GOST 18874-73 Lathe slotting and cutting cutters made of high-speed steel. Design and dimensions

Cutters are used for processing metal or wooden products, metal ceramics. They are mounted on technical machines that can perform a variety of jobs (turning, planing, slotting). Cutters are usually made from high-strength varieties of steel, which may contain alloying additives that increase strength and minimize the risk of rust. A popular type of such tool is the groove cutter. It has a number of design differences, and is mainly used for processing conical or cylindrical products made of metal.

The tool allows you to create small but precise grooves, which is required in some part machining scenarios. But what does a groove cutter look like? How can a worker choose the right tool for his machine? What does GOST say about groove cutters? This article will discuss these issues in detail.

Geometric parameters and tool dimensions

The design of any groove cutter is characterized by its geometric parameters.

1. Geometry of the body or holder: L – length of the body, B and H – dimensions of the cross-sectional sides.

Shape of the working cutting plate: l – length of the working part of the cutter, b – height of the plate body, S – thickness.

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2. Location of the cutting element in the body. The socket for the plate can occupy the entire width of the case or one of the corners. In the latter case, the width of the socket is indicated by the letter n. The plate can be placed in the socket at a certain angle to the body.

The blade for cutting the workpiece also has its own parameters, expressed in angles.

1. “Gamma” displays the front sharpening angle - this is the main element of the cutting edge.
2. “Alpha” is the rear main sharpening angle.
3. “Alpha” with index 1 is the rear corner for auxiliary purposes.
4. "Lambda" is the angle at which the cutting edge is inclined.
5. “Phi” is the main purpose angle located in plan.
6. “Phi” with index 1 is an auxiliary angle located in plan.

Geometry and dimensions of groove type cutters

Since groove-type cutters experience significant load during processing, which determines increased requirements for their rigidity, they are manufactured with soldered carbide plates, the characteristics of which are specified in GOST 2209-82. The requirements for the cutter itself, as stated above, are given in GOST 18874-73.

The main feature of the geometry of groove-type cutters is that the shape of their cutting part must exactly match the shape of the groove that is planned to be obtained with their help. The grooves created on the surface of the workpiece are usually small in width. Accordingly, the cutting part of the tool with which they are formed is also quite narrow, which makes it very vulnerable to mechanical damage. In addition, the working head on each side has a narrowing towards the holder (by 1–2 degrees). Such a narrowing of the sides of the cutting part is necessary in order to reduce their friction against the walls of the groove being formed.

Geometric parameters of the groove cutter

To increase the strength of the cutting head of a groove turning tool, its height is made significantly larger than its width. This also requires a small rake angle and a sharpening of the cutting edge with a small radius (curvilinear). The optimal cutting angles for groove-type cutters are 15–250 (front), 8–120 (rear).

The width of the working part of the groove tool, which, according to the requirements of GOST 18874-73, can vary over a wide range, is selected depending on the width of the groove that needs to be formed on the outer or inner surface of the workpiece.

Markings used

The designation of groove cutters is encoded, which provides a complete definition of the geometric parameters of the tool included in the tables of regulatory documents. The main product markings mention parameters such as the alloy with the percentage of metal components in the alloy. For example, if you take a T5K10 cutter, then there will be an alloy based on the titanium-tungsten group, where titanium carbide is up to 5%, and cobalt is up to 10%.

To select cutting groove products, it is not enough to know only the composition of the alloy; you need to proceed from all the parameters specified by GOST.

Features of turning using a groove cutter

The cutting modes when using groove-type cutters have some differences from the modes of processing the workpiece with other types of turning tools. Thus, the depth of cut is taken to be a value equal to the width of the groove being formed, and the tool feed per revolution of the part is measured in the direction perpendicular to its axis. The feed rate, depending on the material from which the cutting part of the groove tool is made, is selected in the range of 0.07–0.2 mm/rev, and the cutting speed is 15–180 m/min.

Several types of grooves can be obtained on the surface of the workpiece.

• Narrow grooves, the width of which corresponds to the width of the cutting part of the tool, are made in one pass of the cutter, which is fed manually. Before this, the exact location of the groove is determined on the surface of the part, and then the cutter is placed opposite this place and fed.
• The grooves on the ledges and ends of the part are made according to the same principle; their diameter is set using the transverse feed dial, and their depth is set using the longitudinal movement dial of the caliper.
• Wide grooves are made in several passes according to the following scheme. First, determine the location of the right edge of the groove and place the cutter opposite this location. Using a transverse feed, the cutter is cut into the part to a depth that is 0.5 mm less than the depth of the groove being cut (this allowance is left for finishing). Then, using a longitudinal feed, the groove tool begins to move to the left edge of the groove being cut, the boundary of which has been previously marked. After the rough groove is formed, its bottom is processed cleanly - to the required depth, carrying out the longitudinal feed of the cutter from left to right. In the event that it is necessary to form a groove with a very precise location of its left and right edges, allowances can also be left on them during roughing, which are then removed using the transverse feed of a groove or scoring cutter.

Types of work performed by grooving cutters

GOST standards for groove cutters

Regulatory documents have been developed for groove cutters of various modifications:

1. GOST 18874-73 regulates the standards for cutting and slotting equipment, which specifies the dimensions and design of the tool, which is made of high-speed steel.
2. GOST 18885-73 describes the design features of groove cutters for thread production, which are equipped with carbide plates.
3. GOST 18884 - 73 - this normative act gives instructions on the size and design of cutting tools for turning, the plates of which are tipped with carbide alloys.
4. GOST 28978-91 - the document defines the standard for prefabricated groove cutting tools.

Selection rules

The first thing you should focus on when choosing a groove turning tool is a drawing of the finished product, which indicates both the dimensions and shape of the grooves, as well as the tolerances for the accuracy of their geometric parameters. Naturally, the choice of cutter and its geometric parameters is influenced by the material from which the workpiece is made.

External groove cutter

When forming grooves on small parts, it is especially important to maintain a low cutting force, which minimizes the distortion that occurs during processing. Compliance with this requirement is ensured by the sharp sharpening of the groove tool, which, however, can lead to its breakage if the carbide plate material and cutting conditions are selected incorrectly - the rotation speed of the workpiece and the feed rate.

When choosing a groove cutter, you should also take into account the shape of its cutting edge, which can be straight and sharpened with a small radius. Naturally, you should not choose a product with a curved sharpening of the cutting edge if the bottom of the groove, according to the provided drawing, should be straight.

Internal groove cutter

Recommendations for selecting groove cutters

When choosing a groove cutter, you should be guided by the following considerations:

1. First of all, they analyze the drawing according to which the part will be manufactured. The drawing shows all the parameters of the grooves: width, depth, shape, as well as standards for manufacturing accuracy and possible tolerances.
2. The metal from which the part is made. For carbide metals, appropriate cutters with a carbide blade are used; for soft metals, ordinary grooved ones are used.
3. When choosing a tool for cutting grooves inside a hole, the diameter of the holder and the size of the protruding edge of the knife are important. Here, too, it is more advisable to use carbide equipment.
4. Equipment for carrying out operations. The choice of groove cutter is determined in this case depending on the possible operating modes of the machine, the configuration and type of tool holder.
5. Features of the technological process. The technical process can affect the processing speed of the product. The higher the speed, the stronger and more durable the grooving equipment must be used to achieve processing goals.
6. Is there any provision for lubrication of the treatment area during the operation? Lubrication has a positive effect on the work, removing part of the load from the groove tool and thereby making it possible to use simpler equipment.

Tool design and geometry

A classic groove cutter consists of two tool parts - a working head-cutter and a fixing rod, with which the spare part is secured in the machine holder. The holder rod is made of high-alloy steel, which provides high strength and protection of the tool, and also minimizes the risk of corrosion and deformation. The cutting part of the KR is made in the form of a rectangular or oval plate, which is also made of high-alloy steel.

The plate is usually made of metal that contains additives based on cobalt, manganese or tungsten - this provides the tool with high strength, so it dulls slowly. On some CDs, the head is made in the form of a replaceable head, which is also made of steel with a high content of cobalt, manganese, tungsten and similar alloying additives. Tool sharpening should be done on a sharpening machine, and it is recommended to entrust this work to an experienced worker.

A few words about the correct sharpening of groove cutters:

• During sharpening and assembly of the part, it is necessary to obtain a rake angle ranging from 15 to 25 degrees. The location of the cutter affects how the workpiece will be processed in the future while the cutting machine is running.
• The working edge should be sharpened evenly along its entire length. If you ignore this rule, then strong vibration will occur during operation of the machine, which will make cutting inaccurate. Due to vibration, the tool also heats up additionally, which will reduce the strength of the tool and make sharpening more difficult.
• Select the optimal geometry experimentally. GOST standards do not provide precise instructions regarding the sharpening of this tool due to the fact that surface treatment has specific features. Therefore, it is not possible to select a universal angle of inclination and quality of sharpening.

To optimize sharpening, it is recommended to perform it in several stages. First, you need to make several test grooves to determine the optimal sharpening parameters. Once the worker has mastered his hand, he can begin the main sharpening. Only experienced turners with experience who are fluent in their craft and know all the intricacies of working with groove cutters can skip the test groove.

Grooving turning cutters - GOSTs, varieties, manufacturers

Due to the peculiarities of their design, groove cutters (also called slotting cutters) are considered multifunctional tools that can be used to form grooves on workpieces of cylindrical and conical configurations.

Such technological operations (especially those associated with radial grooving) are characterized by significant loads, which are successfully carried by a cutter of this type, characterized by high structural rigidity.

Moreover, groove cutters are successfully used for axial grooving and facing, making them versatile turning tools. Grooving cutters for internal and external grooves with mechanical fastening of replaceable cutting inserts

It is advisable to use groove turning tools to obtain parts with complex configurations. The versatility of cutters of this type in such cases allows us to minimize the number of tools used and reduce the time for equipment changeover.

It is also noteworthy that the use of a groove cutter when performing many technological operations makes it possible to form surfaces with higher quality characteristics than when using a conventional turning tool.

Labeling and manufacturers

The description of groove turning tools will be incomplete without mentioning the markings, which determine the composition of the material of their cutting part. For example, the T5K10 cutter is made of a hard alloy of the titanium-tungsten group, which contains 5% titanium carbide and 10% cobalt. The markings of products made from other materials are deciphered in a similar way.

The most famous manufacturers of grooving turning tools are:

• Dnepropetrovsk industrial tools plant (Ukraine);
• (Ukraine);
• Zenitech company (Switzerland);
• Proma company (Czech Republic);
• Itertool company (China).