Metal cutters for a lathe: tool characteristics

Metal cutters for a lathe: detailed characteristics of the tool

Specialists who have repeatedly used metal cutters for a lathe in their practice to perform certain works clearly understand what types of tools these tools are. For beginners who are faced with these elements for the first time, it is difficult to figure out what is the distinctive feature of each particular model and how to choose the right tool to perform certain tasks. This article will help to understand an important issue.

Turning tools are the main working tool of metalworking machines, by means of which the desired shape and dimensions are given to the workpieces to be processed

Design features of the metal turning tool

The design of the element consists of a cutter holder, thanks to which the tool is fixed on the machine, and a working head that directly processes the surface of the workpiece. The holder can have a square or rectangular cross-section. The working part of the tool is formed from several adjacent planes and cutting edges. Their sharpening angle depends on the characteristics of the material being processed and the type of processing.

To achieve the specified parameters of the part, the movement of the cutter and workpiece fixed in the machine relative to each other occurs

The working head can be solid or with welded or soldered plates. A novelty is metal cutters for a lathe with replaceable plates. The first option is represented by a solid element with a holder. Such a tool can be made of special high-carbon tool steel or high-speed steel. But such incisors are rarely used.

Mainly for metalworking on a lathe, cutters with welded or soldered plates are used. The tool is made of high-speed steel or a hard alloy, which contains metals: titanium, tungsten and tantalum. It is characterized by high durability and pricing policy. This turning tool can be used for processing products made of non-ferrous metals, cast iron, any steel and non-metallic materials.

Important! When working with hard alloy plates, safety rules should be followed, since the products are very fragile.

Very often, turning cutters with replaceable plates are used when processing the material. Unlike the previous version, the plate is attached to the head mechanically using special clamps or screws. The tool is convenient for further operation if the plate is made of mineral ceramics, which significantly increases the cost of a cutter with replaceable plates.

A variety of metal turning cutters with replaceable plates

The working part for the lathe cutter can be made of a hard alloy (tantalum-tungsten-titanium, titanium-tungsten, tungsten), high-speed steel (increased or normal efficiency), high-quality carbon steel. The cutters can be used for such types of lathes as planing, turning, slotting, automatic revolver and special.

Classification of turning tools

According to GOST , there are three types of metal turning cutters:

• turning and planing machines, in which the cutting part is made of high-speed steel;
• planing and turning carbide soldered;
•  lathes with mechanical fastening of plates made of ceramics, hard alloys and other superhard materials.

Manufacturers produce these types of cutters:

• walk – throughs;
• cut – off;

Types of turning cutters: o — straight through and b — bent through, c — thrust through, d, d — undercut, e — boring through, w — boring thrust, a — cut-off, I —shaped, k —threaded

• threaded;
• undercut;
• boring;
• universal.

Depending on the direction in which the feeding movements are performed, it is possible to distinguish such types of cutters for a lathe:

• left – hand type;
• right-hand type.

To identify the tool, you need to put your hand on the cutter. The location of the edge relative to the thumb of the right or left hand will indicate the type of tool.

Depending on the nature of the work, there is the following classification of incisors:

• to perform rough work, which is also called stripping;
• for semi-frantic work;
• for finishing works;

The working element of the undercut cutter is a sharp edge (wedge) that cuts into the material layer and deforms it

• for the implementation of fine technological operations.

The cutting plate of all cutters, regardless of the type of tool, is made of a certain grade of hard alloys: TK5K10, VK8, T15K6 and T30K4. The most popular are incisors VK8.

Depending on the installation principle , the following types of metal cutters for a lathe are distinguished:

• radial;
• tangential.

In the first variant, the turning tool relative to the axis of the workpiece that is being processed is located at an angle of 90 degrees. This type of products has become widespread in industrial enterprises, due to the fact that the cutter is quite easily and quickly installed in the machine. In addition, there is a large selection of geometric parameters of the cutting edge.

Radial devices are mounted at an angle that is 90 ° to the planes of the machined parts

The tangential turning tool is positioned at any angle other than 90 degrees. relative to the workpiece axis. Fixing this tool to a lathe turns out to be more time-consuming than in the previous version. However, tangential cutters provide better processing of the metal workpiece. They can be used for automatic and semi-automatic lathes.

Depending on the location of the main cutting edge relative to the rod , there are such types of turning cutters:

• straight – all projections of the part have a straight line;
• bent – the upper projection has a curved line, the lower one is straight;
• curved – the upper projection is displayed as a straight line, and the side projection is curved;
• retracted – the head of the cutter, which can be on the axis or shifted to the left or right, has a smaller width than the rod.

The tangential cutter has more resistance compared to the radial one and removes larger chips under equal conditions

Turning through cutters can be:

• straight;
• bent;
• resistant bent.

Straight-through cutters are used to process the outer surface of a cylindrical workpiece. You can buy a straight through cutter GOST 18877-73 for 280 rubles. Holders for such a tool can be made in two standard sizes:

• traditional rectangular shape – 25×16 mm;
• square shape, which is used for the production of special works – 25×25 mm.

In pass-through bent incisors, the working part can be bent to the left or right side, which makes it possible to bend the workpiece from different sides during the work. In addition to processing the end part of the workpiece on a lathe, the tool is used for chamfering. According to GOST 18877-73 , holders for this type of tool can have the following dimensions:

• 16×10 mm – for training machines;

The through-thrust cutter refers to cutting turning tools that are used for processing cylindrical parts

• 20×12 mm – non-standard product;
• 25×16 mm – universal standard size;
• 32×20 mm;
• 40×25 mm – made to order for use on a dimensional machine.

The most popular is a thrust bent cutting tool for a lathe. It is used for processing cylindrical workpieces. The special bending of the element allows you to remove excess metal from the round part in one pass. When processing the workpiece, the cutter moves along the rotation of the part. Bent through incisors can be left-sided and right-sided. The latter option is used much more often in practice. You can buy a pass-through cutter for 320 rubles. bent

Cutting and undercutting metal cutters

The most common is a cutting cutter. It is designed to cut off a billet of the required size from a metal pipe, a blank, a rod that has a length exceeding the required value. This type of incisors is difficult to confuse with another tool. The design of the product consists of a thin leg with a solid alloy plate soldered at the end. The narrower the leg, the smaller the cut, which accordingly helps to reduce the amount of waste. The workpiece is cut off from the general metal body at a right angle.

The cutting cutter refers to those products that are made of high-speed steel, therefore it cannot be used to work with hot metals and rigid materials

Useful advice! With a cutting tool, thin grooves of different depths can be cut in a metal product.

Depending on the design of the execution, there are left-hand and right-hand cutting cutters. To determine this, you should turn the product with the cutting side down and see which side the tool leg will be located on. You can buy a cutting lathe for 190 rubles.

Manufacturers produce cutting tools with the following holder sizes:

• 16×10 mm – for training machines;
• 20×12 mm;
• 20×16;
• 40×25 – made to order for large-sized machines.

The undercut bent cutter looks very similar to a thrust passing tool. The working part is also represented by a plate made of hard alloys, but has a triangular shape with one rounded side. With this type of cutting tool, it is possible to process the workpiece across the axis of its rotation, exposing the cutter perpendicular.

Undercut Bent Metal Cutter for lathes in operation

Manufacturers also produce undercut thrust cutters, which have significantly less demand in the construction market, which is due to the limited scope of use of the tool.

Holders for the cutting cutter GOST 18877-73 come in the following sizes: 16×10 mm, 25×16 mm, 32×20 mm. The cost of a bent incisor will average 250 rubles.

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Threaded cutters

The tool kit for the lathe machine must include threaded cutters for the lathe. The cutting plate of the products is made of hard-melting metals. There are two versions of the tool: for cutting external and internal threads. The first type is used for bolts, studs and other metal parts that need to be threaded. The incisor plate resembles the tip of a spear in shape. With the help of the tool, you can get a metric or inch thread, which depends on the design of the cutter. The cutters are presented in the following sizes: 16×10, 25×16, 32×20 mm. The price of the product is 120 rubles.

The internal threaded cutter is designed for threading in metal products on universal lathes and CNC machines

For threading with a cutter on a lathe in the cavity of the workpiece, the second version of the threaded tool is used. Despite the fact that the shape of the cutting plate cutter is similar to the previous version, it has a completely different look. Due to the design features of the tool, it can be used for large diameter holes. Manufacturers produce products of the following sizes: 16x16x150 mm, 20x20x200 mm, 25x25x300 mm.

The cutter holder has a square shape, the values of which are determined by the first digits of the designations. The third digit indicates the length of the holder. It is this value that determines the depth to which threads can be cut in the inner cavity of the workpiece. You can buy the tool for 270 rubles.

Important! This type of cutters can be used on lathes equipped with a special device called a guitar.

Boring cutters

There are two types of boring cutters: for boring blind or through holes. If there is no hole in the metal workpiece, it is necessary to use the first version of the tool. The plate of the boring cutter has a triangular shape, like that of the undercut, but its cutting part has a bend. This design allows you to bring the cutter from the end of the workpiece. In this case, the boring of the part will occur from the center, going deeper into the body of the workpiece and making a hole of the required diameter.

Schematic representation of a turning boring cutter for processing blind holes

For such cutters, the holders can have the following dimensions: 16x16x170 mm, 20x20x200 mm, 25x25x300 mm. The maximum diameter of the hole in the metal workpiece will depend on the size of this cutter element. You can buy metal cutters for a lathe for 200 rubles.

Important! You can drill holes of any diameter, the main thing is to choose the right size of the cutter.

To create through holes in the body of the workpiece, the second version of the boring tool is used. Previously, it is necessary to drill a large diameter hole in the metal part. Only then can you start boring it to the desired size. The design of the tool is characterized by a straight plate that has no protrusions, which allows the cutter to easily penetrate into the pre-drilled tube in the body of the workpiece, and, passing through, boring it.

During the processing of the through hole, a layer of metal equal to the bending value of the working part of the cutter will be removed. The cost of the tool is on average 190 rubles. Boring cutters for through holes have the same standard sizes as in the previous version, which corresponds to GOST 18882-73.

Cutting turning tool with replaceable carbide plates for external turning

Universal cutters for lathes

A universal tool can also be called a prefabricated one. This is due to the ability to attach different plates to one holder in a certain way, which makes it possible to process a metal billet of various shapes at any angle. Holders of universal cutters can be different. This type of cutter is used extremely rarely, so it is available in limited quantities. You can meet it in the store at a fairly high price, unlike other versions of the tool.

This type of tool can be used for CNC machines or special machines. The universal cutter is used for boring blind and through holes, contour turning and other specialized work. You can buy cutters for a lathe at a price of 350 rubles.

Rules for sharpening metal cutters for a lathe

In order to ensure efficient, high-quality and accurate machining of the workpiece on a lathe, it is necessary to regularly sharpen the cutters. This helps to give the working part the necessary shape and obtain an angle with the required value.

Machine for sharpening metal turning tools

Important! Only a tool made in the form of a disposable carbide plate does not need sharpening.

At industrial enterprises, the sharpening of cutters is carried out on a machine with special devices, which corresponds to the classification of a lathe. To perform the procedure at home, you can use one of the techniques. Sharpening of the tool can be carried out with the help of chemical reagents, using grinding wheels.

Useful advice! With the help of an abrasive wheel, which can be installed on a lathe, it is possible to perform high-quality and effective sharpening of the cutters, giving the tool certain geometric parameters.

When choosing a grinding wheel, pay attention to the material of manufacture of the working part of the element. If a carbide cutter is to be sharpened, it is necessary to choose a circle of characteristic green color from carborundum. For products made of high-speed or carbon steel, it is better to use a circle of corundum.

Sharpening of the cutter surfaces: a) the front surface; b) the main back surface; c) the auxiliary back surface; d) the radius of the rounded top

Sharpening can be done without cooling or with cooling. The second option is more acceptable. In this case, cold water should be supplied to the place where the turning tool comes into contact with the grinding wheel. If cooling is not applied, after the end of the procedure, the cutter cannot be sharply cooled, which will lead to cracking of the cutting part.

When performing sharpening, it is important to strictly follow the sequence of actions. First, the rear main surface is processed on the grinding wheel, then the rear auxiliary, and at the end the front. The last stage of sharpening consists of processing the tip of the cutter, giving it the required radius of rounding.

Useful advice! When performing the sharpening procedure, the cutter should be constantly moved slowly in a circle, trying not to press it too hard. This is necessary so that the surface wears out evenly, and the cutting edge is as smooth as possible.

Sharpening of lathe cutters designed for metal work is a very important process that should be performed correctly

Among the wide range of metal turning tools, you can choose the most suitable option that will cope with the task. To do this, it is necessary to determine which metal will be processed, which operations should be performed, whether it is important to observe the geometric parameters of the final product or it is necessary to ensure high-quality surface treatment. Only after that you should proceed to the selection of the tool.