When it comes to CNC turning, knife lines can be a real nuisance. CNC turning parts are often machined with knife lines. They’re those pesky little marks that appear on the surface of your turned parts. Knife lines are the result of a tool overhang that causes the tool to cut into the material as it moves past the part’s edge. While they may not seem like a big deal, they can really affect the overall appearance of your finished product. In this blog post, we’ll take a look at what causes knife lines and how you can prevent them from appearing in your parts.
1. Main shaft bearing wear
Main shaft bearing wear is a common issue that can lead to lathe cutting tools having knife lines. As lathe cutting tools rotate at high speeds, the main shaft bearings are subject to a great deal of wear and tear. Over time, this wear can lead to the development of knife lines on CNC turning parts.Knife lines are caused by the uneven wear of the main shaft bearings. As the bearings wear down, they become misshapen and no longer rotate smoothly. This causes the lathe cutting tool to vibrate, which in turn creates knife lines on the finished product.
This can be a serious problem if not addressed, as it can cause the lathe to function less accurately overall. CNC turning parts are especially susceptible to this problem, as the tight tolerances required for these parts means that even a small amount of wear can cause issues.
To avoid knife lines, it is important to regularly inspect and replace main shaft bearings. Doing so will ensure that lathe cutting tools rotate smoothly and evenly, resulting in better quality products.
2. Improper use of tools
If lathe cutting tools are not used correctly, it can result in CNC turning parts having knife lines. In order to avoid knife lines on CNC turned parts, it is important to use the correct lathe cutting tool for the material that you are working with. The type of lathe cutting tool that you use will depend on the material that you are working with and the desired finish.
There are a few different types of lathe cutting tools that can be used for CNC turning.
– HSS (High Speed Steel) Turning Tools: These lathe cutting tools are made from high speed steel and are designed for general purpose lathe turning.
– Carbide Turning Tools: These lathe cutting tools are made from carbide, which is a harder material than high speed steel. Carbide lathe cutting tools are designed for use on harder materials and for finishing operations.
– Ceramic Turning Tools: These lathe cutting tools are made from ceramic, which is an even harder material than carbide. Ceramic lathe cutting tools are designed for use on very hard materials and for very fine finishing operations.
When using a lathe cutting tool, there are a few things to keep in mind in order to avoid knife lines:
– Use the correct lathe cutting tool for the material that you are working with.
– Use the lathe cutting tool correctly.
– Make sure that the lathe cutting tool is sharp. If the lathe cutting tool is not sharp, it will cause knife lines.
– Make sure that the lathe cutting tool is properly lubricated. If the lathe cutting tool is not properly lubricated, it can also cause knife lines.
Improper use of lathe cutting tools is the main cause of knife lines on CNC turned parts. By using the correct lathe cutting tools and using them correctly, you can avoid this issue.
3. The CNC turning material is too soft
Too soft CNC turning material can leads to CNC turning parts have knife lines. This is because the material is not strong enough to withstand the forces exerted by the CNC turning process. As a result, the material will deform and produce visible knife lines on the surface of the finished part. When lathe cutting tools are used on softer CNC turning materials, toolbit digging into and carving out small channels in the workpiece material. The channels will be more visible if the workpiece material is a lighter color, but they can still be present even in darker materials.
In order to avoid this problem, it is necessary to use a harder material that can resist deformation during the CNC turning process.
4. The concentration of cutting fluid is too high
The high concentration of cutting fluid can cause the CNC turning parts to have knife lines. Knife lines are thin, raised lines that form on the surface of the material being cut. They are caused by the accumulation of cutting fluid on the surface of the material. When the cutting fluid is applied too heavily, it can cause the machined surface to be rough and uneven. When the cutting fluid evaporates, it leaves behind a residue that causes the formation of knife lines. In addition, the high concentration of cutting fluid can also lead to corrosion on the CNC turning parts.
Knife lines can be unsightly and can cause the finished product to be of poor quality. In order to avoid the formation of knife lines, it is important to maintain the correct concentration of cutting fluid. If the concentration of cutting fluid is too high, it should be diluted with water.
Conclusion
When it comes to CNC turning parts, knife lines are often an unavoidable side effect of the machining process. However, with the right precautions and by understanding the factors that cause them, you can minimize their appearance on your finished products. By following these tips, you can produce high-quality CNC turned parts that look great and meet all your specifications.
