、 Preventable factors affecting dimensional accuracy of CNC machining
1. Processing technology
Most of the essential machining deviations are formed by different machining process theories. In order to ensure the basic machining process (such as “first rough and then fine, first surface and then hole, first large surface and then small surface” in milling numerical control machining, or “reduce the number of clamping, although select combined clamp” and other basic machining process details in fixture application), the machining deviation of iron chips to aluminum parts is reduced For the aluminum is very soft, the iron scraps removed are very simple to form processing deviation. For example, in FANUC or Huazhong machining center, although the g83 instruction is used to drill deep holes, the scrap iron may be removed instead of the G73 instruction.
2. Numerical calculation in manual programming and automatic programming
3. Three factors of cutting: cutting speed VC, feed F, cutting depth AP and tool compensation
In this respect, in simple words, under the condition of ensuring the machining quality and tool wear, adjust the parameters to fully develop the tool cutting function, so that the cutting efficiency is the highest and the machining cost is the lowest.
In the CNC lathe, there are some factors such as compensation for tool wear. Because I haven’t touched the lathe for a long time, I dare not talk about it in detail. Please search by myself.
4. Inaccurate tool setting is also a factor to form dimensional deviation. Therefore, although a good edge finder is selected, if the machine tool has an automatic tool setting device, it will be better
2、 Irresistible factors:
1. Cooling deformation of workpiece after processing
This is basically impossible to prevent, although in the processing of attention to the use of coolant, and in place measurement, attention to the workpiece deformation after cooling.
2. Stability of machine tool itself
If it is not a new machine tool or the machine tool has been processed a lot without debugging, the size deviation formed by the machine tool itself will appear. There are several factors to form the deviation of machine tool itself:
Mechanical
a. Loose between servo motor and lead screw
b. Ball screw bearing or nut worn
c. Insufficient smoothness between lead screw and nut
Electrical:
a. Servomotor obstacle
b. There is dirt inside the grating ruler
c. Servo amplifier obstruction
PMC recovery can be carried out for system parameters, so it is omitted
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