What is the Reason for the Appearance of Knife Lines in CNC Turning Parts?

CNC turning is a kind of machine tool that is widely used. It can select dozens of tools from the programs preset by the CNC system to CNC turning parts, not only can be controlled by the coordinate system) Accurate cutting or other CNC machining positions , and can also control the rotation speed and the feed speed of the tool according to the part material to achieve flexible machining and the desired part shape.

Most CNC turning parts with knife lines are found during inspection, and some even suffer from user complaints. If you want to avoid user complaints, you need to find out the cause of knife lines. Only in this way can corresponding solutions be adopted to maintain the economy and service life of CNC turning parts. The following will briefly introduce the reasons and solutions for CNC turning parts with knife lines.

The reason why CNC turning parts have knife lines

1. Main shaft bearing wear

When the main draw bearing is too heavy, its radial runout will also increase. Especially the front bearing of the spindle, if the clearance of the front bearing of the spindle is large, it will cause the increase of radial runout. During CNC machining, its force will change, causing the front end of the spindle to retract and offset outward, thereby Knife pattern is formed. At this time, the surface of the CNC turning part will have a full circle of retraction patterns.

2. Improper use of tools

If the passivated tool edge is still used, although the finish and shape tolerance of the CNC turning parts meet the process requirements, the passivation of the tool edge will be directly reflected on the surface of the CNC machined parts, so that after the CNC turning parts are processed , the surface springs back, which causes the tip of the tool to touch the surface of the machined part when it is withdrawn, causing knife lines to appear on the surface of the CNC turning part.

3. The CNC turning material is too soft

If the copper content of the workpiece is too high or the aluminum content is too high, the CNC turning part material is ductile, and the cutting tool or CNC turning part in the high-speed rotation will generate high temperature, which is enough to melt the copper or aluminum. Because copper scraps or aluminum scraps will be discharged from the rake face, over time, a built-up edge will be formed on the rake face. When the CNC turning parts are completed, there will be knife lines on the surface of the CNC turning parts.

4. The concentration of cutting fluid is too high

If the concentration of the cutting fluid is too high, it will be unfavorable for chip removal in the process of CNC turning parts, and the lubricity will also be insufficient, resulting in knife lines on the surface of CNC turning parts.

The solution to the knife pattern of CNC turning parts

1. Replace the spindle bearing; if the wear of the spindle bearing increases, the spindle bearing needs to be replaced. Spindle bearings are relatively expensive. We need to judge carefully to determine whether the spindle bearings are worn. If the CNC turning parts have knife lines and the spindle bearings are not worn, you can carefully check the clearance of the spindle bearings and make correct adjustments.

2. Correct use of the tool: In the process of using the existing tool, according to the cause of the tool failure, establish the correct tool use method, fully meet the adjustment quality of the tool, and solve the failure cause of the tool due to human error.

3. Do not choose CNC turning materials with high copper content: CNC lathes can process a variety of workpiece materials, no matter what type of workpiece materials can be used for CNC turning parts processing, such as copper parts, stainless steel and zinc alloys. There are some metal CNC machining parts of carbon steel material or alloy steel material, etc., as long as the copper star or aluminum content of the CNC turning material is not too high, there will be no knife lines.

4. Adjust the concentration of cutting fluid: In CNC turning parts, the lubricating effect of cutting fluid is very important. When the pressure and concentration of the cutting fluid meet the requirements of CNC turning, it can usually prevent the formation of rake area chips, especially when CNC turning aluminum parts, it is necessary to pay more attention to whether the pressure and concentration of the cutting fluid are normal. Controlled range, and need to add appropriate oily agent and extreme pressure agent.

The above is the relevant content of CNC turning parts with knife pattern. By browsing the above articles, we can understand that the spindle bearing wear, the unreasonable use of the tool, the workpiece material is too soft, and the cutting fluid concentration is too high will cause the processed workpiece to have knife lines. Therefore, in order to maintain the quality of CNC turning parts, according to certain The solution to implement effective control to solve the appearance of knife lines. If you have a better one, you can contact us: [email protected] to discuss with us.

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