Initial wear stage

Wear characteristics and reasons: The cutting edge of the tool will wear out quickly when it is first used. This is mainly because there are micro roughness on the surface of the cutting edge of the tool, and during the cutting process, these small protrusions will be quickly ground flat. At this stage, the wear rate is relatively fast, but the amount of wear is usually small.

Cutting parameter adjustment strategy: At this stage, in order to ensure a smooth transition of the tool to the normal wear stage, the cutting speed can be appropriately reduced by 5% -10%. For example, if the initial cutting speed is set to 100m/min, it can be adjusted to 90-95m/min. At the same time, the feed rate can also be slightly reduced, generally by 3% -5%. If the original feed rate is 0.2mm/r, it can be adjusted to 0.19-0.194mm/r. The cutting depth can be kept constant because the initial wear is mainly concentrated on the edge surface, which has a relatively small impact on the ability to withstand the cutting depth.

Normal wear stage

Wear characteristics and causes: After initial wear, the tool enters the normal wear stage. At this point, the tool wear rate is relatively stable, and the wear amount increases uniformly with the increase of cutting time or cutting length. This is because factors such as friction and cutting heat between the cutting edge of the tool and the workpiece material gradually cause the tool material to wear out.

Cutting parameter adjustment strategy: When the tool wear reaches a certain level (such as the width of the wear band on the back surface of the tool reaching 0.1-0.2mm), the cutting speed can be appropriately reduced by 3% -8% to slow down the wear rate. For example, if the cutting speed is originally 80m/min, it can be adjusted to 74-77m/min. The feed rate also needs to be appropriately reduced by 2% -6%. Assuming the original feed rate is 0.15mm/r, it can be adjusted to 0.14-0.147mm/r. The cutting depth can be adjusted according to the precision requirements of the workpiece and the remaining life of the tool. If the precision requirements are high, the cutting depth can be appropriately reduced by about 0.05-0.1mm each time; If the precision requirement is not high and the remaining tool life is sufficient, the cutting depth can be kept constant.

Rapid wear stage

Wear characteristics and causes: After the tool wears to a certain extent, it will enter a stage of rapid wear. At this point, the wear rate of the cutting tool increases sharply, and the cutting edge may experience phenomena such as chipping and peeling. This is because after tool wear, the cutting force increases and the cutting temperature rises, resulting in a change in the wear mechanism of the tool material, from normal abrasive wear to more serious forms of wear such as adhesive wear and diffusion wear.

Cutting parameter adjustment strategy: Once the tool enters the stage of rapid wear, machining should be stopped immediately. At this stage, it is not recommended to adjust the cutting parameters to continue machining, as this can lead to a serious decrease in machining quality and may even damage the workpiece and machine tool. If you want to continue processing, you must replace the tool and set reasonable cutting parameters based on the condition of the new tool. The cutting speed of the new tool can be reduced by 5% -10% compared to the normal wear stage of the previous tool, and the feed rate can be reduced by 3% -7%. The cutting depth also needs to be re evaluated based on the remaining machining allowance and accuracy requirements of the workpiece. Generally, it should be appropriately reduced compared to before to ensure machining quality and tool life.