Cemented carbide indexable turning blade are the main components of indexable cutters.
The reasonable selection of blade model, geometry and blade groove shape will directly affect the cutting performance, processing quality, tool cost and comprehensive economic benefits of the tool.
The selection of blade model will affect the determination of tool structure in some cases (such as whether the blade has holes, whether the holes are countersunk or round, whether the chip breaking groove is single-sided or double-sided, etc.).
It affects the geometric angle of the tool (if the blade has zero degree or different front and rear angles, the angle of the tool will change accordingly), and affects the cutting strength (such as horizontal ordinary indexable blade or vertical heavy indexable blade).
In turning, except for a few small-diameter inner holes, some special materials and non-ferrous metal workpieces, almost all of them can be processed with carbide indexable turning tools. Many types of turning tools are also suitable for boring, planing, drilling, expanding and other processes.
At present, there are international ISO and national GB standards for the representation rules of indexable turning tool models.
（1） ISO standard indexable turning tool model representation rules
The ISO standard indexable turning tool model is composed of a group of letters and numbers representing a given meaning arranged in a certain order, in which the 8th and 9th digits are represented as required.
In addition, the manufacturer may add two more symbols.
See table 3-6 for an example.
Table 3-6 example of ISO standard indexable turning tool representation
Superhard material blade
For the above codes,
- The first code represents the blade shape;
- The second code indicates the size of the back corner of the blade;
- The third digit code indicates the allowable deviation grade of the main dimension of the blade;
- The 4th digit code indicates the type of blade (whether the blade has chip breaking groove and central fixing hole);
- The 5th digit code indicates the cutting edge length of the blade;
- The 6th digit code indicates the blade thickness;
- The 7th digit code indicates the arc radius of the tool tip;
- The 8th digit code indicates the shape of the cutting edge;
- The 9th digit code indicates the left and right hand cutting direction of the tool;
- The 10th digit code indicates the chamfer width;
- The 11th digit code indicates chamfer angle.
（2） National Standard Specification for model representation of indexable turning tools
According to the provisions of the national standard GB/T2076-2007 “rules for model representation of indexable inserts for cutting tools”, the model of indexable inserts consists of a group of letters and numbers representing a given meaning, arranged in a certain order, with a total of 10 codes.
The marking example is shown in Fig. 3-8.
Fig. 3-8 example of marking method for indexable turning tool blades
For the above 10 digit code, no matter which type of blade, the first 7 digits must be used, and the last 3 digits can be used only when necessary.
If only one of the 8th and 9th digit codes is used, both the 8th and 9th digit codes are written on the 8th digit.
In addition, no matter whether there are the 8th and 9th digits or not, the 10th digit code must be separated from the previous code by a short horizontal “-” and its letters shall not use the letters already used in the 8th and 9th digits.
The first code represents the blade shape.
In addition to the representative letters of the blade shape listed in Fig. 3-8, there are also rhombic blades with H representing regular hexagon, O representing regular octagon, C, E and M representing 80 °, 75 ° and 86 ° tip angles respectively, and parallelogram blades with A, B and K representing 85 °, 82 ° and 55 ° tip angles respectively.
The second code indicates the size of the back corner of the blade method.
The third digit code indicates the allowable deviation grade of the main dimensions of the blade. There are 11 kinds in total.
Class U, M and C are widely used.
The rest are Grade A, F, H, E, G, J, K and L.
The allowable deviation grade of blade size is expressed by the allowable deviation of blade profile, blade thickness and blade m value.
The basic parameters of the blade profile are represented by the inscribed circle diameter D of the blade.
The dimension series of d specified in the standard are 4.76, 5.56, 6.35, 7.94, 9.525, 12.7, 15.875, 19.05, 25.4, 31.75mm.
The tolerance of each grade varies with d.
The dimension series of m value has different values due to different blade profiles, but the tolerance of m value changes according to the dimension series of d.
Table 3-7 shows the allowable deviation values of main dimensions of U, M and G precision grade blades, and table 3-8 shows the allowable deviation values of circular blade d.
Table 3-7 allowable deviation of indexable blades of U, M and G precision (unit: mm)
|Inscribed circle diameter d||Class u||Class M||Class G|
Note: the allowable deviation of blade thickness s is ± 0.13mm.
Table 3-8 allowable deviation of circular blade diameter d (unit: mm)
|Circular blade diameter d||Class u||Class M|