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Selection of Tools and Cutting Parameters in NC Milling
1. Tool Selection in NC Milling Process
First, common types of cutting tools.
The application of numerical control technology in mechanical processing can significantly improve the processing efficiency. Compared with traditional machining, NC machining emphasizes more on the quality and speed of processing. It needs to use computer to adjust the position of cutting tools, so as to ensure the continuous and rapid processing in the process. At present, the cutters in NC milling include milling cutters and hole processing cutters.
Second, the specific selection of processing tools.
The first is to ensure the processing accuracy. In order to ensure the processing accuracy, it is necessary to use tools with high durability and sharpness, and good chip breaking ability. The second is to ensure the processing strength. The strength requirement of NC milling is more stringent, so it is necessary to use cutting tools that meet the requirement of processing strength.
Machining tools should satisfy two conditions. On the one hand, computer is used to adjust the direction, strength and the specific position of the blade. On the other hand, it needs to be able to cut for a long time. Specific selection should be made at the interface provided by the NC program. Workers should choose suitable cutting tools according to machine tool performance, processing sequence and processing requirements. At the same time, the influence of processing materials should be considered to ensure the matching of cutting tools with machine tool specifications.
After choosing the tool, it is necessary to choose the tool handle further. Usually, too long tool handle should be avoided to avoid its adverse impact on the operation of machine tools. In the specific processing link, the cutter needs not only to meet the machine tool specifications, but also the material shape to meet the processing shape. For example, when processing curves or spherical materials, we need to use spherical knives, while when processing closed keyway, we need to use keyway knives.
2. Determination of cutting parameters in NC milling process
The cutting parameters of NC milling process are affected by the processing methods. Therefore, when determining the cutting parameters, we need to focus on the cutting speed, depth and feed. Usually, the roughing process needs to increase the processing speed as much as possible, so as to increase the output per unit time, so the cutting parameters in this process are often relatively large. Finishing links need to improve the accuracy of processing to ensure the quality of processing, which requires reducing cutting parameters.
First, determine the cutting depth. Because there are obvious differences between machine tool types and processing materials, matching work should be done well when determining cutting depth. When determining the cutting depth, the staff should cut according to specific conditions such as processing materials, machine tool types and cutting tools. Usually, when roughing, the cutting depth can be deepened, so that more materials can be cut through one cutting. The precondition is to ensure that the tool stiffness meets the standard, so as to avoid the problem of cutting because the tool stiffness is too low or the material thickness is too thick.
When cutting, it is necessary to make the blade face inward to prevent the blade from contacting directly with the metal of the machine tool. If the tool stiffness is reduced, the material is too thick or the impact load is large, the cutting depth should be reduced appropriately, so that the cutting can be improved accurately, and the tool damage caused by the cutting links should be avoided to the greatest extent.
In addition, the cutting depth should be determined reasonably according to the machining allowance. If the allowance is less, the cutting depth should be reduced, so as to prevent waste of resources, and at the same time, the machining efficiency and quality can be guaranteed. Usually the cutting depth is 0.05-1.0 mm and the semi-finishing depth is 1-3 mm. Staff members should adjust flexibly in this scope in accordance with specific conditions.

Second, determine the cutting feed. The most important factors affecting feed include material type, machining accuracy and cutting tools. In rough machining, it is necessary to focus on the analysis of tool stiffness and processing quality. If the tool stiffness is relatively high, the feed rate can be reasonably increased, and if the tool stiffness is relatively small, the feed rate can be reasonably reduced. Finishing process needs comprehensive analysis of material quality, such as roughness. 1) When the quality requirement of the workpiece can be guaranteed, the production efficiency can be improved. Higher feed speed can be selected, usually in the range of 100-200 mm/min. 2) When cutting, processing deep L or processing with high-speed steel tools, it is advisable to choose a lower feed speed. Generally, it is selected in the range of 20-50 mm/min. 3) When the machining accuracy and surface roughness are required to be high, the feed speed should be selected less, generally in the range of 20-50 mm/min.

Third, determine the cutting speed. Usually, on the basis of determining the speed, the larger the diameter of the milling cutter, the faster the cutting speed will be. However, if the cutting speed is too fast, it is easy to cause the heat generated by the tool to rise, which will cause serious tool wear. In this case, the cutting efficiency will also be affected by the deepening of the cutting depth. Therefore, the staff should scientifically determine the cutting speed to avoid too fast tool wear and affect the quality.
At the same time, staff should also consider other factors, such as material corners need to reduce speed, curve material processing needs the impact of solid radius, the cutting speed of the outer arc is often small, while the cutting speed of the inner arc is often large, which requires staff to determine the speed flexibly. CNC technology is one of the core technologies of manufacturing industry. Scientific determination of cutting tools and cutting in the process of CNC milling is conducive to improving comprehensive benefits, which needs to attract the attention of relevant staff.