How to determine the amount of feed and the amount of cutting in CNC lathe programming - News - Global IC Trade Starts Here.

When programming a CNC lathe, the programmer must determine the amount of cutting for each process. When selecting the amount of cutting, we must fully consider the various factors affecting the cutting, correctly select the cutting conditions, and determine the cutting amount reasonably, which can effectively improve the machining quality and output. The factors affecting the cutting conditions are: machine tool, tool, tool and workpiece rigidity; cutting speed, depth of cut, cutting feed rate; workpiece accuracy and surface roughness; tool life expectancy and maximum productivity; type of cutting fluid, cooling method; The hardness and heat treatment of the workpiece material; the number of workpieces; the life of the machine tool. Among the above factors, the cutting speed, the cutting depth, and the cutting feed rate are the main factors. The cutting speed directly affects the cutting efficiency. If the cutting speed is too small, the cutting time will be lengthened, and the tool will not be able to perform its function. If the cutting speed is too fast, the cutting time can be shortened, but the tool is prone to high heat and affects the life of the tool. There are many factors that determine the cutting speed, which are summarized as follows:

(1) Use of coolant. The machine tool has good rigidity and high precision to increase the cutting speed; otherwise, it needs to reduce the cutting speed. Among the above factors affecting the cutting speed, the influence of the tool material is the most important. The depth of cut is mainly limited by the rigidity of the machine tool. The cutting depth should be as large as possible if the machine tool stiffness is allowed. If the machining accuracy is not limited, the cutting depth can be equal to the machining allowance of the part. This will reduce the number of passes. The spindle speed is determined by the cutting speed allowed by the machine and the tool. It can be selected by calculation or table lookup. The feed rate F (MM/R) or feed rate F (MM/MIN) is selected based on the machining accuracy of the part, surface roughness, tool and workpiece material. The maximum feed rate is limited by the machine stiffness and feed drive and CNC system. When selecting the cutting amount, the programmer must select the cutting amount that suits the machine's characteristics and the optimum durability of the tool according to the requirements of the machine manual and the tool durability. Of course, it is also possible to use an analogy method to determine the amount of cutting by experience. Regardless of the method used to select the amount of cutting, it is necessary to ensure the durability of the tool to complete the machining of a part, or to ensure that the durability of the tool is not less than one working shift, and the minimum can not be less than half a shift.

(2) Workpiece materials. The hardness of the workpiece material will affect the cutting speed of the tool. When the same tool is used to process hard materials, the cutting speed should be reduced. When the soft material is processed, the cutting speed can be improved.

(3) Tool material. The maximum cutting speed allowed is different for different tool materials. High-speed steel cutting tools have a high-temperature cutting speed of less than 50M/MIN, carbide cutting tools with high-temperature cutting speeds of up to 100M/MIN, and high-temperature cutting speeds of ceramic tools up to 1000M/MIN.

(4) Cutting depth and feed amount. The cutting depth and the amount of cutting are large, the cutting resistance is also large, and the cutting heat is increased, so the cutting speed should be reduced.

(5) Tool life. If the tool life (life) is long, a lower cutting speed should be used. Conversely, a higher cutting speed can be used.

(6) The shape of the tool. The shape of the tool, the size of the angle, and the sharpness of the cutting edge all affect the selection of the cutting speed.