é»›Jie CBN tool processing application

CBN cutters have high hardness, long-term wear resistance, excellent thermal stability, good chemical stability, second only to the thermal conductivity of diamond, very low friction coefficient, can be repeatedly reground, now CBN inserts Widely used in aerospace, automotive, electronics, rail transit and other fields, it has greatly promoted the rapid development of high-speed machining and advanced manufacturing technology. Authoritative organizations even use this tool to measure the proportion of a country. The advanced level of processing technology.

CBN (cubic boron nitride) is a hexagonal boron nitride BN which is metamorphosed into cubic crystals under high pressure and high temperature, and does not exist in nature. CBN cutters are made by sintering CBN particles with Co, AL or other special ceramics at the same ultra-high pressure and high temperature. Its hardness is only diamond, and CBN tools have far better stability and chemical stability than diamond, which is unmatched by diamond.

CBN tools can be used for semi-finishing and finishing of hardened steel, chilled cast iron, superalloys, etc. with carbide cutting speed of ordinary steel and cast iron. The machining precision can reach IT5~IT6, and the surface roughness can be as small as Ra0. .8~0.2um can replace grinding.

1) Milling

In order to introduce a new CBN mirror ball-end milling insert in the autumn 2010 new product exhibition, many mold manufacturers generally need to use 2~5 coated blades to complete the large-scale stamping die finishing. However, it is easy to produce a knife mark on the finished surface. Therefore, whether or not only one blade can be used, the processing is completed while ensuring high-speed and high-efficiency processing and the finished surface is mirror-finished, which becomes the key to improving the processing precision and quality. In this regard, the new CBN mirror ball-end milling insert developed by Yan Jie can perform long-life high-speed cutting, which greatly shortens the processing time of large-scale stamping die finishing. The use of CBN material extends the life of the tool. Almost all automotive exterior parts can be finished with only one blade, and the blade can be reground, saving machining costs.

(Left - Table 1 Right - Table 2)

In the processing of cast iron stamping dies, CBN mirror ball-end inserts have extraordinary remarkable effects. The following are two cutting tests made by our company with the inserts. The test materials are made of FC250 gray iron and FCD600 ductile iron.

Table 1 In the CBN test, a set of gray iron stamping die was machined using CBN material BNM-300 blade. The cutting speed was Vc=1.414m/min, the feed f=0.6mm/rev, and the average processing of cemented carbide coated inserts. For 60 hours, the processing time of the CBN insert processing die is shortened to 40 hours, which is nearly 2/3 shorter than that of the carbide coated blade. The surface of the machined workpiece has a luster, especially the convex effect. General gray cast iron machining generally uses a coating hardness alloy below 300m/min, 300~500m/min for ceramics, 500m/min or more, and the practical tool material is CBN. However, recent studies have shown that cutting ordinary gray cast iron with CBN, when the speed exceeds 800m/min, the tool life is longer with the increase of cutting speed. The mechanism is generally considered to be due to the formation of Si3N4 on the surface of the cutting edge during the cutting process. , AL2O3 and other protective film instead of the blade wear. Therefore, it can be said that CBN will be the first choice for tool materials for ultra-high speed machining.

Figure 2 This time we use CBN to process another pair of harder ductile iron stamping dies. It is difficult to machine a pair of ductile iron stamping dies with a piece of carbide coated blade, often requiring 2 coated blades. And the processing parameters of the carbide coated blade are usually n=8000min-1, Vf=5000mm/min, it is difficult to reach the processing parameters of the CBN insert, and the processing efficiency of the CBN insert is improved by 1.8 times compared with the cemented carbide insert. The length is about 7km, and only one mold is processed in 22 hours. In this CBN processing test, the spray-cooled surface is very relevant, which can effectively shorten the grinding time.

In summary, CBN can show superior wear resistance and smoothness in the surface processing of traditional large molds.

2) Turning processing

Yanjie Company also made great efforts in the turning of CBN tools. The JBN series is a cubic boron nitride material produced by Qijie Company using original technology. It has low affinity with iron materials, low reactivity, and can be cut more stably at high temperatures. It is a series of high hardness materials for iron series processing. The most ideal tool for ultra-high speed machining.

In recent years, in order to improve machine characteristics, the amount of sintered alloy materials produced by heat treatment, high density, or addition of elements has been increasing, and the cutting properties of these sintered alloys are getting worse. CBN tools are very effective for cutting such materials.

From the test results, CBN tools can have significant processing efficiency when processing sintered alloy workpieces, and the original JBN cubic boron nitride material is the first choice for CBN tools for processing such difficult-to-machine materials.

to sum up

It can be seen from the above cases that in the automotive and mold processing industries, CBN tools have outstanding effects, and CBN blades in other aerospace, electronics, rail transit and other fields have a good performance.

To this end, the level of manufacturing technology should be improved as soon as possible, and the promotion of the use of CBN tools to improve manufacturing technology is a powerful measure, which not only requires strong funding and support from relevant authorities, but also systematically and systematically promotes the technical support of CBN tools. Use, but also requires users to accept new materials, new technologies, change the old obsolete production concepts and management methods, that is, the tool consumption cost index is very low, only about 1 / 100 of the cost of the product, rather than improve production efficiency And to ensure product quality, this will limit the quality and efficiency of tool applications and advanced equipment production capacity. Practice has proved that the effectiveness of CBN tools can not only improve the processing quality of products, but also improve economic efficiency.

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