CNC machine tools are widely used in production and processing because of their high precision and high efficiency. CNC machine tools cut metal through programming, which ensures the error caused by manual operation and improves the production accuracy. At the same time, mechanical processing is faster than manual processing, which also improves the processing efficiency to a certain extent.
Reasonable selection of cutting parameters
For high-efficiency metal cutting, the three elements are: processed materials, cutting tools, and cutting conditions. These have a certain impact on processing time, tool life and processing quality. Among them, if you want to process economically and effectively, you need to choose reasonable cutting conditions.
Cutting conditions are also composed of three elements: cutting speed, feed rate and cutting depth (cutting depth).
Cutting speed will have a serious impact on the tool. The increase of cutting speed will lead to the increase of tool tip temperature, resulting in mechanical, chemical and thermal wear. Data shows that cutting speed increases by 20%, and tool life will be reduced by 1/2.
The feed rate has little to do with tool wear, but if the feed rate is large, the cutting temperature will rise and the subsequent tool wear will increase. However, the feed rate has less effect on tool wear than cutting speed.
Although the cutting depth has less influence on tool wear than the first two, when cutting with small cutting depth, the hardened layer of the material to be cut will also affect the service life of the tool.
Therefore, during production, users need to choose the appropriate cutting speed according to the processed material, hardness, cutting state, material type, feed rate, cutting depth and so on.
How to determine the three elements of machining
1. Cutting speed: to select the revolutions per minute of the spindle, you must know the linear speed of cutting. The choice of this linear speed depends on the tool material, workpiece material and processing conditions, etc.
(1) Cutting tool material: selecting cemented carbide cutting tools can obtain higher linear speed, generally more than 100m/min. For high-speed steel, the linear speed can only be low, generally not more than 70m/min, and in most cases, it is less than 20-30m/min.
(2) Workpiece material: the workpiece material with high hardness has low linear speed. The linear speed of cast iron is low, and the use of cemented carbide tools is 70-80m/min.
(3) Processing conditions: rough processing, low linear speed; Finish machining, and the linear speed is higher.
2. Feed rate
The feed rate mainly depends on the requirements for the machined surface roughness of the workpiece. When finishing, the surface requirements are increased and the feed rate is taken as small. During rough machining, the feed rate can be larger. It mainly depends on the tool strength, which can generally be more than 0.3. When the main rear angle of the tool is large, the tool strength is poor, and the feed amount cannot be too large.
3. Cutting depth (cutting depth)
Generally, it can be less than 0.5 (radius value) when finishing. During rough machining, it is determined according to the conditions of workpiece, cutter and machine tool. Generally, when turning No. 45 steel in normalized state, the cutting depth in radius direction is generally not more than 5mm.