Classification of superhard tools | how to select superhard tools?

With the higher and higher requirements of hardness in modern engineering material processing, the hardness of tools is also higher and higher, and more superhard tools are applied. Superhard tools are mainly used for cutting hardened steel, including carbon tool steel, alloy tool steel, high-speed steel, bearing steel, die steel, etc., or cutting various iron-based, nickel based, cobalt based and other thermal spraying (welding) parts. However, cutting different materials will have different superhard tools, so it is very important to understand the classification of superhard tools. Here is a brief introduction for you.

(1) PCD metal cutting tool

Tool type: take turning tool as an example, other tools include milling cutter, reamer and boring cutter.

Structural form: these tools can be divided into welding type PCD tools and indexable PCD tools. The structure of PCD cutter is the same as that of common carbide welding cutter. The difference is that the material of the cutting edge is different,

Different geometric parameters and different machining objects. The indexable PCD blade is made by welding a small piece of PCD blank on the cemented carbide indexable blade and grinding it. It can be clamped on the corresponding high-precision tool bar for efficient and mass processing.

With the popularization of numerical control machine tools and automatic production lines, the use of indexable PCD blades will be more and more widespread. Under certain conditions, the tool durability can be increased by tens to hundreds of times compared with carbide tools.

Geometric parameters of cutting tools: the geometric parameters of diamond cutting tools are generally 0 ° – 5 ° and 5 ° – 12 ° with two ends, one is circular arc and the other is straight line. The latter is sometimes called polishing edge, and its length is selected according to the material to be processed. The adjustment of the arc turning tool in the cutting process is relatively simple, while the adjustment of the flat edge is relatively time-consuming. If it is used in high-precision surface machining, the requirements of arc grinding are very strict, and its accuracy will be copied on the surface.

Typical application

High speed, high stability, low roughness processing and mirror processing of non-ferrous metals when PCD tools are used to process non-ferrous metals, due to the high hardness of diamond and the small affinity between the surface and the metal, the processing dimension is stable

And the surface quality is very good, and the tool life is long.

 (2) PCD woodworking tools

PCD woodworking tools are mainly used for processing laminate flooring. When processing the Al2O3 wear-resistant layer of laminate flooring, the cutting speed can reach 3000m / min, the feed rate can reach 20m per minute, and the noise during processing is small,

The durability of PCD tools is more than 200 times that of cemented carbide tools, which has completely replaced cemented carbide tools. Other PCD woodworking tools mainly include PCD saw blade and PCD furniture forming milling cutter. Because the price is expensive or the furniture is updated quickly, there are not many domestic applications.

 (3) PCBN metal cutting tool

Although the hardness of cubic boron nitride (CBN) is slightly lower than that of diamond, it is the hardest tool material that can be used to work harden ferrous metals.

The above is the classification of superhard tools. There are many kinds of superhard tool materials, especially diamond. The chemical composition of superhard materials and the law of forming hardness are different from other tool materials, and their hardness is much higher than that of other materials. So, how to choose super hard tools? When selecting superhard tools, the following points should be noted:

1. Selection of cutting parameters.

The best combination of cutting parameters for using superhard tools is high cutting speed, small cutting depth and small feed rate. Different processed materials have different ranges of cutting parameters. Please refer to the data provided by the tool manufacturer for details. When PCBN tool is used to cut hard materials at high speed, its service life is higher than that at low speed due to the softening effect of metal. Therefore, when PCBN tool is used, the cutting speed should be as high as possible.

2. Selection of blade material.

First, select the appropriate composite sheet material grade according to the processing object, and pay attention to the particle size, content and type of adhesive of superhard materials.

3. Selection of cutting edge form.

The geometric parameters of super hard tool are the most important factors that affect the tool life and machining effect. Therefore, different cutting edge parameters should be selected for different machining objects. Because of its poor heat resistance, diamond tools must choose sharp edges, and the serration should be within 3; Because PCBN tool has poor toughness but good heat resistance, its edge must be chamfered. The selection of other geometric parameters depends on the specific processing object.

In addition, other matters should be noted. For example, because the toughness of super hard tools is lower than that of hard alloy tools, the process system must have sufficient rigidity and accuracy when used. PCD tools require cutting fluid. Dry cutting is preferred for PCBN tools when conditions permit. The impact of grinding quality of superhard tool edge on tool life is much greater than that of cemented carbide tool. Therefore, after grinding, the edge quality should be checked with a microscope more than 50 times. PCBN tools are not suitable for machining materials with medium hardness (hrc35-50). To learn more about superhard tools, you can continue to pay attention to quick screening.