How to choose cnc machining cutting amount?

- Jul 19, 2019-

Before the cnc machining parts are processed, the cnc machining center equipment will be programmed. The selection of the cutting amount is very key, because this will directly determine the important process of the processed products, so how to choose cnc What is the processing and cutting amount?


Cnc processing


(1) Determine the amount of backing knife (mm)


The size of the back-feeding knife is mainly determined by the stiffness of the process system consisting of machine tools, fixtures, tools and workpieces. In the case of system stiffness, in order to ensure the machining allowance of the blank is removed with a minimum number of feeds, according to the processed The margin of the part determines the delamination depth and selects a larger amount of back knives to increase production efficiency. In CNC machining, in order to ensure the necessary machining accuracy and surface roughness of the part, it is recommended to leave a small amount of allowance (0.2 ~ 0.5mm), and take a knife along the contour in the final finishing. In roughing, in addition to the necessary semi-finishing and finishing allowance, roughing should be done in a minimum number of times under the conditions of the rigidness of the process system. The margin left for finishing should be greater than the amount of deformation of the part and to ensure the surface integrity of the part.


(2) Determine the spindle speed n (r/min)


The spindle speed n is mainly determined by the cutting speed VC (m/min) that the tool allows:


Among them: VC - cutting speed.


d - the diameter of the part or tool (mm). The cutting speed VC is closely related to the durability of the tool. As the VC increases, the tool durability will drop sharply. Therefore, the choice of VC mainly depends on the durability of the tool. After the spindle speed n is determined, it must be written into the NC program according to the format specified by the CNC machine control system. In actual operation, the operator can control the spindle speed by appropriately adjusting the spindle speed override switch on the control panel of the CNC machine according to the actual machining conditions to determine the optimal spindle speed.


(3) Selection of feed rate or feed rate F (mm/r, mm/min)


The feed speed F is the relative displacement of the part and the milling cutter in the feed direction per unit time during cutting, and the unit is mm/r or mm/min.


When the cnc machining center selects the feed amount F during programming, the movement speed of the tool center is fixed. In linear cutting, the speed at which the cutting point (cut point of the tool and the machined surface) is the feed rate given during programming. However, when cutting a circular arc, the actual feed amount of the cutting point is not equal to the feed amount of the tool center selected at the time of programming.


When programming a cnc machining center, the programmer must determine the amount of cutting for each process and write it in the program as an instruction. The amount of cutting includes the spindle speed, the amount of backfeed and the feed rate. For different processing methods, different cutting amounts are required. In order to obtain the highest, the cutting parameters should be determined reasonably.


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Dongguan Lemo Precision Metal Products Co.,Ltd

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