How to maintain dimensional stability at CNC machining for aluminium parts

In the CNC home of CNC processing, if we want to process aluminium parts, to maintain dimensional stability, we need to consider the following two categories of factors:

I. Force Majeure:

1. Stability of machine tool itself.

If the machine tool is not new or the machine tool has been processed by large quantities of CNC without debugging, the size deviation caused by the machine tool itself may occur. And the deviation factors of machine tool itself are as follows:

In terms of machinery:

A. Looseness between servo motor and screw.

B. Wear of ball screw bearings or nuts.

C. Insufficient lubrication between screw and nut.

Electrical aspect:

A. Servo motor failure

B. There is dirt inside the grating ruler.

C. Servo amplifier failure.

2. Hot expansion and cold contraction deformation of workpiece.

The thermal expansion and contraction deformation of the workpiece after processing is unavoidable, so we should pay attention to the cooling effect, increase the frequency of on-line measurement, and pay attention to the deformation of the workpiece after cooling.

Avoidable factors:

CNC processing technology

In order to control the processing error well, it is indispensable to have reasonable processing technology. In the process arrangement, we should not only ensure the basic processing technology (such as milling NC processing "first rough then fine, first face then face, first big face then small face" or the basic processing technology details such as "reducing clamping times, using modular fixture as far as possible" in the use of fixture), but also reduce the basic processing technology details as possible. Aluminum chips cause processing errors for aluminium parts. We all know that aluminium parts are very soft, and the discarded chips are very easy to cause processing errors for aluminium parts.

2. Cutting Three Elements: Cutting Speed vc, Feed f, Cutting Depth AP and Tool Compensation

In this regard, simply speaking, on the premise of ensuring tool wear and processing quality, the cutting parameters are adjusted so that the cutting performance of the tool can be brought into full play, so that the cutting efficiency can reach the highest and the processing cost is the lowest.

In CNC lathe, there are also some factors to be considered, such as tool wear compensation.

3. The numerical calculation of manual programming

In manual programming, it is very common that errors occur in the calculation process. Although most of them are automatically programmed now, we should pay more attention to them if we encounter manual programming.

4. Accurate tool setting.

If the tool is not accurate, it will also cause dimensional errors. Therefore, the edge finder should try to choose a better one. If conditions permit, it is better to equip the machine tool with laser tool setter to ensure the accuracy of tool settings.

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