Professionals who have repeatedly used metal cutters for a lathe in their practice to perform certain tasks clearly understand what types of tools these are. For beginners, who first encounters these elements, it is difficult to figure out what is the distinguishing feature of each particular model and how to choose the right tool to perform certain tasks. This article will help you understand an important issue.
Design features of a metal turning tool
The design of the element consists of a tool holder, due to which the tool is fixed on the machine, and the working head, which directly processes the surface of the workpiece. The holder may have a square or rectangular cross section. The working part of the tool is formed of several adjacent planes and cutting edges. Their sharpening angle depends on the characteristics of the material being processed and the type of processing.
The working head can be solid or with welded or soldered plates. Novelty are metal cutters for a lathe with replaceable plates. The first option is an integral element with a holder. Such a tool can be made of special high-carbon tool or high-speed steel. But such incisors are used extremely rarely.
Mainly for metalworking on a lathe, cutters with welded or soldered plates are used. A tool is made of high-speed steel or a hard alloy, which contains metals: titanium, tungsten and tantalum. It is characterized by high strength and price policy. This turning tool can be used to process products from 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, when processing material, turning tools with replaceable plates are used. Unlike the previous version, the plate is attached to the head mechanically using special clamps or screws. The tool is convenient in further operation if the plate is made of mineral ceramic, which significantly increases the cost of the cutter with interchangeable plates.
The working part for a turning machine tool can be made of hard alloy (tantalum-tungsten-titanium, titanium-tungsten, tungsten), high-speed steel (high or normal efficiency), high-quality carbon steel. Cutters can be used for such types of lathes as planing, turning, grooving, automatic revolver and special.
Classification of turning tools
According to GOST, there are three types of metal turning tools:
- turning and planing, in which the cutting part is made of high speed steel;
- planing and turning carbide brazed;
- turning with mechanical fastening of plates made of ceramics, hard alloys and other superhard materials.
Manufacturers produce these types of cutters:
Depending on the direction in which the feeding movements are made, it is possible to distinguish the following types of cutters for a lathe:
- left-side type;
- right-handed 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 instrument.
Depending on the nature of the work, there is the following classification of cutters:
- to perform rough work, which is also called peeling;
- for semi-finished works;
- for finishing work;
- for the implementation of delicate technological operations.
The cutting insert 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 the cutters VK8.
Depending on the installation principle, the following types of metal cutters for a lathe are distinguished:
In the first embodiment, the turning tool relative to the axis of the workpiece, which is being processed, is located at an angle of 90 degrees. This type of product is widely used 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.
The tangential turning tool is located at any angle other than 90 degrees. relative to the axis of the workpiece. Attaching this tool to a lathe is 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 shaft, there are such types of turning tools:
- straight lines – all projections of the part have a straight line;
- bent – the upper projection has a curved line, the lower – a straight line;
- curved – the upper projection is displayed directly by the line, and the lateral projection is curved;
- drawn – the head of the cutter, which can be on the axis or be shifted to the left or right, has a smaller width than the shaft.
Turning boring tools can be:
- persistent bent.
Straight cutters are used to process the outer surface of a cylindrical workpiece. You can buy a direct GOST 18877-73 straight cutter for 4$. Tool holders for such a tool can be made in two sizes:
- traditional rectangular shape – 25×16 mm;
- square shape, which is used for special works – 25×25 mm.
In bent-through passage incisors, the working part can be bent to the left or right side, which makes it possible to bend the workpiece from different sides during the execution of work. In addition to machining the end of the workpiece on a lathe, the tool is used to chamfer. According to GOST 18877-73, the holders for this type of tool can have the following dimensions:
- 16×10 mm – for educational machines;
- 20×12 mm – non-standard product;
- 25×16 mm – universal standard size;
- 32×20 mm;
- 40×25 mm – made to order for use on a dimensional machine.
The most popular is the persistent bent tool cutting for a lathe. It is used for processing cylindrical workpieces. The special bending of the element allows removing excess metal from a round part in one pass. When processing a workpiece, the cutter moves along the rotation of the part. Bent through cutters can be left-handed and right-handed. The latter option in practice is used much more often. You can buy a cutting tool for 4,60$.
Cutting and undercutting tools for metal
The most common is a cutting tool. It is designed to cut the workpiece of the required size from a metal pipe, blank, bar, which has a length exceeding the required value. This type of incisor is difficult to confuse with another tool. The design of the product consists of a thin leg with a hard 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 common metal body at a right angle.
Helpful advice! Cutting cutting tools can cut thin grooves of different depths in a metal product.
Depending on the design, there are left and right cutters. To determine this, turn the product with the cutting side down and see which side the tool leg will be on. You can buy a detachable turning tool for 2.7$.
Manufacturers produce cutting tools with the following tool holder sizes:
- 16×10 mm – for educational machines;
- 20×12 mm;
- 40×25 – made to order for large machines.
Undercutting bent cutter outwardly very similar to a persistent tool through passage. The working part is also represented by a plate of hard alloys, but has a triangular shape with one rounded side. Using this type of cutting tool, the workpiece can be machined across the axis of its rotation, exposing the cutter perpendicularly.
Manufacturers also produce cutting thrust cutting tools, which have significantly lower demand in the construction market, due to the limited scope of use of the tool.
Holders for cutting tool come in the following sizes: 16×10 mm, 25×16 mm, 32×20 mm. The cost of a bent cutter will average 3,60$.
The tool kit for the lathe must include threaded cutters on the lathe. The cutting plate of products is made of hard-melting metals. There are two options for 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 cutter plate is shaped like a spear tip. Using a tool, you can get metric or inch threads, depending on the design of the cutter. Cutters are presented in such standard sizes: 16×10, 25×16, 32×20 mm. The price of the product is 1,7$.
To thread a cutter on a lathe in the cavity of the workpiece, a second version of a threaded tool is used. Despite the fact that the cutter is similar in shape to the previous version, it has a completely different look. Due to the design features of the tool, it can be used for large diameter holes. Manufacturers produce products of such standard sizes: 16x16x150 mm, 20x20x200 mm, 25x25x300 mm.
The tool holder has a square shape, the values of which are determined by the first digits of the designations. The third digit indicates the length of the holder. It is this value that determines the depth to which the thread can be cut in the inner cavity of the workpiece. You can buy a tool for 3,88$.
Important! This type of cutter can be used on lathes equipped with a special device called a guitar.
There are two types of boring tools: for boring blind or through holes. If there is no hole in the metal workpiece, you must use the first version of the tool. The plate of the boring tool has a triangular shape, like that of the cutting tool, but its cutting part has a bend. This design allows you to bring the cutter from the end face 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.
For such cutters, holders can have such dimensions: 16x16x170 mm, 20x20x200 mm, 25x25x300 mm. The maximum diameter of the hole in the metal blank will depend on the size of this element of the cutter. You can buy metal cutters for a lathe for 2,88$.
Important! You can bore holes of any diameter, the main thing is to choose the correct size of the cutter.
To create through holes in the body of the workpiece, the second version of the boring tool is used. It is first necessary to drill a large diameter hole in a metal part. Only then can you begin to bore it to the desired size. The design of the tool is characterized by a straight plate that does not have protrusions, which allows the cutter to easily penetrate into the pre-drilled tube in the body of the workpiece, and, passing through, bore it.
During processing of the through hole, a metal layer equal to the amount of limb of the working part of the cutter will be removed. The cost of the tool is an average of 2,73$. Cutters boring for through holes have the same standard sizes as in the previous version.
Universal Cutters for Lathes
A universal tool can also be called a team. 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 workpiece of various shapes at any angle. Universal tool holders may vary. This type of cutter is used extremely rarely, therefore it is available in limited quantities. You can meet him in the store at a rather high price, unlike other options 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 works. You can buy cutters for a lathe at a price of 5$.
Rules for sharpening metal cutters for lathe
To ensure efficient, high-quality and accurate machining of the workpiece on a lathe, it is necessary to sharpen the cutters regularly. This helps to give the working part the necessary shape and obtain an angle with the desired value.
Important! Only a tool made in the form of a disposable carbide plate does not need to be sharpened.
At industrial enterprises, 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 methods. Tool sharpening can be carried out using chemicals, using grinding wheels.
Helpful advice! Using an abrasive wheel that can be installed on a lathe, you can perform high-quality and effective sharpening of the cutters, giving the tool certain geometric parameters.
When choosing a grinding wheel, you should pay attention to the material of manufacture of the working part of the element. If carbide cutter is to be sharpened, it is necessary to choose a circle of characteristic green color from carborundum. For high-speed or carbon steel products, it is better to use a corundum circle.
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 is in 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 machined on the grinding wheel, then the rear auxiliary surface, and finally the front. The last sharpening stage consists of processing the tip of the cutter, giving it the required radius of curvature.
Helpful advice! When performing the grinding procedure, the cutter should be constantly slowly moved in a circle, trying not to press it too hard. This is necessary so that the surface is evenly worn out, and the cutting edge is obtained as even as possible.
Among the wide range of turning tools for metal, 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, what operations must be performed, is it important to observe the geometric parameters of the final product, or is it necessary to ensure high-quality surface treatment. Only after this should you begin to select a tool.