Cutting tools are used in CNC machines general purpose, i.e., a tool that is usually used on manually operated machines. However, tools intended for use in CNC machines are subject to increased requirements for rigidity, interchangeability, quality of sharpening, wear resistance, etc.

To fasten the tool, tool holders and cutting mandrels are used.

The cutting tool is adjusted by changing its position in the tool holder. If cutting mandrels are fixed in the machine support or turret head, then small-sized cutting inserts adjusted to the size are installed in them (Fig. 124). Rice. 124.

Inserts with pre-set size A

Currently, most modern machines use tool holders (cutting blocks) to secure cutters, since in this case there is no need for a special cutting tool and you can work with ordinary cutters (Fig. 125).

Rice. 125.

Among the most important requirements for cutting blocks, we should note the precise and stable installation of the block in the machine support (the repeatability of the installation should be in the range of 0.001-0.003 mm) and the low weight of the block. The mounting surfaces for cutting blocks are most often prisms and racks.

CNC machines often use cutters with mechanical fastening of multifaceted, non-sharpenable, quick-change inserts made of carbide (Fig. 126). Rice. 126. Prefabricated cutters with mechanical fastening of non-grindable carbide inserts

The peculiarity of non-sharpenable plates is that during operation there is no need to sharpen them. After one cutting edge has become dull, it is necessary to unroll the plate, introducing the other edge into the work. When the blade is rotated, the top of the cutting edge may take a position that differs from the previous one by up to 0.2 mm. To prevent defects when turning the plate, you should enter an adjustment on the machine console starting position calipers Using position correctors, dimensions are obtained within the tolerance range without removing the cutting block from the machine for adjustment in the fixture. You can work with one rod, replacing only carbide plates.

When processing on a CNC machine, the programmed modes may be accompanied by undesirable phenomena, for example, during turning, drain chips are formed, which are difficult to remove from the cutter and can cause breakage of the cutting insert. Using feed correctors, it is necessary to increase its value and achieve chip crushing. If the roughness is below the requirements of the drawing, then the roughness can be reduced by reducing the feed rate. In this case, it is necessary to check the installation of the cutting edge of the cutter relative to the axis of the machine. Cutting is sometimes accompanied by a specific sound (humming or whistling) or pattern on the machined surface, which occurs as a result of vibrations in the cutting zone. Vibrations can be dampened by increasing the feed or changing the cutting speed.

Rice. 127. CNC Tools:

a - drill, b - countersink

For processing holes on CNC machines Drills, countersinks, and reamers are used, both of the usual design and with a cylindrical shank, driver and screw to set their reach (Fig. 127). For finishing of holes with a diameter of over 20 mm, boring bars with micrometric adjustment are used. The cutter 1 is mounted in a sleeve 3, in which it can make translational movement with the help of a dial nut 2 relative to the mandrel 4 (Fig. 128).

Rice. 128.

Tool change in CNC machines with turret heads is carried out automatically.

Tools and accessories fixed in the holes of the turret heads of CNC machines must not have damage (scratches, nicks, marks) on the shanks.

Professionals who frequently use cutters for lathe when performing metal work, as well as those who sell these products or supply machine-building enterprises, are well aware of the types of these tools. For those who rarely encounter turning tools in their practice, it is quite difficult to understand their types presented on modern market in great variety.

Types of turning tools for metal processing

Lathe cutter design

In the design of any cutter used for, two main elements can be distinguished:

1. holder with which the tool is fixed on the machine;
2. a working head through which metal processing is performed.

The working head of the tool is formed by several planes, as well as cutting edges, the sharpening angle of which depends on the characteristics of the workpiece material and the type of processing. The cutter holder can be made in two versions of its cross section: square and rectangle.

According to their design, turning cutters are divided into the following types:

• straight - tools in which the holder together with their working head are located on one axis, or on two, but parallel to each other;
• curved cutters - if you look at such a tool from the side, you can clearly see that its holder is curved;
• bent - the bend of the working head of such tools in relation to the axis of the holder is noticeable if you look at them from above;
• drawn - with such cutters the width of the working head is less than the width of the holder. The axis of the working head of such a cutter can coincide with the axis of the holder or be offset relative to it.

Classification of cutters for turning

The classification of turning tools is regulated by the requirements of the relevant GOST. According to the provisions of this document, incisors are classified into one of the following categories:

• one-piece instrument made entirely of . There are also incisors that are made entirely from, but they are used extremely rarely;
• cutters, onto the working part of which a plate made of hard alloy is soldered. Tools of this type have received greatest distribution;
• cutters with removable carbide plates, which are attached to their working head using special screws or clamps. Cutters of this type are used much less frequently compared to instruments of other categories.

(click to enlarge)

The cutters also differ in the direction in which the feeding movement occurs. Yes, there are:

1. left-hand turning tools - during processing they are fed from left to right. If you put it on top of such a cutter left hand, then its cutting edge will be located on the side of the bent thumb;
2. right incisors - the type of tool that has become most widespread, the feed of which is carried out from right to left. To identify such a cutter, it is necessary to place right hand- its cutting edge will be located, respectively, on the side of the bent thumb.

Depending on what work is performed on turning equipment, cutters are divided into the following types:

• for finishing metal work;
• for rough work, which is also called roughing;
• for semi-finishing work;
• for performing delicate technological operations.

In the article we will look at the entire range and determine the purpose and features of each of them. An important clarification: no matter what type the cutters are, certain grades of hard alloys are used as the material for their cutting inserts: VK8, T5K10, T15K6, much less often T30K4, etc.

A tool with a straight working part is used to solve the same problems as bent-type cutters, but it is less convenient for chamfering. Basically, such a tool (by the way, not widely used) is used to process the outer surfaces of cylindrical workpieces.

The holders of such cutters for a lathe are made in two main sizes:

• rectangular shape – 25x16 mm;
• square shape– 25x25 mm (products with such holders are used to perform special work).

These types of cutters, the working part of which can be bent to the right or left side, used for processing the end part of the workpiece on a lathe. They are also used to remove chamfers.

Tool holders of this type can be made in various sizes (in mm):

• 16x10 (for training machines);
• 20x12 (this size is considered non-standard);
• 25x16 (the most common size);
• 32x20;
• 40x25 (products with a holder of this size are made mainly to order; they are almost impossible to find on the open market).

All requirements for metal cutters for this purpose are specified in GOST 18877-73.

Such tools for a metal lathe can be made with a straight or bent working part, but they do not focus on this design feature, but simply call them through-thrust tools.

A continuous thrust cutter, which is used to process the surface of cylindrical metal workpieces on a lathe, is the most popular type of cutting tool. The design features of such a cutter, which processes the workpiece along the axis of its rotation, make it possible to remove from its surface even in one pass significant amount excess metal.

Holders for products of this type can also be made in various sizes (in mm):

• 16x10;
• 20x12;
• 25x16;
• 32x20;
• 40x25.

This tool for a metal lathe can also be made with a right or left bend of the working part.

Outwardly, such a scoring cutter is very similar to a pass-through cutter, but it has a different cutting plate shape - triangular. With the help of such tools, workpieces are processed in a direction perpendicular to their axis of rotation. In addition to bent ones, there are also persistent types of such turning cutters, but their scope of application is very limited.

Cutters of this type can be manufactured with the following holder sizes (in mm):

• 16x10;
• 25x16;
• 32x20.

The parting cutter is considered the most common type of metal lathe tool. In full accordance with its name, such a cutter is used for cutting workpieces at right angles. It is also used to cut grooves of varying depths on the surface of a metal part. Determining that what you have in front of you is a cutting tool for a lathe is quite simple. His characteristic feature is a thin leg onto which a hard alloy plate is soldered.

Depending on the design, there are right- and left-handed types of cutting tools for metal lathes. It is very easy to distinguish them from each other. To do this, you need to turn the cutter over with the cutting plate down and see which side its leg is located on. If it is on the right, then it is right-handed, and if it is on the left, then, accordingly, it is left-handed.

Such tools for a metal lathe also differ in the size of the holder (in mm):

• 16x10 (for small training machines);
• 20x12;
• 20x16 (the most common size);
• 40x25 (such massive turning cutters are difficult to find on the open market; they are mainly made to order).

Threading cutters for external threads

The purpose of such cutters for a metal lathe is to cut threads on the outer surface of the workpiece. These serial tools cut metric threads, but you can change their sharpening and use them to cut threads of other types.

The cutting plate mounted on such turning tools has a spear-shaped shape and is made from the alloys mentioned above.

Such cutters are made in the following sizes (in mm):

• 16x10;
• 25x16;
• 32x20 (used very rarely).

Such cutters for a lathe can cut threads only in large diameter holes, which is explained by their design features. Outwardly, they resemble boring cutters for processing blind holes, but they should not be confused, as they are fundamentally different from each other.

Such metal cutters are produced in the following standard sizes (in mm):

• 16x16x150;
• 20x20x200;
• 25x25x300.

The holder of these tools for a metal lathe has a square cross-section, the dimensions of the sides of which can be determined by the first two digits in the designation. The third number is the length of the holder. This parameter determines the depth to which a thread can be cut in the internal hole of a metal workpiece.

Such cutters can only be used on those lathes that are equipped with a device called a guitar.

Boring cutters for machining blind holes

Boring cutters, the cutting plate of which has triangular shape(as with scoring ones), they process blind holes. The working part of tools of this type is made with a bend.

The holders of such cutters can have the following dimensions (in mm):

• 16x16x170;
• 20x20x200;
• 25x25x300.

The maximum diameter of the hole that can be machined using this turning cutter, depends on the size of its holder.

Boring cutters for machining through holes

Such cutters, the working part of which is made with a bend, process through holes, previously obtained by drilling. The depth of the hole that can be machined using a tool of this type depends on the length of its holder. The layer of metal that is removed is approximately equal to the bend of its working part.

The following standard sizes are available on the modern market, the requirements for which are specified in GOST 18882-73 (in mm):

• 16x16x170;
• 20x20x200;
• 25x25x300.

Prefabricated cutters for lathes

Considering the main types of turning tools, one cannot fail to mention tools with a prefabricated structure, which are universal, as they can be equipped with cutting inserts for various purposes. For example, fixing cutting inserts on one holder various types, you can get cutters for different angles.

To begin with, let's take into account that work on CNC machines is performed with general-purpose cutting tools (i.e., such a tool is used on machines that have manual control). But it’s not so simple, because if the tool is used on CNC machines, it must meet the following requirements: have high quality sharpening, be interchangeable, must meet increased requirements for rigidity and wear resistance.

One type of cutting tool is a cutter. Thus, a turning cutter can perform many operations, including on CNC machines. And, of course, turning tools differ in purpose.

Therefore, the following subsystems were identified:

Turning cutters performing operations such as turning, threading, boring, grooving, cutting on medium and light series machines;

Turning cutters performing special work (for example, a shaped cutter or a cutter for plasma-mechanical processing);

Lathe cutters, which are installed on heavy, rotary and large machines;

Lathe cutters mounted on TBMs and multi-tasking machines.

Cutter subsystem for CNC machines.

Let's take a closer look at the cutter subsystem for CNC machines. For example, a cutter with a modernized wedge fastening SMP - a wedge-clamp - is used to carry out preliminary and final operations on universal machines. The essence is to press the SMP with a wedge to the pin and to the support plate. Having such a fastening, we can observe an open auxiliary cutting edge.

Now, let's look at the subsystems of cutters that make up groove cutters and turning cutting cutters.

So, based on the structural features, the cutter can be:

1. Cut-off holder, in which replaceable non-sharpening carbide cutting inserts are mechanically fastened.

This cutter has in its structure: a spring-loaded clamp, a non-sharpening single-edge cutting plate, and a holder.

In order to install the cutting plate in the V-shaped groove of the holder socket, a V-shaped protrusion is required directly on the supporting surface of this very plate.

I would also like to note that if the cutting inserts are made of hard alloys with a wear-resistant coating, then the durability increases by 2-3 times.

2. Cutting, having soldered carbide plates.

Here they are already using new (including three-layer) brands of solders for manufacturing. And the holder can be made from steel 35KhGSA or 30KhGSA, which significantly reduces, or rather, practically eliminates cracking during soldering. Thus, the consumption of cutters is reduced by 3-4 times.

Very good quality and sharpening accuracy leads to a reduction in the cost of primary sharpening (by approximately 0.3 - 0.4 rubles).

3. Groove holder, in which replaceable regrindable carbide cutting inserts are mechanically fastened.

From the name it is clear that such a cutter must be used to cut a groove (with exact dimensions). The cutting element is nothing more than a carbide plate made in accordance with GOST 2209-83. The structure of this cutter includes: a holder, a cutting plate (the shape of which is prismatic), a thrust element (which looks like a cracker), an adjusting screw and a clamp.

To prevent transverse displacements of the supporting surface of the cutting plate, it (the plate) is made at an angle to the side, and it is fixed with a clamp. The adjusting screw ensures that the cutting plate extends after regrinding, and subsequently fixes this same plate, thereby preventing longitudinal displacement.

The basis of this design served as the release of groove cutters, which allow the processing of internal threaded, angular, straight grooves and external angular and straight grooves.

Well, it’s worth noting that rational operation involves at least 20 resharpenings.

4. Cutting plate, having replaceable carbide cutting plates.

(But, such a cutter is primarily applicable for universal manually operated machines)

Such a cutter has in its structure: a block (which is fixed in the tool holder), a non-sharpening double-edge cutting plate, which is secured by an elastic blade of the holder, and a plate holder.

The cutter becomes more versatile because the plate holder allows you to adjust the indicators of its departure from the block to a given size.

5. Groove, in which replaceable non-regrindable carbide cutting inserts are mechanically fastened.

This type of cutter has in its structure: a holder, a clamping screw with a washer, and a double-edged cutting plate. The cutting plate is secured with a screw. As for the presence of two cutting edges, this allows you to save carbide.

Further, it is worth noting the subsystem of multi-purpose cutters, consisting of prefabricated cutters that allow roughing, semi-finishing and finishing turning of workpieces made of cast iron and steel.

Thus, workpieces can be turned, trimmed, processed, slotted, and bored.

The subsystem includes a small number of groups:

TTO

The cutter of this group is installed on heavy lathes (workpiece diameter 1250 - 4000 mm) and on rotary machines (workpiece diameter 3200 - 12000 mm), which have conventional tool holders.

Chamber of Commerce and Industry

The cutter of this group is installed on heavy lathes that have plate tool holders of CNC machines.

WHO

The cutter of this group is installed on large lathes (workpiece diameter 800 - 1000 mm), which have standard tool holders, and rotary machines (workpiece diameter 1600 - 2800 mm).

It is necessary to improve the quality of cutting tools by everyone possible ways, including, using the experience of inventors, to develop new methods of fastening and changing plates, and to use advanced technologies to increase labor productivity.

TURNING CUTS FOR CNC MACHINES

Requirements for cutters for CNC machines.

Maximum use of MNPs with mechanical fastening on cutter bodies and holders. This will ensure the constancy of the design and geometric parameters of the cutters during operation.

Use of rational plate shapes. This gives versatility to the instrument, i.e. makes it possible to process the maximum number of surfaces of a part with one cutter.

Unification of the main and connecting dimensions of the tool.

Cutters with different plan angles must have the same basic coordinates.

This creates convenience for programming technological operations.

Possibility of working cutters in straight and inverted position. Possibility of using left-handed cutters. Increased tool accuracy, especially of cutting inserts. This is necessary to improve accuracy

Satisfactory chip formation. Provided by grooves obtained during the manufacture of carbide or grooves sharpened with a diamond wheel on the front surfaces of the inserts.

Nomenclature of turning tools. To perform various operations on CNC lathes, standard designs of prefabricated cutters equipped with multifaceted plates made of hard alloy, cutting ceramics and superhard materials have been developed.

Depending on the model of lathes, it is possible to use cutters with a cross-section from 16x16 to 40x40 mm. The range of cutters should ensure processing of typical surfaces of parts and includes the following varieties:

bent through cutters with an angle φ = 45° for external turning, end processing, chamfering, recess processing (GOST 21151-75, type 1);

contour cutters with parallelogram plates and angle φ = 95° for turning parts along a cylinder, end, reverse cone with a slope angle of up to 30°, machining radius surfaces and grooves (GOST 20872-80, type 1);

copying cutters with parallelogram plates and φ = 63° for processing hemispherical surfaces and cones with a slope angle of up to 57° (GOST 20872-80, type 2);

thread cutters with rhombic plates and fastening with clamps for cutting external threads with a pitch of 2...6 mm (design of the All-Russian Scientific Research Institute of Tools);

cutters for cutting internal threads with a pitch of up to 2 mm and a minimum processing diameter of 35 mm (GOST 22207-76, type 2);

cutters with a rhombic plate and φ = 95° for boring through holes and turning recesses (GOST 26612-85, type 6);

boring cutters with φ = 92° and a minimum processing diameter of 22 mm (GOST 20874-75, type 3);

cutters with φ = 45° with square plates, left, for external turning, end processing, chamfering, recess processing (GOST 21151-75, type 1);

cutters for cutting external straight grooves with a width of 1...6 mm and a depth equal to the width (design of VNIIinstrument);

contour cutters with a triangular plate and φ = 63° (GOST 20872-80, type 4);

contour incisors with a triangular plate correct form and φ = 93° (GOST 20872-80, type 3);

thread cutters for cutting external threads with pitches up to 2 mm (GOST 22207-76, type 1);

pass-through persistent cutters with triangular plate irregular shape and φ = 93° for processing stepped surfaces, chamfers, ends (GOST 21151-75, type 4).

Cutters are used in three designs:

Full size. They are used on machines with removable blocks, which, when assembled with cutters, are adjusted to size outside the machine.

Shortened with adjustable elements.

Insert cutters.

Short cutters and insert cutters are adjusted to size using set screws outside the machine in a special fixture and then installed in the slots of the tool heads and tool holders. Produced according to OST-23.5.551-82, GOST 23.5.552-82 and OST 21110-1-83.

Cutters for turning on CNC machines. 1

Differences between turning tools by purpose. 1

Basic cutter patterns. 4

Cutter subsystem for CNC machines. 7

Tool materials. 15

Sharpening cutters. 23

Bibliography. 28

Cutters for turning on CNC machines.

Turning cutters are designed to perform a wide variety of different operations on CNC machines, on GPM and GPS, as well as on manually controlled turning machines.

Differences between turning tools by purpose.

According to their purpose, the turning tool system is divided into the following subsystems:

· for external turning, boring, threading, cutting grooves on light and medium series machines;

· for work on heavy, large lathes and rotary machines;

· for work on GPM, multi-purpose machines with built-in robotic systems automatic change tool;

· for special work (cutters for plasma-mechanical processing, shaped).

Each of the subsystems has its own specific features, determined by many factors, primarily the design of the equipment, its technological purpose, etc. The cutter system is based on general methodological principles and provides for:

· development (selection) and unification of reliable methods for fastening replaceable plates in the holder (including solid and composite cutters, with soldered plates, prefabricated ones);

· ensuring satisfactory crushing and removal of chips from the cutting zone;

· sufficiently high positioning accuracy of the vertices of the replaceable plates (due to the creation of precise bases of the socket);

· quick change and ease of removal and replacement of replaceable plates, cutting element or cassette (block);

· unification and maximum permissible reduction (reduction to the optimal value of technical and economic indicators industrial production and application) number of methods for securing plates in the holder;

· the ability to use the entire range and sizes of replacement plates of domestic and foreign production;

· compliance of the precision parameters of the cutters with international standards;

· mandatory use of special fasteners (screws, pins, etc.) of increased accuracy and reliability; development of new shapes and sizes of cutting inserts, shapes of their front surfaces, ensuring satisfactory crushing and removal of chips;

· using the experience of innovators and inventors;

· application of progressive resource-saving technologies for the manufacture of fasteners and keys; manufacturability and cost-effectiveness of manufacturing (saving materials and labor resources);

· the possibility of using composite (found, solid, glued and other similar connections) carbide inserts with tool blocks (holders) in cases of their undoubted technical and economic efficiency or the impossibility of designing a cutter in a prefabricated version (primarily for small sections of holders, some boring and cutting operations, etc.).

The cutter design subsystems are created on the basis of a generally accepted world practice system of toolholder shapes and plan angles to ensure all turning operations. For example, for the subsystem of external turning and boring of the shape of holders, which ensures the implementation of the entire variety of turning transitions, international (ISO 5910, 5909, etc.) and domestic standards are provided.

Basic cutter patterns.

Currently, despite the huge variety of designs and patterns of fastening units for replaceable polyhedral plates in holders, leading foreign manufacturers of cutters use a very limited number of fastening methods in mass production. Their number is also limited in domestic cutter subsystems. For example, in subsystems for external turning and boring on machines of light and medium series, four basic design schemes for SMP fastening units are adopted (designation of fastenings according to GOST 26476-85):

· without hole – with clamp (type C);

· with a cylindrical hole – lever mechanism (type P);

· pin and clamp (type M);

· with a toroidal hole – screw mechanism (type S).

Plates without holes are fixed using method C. The design is based on a design widely used in automobile factories. With this method of fastening, the cutting inserts are based in a closed holder socket along two base surfaces and pressed from above to the supporting surface with a clamp. Quick plate removal is ensured by a differential screw. The carbide support plate is secured with a screw to the cutter holder or a split spring bushing.

Cutters with SMP fastening according to method C have different designs: for cutting inserts with a clearance angle and without a clearance angle; with support plates; without support plates.

It should be noted that the relief angle SMPs have 2 times more cutting edges than the clearance angle SMPs. On the front surface of the SMP with a rear angle there are chip-breaking grooves for crushing and removing drain chips. When using SMP without a clearance angle, overhead chipbreakers are used.

Cutters with a base plate are widely used for turning and boring; cutters without a support plate - when boring small holes and turning on light series machines (section h [ b cutter holder 12 x 12...16 x 16 mm). The operation of the cutters has shown that cutters with carbide chipbreakers have proven themselves well when working on universal and special machines in large-scale and mass production.

In such cutters, you can use SMP made of hard alloy, ceramics, etc.

Cutters with SMP with positive angles provide a reduction in cutting forces, so they are recommended for use when processing non-rigid parts. These cutters can also be used with overhead chipbreakers.

For external turning and boring in cutters with clamping according to method C, square, triangular, rhombic SMPs are used, as well as parallelogram plates of the KNUX type with fastening with a special shaped clamp. SMP with a central cylindrical hole is secured with a lever mechanism using the P method and a modernized wedge fastening (wedge-interception) using the M method. Fastening with a lever mechanism is the most rational for cutters with a holder section from 20 x 20 to 40 x 40 mm. This design is effectively used on CNC machines. A domestic original design of the lever mechanism has been developed, which corresponds to the best world standards, and in terms of purpose is completely unified with the designs of cutters produced at some large machine-building plants of the domestic industry, and with tools produced abroad.

The SMP is based in a closed socket of the holder, and a lever driven by a screw pulls it to the two side walls of the socket and presses it securely against the support. The support plate is secured with a split sleeve. The design of the fastening unit provides the ability to quickly and accurately rotate or change the SMP and securely fasten it. It allows the whole range of new progressive domestic and foreign plates, as well as SMP with complex shape rake surface, providing good chip crushing in a wide range of feeds and cutting depths.

For contour processing on machines with CNC, GPM and GPS, which allows turning several surfaces of a part in one working stroke, cutters with rhombic SMP (e = 80° and 55°) are used. Industrial batches of cutters with an L-shaped lever for external turning and boring are widely used in mass production by tool factories of the Ministry of Machine Tools and Industry; they are produced in accordance with TU2-035-892 and GOST 26613-85.

Cutter subsystem for CNC machines.

To perform preliminary and final operations with one cutter, primarily on universal manually controlled machines, a range of cutters with a modernized wedge fastening with an SMP wedge-clamp (method M) has been developed. The wedge presses the SMP not only to the pin on which it is installed with the central hole, but also to the support plate. With this fastening of the SMP, the auxiliary cutting edge remains open.

A subsystem of turning cutting and grooving cutters for CNC and GPM machines has also been developed, which includes the following cutters.

1. Cut-off cutters increased reliability with brazed carbide plates. They are distinguished from cutting tools produced in accordance with GOST 18884-73 by:

· increased accuracy manufacturing and relative position of holder surfaces, which ensures their use on CNC machines;

· the use of new, including three-layer, grades of solders and the replacement of the holder material with steel 35KhGSA or 30KhGSA virtually eliminates cracking during soldering, which will reduce the consumption of cutters by approximately 3-4 times;

· increased quality and the accuracy of sharpening the cutter reduce the consumer's costs for primary sharpening by 0.3-0.4 rubles;

· improved appearance.

The main dimensional parameters of the cutters fully comply with the ISO243-1975 (E) standard.

2. Holder cutting cutters with mechanical fastening of replaceable non-sharpening carbide cutting inserts.

The cutter consists of a holder, a non-sharpening single-edge cutting plate, and a spring-loaded clamp. There is a V-shaped protrusion on the supporting surface of the cutting insert, with which it is installed in the V-shaped groove of the holder seat. When fastening, the cutting plate is pressed against the side of the socket's thrust surface. The geometric parameters of the cutting part ensure good removal of chips from the cutting zone, which is especially important when processing workpieces made of viscous materials.

The use of cutting inserts made of hard alloys with a wear-resistant coating ensures an increase in durability by 2-4 times.

3. Cutting-off plate cutters with mechanical fastening of replaceable non-resharpening carbide cutting inserts are designed to perform cutting operations primarily on manually operated universal machines. The cutter consists of a block fixed in the tool holder of the machine, a plate holder and a non-sharpening double-edged cutting plate, which is secured by an elastic blade of the holder. The supporting surfaces of the cutting insert are made in the form V-grooves, with which it interacts with the V-shaped protrusions of the socket and the elastic petal of the holder.