In recent years, the development of multi-functional and high-functional mechanical products is very strong, and parts must be miniaturized and miniaturized. In order to meet these requirements, the materials used must have high hardness, high toughness and high wear resistance, and materials with these characteristics are also very difficult to process, so new difficult-to-process materials have emerged. In this way, difficult-to-machine materials have emerged with the development of the times and different professional fields, and their unique processing technology has also continued to advance with the research and development of the times and various professional fields.

On the other hand, with the advent of the information society, information on cutting technology for difficult-to-machine materials can also be exchanged through the Internet. Therefore, in the future, information on cutting data of difficult-to-machine materials will be more abundant, and processing efficiency will inevitably improve. To improve, this paper takes the machining of difficult-to-machine materials as the core, and introduces the development trend of this technology in recent years.

Difficult-to-machine materials in the cutting field

In cutting machining, tool wear usually occurs in the following two forms:

(1) Wear due to mechanical action, such as chipping or abrasive wear;

(2) Wear due to heat and chemical action, such as adhesion, diffusion, corrosion, etc., as well as breakage, thermal fatigue, thermal cracking, etc. caused by softening and melting of the cutting edge.

When cutting difficult-to-machine materials, the above-mentioned tool wear occurs in a very short period of time, because there are many factors that promote tool wear in the material to be machined. For example, most difficult-to-machine materials have the characteristics of low thermal conductivity, and the heat generated during cutting is difficult to diffuse, resulting in high temperature of the tool tip, and the cutting edge is greatly affected by heat. As a result of this influence, the bonding strength of the tool material binder will decrease at high temperature, and particles such as wc (tungsten carbide) will be easily separated, thereby accelerating tool wear. In addition, some components of the difficult-to-machine material and some components of the tool material react under high temperature cutting conditions, and appear to be separated out, fall off, or generate other compounds, which will accelerate the formation of tool wear such as chipping.

When cutting materials with high hardness and high toughness, the temperature of the cutting edge is very high, and similar tool wear occurs when cutting difficult-to-machine materials. For example, when cutting high-hardness steel, compared with general steel, the cutting force is larger, and the insufficient rigidity of the tool will cause chipping and other phenomena, which will make the tool life unstable and shorten the tool life, especially when machining short-chip workpiece materials , crater wear will occur near the cutting edge, and tool breakage often occurs in a short period of time.

When cutting superalloy, due to the high hardness of the material at high temperature, a large amount of stress is concentrated at the tip of the cutting edge during cutting, which will lead to plastic deformation of the cutting edge; at the same time, the boundary wear is also serious due to work hardening.

Because of these characteristics, when users are required to cut difficult-to-machine materials, they must carefully select the cutting conditions of tool varieties to obtain ideal machining results.

Problems should be paid attention to when machining difficult-to-machine materials

The cutting process is roughly divided into turning, milling and cutting with core teeth as the main cutting (drill, end mill face cutting, etc.), and the cutting heat of these cutting processes has different effects on the cutting edge. Turning is a kind of continuous cutting, the cutting force on the cutting edge does not change significantly, and the cutting heat continuously acts on the cutting edge; milling is an intermittent cutting, the cutting force acts on the cutting edge intermittently, vibration will occur during cutting, and the cutting edge is heated Influence, heating during cutting and cooling during non-cutting are alternately performed, and the total heat received is less than that during turning.

The cutting heat is an intermittent heating phenomenon during milling. The cutter teeth are cooled when they are not cutting, which will help to prolong the tool life. The Japan Institute of Physics and Chemistry has made a comparative test on the life of turning and milling tools. The tool used for milling is a ball end mill, and the turning tool is a general turning tool. The cutting conditions of the two are the same (due to different cutting methods, cutting depth, feed , cutting speed, etc. can only be roughly the same) and cutting comparison tests under the same environmental conditions, the results show that milling is more beneficial to prolong tool life.

When cutting tools such as drills and ball end mills with a core edge (ie cutting speed = 0m/min), the tool life near the core edge is often low, but it is still stronger than turning.

When cutting difficult-to-machine materials, the cutting edge is greatly affected by heat, which often reduces tool life. If the cutting method is milling, the tool life will be relatively long. However, the difficult-to-machine materials cannot be milled from beginning to end, and there is always a need for turning or drilling. Therefore, corresponding technical measures should be taken according to different cutting methods to improve the processing efficiency.