The most common operation in the production of various parts is, perhaps, turning. The tool industry produces a large number of varieties and types of cutters for processing bodies of revolution on lathes, as well as for boring holes on coordinate-boring aggregates and machining centers. Turning allows you to remove stock and get products with a cylindrical and shaped surface (including threaded). You can also cut the bar into blanks of the desired length.
Design of turning tools
Despite the large number of types of incisors, they all have the same structural elements. Both a conventional turning tool with a solder plate made of tool steel, and a tool with a replaceable cutting plate made of modern powder materials, are similar in design. Each incisor has a holder. It is mounted in the turret of a CNC lathe or in a four-position fixture for mounting a tool for a universal machine.
For any type of cutter, a head is also an indispensable element, on which a plate of tool steel is soldered (type TK15). Currently, tools with soldered plates are used very rarely. Companies primarily purchase toolholders with quick-detachable blades. For the manufacture of such plates are used the most advanced materials obtained by means and methods of powder metallurgy.
General classification of turning tools
Depending on the shape of the holder, in the cross section, rectangular and round incisors are distinguished. The toolholder has a rectangular cross-section for cutting external surfaces (thread, grooves, cylinder, and so on). The round-shaped holder is characteristic for the cutters that process internal surfaces (internal thread, internal grooves for bearing retaining rings, holes, and so on). These types of cutters (with a round holder) are installed in the turret through a special adapter that allows you to adjust the angle of rotation of the cutter around the axis in order to align the tip of the cutter with the axis of rotation of the workpiece. If the tip of the cutter does not coincide with the axis of rotation of the workpiece, the tool will be subject to increased wear due to improper chip retraction and increased load.
Another feature by which turning tools are classified is the direction of the cutting feed. On this basis, the incisors are divided into right and left.
Depending on the type of the working part of the tool, the cutters are straight and bent.
In addition, there are cutters of integral and composite types. Compound-type turning tools are collapsible. The cost of such incisors is an order of magnitude higher than a conventional tool. Compound heads have a complex structure and are made of very expensive materials.
Classification of turning tools depending on orientation relative to the workpiece
According to this feature, the entire turning tool can be divided into the following types: tangential, parallel, radial.
The tangential tool is set to the axis of rotation of the workpiece at an acute angle. Thus, chamfers and other shaped surfaces are obtained. Theoretically, chamfers can be sharpened by combining longitudinal and transverse feeds. However, this method requires high qualification of the turner and is not always feasible.
A parallel installation is used to drill and bore holes along the axis of rotation of the workpiece from the end side.
Radial installation is used for turning external surfaces.
The main types of metal turning tools
Not only metals and steels are subjected to turning, but also other materials: wood, plastic and even glass. And, of course, there are no such incisors that would be suitable for processing all these materials. And if earlier TK15 high-speed steel (and its analogues) was used almost everywhere, today this material cannot satisfy the growing need for a high-quality and durable tool. Such incisors blunt very quickly, and they need to be re-sharpened. And this time and money for the salary of a highly qualified specialist.
It is much more profitable and convenient to use cutters with interchangeable plates. The durability of such plates of powder composite materials is an order of magnitude higher than traditional tool cutting steel. In addition, one such plate can have up to six working faces. The insert allows machining at very high cutting speeds. When the working edge becomes unusable, it is enough just to turn it on the other side. The positioning accuracy of such a plate is very large, which means that there is no need to stop the equipment for readjustment.
The tool industry has mastered the production of cutting inserts for a wide range of materials: steel, copper, aluminum, plastic and so on. The intended use of the plates guarantees the production of the durability, roughness and cleanliness of the surface declared by the tool manufacturer.
Classification of cutters by type of processing
In accordance with the established and current GOST, the types of cutters by type of processing are as follows: for black turning, for finishing (semi-finishing) processing.
The cutting insert for rough grinding of forgings and rolled products has a large radius at the apex, which allows you to remove a significant allowance in one pass (up to 4 millimeters or more on a CNC machine).
Finishing plates, as well as plates for processing non-ferrous metals (aluminum and copper) have a small radius at the top of the cutter. Processing with such plates is carried out at very high speeds (from a thousand or more units per minute), which allows to obtain a very high-quality and clean surface.
Based on this feature, both boring cutting tools and various types of boring tools can be classified.
Description of threaded cutters for external thread
As the name implies, this cutter is used to process threaded surfaces.
Threads can be cut both externally and internally. The threaded cutter for the external thread resembles a straight through cutter type. The difference is only in the angle of sharpening - it is 60 degrees (if you need to cut a metric thread) or 55 degrees (to get an inch thread).
Description of threaded cutters for cutting internal threads
The cutter for cutting internal threads looks very much like a tool for boring the inner diameter of the holes. The differences are the same: shaped sharpening at a certain angle.
Sharpening, as well as installing the tool on the machine and its adjustment is a very complicated matter. Only a specialist with extensive experience in similar work can handle this task. The use of threaded cutters with interchangeable blades solves this problem and greatly simplifies the process of setting up the machine.
Characteristics of through cutters
The through cutter is most often used in turning. Without it, it is simply impossible to give the forging or billet from the bar the shape and dimensions necessary for carrying out subsequent technological operations. Therefore, the passage refers to the main type of incisors.
This type is used to remove the allowance on the outer surface of the body of revolution, as well as to trim the end surfaces. The angle at the top can be different: 45, 60, 75 and even 90 degrees. The value of the angle is dictated by the purpose of the cutter. Appointment and types of passage cutters: peeling, cutting, finishing.
Features of wood turning tools
The entire turning cutting tool has one purpose - the processing of workpieces (bodies of revolution) on the machines and giving them the desired shape. But despite this, the very principle of the tool working on wood and the physics of the cutting process are very different from the processes occurring in the process of cutting metal.
The main difference is a slight cutting force. Most masters of carpentry prefer to use hand tools in their work. This creates exclusive products. But for turning wood in serial and mass production, so-called copiers are used. The essence of this technology is as follows: the probe moves along the template and transmits movement to the working body of the machine, as a result of which the contour of the part is formed.
It should be noted that a quality product can be obtained only with manual processing. Billets obtained using automatic and semi-automatic methods require subsequent fine-tuning and grinding with polishing.