What is tool durability? What are the principles for determining a reasonable value for tool durability?

       In production practice, it is impossible to frequently unload the tool to measure whether the wear amount reaches the dullness standard. Therefore, it is necessary to find a quantity that can reflect the tool grinding to the dullness standard, which is the tool durability.



    Tool durability refers to the continuous cutting time of a newly sharpened tool from the start of cutting to the wear limit. Tool durability is represented by t(min). The tool durability can also be expressed by the cutting path Lm (Lm=ut is the cutting speed multiplied by the time) that the tool passes through to reach the wear limit or the number of parts N processed.

    From the meaning of tool durability, it can be known that it is based on a certain wear limit (VB value), but with different cutting conditions, the time for the tool to reach a certain wear limit is different. Therefore, in order to facilitate the application in production, the level of tool durability must be specified.

    Tool durability directly affects productivity and machining costs. During cutting, the tool durability is mainly affected by the cutting amount.

    From the perspective of production efficiency, when the tool durability is specified too high (that is, the time is too long), the cutting speed will be too low when the processing conditions remain unchanged, which will increase the cutting time and reduce the productivity; when the tool durability is specified too low ( That is, when the time is too short), although the cutting speed can be increased and the cutting man-hours can be reduced, the time for unloading the tool, loading the tool and adjusting the machine tool increases, and the productivity will also decrease.

    Considering the processing cost, when the tool durability is set too high, the cutting speed will be too low, and the cost of using machine tools and labor will increase, so the cost will increase; when the tool durability is set too low, the cutting speed may be However, the tool change time increases, the tool consumption and the cost related to the sharpening of the tool increase, and the time for the machine tool to stop due to the tool change also increases, so the processing cost also increases.

    In summary, the determination of a reasonable value of tool durability is usually formulated from the principles of highest productivity and lowest cost.