The main tools for processing workpieces on lathes are cutters. With their help, you can separate the necessary layer of material from any cylindrical part to give it the required size.
What is a turning scoring tool used for?
There are 8 types of cutters in total: passing, boring, cutting, slotting, chamfering, shaping and cutting. Each of them is used in specific operations. For example, cutting cutters are designed to separate finished products from workpieces, and boring cutters are designed to bore holes or create internal chamfers. But the scoring cutter has a wider application. Almost every major operation on a lathe is performed using this tool. With it, you can cut ledges at a right or sharp angle, create external chamfers, machine an end face and any other outer surface of a cylindrical part. Thus, it is one of the most important tools, as it directly affects the initial formation of the finished product.
Types of scoring cutters
Firstly, depending on the feed direction, scoring cutters are left and right. It is quite easy to determine the type according to this principle, you just have to put your palm on the instrument and see which way the thumb is pointing. If the direction of the thumb to the left is the left one, and to the right is the right incisor.
Secondly, depending on the design features, there are:
- Cutting cutter bent. It has cutting edges inclined to one side of the holder axis.
- Scoring straight cutter. It has cutting edges parallel to the holder axis.
- Cutting end cutter (or persistent). This tool also has cutting edges that are parallel to the axis of the holder, but at a smaller angle.
Thirdly, there is a classification of incisors according to the method of manufacture. Depending on this, they are of two types:
- Solid - tools whose holder and head are made from the same material.
- Composite - tools, the components of which are made of different materials. For example, the holder is made of T10K5 carbide, and the cutting insert located on the head is made of P9 high speed steel.
Cutter selection for part processing
Before choosing a scoring cutter for processing, you need to decide on some features:
- First, you need to consider the material of the tool insert. The cutter must be stiffer than the workpiece itself.
- Second, you need to take into account the geometry and designcutter.
These two parameters will affect the further choice of feed and cutting speeds, as well as its durability, i.e. the duration of continuous work until the cutting edges become dull.
Cutter elements and their sizes
The scoring cutter consists of two elements:
- Holders (rods) - the main part of the cutter, which makes it possible to install the tool on the machine.
- The head or the working part, which, in fact, performs the processing of the part. The head consists of several surfaces: the front (on which the chips are removed), the main back (which supports the cutting insert) and the auxiliary back (allows the tool to move along the surface to be machined). In addition, it has two cutting edges - main and auxiliary, which are responsible for performing basic turning operations.
Depending on the dimensions of the tool holder of the machine and the workpiece being processed, toolholders and tool heads are made in various sizes. The main dimensions of the tool on the example of a turning right scoring face cutter are shown in the table below.
| Length, L | Width, b | Height, H | Insert plunging angle |
| 100 mm | 10mm | 16mm | 15° |
| 120mm | 12mm | 20mm | |
| 140mm | 16mm | 25mm | |
| 170mm | 20mm | 32mm | |
| 200mm | 25mm | 40mm |
Marking
As a rule, many turners who choose a tool for processing a part immediately pay attention to the marking and for good reason, because it indicates the grade of steel used to create cutting inserts. For example, the cutter thrust T5K10 has a hard-alloy plate, which belongs to the titanium-tungsten group of alloys containing titanium and cob alt carbides. Such a tool can only be suitable for rough turning of carbon and alloy steel blanks at low speeds and at low heating temperatures.
In other cases, you will have to choose cutters from high speed steel. They last longer at high speeds and are less likely to soften when heated to over 200°C.
Materials used to make the cutting insert
As you already know, a scoring cutter consists of two parts: a holder and a head. Both of these elements are important for the tool and each of them performs its function. For example, the holder, which is mounted in the tool holder, must be hard, resistant to wear and impact, and the cutting insert must not heat up at high temperatures. That is why inIn most cases, both parts of the cutter are made from different materials. In addition, this allows you to save on the production of the tool itself, which significantly affects the reduction in the final price.
Thus, cutting inserts are made of high speed steel or hard alloys with the addition of cob alt, because, as you know, this material is resistant to wear and works well at high temperatures. Popular materials for the manufacture of cutter inserts are high-speed steels (R9K5, R9K5F2) and hard alloys (T5K10, T5K6).
If it is necessary to process softer iron alloys, such as cast iron, then it is recommended to choose a cutter whose cutting insert consists not only of cob alt, but also of tungsten. These include the grades VK6, VK8, VK10, VK3M and VK6V.
List of current GOSTs
Due to differences in design, size and geometry, many cannot choose the right scoring cutter. GOST should get rid of these difficulties. The standard contains all the necessary information about turning tools, their design, geometric parameters and other equally important features that will be useful when calculating cutting conditions and choosing a cutter.
There are 4 state standards in total that mention turning scoring cutters:
- GOST 18880-73 (reissue with amendment 2003). The standard contains brief information about the main designations, design, geometric parameters and dimensions of undercut bent cutters with brazed cutting inserts made of carbide.
- GOST 18871-73 (reissue fromrev. 2003). The standard contains the necessary information on the design and dimensions of turning scoring tools with brazed HSS inserts.
- GOST 28980-91 (reissue as amended in 2004). We are talking about passing and scoring cutters with replaceable carbide inserts.
- GOST 29132-91 (reissue as amended in 2004) There is information about through and scoring cutters with replaceable polyhedral inserts, which are used in production together with a special device, a copier.
