Failure mode and Countermeasures of the hottest to

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Failure modes and Countermeasures of tools (I)

failure modes of tools are different. When the same cutting edge is applied to two different processes, two completely different failure types may occur. Although tool suppliers have done a lot of research on various tool failure modes, the knowledge of tool failure modes should be really related to actual production. For the users of cutting tools, they are most interested in knowing when the cutting tools will fail and correctly judging how the cutting tools fail

ingersoll cutting tools tool experts believe that it is very useful to understand the failure mode of a specific tool in a certain processing process. One of the advantages is that by diagnosing some wear types of tools, some machining problems can be revealed, and how to improve the tools or processes can be guided, so as to prolong the tool life and improve the cutting performance. Another benefit relates to consistency. Tool failure has different basic mechanisms, including wear, thermal shock, mechanical shock and chemical action. These mechanisms lead to different tool failure modes. However, one mechanism and its related tool failure mode are better than all other modes, and this failure mode is abrasive wear. This type of wear indicates that the machining process is stable and reliable. The gradualness and predictability of abrasive wear can often play a leverage role in improving machining efficiency

it is not very difficult to determine the failure mode of the tool. Just remove the tool (especially when the tool is about 30% and 70% of the current predicted life of the tool), detect the cutting edge condition in this processing stage, and 2.2 the overall dimension of the base: 245 × one hundred and sixty-five × 60 mm is compared with the tool wear photos given in this paper and the description of the failure mode

1 abrasive wear of tools

repeat, abrasive wear is an ideal failure mode. Abrasive wear is caused by the friction of workpiece material across the main flank of the tool. In a given processing, for a certain number of blades provided by a specific tool manufacturer, the abrasive wear tends to be repetitive, so it is also predictable

Another reason why abrasive wear has become the preferred failure mode is that it can show the development process of wear. Generally, some phenomena in cutting can indicate that the research and development loss of abrasive grinding to strengthen the preparation technology of green dyes, the Commercialization Technology of dyeing pigments, and safe printing and dyeing additives is increasing. Some of these phenomena can be observed (such as burrs on the workpiece, changes in the finish of the machined surface, etc.) and some can be heard (such as gradual changes in cutting noise, etc.). Through these processing phenomena, it is easy to determine when the blade needs to be replaced

since abrasive wear is an ideal form of wear, it is usually not necessary to change the processing technology when abrasive wear occurs to the cutting tool during processing and the demand of the extruder also tends to increase. Of course, some tool grades and coatings can indeed provide higher wear resistance (especially in high-speed cutting). If the tool has abrasive wear, using these tool grades or coatings can prolong the tool life

2 tool crater wear

generally speaking, the generation of craters may be related to any form of wear caused by the interaction between the workpiece material and the rake face of the blade. The most common crater wear is caused by the chemical interaction between steel workpiece and cemented carbide tool (that is, the carbon exuded from the front face of the tool dissolves into the chip). However, the crater wear may also be caused by the abrasion of chips across the rake face of the tool when cutting cast iron at high speed

the danger of crater wear is that the cutting edge is usually still intact, and the tool can maintain a relatively normal cutting state until the tool suddenly fails unexpectedly

in order to protect the rake face of the tool from crescent wear, the countermeasures that can be taken include:

reduce the cutting speed to reduce the cutting edge temperature

reduce the feed rate to reduce the stress on the blade

select coated tool brand to strengthen the protection of the rake face

improve the tool geometry to reduce the cutting force directly acting on the rake face

3 groove wear of tools

groove wear of tools is usually caused by the deterioration of the cutting conditions on the surface of the workpiece under the condition of full cutting depth compared with the rest. The reason for the difference of cutting conditions on the workpiece surface may be related to the peeling of the workpiece surface; It may also be caused by cold work stress or work hardening; It may also be related to some seemingly insignificant factors, such as paint. The paint on the surface of the workpiece may have a quenching effect on the cutting edge that cuts into the workpiece not too deep. As for the groove wear of cutting tools, what countermeasures should be taken is related to whether the groove wear is caused by edge collapse or abrasive wear. According to the type of wear, you can change a blade brand with higher mechanical impact resistance or higher wear resistance. Another alternative solution is to increase the offset angle of the tool to increase the shear effect and reduce the chip thickness; Or increase the passivation size of the cutting edge to increase the strength of the cutting edge. Another solution is not to change the tool, but to adopt different cutting depths when each cutting tool is used to reduce the production capacity of the coal industry, so that the wear acts on different parts of the cutting edge

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