CNC machine tools are computer-controlled, high-precision automated machines that use cutting tools in repetitive patterns for precise feed movements. CNC machining tools are usually used in the manufacture of parts that require high precision and accuracy. Once the CNC machining tool is damaged, it will lose the ability to cut the workpiece material, thus making the accuracy of the machined part decrease or even unable to complete the machining as scheduled. The following article will introduce in detail the causes and solutions of damage to CNC machining tools.
Damage to CNC machining tools is the failure and gradual failure of cutting tools due to routine operation. Every tool will experience minor wear and tear at some point in its life cycle. However, tool damage can harm the workpiece, so avoiding tool damage is important to achieve optimal end-mill performance. CNC machining tool damage can also lead to equipment failure, which can result in serious damage, rework, and part scrap.
In order to extend CNC machining tool life, identifying and mitigating the various signs of tool damage is key. Both thermal and mechanical stresses can lead to CNC machining tool damage, with heat and wear being the primary causes. Learning how to identify the most common types of CNC machining tool damage and their causes can help machinists quickly solve problems and extend tool life.
CNC machining tool damage causes and solutions
1. CNC machining tool damage surface flaking
For brittle CNC machining tools, brittle materials such as carbide and porcelain are prone to spall conditions when the surface of the machining tool is subjected to alternating contact stresses due to defects or potential cracks in the surface structure, or residual surface stresses from welding, grinding processes, etc. Tool flaking may occur on the front tool face as well as the rear tool face. The flakes are flaky and the peeled area is large. The coated tool may flake off and the machining tool may continue to work in less severe cases, while in severe cases it will lose its cutting ability.
2. Cutting part plastic deformation
Some CNC machining tools of steel and high-speed steel material strength and hardness are relatively low, the cutting part may occur plastic deformation. Carbides in high temperature and three-dimensional compressive stress when working directly under the surface will also produce plastic flow, or even cause plastic deformation of the cutting edge or tooltip, resulting in surface collapse. The collapse generally occurs at high cutting volumes and when machining hard materials. TiC-based carbide has a smaller modulus of elasticity than WC-based carbide, so the former has accelerated plastic deformation resistance.PCD and PCBN are essentially free of plastic deformation.
3. Thermal cracking of CNC machining tools
When CNC machining tools are subjected to alternating mechanical and thermal loads, alternating thermal stresses will inevitably be generated on the surface of the cutting part due to repeated thermal expansion and cold contraction, resulting in cracking of the CNC machining tool and thus scrapping. For example, when a tool made of hard alloy is used for high-speed milling, the teeth of the tool are constantly subjected to cyclic impact and alternating thermal stresses, resulting in vertical cracking on the surface of the front tool. Some CNC machining tools are not subject to significant alternating loads and stresses, but they can also be subject to thermal stresses due to inconsistent surface and internal temperatures. In addition, there are unavoidable defects in the CNC machining tool material, so cracks may also occur in the insert. After cracks form, the tool can sometimes continue to work for some time.
4. CNC machining tool backside wear
CNC machine tool grain wears usually occurs on the back face of the tool, and this is caused by mechanical alternating stresses. If the tool material hardness is not high, the cutting speed is too high during machining and the feed is too small, it can lead to excessive damage on the back surface of the CNC machining tool, which reduces the size. The accuracy of the machined surface increases the frictional resistance during large cutting. Therefore, as far as possible, you should use tool materials with high wear resistance, while reducing the cutting speed, increasing the amount of feed, and increasing the back angle of the tool to avoid or reduce the possibility of tool surface wear after the generation of CNC machining tools.
