High-temperature alloy machining must pay attention to: both the requirements of the tool sharp, but also to ensure adequate tip strength. The edge must be carefully sharpened, to maintain a better surface roughness of the tool, to ensure that the edge is smooth, do not allow any chipping, notching, cracks and burrs, to prevent the blade from crashing damage in the processing of high temperature alloys. When choosing carbide cutting tool materials, attention should be paid to the size of the alloy particles.
The smaller the particles, the higher the tool life and the greater the resistance to boundary wear. The wear resistance of the blade should be good in order to ensure the processing of high temperature alloy engine parts high technical conditions and surface quality. An engine part, the material is Inconel 718, in the turning bore process: processing length 109.5mm, hole diameter of 166mm. As the surface runout value of the bore is 0.02mm, the surface roughness is R, 0.8μm, the requirements are very high, and the material itself is very poor machinability. Finishing the use of general inserts has been difficult to ensure that the requirements of the runout value is generally 0.05mm, often exceeded; and processing efficiency is low, the blade is easy to wear. In order to solve this problem, we have tested and compared the selection of VNGP160408 S05F. This insert adopts a new technology, which is designed for the cutting of nickel-based high temperature alloys. The insert is made of finer grain and has a thin coating of CVDTiCN-ALO3-TiN of 4μm on the surface.
According to the product catalog: this insert is particularly suitable for finishing nickel-based high-temperature alloys with good wear resistance and for small depth of cut. The parameters we used in the test: rotational speed 40r/min, feed 0.18mm/r, depth of cut 0.1mm, but the runout value is still 0.025mm, and the insert has wear. Through the analysis, we believe that the cutting parameters are too low. First of all, 0.1mm depth of cut, is cutting on the hardened layer, strictly speaking, not cutting but grinding; Moreover, the hardened layer is much harder than the substrate, natural blade wear faster. On the other hand, its line speed is too low, easy to cause cold welding phenomenon, resulting in poor surface quality, and this blade is G tolerance, higher speed to show the superiority. So improve the parameters: speed 60 r/min, feed 0.18mm/r, depth of cut 0.25mm. Processing a few cuts, the blade is almost no wear, runout value of 0.01mm, within tolerance. The surface is very good. It reaches R.0.8μm or less. Cutting time compared to the original compared to reduce the 7min. using this new insert to solve the problem of ultra-differential, to ensure the quality, and the comprehensive calculation of the cost has been reduced. Another high-temperature alloy parts, there are end grooves, about 10mm wide, 28mm deep, and groove surface runout value of 0.015mm, with the original insert is difficult to ensure that often exceeds the difference. Because the general manufacturers of groove knife positioning is V-type arc positioning, with the side of the edge processing will have a small fluctuation, although these small fluctuations only in a number of micron interval, but if repeated, so that the cutting edge in the inappropriate position, will affect the accuracy of 0.015mm guarantee. We reviewed the information and chose a new type of insert from a manufacturer. This insert and the toolholder with is T-guide positioning, this T-guide design will be accurately fixed in the blade body, and highly stable to maintain the cutting edge position, will not produce runout. We use T-guide positioning groove tool machining, effectively solve the problem of groove surface runout value over the difference, to ensure that the runout accuracy of 0.015mm. My company processing a sub-package parts are more than 1 meter in diameter ring-shaped parts, wall thickness of 2mm, the runout value is very high, and is a high-temperature alloy materials, it is difficult to ensure the shape and position tolerance. Because of the large diameter and thin wall, general blade processing will produce deformation. And after the deformation of the knife phenomenon, surface hardening, the tool is very easy to wear. Through analysis, we believe that preventing deformation is the main task when machining this piece, which requires a sharp tool that does not produce work hardening. We boldly adopted a large front-angle polishing insert for machining aluminum alloys.
This kind of insert is originally for processing aluminum materials, and now it is used in the processing of high-temperature alloy thin-walled parts with good results. We have tested two kinds of inserts VBGT160408-W-25, VCGT160408F-AL KX results are very good. The original processing of a large surface with high-temperature alloy inserts, the middle to change the knife, there is a knife mark and deformation in the amount of 0.05mm or more, need to make up the processing. With a large front angle polishing inserts in the middle without changing the knife, due to the sharp tip, but also greatly reduce the amount of deformation, the amount of deformation is controlled within 0.02mm, to ensure that the shape and position tolerance requirements.
Post time: Aug-05-2023
