How to high speed and high precision hole machining?

October 29, 2023

Answer: In addition to Precision Machining of the hole by CNC cutting method, the hole can be processed with high precision by boring and reaming. With the high speed of the machining center spindle, the boring tool can be used to perform high-speed precision machining of the hole. It has been reported that the cutting speed can be increased to more than 1500 m/min when φ40 mm boring is performed on an aluminum alloy material. Such a cutting speed can also be employed when machining a steel, cast iron, and high hardness steel using a CBN sintered body as a cutting edge. It is expected that the speed of boring and processing will be popularized in the future.
In order to achieve high speed and high precision of boring, it is necessary to pay attention to the influence of tooth vibration on the surface roughness and tool life. In order to prevent machining accuracy and tool life from falling, the selected machining center must be equipped with a spindle with excellent dynamic balance. The selected boring tool must also have high dynamic balance characteristics. Especially for the cutter part of the boring tool, the geometry, tool material and the clamping method suitable for high-speed cutting should be selected. The R of the end of the cutting edge should be larger to improve the processing efficiency; the feed rate should be increased under the premise of ensuring the same surface roughness. However, increasing the feed rate should be adequate, otherwise it will increase the cutting resistance, which is not conducive to improving the processing efficiency. The cutting edge should be set with a negative chamfer of 0.1mm or less, which can effectively maintain the stability of the tool life.
As for the tool material, it varies depending on the nature of the material being processed. For materials such as steel below 40HRC, cermet cutters can be used. This tool can achieve good surface roughness and long tool life under high-speed cutting conditions of v=300m/min. Coated cemented carbide tools are suitable for high-speed cutting of steels below 60HRC. The tool life is very stable, but the cutting speed is slightly lower than that of cermet tools.
CBN sintered body cutter is suitable for processing high hardness steel, cast iron and other materials, cutting speed can reach more than 1000m / min, and the tool life is very stable. The edge portion of the CBN cutter should be properly chamfered, which is extremely beneficial for stable high speed cutting and extended tool life. In the case of ultra-high-speed cutting of non-ferrous metals and non-metallic materials such as aluminum alloys, diamond sintered body tools are available, which are stable in cutting and long in tool life. It should be noted that when using a diamond tool, the blade edge must be chamfered, which is an important condition for ensuring the stability of the cutting.
In terms of reaming, there has not been a new high-speed, high-precision tool, and the research and development work in this field seems to be in a state of stagnation. High-speed reamers have so far been used by some specific users for high-speed, high-precision hole machining. This reamer has a negative rake angle, high rigidity, good chip breaking effect, and stable precision hole machining under high-speed cutting conditions. The reamer is characterized by a large negative rake angle and an odd number of teeth, and the speed of high-speed cutting is unachievable by the past reamer. Therefore, it can be said that this design has bolded the traditional concept of the reamer. Breakthrough is a highly efficient reaming tool.

Author:

Ms. YolandaG

E-mail:

seals@jakeconn.com

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+8613802258285