What are the selection principles of NC cutting parameters?

The selection principle of cutting parameters is to ensure the machining accuracy and surface roughness of parts, give full play to the cutting performance of tools, ensure reasonable tool durability, give full play to the performance of machine tools, maximize productivity and reduce costs.

1. Determine spindle speed

The spindle speed shall be selected according to the allowable cutting speed and workpiece (or tool) diameter. The calculation formula is: n = 1000 V / 7 1D, where: v? Cutting speed, in M / m, determined by the durability of the tool; N -- spindle speed, unit: R / min, D is workpiece diameter or tool diameter, unit: mm. Calculate the spindle speed n, and finally select the speed that the machine tool has or is close to.

2. Determine feed rate

Feed rate is an important parameter in the cutting parameters of NC machine tools. It is mainly selected according to the machining accuracy and surface roughness requirements of parts and the material properties of tools and workpieces. The maximum feed speed is limited by the stiffness of the machine tool and the performance of the feed system. The principle of determining the feed speed: when the quality requirements of the workpiece can be guaranteed, a higher feed speed can be selected to improve the production efficiency.

Generally, it is selected in the range of 100-200mm / min; When cutting and machining deep holes or machining with high-speed steel tools, it is advisable to choose a lower feed speed, generally in the range of 20-50mm / min; When the requirements of machining accuracy and surface roughness are high, the feed speed should be smaller, generally in the range of 20-50mm / min; The maximum feed speed set by the NC system of the machine tool can be set when the tool has no travel, especially when it is "back to zero" at a long distance.

3. Determine the amount of back knife

The back draft is determined according to the stiffness of the machine tool, workpiece and tool. If the stiffness allows, the back draft should be equal to the machining allowance of the workpiece as much as possible, so as to reduce the number of tool walking and improve the production efficiency. In order to ensure the quality of the machined surface, a small amount of finishing allowance can be reserved, generally 0.2-0.5m M. in short, the specific value of cutting parameters should be determined by analogy according to the performance of the machine tool, relevant manuals and practical experience.

At the same time, the spindle speed, cutting depth and feed speed can adapt to each other to form the best cutting parameters.

Cutting parameters are not only important parameters that must be determined before machine tool adjustment, but also have a very important impact on machining quality, machining efficiency and production cost. The so-called "reasonable" cutting parameters refer to the cutting parameters that make full use of the cutting performance of the tool and the dynamic performance of the machine tool (power and torque) and obtain high productivity and low processing cost on the premise of ensuring the quality.