped with a flat-belt transmission are used as machine tools, sawmills, generators, fans, as well as in other areas where it is necessary to work devices with increased level flexibility and slippage. If the equipment is used for high speeds using synthetic materials. For more low speeds Cord fabric and rubberized belts are used.
Wedge-type analogs are used in the agricultural industry. Transmission of various sections is able to withstand high loads and great speed. Industrial-grade machines involve the use of CVTs. best performance have toothed belts. They are used in both industrial and domestic areas. Round belt transmission is used for low-power devices.
The main disadvantage of a CNC belt drive is the quality of the belt. Even the highest quality products tend to stretch. Long views stretch the fastest. The tool on stretched belts cannot provide high machining accuracy. The stretching effect can be reduced by attaching two straps on top of each other. Only a certain length is stretched, so this drawback is not so dangerous.
This type of transmission provides soft movements, in the absence of resonance. Dust and chips are not able to adversely affect its operation. It is possible to tighten the belt.
When using a CNC machine, there are several factors to remember:
- toothed belts provide movement of the moving parts of the unit;
- belts are divided into closed and open;
- polyurethane belts are more wear-resistant;
- on CNC machines, the use of reinforced belts is allowed.
This type of transmission on CNC machines at high speeds can reduce power and accuracy levels. This shortcoming is solved by installing special equipment. After installing them, you may need to configure the drivers. This action required in order to smooth the operation of the unit. It is done in the program settings. The value for pulleys that provide correct movement depends on which model of machine or ball screw is selected.
CNC units using a belt drive do not require special software media. The program is compiled and developed depending on the type of work it is needed for. In order for the device to work properly offline, you should periodically check its status. The program cannot solve the problem of faulty hardware.
Automotive mechanics includes a fairly large number of mechanisms that transmit various rotational or translational movements to other devices. One such device is the V-belt drive. In this article we will try to tell you in as much detail as possible what it is, what it is for and how it works?
What is V-belt transmission and how does it work?
Belt transmission is a way of transferring rotating mechanical energy from its source to another mechanism. IN this case, such energy is torque. Any belt drive consists of one belt and at least two pulleys.
The belt, as a rule, is made of rubber that has undergone a special treatment, which allows it to endure not too strong mechanical influences tensile and some thermal deflections. There are many varieties of belt drives, but we will focus on the most common option - V-belt, which has become quite widespread in the automotive industry.
V-belt transmission is made in the form of a wedge-shaped belt and corresponding pulleys. The V-belt pulley is a metal disk with special branches around the circumference designed for the belt itself. The belt, in turn, has two versions: a toothed belt or a smooth one.
Initially, a large number of different car mechanisms were driven by such a belt. The main to this day remain the generator and water pump. On trucks and many others modern cars with the help of such a belt, special and air compressors for amplifiers brake system car.
The main feature of the V-belt pulley should be a special ditch for the belt. Without her, this belt simply jump off the mechanism, as it has a relatively small thickness. This approach allows to reduce the space occupied by the belt drive by reducing its dimensions.
The dimensions of the pulleys depend on the gear ratio. If the gear is downshift, then the drive pulley must be smaller than the driven pulley and vice versa.
The belt must have a certain softness in various weather conditions. Since the vehicle is intended for operation in winter and summer period, which means that the belt should not lose its elastic properties under any circumstances. The use of any other belt in V-belt transmission is unacceptable.
Video - Belt drive device - pulleys and belts
Advantages and disadvantages of belt drive
Like all mechanisms, belt transmission also has its advantages and disadvantages, all of which, unfortunately, cannot be solved, which makes it possible to use this mechanism only in certain activities.
Advantages:
- Increased smoothness of work. Since rubber has sufficient elasticity, this allows it to reduce shock loads and reduce vibrations that occur.
- Possibility of inaccurate installation of pulleys. The elastic belt allows for slight misalignment, which will not affect common work mechanism. That is why this transmission has the ability to change the gear ratio on the go and is so widely used on CVT gearboxes.
- No noise. Always and everywhere belt drive was famous for the lack of noise. This forced the developers of the VAZ 2105 to release it with a timing belt drive.
- Complete absence of overload. The fact is that the belt can slip during its operation, which reduces the load on the mechanism and protects expensive metal parts of the device from wear. For example, if the rotation is too fast crankshaft, does not receive the same torque, but rotates at its initially obtained speed, since by increasing the traction, the belt begins to slip relative to the second pulley. In addition, in walk-behind tractors, a belt drive is used as a clutch drive, as it works much softer and smoother.
- Economic expediency. The fact is that pulleys and belts are quite cheap and do not need to be replaced so often. Perhaps the belt drive is the most economical of all.
- Belt drive does not need to be lubricated. Moreover, lubrication will negatively affect the operation of the belt, as it will begin to slip more often and will not be able to transmit the required torque.
- In case of damage to the belt, it simply flies off the mechanism without consequences, unlike the chain, which breaks everything that it “gets”.
- over a sufficiently large distance. Not only that, some belts have the ability to stretch, which makes them even softer over time.
Flaws:
- Belt drive pulleys are much larger than any other gear pulleys. This makes this design too large, although the load on both types of gears is exactly the same.
- The low strength of the belt and accelerated wear. When tightening, the belt constantly heats up and breaks, which causes the mechanism to stop.
- Violation of the gear ratio due to slippage of the belt relative to other pulleys. This problem almost completely absent in the toothed belt version.
- Need for additional devices: belt tensioning device, devices that dampen vibrations and hold the belt in the grooves.
- Too little bearing capacity.
That's all that is a V-belt transmission. IN modern mechanical engineering she plays an important role, so do not underestimate her.
belt drive is called a kinematic mechanism that transmits energy using a flexible connection using friction between the belt and the pulley.
Components belt drive are the driving and driven pulleys located at some distance from each other, which are wrapped around by a special drive belt.
The level of the transmitted load at belt drive depends on factors such as belt tension, coefficient of friction and sheave angle.
Belt drives
Belt drives there are various types and are classified depending on the shape of the cross section of the belt. According to this criterion, experts distinguish between round-belt, V-belt and flat-belt transmissions. At the same time, wedge-shaped and flat belts are the most common in technology.
The main advantage of flat belts is that their tension at the points of contact with the pulleys is minimal, and wedge-shaped belts are that, due to their profile, they are characterized by increased traction. As for round belts, they can most often be found in machines and mechanisms that have relatively little big sizes, for example, devices, desktop machines, equipment for the food and clothing industry.
Advantages and disadvantages of belt drivesThe main advantages that have belt drives, are the following: simple design and low cost; the possibility of ensuring the transmission of torque over long distances; ease of operation and maintenance; smooth operation and smooth running.
At the same time, belt drives have whole line shortcomings, which should include: relatively large sizes that do not allow their use in a number of cases; fragility when used on high-speed mechanisms; the impossibility of ensuring a constant gear ratio due to belt slippage; heavy loads on supports and shafts.
It should also be emphasized that the reliability belt drives significantly lower than other types of transmissions, since belt breaks and their jumping off the pulleys are not excluded and quite often occur. That is why belt drives require more attention in terms of maintenance, and they need to be monitored constantly.
Types of flat belt drivesDepending on how the axes of the pulleys are located, as well as on their purpose, flat belt drives are divided into the following types: open gears, gears with stepped pulleys, cross gears and gears with tension roller.
Open gears are characterized by parallel axes and the fact that the pulleys rotate in the same direction.
Gears with stepped pulleys provide the ability to change angular velocity rotation of the driven shaft at constant speed drive shaft.
In cross gears, the pulleys rotate in opposite directions, and their axes are parallel.
Gears with a tension roller provide belt tension in automatic mode and increasing the wrap angle of a pulley with a small diameter.
The main materials for the manufacture of flat belts are leather, woolen, rubberized and cotton fabrics, and they can have different widths. Which of them are used in each case depends on the purpose of the belt and the conditions of its operation. In addition, the load that the belt will experience during the operation of the transmission is also of no small importance.
The design of a flat belt transmission is relatively simple, it can be successfully used when high speed characteristics kinematic mechanisms and large distances between the axes of the pulleys.
V-belt transmissionThe main feature of a V-belt transmission is that its drive belt has a trapezoidal section with a profile angle equal to 40°. Compared to a flat type belt, it is capable of transmitting sufficiently large traction forces, however efficiency it is significantly lower.
The main function of any drive belt is transmission tractive effort, and therefore it needs to be strong, wear-resistant, durable, provide good grip with pulleys and at the same time be relatively inexpensive.
Main area of use V-belt drives- machines and mechanisms with small center distances and large gear ratios. In this case, the shaft axes are most often located in a vertical plane.
timing beltsTiming belts are most often made from such a durable and modern synthetic material like polyamide. They quite successfully combine the advantages that gearing and flat belts have.
These belts have small protrusions on their working surfaces, which, during operation, enter into small recesses located on the pulleys. They are well suited for those gears that transmit rotation at high speeds, and the center distance is small.
Belt pulleysFor flat belt drives, the most preferred form working surface, which the pulley has, is a smooth surface that has some bulge. As for the wedge-shaped belts, their workers are side surfaces pulleys. Pulleys are made from materials such as steel, plastics, aluminum alloys and cast iron.
Mechanical transmission of rotational motion using a tensioned drive belt, thrown over pulleys mounted on shafts. There are flat, wedge and round belt drives, as well as gears with a toothed belt ... Big Encyclopedic Dictionary
Belting- drive belt - Topics oil and gas industry Synonyms drive belt EN belt gearbelting ...
Belting- diržinė perdava statusas T sritis automatika atitikmenys: angl. belt transmission; belt drive vok. Riemengetriebe, n; Riementrieb, n rus. belt drive, f pranc. commande par courroife, f ryšiai: sinonimas – diržinė pavara … Automatikos terminų žodynas
One of the most ancient species power transmission, which uses drive belts and pulleys. Her the simplest circuit shown in the figure: two shafts are fixed on the frame; they carry pulleys (in bearings) over which a drive belt is pulled. Belt… … Collier Encyclopedia
Used to transmit rotation. movement with the help of pulleys, fixed. on the shafts, and the drive belt. There are flat, wedge and round belt drives, as well as gears with a toothed belt. R. p. are common in drives with. X. machines, generators... Big encyclopedic polytechnic dictionary
Belting- belt mechanism A mechanism in which the transformation of motion occurs through the contact of a belt with a pulley. Code IFToMM: Section: STRUCTURE OF MECHANISMS ... Theory of mechanisms and machines
synchronous belt drive- Transmission consisting of a synchronous belt and at least two synchronous pulleys; power or rotation is transmitted by meshing the teeth of the belt with the teeth of the pulleys [GOST 28500 90 (ISO 5288 82)] EN synchronous belt drive A system composed of a… … Technical Translator's Handbook
AND; and. 1. to Transfer to transfer. P. order. P. telephone messages. P. knowledge and experience. P. opera on radio, on television. P. baton. P. thoughts at a distance. P. land in the property. Receive the ball from a defender's pass. 2. One or the other ... ... encyclopedic Dictionary
Broadcast- a mechanism for transmitting motion, as a rule, with a speed conversion and a corresponding change in torque. With the help of transmission, the following tasks are solved: lowering (rarely increasing) speed ... ... Encyclopedic Dictionary of Metallurgy
broadcast- And; and. see also transmission, transmission 1) to transmit to transmit. Transfer / cha order. Sending / cha telephone messages ... Dictionary of many expressions
Typically, a V-belt drive is an open drive with one or more belts. The working surfaces of the belt are its sides.
Compared to flat belts, V-belt transmissions have greater traction, have a smaller center distance, allow a smaller angle of wrapping of a small pulley and large gear ratios. (And< 10). Однако стандартные клиновые ремни не допускают скорость более 30 м/с из-за возможности torsional vibrations of the driven system, associated with the inevitable difference in the width of the belt along its length and, as a result, the variability of the gear ratio for one run of the belt. At v-belts big losses on friction and bending stresses, and the design of pulleys is more complicated.
V-belt drives are widely used in individual drives up to 400 kW. V-belt transmission efficiency η = 0.87 ... 0.97.
V-ribbed belt drives do not have most of the disadvantages inherent in V-belt drives, but retain the advantages of the latter. V-ribbed belts have a flexibility comparable to rubber-fabric flat belts, so they run more smoothly, the minimum diameter of the small transmission pulley can be taken smaller, gear ratios can be increased to And< 15, а скорость ремня - до 50 м/с. Передача обладает большой демпфирующей способностью.
V-belts and V-ribbed belts. V-belts are made of endless rubber-fabric construction of trapezoidal section with a wedge angle φ 0 = 40°. Depending on the width ratio b a the greater base of the trapezoid to its height h V-belts come in normal sections ( b 0 /h = 1.6, see); narrow (b 0 /h=1.2); wide (b 0 /h=2.5 and more; used for V-belt variators).
At present, V-belts of normal sections are standardized for machine tool drives, industrial installations and stationary agricultural machines. The main dimensions and methods of control of such belts are regulated by GOST 1284.1-89. Section belts E0 apply only for operating machines and settings. Standard belts are produced in two types: for temperate and tropical climates, operating at air temperatures from minus 30 to plus 60 °C, and for cold and very cold climates, operating at temperatures from minus 60 to plus 40 °C. To increase flexibility, belts of sections A, B and C can be made with teeth (grooves) on the inner surface, obtained by cutting or molding (Fig. 6.9, c).
V-belts (Fig. 6.9, a, 6) consist of a rubber or rubber-fabric stretching layer 1, carrier layer 2 based on chemical fiber materials (cord fabric or cord cord), compression rubber layer 3 and wrapping layer of rubberized fabric 4. Cross section of cord fabric belt (A), cord-cord (b) structures are shown in fig. 6.9. Cord-cord belts used in high-speed gears are more flexible and durable. Permissible speed for normal section belts v< 30 м/с.
Specifications for V-belts of normal sections are regulated by GOST 1284.2-89, and transmitted power - by GOST 1284.3-89.
In addition to the above-mentioned drive V-belts, the following are standardized: fan V-belts (for engines of cars, tractors and combines) and drive V-belts (for agricultural machines).
If it is necessary to operate a belt with a bend in two directions, hex (double V-belts) belts are used.
Very promising are narrow V-belts, which transmit 1.5-2 times high power than belts of normal sections. Narrow belts allow smaller diameters of the small pulley and operate at speeds up to 50 m/s; gears are more compact. Four sections of these belts U0 (SPZ), UA (SPA), UB (SPB), UV (SPC) replace the seven normal sections.
Narrow belts have increased traction due to better load distribution across the width of the carrier layer, which consists of high-strength synthetic cord. The use of narrow belts significantly reduces the material consumption of belt drives. Narrow belts are not yet standardized and are manufactured in accordance with TU 38 605 205-95.
It should be noted that in V-belt transmissions with several belts, due to different lengths and unequal elastic properties, the load between the belts is unevenly distributed. Therefore, it is not recommended to use more than 8 ... 12 belts in the transmission.
V-ribbed belts (see fig. 6.1, G) are endless flat belts with ribs on the underside, running on pulleys with V-grooves. A high-strength synthetic cord is located across the entire width of the belt; the width of such a belt is 1.5-2 times less than the width of a set of belts of normal sections at the same transmission power.
V-ribbed belts are not yet standardized; on the basis of the normal, three sections of corded multi-ribbed belts are made, designated K, L and M, with the number of ribs from 2 to 50, the length of the belt from 400 to 4000 mm and the wedge angle φ 0 = 40 °.
Compared to flat belts V-belt transmissions have a significantly greater traction capacity due to increased adhesion, due to the reduced coefficient of friction f between belt and pulley.
As is known from the considered theoretical mechanics the theory of wedge slider friction,
f"= f sin( a/2),
Where f- coefficient of friction on the plane (for rubberized fabric on cast iron f = 0,3); a- pulley groove profile angle.
Having accepted a= φ 0 = 40°, we get
f" = f sin20°=3 f.
Thus, ceteris paribus, V-belts are capable of transmitting three times more circumferential force than flat belts.
Calculation of transmission with V-belts. The calculation is carried out from the conditions for ensuring the traction capacity and durability of the belts; it is based on the same assumptions as the calculation of flat belt drives.
Belts are calculated using tables containing the rated power transmitted by one belt depending on the belt section, the calculated diameter of the small pulley, its speed and gear ratio (the calculated diameter of the V-belt drive pulley corresponds to the position of the neutral layer of the belt installed in the pulley groove; see Fig. diameter dp in fig. 6.14).
The design calculation of a V-belt transmission begins with the selection of the belt section for a given transmitted power and the speed of a small pulley using graphs (Fig. 6.10). For powers up to 2 kW, section Z is used, and section EO- at capacities over 200 kW.
belt............. Z A B C D E YO UA UB SW
d min , mm......... 63 90 125 200 355 500 63 90 140 224
It should be remembered that the above values of the calculated diameters of the small pulley provide the minimum dimensions of the transmission, but with an increase in this diameter, the traction capacity and transmission efficiency increase, as well as the durability of the belts. In the absence of strict requirements for the dimensions of the transmission, the estimated diameter d1 small pulley should be taken more than the minimum allowable value. Diameter d2 large pulley is determined by the formula
d2=ud1,
Where And- gear ratio transfers; the resulting value is rounded to the nearest standard size.
The calculated diameters of V-belt pulleys are selected from the standard range (mm):
63; 71; 80; 90; 100; 112; 125; 140; 160; 180; 200; 224; 250; 280; 315; 355; 400; 450; 500 etc.
v= πd 1 n 1 / 60 ,
Where d 1, n 1 - the estimated diameter and speed of the small pulley.
In the course of further calculation, all geometric parameters transmission.
center distance A pre-determined by the condition
0,55(d1 + d2) + h
Where h- the height of the section of the belt. It should be remembered that with an increase in the center distance, the durability of the belts increases.
Estimated belt length Lp calculated according to the formula given in § 6.1 and rounded up to the nearest standard length from the series (for section B) (mm): 800; 900; 1000; 1120; 1250; 1400; 1600; 1800; 2000; 2120; 2240, etc. up to 6300. Then, using the formula given in § 6.1, determine the final center distance A depending on the accepted standard estimated belt length.
Wrap angle a, on a small pulley is calculated by the formula,
given in § 6.1.
The power P p transmitted by one belt is calculated from
P p \u003d P o C a C L / C p,
where R o is the rated power transmitted by one belt (for belts of section B it is according to Table 6.2; for other sections - according to GOST tables).
C a - wrap angle coefficient:
a° 1 .............. 180 160 140 120 90
S a................ 1.0 0.95 0.89 0.82 0.68
C L - belt length coefficient, depending on the ratio of the accepted length L of the belt to the original length L P specified in the standard:
L/L p .......... 0.3 0.5 0.8 1.0 1.6 2.4
C L .............. 0.79 0.86 0.95 1.0 1.1 1.2
(a detailed table of C L values is given in the standard); C p - coefficient of dynamism and mode of operation; tentatively taken as for flat belt drives, see § 6.2 (a detailed table of C p values \u200b\u200bis given in the standard).
Further calculation of the V-belt transmission is reduced to determining the number of belts z according to the formula
where P is the transmitted power on the drive shaft; C z - coefficient that takes into account the number of belts in the set, is entered at z > 2:
z...................... 2-3 4-6 >6
Cz ................... 0.95 0.90 0.85
In order to avoid significant uneven load distribution between the belts, it is not recommended to use more than 8 belts of normal section and 12 narrow belts in one gear; the number of belts of small sections should not be taken more than 6.
R = 2F0 z sin( a 1/2), where F o- tension of a branch of one belt; a 1- angle of wrapping of the small pulley.
The value F 0 of the tension of the branch of one belt is calculated by the formula
F 0 \u003d (0.85RS p C z) / zνC a +θν 2
Where v- circumferential speed of the belt; θ- coefficient taking into account the influence centrifugal forces:
Belt section.... Z A B C D E E0
θ, N*s 2 /m 2 0.06 0.1 0.18 0.3 0.6 0.9 1.5
Gears with narrow and V-ribbed belts are calculated using a similar method. Tables of power transmitted by a single narrow belt and a poly-V-belt with 10 ribs are available in course manuals for the design of machine parts.
When calculating poly V-belts, the number of ribs z is determined by the formula
z=10P/P p
Where R- transmitted power on the drive shaft; R p- power transmitted by a belt with 10 ribs.
The calculation of the durability of V-belts of normal sections is established by GOST 1284.2-89. The average resource L h cf belts in operation for an average operating mode is set to 2000 hours. For light, heavy and very heavy operating modes, the calculated resource is calculated by the formula
L hp \u003d L h cf K 1 K 2
Where K 1- operating mode coefficient equal to: for light mode- 2.5; for heavy duty - 0.5; for very heavy duty - 0.25; K 2- coefficient taking into account climatic conditions operation, equal to: for areas with a cold and very cold climate - 0.75; for other regions - 1.0.
The operating mode for specific machines is set according to GOST. So, for example, for machines with a continuous cutting process (turning, drilling, grinding), the operating mode is assumed to be light; for milling, gear-cutting machines, the operating mode is assumed to be medium; planing, slotting, gear shaping and woodworking machines operate in heavy duty; Very heavy duty work is required for lifts, excavators, hammers, crushers, sawmills, etc.
