Machining slurry pumps:carbide vs ceramic vs CBN tools

Halnn journal

Machining slurry pumps carbide vs ceramic vs CBN tools With the rapid development， various light and heavy industries have risen and developed rapidly, and the demand for slurry pumps has also increased. How to manufacture and process slurry pumps with excellent performance in all aspects has become a goal of continuous exploration in contemporary academic circles.This article mainly describes the use of slurry pumps, materials and processing technology of slurry pump parts, and tools suitable for processing slurry pump parts.

一、What are the uses and materials of slurry pumps?

The slurry pump can also be called a centrifugal pump. It is a mechanical device that uses the rotation of the impeller of the centrifugal pump to increase the energy of the solid and liquid mixed media and convert electrical energy into kinetic energy and potential energy of the medium.

Due to the harsh working environment of the slurry pump, it often works in the environment of corrosive substances such as strong acid and strong alkali, resulting in a short service life. In order to ensure a long service life of the slurry pump, high-chromium alloy cast iron with high strength, high hardness, corrosion resistance and abrasion resistance is often selected as the main material of the slurry pump, such as Cr15Mo3、Cr15Mo2Cu、KmTBCr12、Cr20、Cr26, etc.

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The hardness of high-chromium alloy cast iron after casting is as high as about HRC60,which is one of the best wear-resistant materials currently.It is widely used in mining 、 electric power 、 metallurgy 、 coal 、 environmental protection and other industries to transport slurry containing abrasive solid particles. As the working environment of the slurry pump is different, the name also changes. For example, in the coal washing industry, seawater sand selection, river dredging and other fields, it is also called a mud pump, mud pump, etc.

二、Processing technology of slurry pump parts

There are many parts of the slurry pump. The main components are the impeller, pump shaft, sheath, front guard plate, rear guard plate, pump casing and shaft seal device. The function of the impeller is to directly transfer the mechanical energy of the prime mover to the liquid to increase the static pressure energy and kinetic energy of the liquid (mainly increasing the static pressure energy). The function of the shaft

Halnn journal seal device is to prevent the liquid in the pump casing from leaking along the shaft or external air from leaking into the pump casing. The following is a brief introduction to the processing technology of the slurry pump components impellerand pump shaft .

The processing technology of the impeller: rough turning of the inlet port ring and front plate surface - fine turning of the front port ring and inner hole (to ensure concentricity requirements) - keyway insertion (to ensure keyway symmetry) drilling of impeller balance holes (to ensure uniform size distribution) - Inspection (balance test) - Inspection and storage.

The processing technology of the pump shaft: rough turning - heat treatment (quenching and tempering) - semi-finishing turning - finishing - keyway milling cylindrical grinding - inspection and storage.

Halnn journal Among them, the pump impeller is the only workpiece in the slurry pump, and Cr26 is often used as the main material. The impeller has 5-12 blades, which is difficult to process using a lathe. There are two reasons: First, Cr26 (high chromium cast iron) has high hardness after casting, and large castings often have casting defects, such as white spots, hard spots, etc. ; Second, the impeller is an intermittent cutting, which adds to the difficulty of processing. 三、How to choose tools for processing slurry pump parts

There are currently three types of cutting tools on the market that can process slurry pump parts: carbide tools, ceramic tools and cubic boron nitride（CBN） tools.

Personally, I think CBN tools are more suitable for machining slurry pump parts.

VS

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Due to the high hardness of the slurry pump parts after casting or heat treatment, they are difficult to process. Machinery manufacturers were the first to use carbide tools to process slurry pump parts. But due to the insufficient hardness of the body of the carbide tool, the surface of the slurry pump parts processed, especially the large castings, is uneven and has casting defects. The carbide tool wears quickly during the machining process, and a workpiece must be replaced before it is finished,which affects processing efficiency and high tool costs.

Ceramic tools are also not suitable for machining slurry pump parts. If choosing ceramic tools, you have to choose small feed amounts for fine machining of slurry pump parts without considering the overall benefits of the company.

Neither of the above two tools can solve the problem of difficult processing of slurry pumps. Then, CBN tools were developed. Although the brittleness of CBN tools is an indisputable fact, they are still impact-resistant compared to ceramic tools , but initially it is also mainly applicable to the finishing process. It was not until the non-metallic adhesive BN-K1 CBN inserts developed in my country that rough machining of slurry pump parts became a reality.

Halnn journal In terms of hardness: Halnn BN-K1 CBN inserts = traditional CBN tools > ceramic tools > carbide tools; In terms of toughness: Halnn BN-K1 CBN inserts > traditional CBN tools > hard Alloy tools>Ceramic tools; The advantages of my country's non-metallic binder CBN tool BN-K1: compared with carbide tools, it has high hardness and good wear resistance; compared with ceramic tools and traditional CBN tools, it has strong impact resistance and can Intermittent cutting of slurry pump parts impeller.

The following is a brief introduction to the case of my country's non-metallic adhesive CBN tool BN-K1 processing the impeller of slurry pump parts. 四、An example of using the non-metallic adhesive CBN tools BN-K1 to process the impeller of a slurry pump component (As shown below)

Processing material: high chromium cast iron Cr26; Processing process: turning outer circle and end face; Tool brand: BN-K1; Cutting parameters: vc=75m/min, ap=2.5-5mm, f=0.1mm/r; Processing method: interrupted cutting; dry cutting.

Processing effect: When turning the impeller, because the impeller has 5-12 blades, the tool must withstand 5-12 impacts per revolution of the impeller. There is no breakage during the intermittent cutting process of the BN-K1 CBN tool, and while the cutting speed of the non-metallic binder CBN tool BN-K1 is higher than that of the ceramic tool, the life of a single edge is 7 times that of ceramic tools, fully demonstrating the impact resistance of non-metallic binder CBN tools, which not only reduces the cost of tool use, but also improves turning efficiency. 五、Conclusion

With

the

continuous

development

of

modern

technology,

machinery

manufacturers are working hard to ensure a better service life of workpieces. For

Halnn journal example, the slurry pump industry also uses high-chromium cast iron that is more wear-resistant and corrosion-resistant as the main material, which is an invisible pressure on the tool industry. Faced with the above situation, the tool industry can only work hard to develop high-quality, high-performance and efficient tool materials in order to adapt to the development of the times.

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