What are the cutting parameters when processing parts on a CNC lathe

When programming for parts processing on a CNC lathe, the programmer must determine the cutting parameters for each process and write them into the program in the form of instructions. Cutting parameters include spindle speed, depth of cut and feed rate, etc. Different cutting parameters need to be selected for different processing methods. The principle for selecting cutting parameters is to ensure the machining accuracy and surface roughness of the parts, give full play to the cutting performance of the tool, guarantee reasonable tool durability, and fully utilize the performance of the machine tool to maximize productivity and reduce costs.

1. Determine the spindle speed

The spindle speed should be selected based on the allowable cutting speed and the diameter of the workpiece (or tool). Its calculation formula is: n=1000 v/7 d, where: v? The cutting speed, measured in m/m motion, is determined by the durability of the cutting tool. n - Spindle speed, with the unit of r/min, and D - workpiece diameter or tool diameter, with the unit of mm. The calculated spindle speed n should finally be selected from the speed that the machine tool has or is relatively close to.

2. Determine the feed rate

Feed rate is an important parameter in the cutting parameters of CNC machine tools. It is mainly selected based on the machining accuracy and surface roughness requirements of the part, as well as the material properties of the tool and workpiece. The maximum feed rate is limited by the stiffness of the machine tool and the performance of the feed system. The principle of determining the feed rate: When the quality requirements of the workpiece can be guaranteed, to improve production efficiency, a higher feed rate can be selected. It is generally selected within the range of 100 to 200mm/min. When cutting, machining deep holes or using high-speed steel tools, a lower feed rate should be selected, generally within the range of 20 to 50mm/min. When high processing accuracy and surface roughness are required, the feed rate should be selected smaller, generally within the range of 20- 50mm/min. When the tool is idle, especially when it is "returning to zero" at a long distance, the maximum feed rate set by the numerical control system of this machine tool can be set.

3. Determine the depth of the back cut

The depth of cut is determined by the stiffness of the machine tool, workpiece and cutting tool. Under the condition that the stiffness is allowed, the depth of cut should be as equal as possible to the machining allowance of the workpiece. This can reduce the number of tool passes and improve production efficiency. To ensure the quality of the machined surface, a small amount of finish machining allowance can be left, generally 0.2 to 0.5m. In summary, the specific value of the cutting parameters should be determined by analogy based on the performance of the machine tool, relevant manuals, and practical experience.

Meanwhile, the spindle speed, cutting depth and feed rate should be adapted to each other to form the optimal cutting parameters.

Cutting parameters are not only important parameters that must be determined before adjusting the machine tool, but also whether their values are reasonable or not has a very significant impact on processing quality, processing efficiency, production costs, etc. The so-called "reasonable" cutting parameters refer to those that fully utilize the cutting performance of the tool and the dynamic performance (power, torque) of the machine tool, and achieve high productivity and low processing costs under the premise of ensuring quality.