What problems should be considered in CNC machining to control dimensions?

What problems should be considered in CNC machining to control dimensions

In CNC machining, if we want to keep the dimension stable when machining aluminum parts, we need to consider the following two factors:

1、 Force Majeure:

1. Stability of machine tool itself.

If the machine tool is not brand-new or the machine tool has too many CNC machining and has not been debugged, the size deviation caused by the machine tool itself may occur. The deviation factors of machine tool itself are as follows:

Mechanical:

a. The servo motor and the lead screw are loose.

b. The ball screw bearing or nut is worn.

c. Insufficient lubrication between screw and nut.

Electrical:

a. Servo motor failure.

b. There is dirt inside the grating ruler.

c. Servo amplifier failure.

2. Thermal expansion and cold contraction deformation of workpiece.

The deformation of the workpiece after heat expansion and cold shrinkage is inevitable, so we should pay attention to the cooling effect, increase the frequency of in-process measurement, and pay attention to the deformation of the workpiece after cooling.

2、 Avoidable factors:

CNC processing technology

In order to control the machining error, it is necessary to have a reasonable machining process. In the process layout, in addition to the basic machining process (such as milling the basic machining process (such as “first rough and then fine, first face and then hole, first big face and then small face” or the basic machining process details such as “reduce the number of clamping, use the combined clamp as much as possible”) in the use of the fixture, it is also necessary to minimize the number of machining process details We all know that the aluminum parts are very soft due to the processing error caused by the aluminum scraps, and the waste scraps removed can easily cause the processing error of the aluminum parts.

2. Three cutting elements: cutting speed VC, feed F, cutting depth AP and tool compensation

In this respect, simply speaking, on the premise of ensuring the tool wear and machining quality, adjust the cutting parameters so that the cutting performance of the tool can be brought into full play, so as to achieve the highest cutting efficiency and the lowest machining cost.

In the numerical control lathe, there are other factors to be considered, such as cutter head wear compensation.

3. Numerical calculation of manual programming

In the manual programming, it is very common that there are errors in the calculation process. Although it is almost automatic programming now, we should pay more attention to it if we encounter the situation of manual programming.

4. Accurate knife setting.

If the tool setting is not accurate, it will also cause dimensional errors. Therefore, it is necessary to choose a better edge finder. If conditions permit, the machine tool should be equipped with a laser tool setting instrument to ensure the accuracy of the tool setting. If there is no edge finder and no condition, only a simple trial cutting method can be used!

The above is a summary of CNC machining, easy to make the accuracy error of several factors.