White cast iron is a kind of wear-resistant material that has been used earlier and is relatively widely used. As early as the Spring and Autumn Period, China made white cast iron with good abrasion resistance and used it as some anti-wear parts. White cast iron includes ordinary white cast iron, low-alloy white cast iron, medium-alloy white cast iron, and high-alloy white cast iron. Ordinary white cast iron is ordinary white cast iron with no added alloying elements, and is used in engineering for anti-wear castings with low wear resistance requirements. Low-alloy white cast iron is still relatively brittle, and is suitable for occasions where the requirements for wear resistance and toughness are not too high. Medium-alloy white cast iron uses chromium as the main alloying element. When chromium is added up to 9%, this carbide is in the shape of an isolated rod or plate with poor continuity, so it has good toughness and high strength. At present, the most widely used high-alloy white cast iron is high-chromium white cast iron with a chromium content of 12% to 20%. It has high hardness, good wear resistance and toughness, and is widely used in mining, cement, Electricity, road construction machinery, etc.

With the increasing application of high chromium white cast iron, various new tools such as cemented carbide tools, ceramic tools and cubic boron nitride tools and other super-hard tools are increasingly widely used. But only by choosing the right tool can the problem of difficult machining of high chromium white cast iron be better solved. When I talked to an engineer before, I said that the cubic boron nitride tool BN-K1 is more effective in processing high chromium white cast iron. The reason is that the cubic boron nitride tool BN-K1 belongs to a non-metallic adhesive and is an integral polycrystalline cubic boron nitride tool with high hardness, good wear resistance and impact resistance, and can effectively improve processing efficiency.

The following is an actual machining case of the cubic boron nitride tool BN-K1 for machining high chromium white cast iron.

First, the characteristics of high chromium white cast iron

High chromium white cast iron is the third generation of white cast iron developed after ordinary white cast iron and nickel hard cast iron. At present, high-chromium cast iron has been recognized as an excellent wear-resistant material in the world, and it is widely used in mining, cement, electric power, road construction machinery, refractory materials, etc. High chromium white cast iron as a wear-resistant casting without any heat treatment, the hardness is generally above HRC45, and the tensile strength is 650-850MPa. And the high chromium white cast iron is formed by casting, especially the large pieces of casting have a large cutting margin, and the surface will have casting defects such as sand inclusions and pores. Therefore, it is very important to choose the right tool when processing high chromium white cast iron.

Two. Tool selection for machining high chromium white cast iron

High chromium cast iron is one of the difficult-to-cut materials. Due to its high hardness, cemented carbide tools wear quickly and are difficult to process normally. Ceramic tools are generally only used for finishing due to their brittleness; The integral polycrystalline cubic boron nitride tool BN-K1, specially developed for high chromium white cast iron, has a hardness four times higher than that of cemented carbide and two times higher than that of ceramic tools. The cubic boron nitride tool BN-K1 is non-metallic The adhesive has good wear resistance and impact resistance, which can improve processing efficiency and reduce processing costs.

The following is a case of machining high chromium white cast iron with cubic boron nitride tool BN-K1 to illustrate the advantages of cubic boron nitride tool.

Case of processing high chromium white cast iron with cubic boron nitride tool BN-K1

Material: high chromium white cast iron Cr26

Material hardness: 60HRC

Machining parts: wear-resistant and corrosive industrial pump impeller, pump body, etc.

Tool brand: BN-K1

Cutting parameters: ap=3.5mm, Fr=0.1mm/r, Vc=75m/min

Cutting method: dry cutting.

The comparison between the effects of BN-K1 and ceramic inserts is as follows: When the cutting speed of BN-K1 is twice that of ceramic inserts, and the feed rate is 40% higher than that of ceramic inserts, the single-edge life of BN-K1 is ceramic The blade is more than seven times larger, which not only improves the processing efficiency, but also saves the processing time and reduces the processing cost.

Four, cubic boron nitride tool BN-K1 machining the outer circle of the slurry pump impeller

Because the impeller has 4 blades, it is cut intermittently. The cutting parameters of cubic boron nitride tools are: vc=75m/min, ap=5mm, f=0.1mm/r. During the cutting process, the tool has to withstand 4 impacts per revolution of the impeller, and one cutting edge has to withstand more than 3,000 impacts at a time. The cutting results showed that the cubic boron nitride tool did not produce fracture after cutting a workpiece. One blade is equivalent to 25 ceramic blades, which fully demonstrates its heat and impact resistance, which not only greatly reduces the cost of the tool, but also makes production The efficiency is increased by 5 times.

Five. Summary

With the increasingly fierce competition in the machinery industry, every company is thinking about how to choose the right tool material to cut the workpiece, so as to improve processing efficiency and reduce processing costs. If the tool industry can understand the performance of various materials in the machinery industry and Choosing the right tool can definitely bring good economic benefits to the enterprise.