Chipping means that the cutting tools are missing, such as fine and jagged edges. The causes of chipping are that dusty tools such as carbide tools and ceramic tools are caused by sudden fluctuations such as cutting power and mechanical vibration, and major changes in the cutting temperature. Tool abnormalities such as chipping must prevent subsequent major chips (missing) and reduced processing accuracy, so it must be prevented. This article explains the causes of chipping in cutting and countermeasures.
Both wear and chipping are abnormal tools that interfere with normal cutting, but wear refers to the gradually decrease in the edge of the blade. Typical wear types include frank wear and crater wear. Frank wear refers to the wear that occurs on the horizontal surface (escape surface) on the scooping surface. Wearing on the escape side often occurs because the escape angle is weak. Therefore, it is necessary to change the mechanical angle and the processing angle with the tool. On the other hand, the crater wear is also called "scooping surface wear", and is the main cause of the tool species that are too soft and the cutting heat is too high. The scooping surface is constantly exposed to severe frictional heat between the chips, so it is easy to make a hollow on the scooping surface as a wear mark. On the other hand, chipping refers to a phenomenon in which a mechanical impact is applied to the edge of the blade due to the reasons described later.
Tool materials and cutting conditions have a significant effect on chipping. Chipping occurs when the amount of sending is large, if it is too small, the cutting tool is hard, and the cutting edge is sharp. In response to this measure, it is necessary to pay attention to elements such as the relative hardness of the tools and the amount of transmitting of the tools.
The harder tools, the better the wear resistance, but as the hardness increases, the strength (the strength of the tool) becomes weaker. If the tools are harder than necessary for the processing work, they will also lack the necessary strength at the same time, making it easier for chipping to occur. In particular, hard tools such as carbide and ceramic tools require attention to the shock and vibration during cutting.
If the amount of sending is large, the load on tools and frictional heat will increase, causing chipping. In addition, the occurrence of chopping resistance and the occurrence of cannot be processed can cause intermittent impacts to the tools, causing chipping.
If the tip of the configuration on the edge of the blade drops off, the edge of the blade may come off with the tip of the configuration, causing chipping. In addition to chipping, the configuration blades cause dimensional accuracy, so it is important to pay special attention in extension materials such as soft steel, such as soft steel, which tends to have a configurated blade tip.
The following issues caused by chipping include: Finished surface deterioration Tool folding
If you continue to process while chipping occurs, the cutting resistance will increase and the finish will deteriorate. If the finish surface becomes a surface like a pears without glossy, it is necessary to check the condition of the blade because there is a possibility that chipping and configuration tip may have occurred.
If you continue to process while chipping occurs, you will be able to split from the chipping area, leading to a tool fold. In order to prevent the tools during processing, preliminary measures for chipping are required.
In order to prevent the occurrence of chipping, measures on site, such as tool selection and setup, are indispensable. The following measures for each three cases that cause the occurrence of the chipping are as follows.
We will review the selection of tools, such as tool material and blade shape, and take measures to prevent them. In the selection of tools, the balance between the compatibility with the work material and the processing efficiency and quality is important.
In the large intermittent processing of the impact, it is changed to a soft tool material. It is important to note that if the tool material is too soft, the tools will soften and plastic deformation due to cutting heat. When using hard tools such as carbide, coating processing can increase the resistance to shock and vibration and prevent chipping.
The sharpness of the blade, the easier it is to chips, so chipping is prevented by changing the shape of the tip of the blade to a corner R (rounded). Honing (chamfering of the blade) that keeps the strength of the blade and tools with a land (edge) are also effective. The end -mill with a strong twist is basically suitable for processing soft metals such as aluminum and copper, so if it is used for hard metals such as stainless steel, tools such as radius end mills. You should replace it with.
A tool with a low compatibility with the work (the property of tying) suppresses the occurrence of the configuration tip and prevents chipping. In the case of steel material, we recommend coated tools and serumets with coated processing. In particular, the thermet has a low affinity with iron and is ideal for finishing steel materials.
We will review the cutting conditions such as the cut amount and the number of revolutions and take measures to prevent it. Adjustment of cutting conditions also affects processing efficiency and finishing quality, so balance is important.
By reducing the cut amount and reducing the cutting resistance, it prevents chipping. Reducing cutting resistance can also help suppress vivis and emission of cut powder. It is also effective when using hard tools that tend to chips, such as ceramic tools and thermets.
By increasing the lubricity by coolant, it prevents chipping. By suppressing the heat generation of the cutting point, it can be expected to prevent chipping due to sudden temperature change. It is important to note that if the cutting temperature is too low, it will lead to the development of a configuration blade.
Generally, the lower the number of tools and work rotations, the less the cutting resistance and the less chipping. At low speeds, the configuration blade tip is likely to occur, so during actual work, the rotation speed is gradually reduced and adjusted while watching the situation.
In this article, we explained the causes of chipping generated by cutting and countermeasures. It is almost always a chipping that occurs in machine processing, but it is important to detect early because small chipping can eventually lead to unexpected mechanical suspension. In particular, how to detect tools such as chipping and other abnormalities in the labor -saving line using CNC machine tools is an issue for improving productivity.
