PCBN tools with high quality and good stability, in the automotive, aerospace and medical equipment and other industrial areas of many mechanical processing has a strong competitive. In the rigidity of better machine tools and tool rest installed on the PCBN tool, manufacturers can make full use of the PCBN has the potential to improve productivity.
The basic form of PCBN tool
The new PCBN integral cutting tool with larger size and thicker has good wear and impact resistance characteristics. The tool has good wear resistance and impact resistance, which is the key means to process iron materials containing less than 10% ferrite. The improvement of tool wear resistance and impact resistance is particularly important for the processing of alloy cast iron parts in automobile industry. In the past, such alloy cast iron parts could be machined only through grinding. In rough machining of alloy cast iron, the tool must undergo discontinuous cutting caused by surface cracks, sand residue and other original surface discontinuities left over from the casting process. Good wear resistance also plays a big role in finishing, especially for the workpiece containing 28% ~ 30% chromium and the hardness between 68 ~ 70HRC.
(1) The integral PCBN blade has multiple cutting edges on both sides, thus reducing the tool cost per unit of production parts. Its cross section is 4.76mm thick, which is thicker than the 3.17mm of a conventional tool. This enables the blade to be mounted reliably on the standard gasket type carbide tool handle slot.
(2) PCBN blade is also made of full section and tip shaped. The full-section blade has a complete PCBN top surface, sintered on a cemented carbide substrate, and provides multiple cutting edges on only one side of the blade, which is less expensive than the monolithic blade.
(3) the tip blade is a PCBN blade welded on a corner of the carbide base. The tip blade is either a single cutting edge or a double cutting edge. Now most of the PCBN blades are tip - shaped. Both full - section and tip - shaped blades are manufactured to industry standard sizes and can be mounted in standard barrel-blade slots and milling slots as integral blades.
Dry cutting of PCBN tool
Although the PCBN tool in cutting has enough hardness to resist the deformation caused by cutting heat, but it is very brittle, if the coolant is added, due to the sudden drop in temperature prone to blade collapse. So the PCBN tool processing parts should be generally dry cutting, especially in the case of intermittent cutting, processing must not use coolant. The quality of the cutting tool has a great influence on the success of the PCBN tool processing. In order to prolong the life of the tool, the cutting edge of the tool must be strengthened with the appropriate tool grinding method. The grinding of PCBN tool varies with the processing materials and rough finishing.
PCBN cutting tools are more suitable for machining hard parts
The cutting tool made of PCBN is most suitable for the cutting of hard parts. In fact, the lower limit for the hardness of the machined part is 45HRC. If the PCBN tool processing hardness below 45HRC parts, will produce a mark. The cutting speed of the proper PCBN tool finishing varies significantly with the material of the workpiece, the height of the material, and the size and shape of the part. For example, you can achieve a cutting speed of 183m/min at a depth of 0.51mm in hardened steels with Rockwell hardness of 60 to 62HRC. The low surface roughness can be obtained when the feed rate is 0.05-0.1mm /r. The harder the material, the higher the cutting speed is required. However, cutting speeds greater than about 198m/min will lead to excessive wear. Ordinary cast iron can be machined at very high cutting speeds.
Conclusion
At present, the biggest development area of PCBN tool is high hard cutting -- the finishing of automobile engine alloy steel parts such as gears, shafts and bearings with a Rockwell hardness of 60 ~ 65HRC. Traditionally, such parts can only be made by grinding them. Moreover, the dimensional tolerances of the parts are very small and the surface roughness is very fine. High hard cutting allows the same results to be achieved on a CNC lathe at half the cost of machining the same quality parts on a CNC grinder, and the lathe's maintenance costs are also lower. High hard cutting due to the cutting depth of only 0.3 ~ 0.38mm, available low-cost PCBN tip tool. The test results of Carboloy Materials Corporation show that the surface roughness of hardened steel parts (60 ~ 62HRC) is 0.2 μm or less by continuous machining with knife tip PCBN.
